From nobody Tue Jun 23 16:12:04 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 572F0C433EF for ; Wed, 2 Mar 2022 15:48:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240668AbiCBPtN (ORCPT ); Wed, 2 Mar 2022 10:49:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52442 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240399AbiCBPtG (ORCPT ); Wed, 2 Mar 2022 10:49:06 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2089112A80 for ; Wed, 2 Mar 2022 07:48:22 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id B151F61735 for ; Wed, 2 Mar 2022 15:48:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E967FC340F3; Wed, 2 Mar 2022 15:48:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646236101; bh=lrSD1SAPG1K49lgvrlMSeV7b6eHs5r6JW1h42/uZTAw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jrr2BWmarghJx1xzUsDRsq9BNUuqYX9FyNguYMWSIgBbLcuX6w/cyzhPP+3EnLKR9 gE5IRilsTq5dlFj8fx17lNb9oP0wmGXk5sE7BRg++WzcdaW3Ik+qR8UthvMxHexwmR Vy4SBnNxcIMaDSNmzeo88oAFvXJ9jSPV5HtfokqDYHY0UnmLyIYeai8daoICj4SCq1 kkwoI3ueyeQtRclKWbK1ak1W4IEVdx0Yp9zLAxNKo90mS+lTshBOXVWg+FbPBKkD6A sGPFauNnybg0dgSxlFF/kRetl/ZGW24kH9eyouHiCaMQUVj2PoPRfkAEOpkVhnVml6 1c5TzORZOEhtg== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: [PATCH 01/19] context_tracking: Rename __context_tracking_enter/exit() to __ct_user_enter/exit() Date: Wed, 2 Mar 2022 16:47:52 +0100 Message-Id: <20220302154810.42308-2-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220302154810.42308-1-frederic@kernel.org> References: <20220302154810.42308-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The context tracking namespace is going to expand and some new functions will require even longer names. Start shrinking the context_tracking prefix to "ct" as is already the case for some existing macros, this will make the introduction of new functions easier. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits Acked-by: Paul E. McKenney --- include/linux/context_tracking.h | 12 ++++++------ kernel/context_tracking.c | 20 ++++++++++---------- 2 files changed, 16 insertions(+), 16 deletions(-) diff --git a/include/linux/context_tracking.h b/include/linux/context_track= ing.h index 7a14807c9d1a..773035124bad 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -14,8 +14,8 @@ extern void context_tracking_cpu_set(int cpu); =20 /* Called with interrupts disabled. */ -extern void __context_tracking_enter(enum ctx_state state); -extern void __context_tracking_exit(enum ctx_state state); +extern void __ct_user_enter(enum ctx_state state); +extern void __ct_user_exit(enum ctx_state state); =20 extern void context_tracking_enter(enum ctx_state state); extern void context_tracking_exit(enum ctx_state state); @@ -38,13 +38,13 @@ static inline void user_exit(void) static __always_inline void user_enter_irqoff(void) { if (context_tracking_enabled()) - __context_tracking_enter(CONTEXT_USER); + __ct_user_enter(CONTEXT_USER); =20 } static __always_inline void user_exit_irqoff(void) { if (context_tracking_enabled()) - __context_tracking_exit(CONTEXT_USER); + __ct_user_exit(CONTEXT_USER); } =20 static inline enum ctx_state exception_enter(void) @@ -74,7 +74,7 @@ static inline void exception_exit(enum ctx_state prev_ctx) static __always_inline bool context_tracking_guest_enter(void) { if (context_tracking_enabled()) - __context_tracking_enter(CONTEXT_GUEST); + __ct_user_enter(CONTEXT_GUEST); =20 return context_tracking_enabled_this_cpu(); } @@ -82,7 +82,7 @@ static __always_inline bool context_tracking_guest_enter(= void) static __always_inline void context_tracking_guest_exit(void) { if (context_tracking_enabled()) - __context_tracking_exit(CONTEXT_GUEST); + __ct_user_exit(CONTEXT_GUEST); } =20 /** diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index 36a98c48aedc..ad2a973393a6 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -51,15 +51,15 @@ static __always_inline void context_tracking_recursion_= exit(void) } =20 /** - * context_tracking_enter - Inform the context tracking that the CPU is go= ing - * enter user or guest space mode. + * __ct_user_enter - Inform the context tracking that the CPU is going + * to enter user or guest space mode. * * This function must be called right before we switch from the kernel * to user or guest space, when it's guaranteed the remaining kernel * instructions to execute won't use any RCU read side critical section * because this function sets RCU in extended quiescent state. */ -void noinstr __context_tracking_enter(enum ctx_state state) +void noinstr __ct_user_enter(enum ctx_state state) { /* Kernel threads aren't supposed to go to userspace */ WARN_ON_ONCE(!current->mm); @@ -101,7 +101,7 @@ void noinstr __context_tracking_enter(enum ctx_state st= ate) } context_tracking_recursion_exit(); } -EXPORT_SYMBOL_GPL(__context_tracking_enter); +EXPORT_SYMBOL_GPL(__ct_user_enter); =20 void context_tracking_enter(enum ctx_state state) { @@ -119,7 +119,7 @@ void context_tracking_enter(enum ctx_state state) return; =20 local_irq_save(flags); - __context_tracking_enter(state); + __ct_user_enter(state); local_irq_restore(flags); } NOKPROBE_SYMBOL(context_tracking_enter); @@ -132,8 +132,8 @@ void context_tracking_user_enter(void) NOKPROBE_SYMBOL(context_tracking_user_enter); =20 /** - * context_tracking_exit - Inform the context tracking that the CPU is - * exiting user or guest mode and entering the ker= nel. + * __ct_user_exit - Inform the context tracking that the CPU is + * exiting user or guest mode and entering the kernel. * * This function must be called after we entered the kernel from user or * guest space before any use of RCU read side critical section. This @@ -143,7 +143,7 @@ NOKPROBE_SYMBOL(context_tracking_user_enter); * This call supports re-entrancy. This way it can be called from any exce= ption * handler without needing to know if we came from userspace or not. */ -void noinstr __context_tracking_exit(enum ctx_state state) +void noinstr __ct_user_exit(enum ctx_state state) { if (!context_tracking_recursion_enter()) return; @@ -166,7 +166,7 @@ void noinstr __context_tracking_exit(enum ctx_state sta= te) } context_tracking_recursion_exit(); } -EXPORT_SYMBOL_GPL(__context_tracking_exit); +EXPORT_SYMBOL_GPL(__ct_user_exit); =20 void context_tracking_exit(enum ctx_state state) { @@ -176,7 +176,7 @@ void context_tracking_exit(enum ctx_state state) return; =20 local_irq_save(flags); - __context_tracking_exit(state); + __ct_user_exit(state); local_irq_restore(flags); } NOKPROBE_SYMBOL(context_tracking_exit); --=20 2.25.1 From nobody Tue Jun 23 16:12:04 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A06E9C433F5 for ; Wed, 2 Mar 2022 15:48:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241023AbiCBPtY (ORCPT ); Wed, 2 Mar 2022 10:49:24 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53342 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240739AbiCBPtS (ORCPT ); Wed, 2 Mar 2022 10:49:18 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 624AE28992 for ; Wed, 2 Mar 2022 07:48:27 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 0B507B82082 for ; Wed, 2 Mar 2022 15:48:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 995BFC340ED; Wed, 2 Mar 2022 15:48:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646236104; bh=xdaFWjEPuZZ7+O1T/pWENcxRLDLAM4Um3CNcb2LkEbM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PMa3KGaRCHoapiIry4hesvZv+djJ4pqgxEX7ey67y9R4tpzGS5PBCkEAJtqc6G0C6 L9tTHPwiYoZBVFGUfUvP2I4W+xoTje7eej2JD459RaU5LSlAIAnKVf4tMhj99pfifs zEm2xbjziErlN3Qe6cqeNUDsToJM62L4NEMQznEJo6lrw9NOrJydE92tzKlqGEYxXI oZvjdW9t3uXcOhn2SOaJLKYgYKoJWuO5DMvU0I2LYqWHrbZ19e7XFuLEkpwboR2IRK 2MkZFTzEFvaCzYaywC/19mJ4xgNDzs9ytWXEKiwtcCiQc7C8cSNnBINa1JzrXXepql rhRB2c7TyL5qA== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: [PATCH 02/19] context_tracking: Rename context_tracking_user_enter/exit() to user_enter/exit_callable() Date: Wed, 2 Mar 2022 16:47:53 +0100 Message-Id: <20220302154810.42308-3-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220302154810.42308-1-frederic@kernel.org> References: <20220302154810.42308-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" context_tracking_user_enter() and context_tracking_user_exit() are ASM callable versions of user_enter() and user_exit() for architectures that didn't manage to check the context tracking static key from ASM. Change those function names to better reflect their purpose. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits --- arch/arm/kernel/entry-header.S | 8 ++++---- arch/csky/kernel/entry.S | 4 ++-- arch/riscv/kernel/entry.S | 6 +++--- include/linux/context_tracking.h | 4 ++-- kernel/context_tracking.c | 18 ++++++++++++++---- 5 files changed, 25 insertions(+), 15 deletions(-) diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S index ae24dd54e9ef..3af2a521e1d6 100644 --- a/arch/arm/kernel/entry-header.S +++ b/arch/arm/kernel/entry-header.S @@ -364,10 +364,10 @@ #ifdef CONFIG_CONTEXT_TRACKING .if \save stmdb sp!, {r0-r3, ip, lr} - bl context_tracking_user_exit + bl user_exit_callable ldmia sp!, {r0-r3, ip, lr} .else - bl context_tracking_user_exit + bl user_exit_callable .endif #endif .endm @@ -376,10 +376,10 @@ #ifdef CONFIG_CONTEXT_TRACKING .if \save stmdb sp!, {r0-r3, ip, lr} - bl context_tracking_user_enter + bl user_enter_callable ldmia sp!, {r0-r3, ip, lr} .else - bl context_tracking_user_enter + bl user_enter_callable .endif #endif .endm diff --git a/arch/csky/kernel/entry.S b/arch/csky/kernel/entry.S index a4ababf25e24..bc734d17c16f 100644 --- a/arch/csky/kernel/entry.S +++ b/arch/csky/kernel/entry.S @@ -23,7 +23,7 @@ mfcr a0, epsr btsti a0, 31 bt 1f - jbsr context_tracking_user_exit + jbsr user_exit_callable ldw a0, (sp, LSAVE_A0) ldw a1, (sp, LSAVE_A1) ldw a2, (sp, LSAVE_A2) @@ -160,7 +160,7 @@ ret_from_exception: cmpnei r10, 0 bt exit_work #ifdef CONFIG_CONTEXT_TRACKING - jbsr context_tracking_user_enter + jbsr user_enter_callable #endif 1: #ifdef CONFIG_PREEMPTION diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index ed29e9c8f660..5fbaa7be18a2 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -112,11 +112,11 @@ _save_context: #endif =20 #ifdef CONFIG_CONTEXT_TRACKING - /* If previous state is in user mode, call context_tracking_user_exit. */ + /* If previous state is in user mode, call user_exit_callable(). */ li a0, SR_PP and a0, s1, a0 bnez a0, skip_context_tracking - call context_tracking_user_exit + call user_exit_callable skip_context_tracking: #endif =20 @@ -252,7 +252,7 @@ resume_userspace: bnez s1, work_pending =20 #ifdef CONFIG_CONTEXT_TRACKING - call context_tracking_user_enter + call user_enter_callable #endif =20 /* Save unwound kernel stack pointer in thread_info */ diff --git a/include/linux/context_tracking.h b/include/linux/context_track= ing.h index 773035124bad..69532cd18f72 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -19,8 +19,8 @@ extern void __ct_user_exit(enum ctx_state state); =20 extern void context_tracking_enter(enum ctx_state state); extern void context_tracking_exit(enum ctx_state state); -extern void context_tracking_user_enter(void); -extern void context_tracking_user_exit(void); +extern void user_enter_callable(void); +extern void user_exit_callable(void); =20 static inline void user_enter(void) { diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index ad2a973393a6..83e050675b23 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -125,11 +125,16 @@ void context_tracking_enter(enum ctx_state state) NOKPROBE_SYMBOL(context_tracking_enter); EXPORT_SYMBOL_GPL(context_tracking_enter); =20 -void context_tracking_user_enter(void) +/** + * user_enter_callable() - Unfortunate ASM callable version of user_enter(= ) for + * archs that didn't manage to check the context tracking + * static key from low level code. + */ +void user_enter_callable(void) { user_enter(); } -NOKPROBE_SYMBOL(context_tracking_user_enter); +NOKPROBE_SYMBOL(user_enter_callable); =20 /** * __ct_user_exit - Inform the context tracking that the CPU is @@ -182,11 +187,16 @@ void context_tracking_exit(enum ctx_state state) NOKPROBE_SYMBOL(context_tracking_exit); EXPORT_SYMBOL_GPL(context_tracking_exit); =20 -void context_tracking_user_exit(void) +/** + * user_exit_callable() - Unfortunate ASM callable version of user_exit() = for + * archs that didn't manage to check the context tracking + * static key from low level code. + */ +void user_exit_callable(void) { user_exit(); } -NOKPROBE_SYMBOL(context_tracking_user_exit); +NOKPROBE_SYMBOL(user_exit_callable); =20 void __init context_tracking_cpu_set(int cpu) { --=20 2.25.1 From nobody Tue Jun 23 16:12:04 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 173A4C433F5 for ; Wed, 2 Mar 2022 15:48:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241325AbiCBPtf (ORCPT ); Wed, 2 Mar 2022 10:49:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53358 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240842AbiCBPtS (ORCPT ); Wed, 2 Mar 2022 10:49:18 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 20F8F29819 for ; Wed, 2 Mar 2022 07:48:31 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id C705AB82084 for ; Wed, 2 Mar 2022 15:48:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 45AEEC340F2; Wed, 2 Mar 2022 15:48:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646236108; bh=b9g+mN/ZAtwltAyMV/mSLAV7goZAk3S3vfRPncmJ4xY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=onbUAlHDET9OqsvCzKqWXGdJlDrv9JTIL4U3pvQYJQkiVlADwu27jENpZWXlQqODi /4cCMKP9vE5KUAptZajfQBDlmw0xcuqNnb6keCvxn8Er89Jm7+4usCI6gs57s1hLyx kPnmSnbIIX+naKTgcKdwON0quUBIZbrau6MJjLM8Yq8yDIcnsBP0fhTYyEde7bBBDy 1If4G6fVpiHl81o8EJKWdPJl03O9HVFzglQ+IMBcYW9JzgeNtKcQ2DQgH0fu2mQIvk cS5vjnmMUKgZVMry5iI2jU7KlUbOJRD92PUZLuaOYytJ8NhucRukb5bIXwNAymVE8Q 9TjlWKevj6Z9w== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: [PATCH 03/19] context_tracking: Rename context_tracking_enter/exit() to ct_user_enter/exit() Date: Wed, 2 Mar 2022 16:47:54 +0100 Message-Id: <20220302154810.42308-4-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220302154810.42308-1-frederic@kernel.org> References: <20220302154810.42308-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" context_tracking_enter() and context_tracking_exit() have confusing names that don't explain the fact they are referring to user/guest state. Use more self-explanatory names and shrink to the new context tracking prefix instead. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits --- include/linux/context_tracking.h | 13 +++++++------ kernel/context_tracking.c | 12 ++++++------ 2 files changed, 13 insertions(+), 12 deletions(-) diff --git a/include/linux/context_tracking.h b/include/linux/context_track= ing.h index 69532cd18f72..7a5f04ae1758 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -17,21 +17,22 @@ extern void context_tracking_cpu_set(int cpu); extern void __ct_user_enter(enum ctx_state state); extern void __ct_user_exit(enum ctx_state state); =20 -extern void context_tracking_enter(enum ctx_state state); -extern void context_tracking_exit(enum ctx_state state); +extern void ct_user_enter(enum ctx_state state); +extern void ct_user_exit(enum ctx_state state); + extern void user_enter_callable(void); extern void user_exit_callable(void); =20 static inline void user_enter(void) { if (context_tracking_enabled()) - context_tracking_enter(CONTEXT_USER); + ct_user_enter(CONTEXT_USER); =20 } static inline void user_exit(void) { if (context_tracking_enabled()) - context_tracking_exit(CONTEXT_USER); + ct_user_exit(CONTEXT_USER); } =20 /* Called with interrupts disabled. */ @@ -57,7 +58,7 @@ static inline enum ctx_state exception_enter(void) =20 prev_ctx =3D this_cpu_read(context_tracking.state); if (prev_ctx !=3D CONTEXT_KERNEL) - context_tracking_exit(prev_ctx); + ct_user_exit(prev_ctx); =20 return prev_ctx; } @@ -67,7 +68,7 @@ static inline void exception_exit(enum ctx_state prev_ctx) if (!IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK) && context_tracking_enabled()) { if (prev_ctx !=3D CONTEXT_KERNEL) - context_tracking_enter(prev_ctx); + ct_user_enter(prev_ctx); } } =20 diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index 83e050675b23..e8e58c10f135 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -103,7 +103,7 @@ void noinstr __ct_user_enter(enum ctx_state state) } EXPORT_SYMBOL_GPL(__ct_user_enter); =20 -void context_tracking_enter(enum ctx_state state) +void ct_user_enter(enum ctx_state state) { unsigned long flags; =20 @@ -122,8 +122,8 @@ void context_tracking_enter(enum ctx_state state) __ct_user_enter(state); local_irq_restore(flags); } -NOKPROBE_SYMBOL(context_tracking_enter); -EXPORT_SYMBOL_GPL(context_tracking_enter); +NOKPROBE_SYMBOL(ct_user_enter); +EXPORT_SYMBOL_GPL(ct_user_enter); =20 /** * user_enter_callable() - Unfortunate ASM callable version of user_enter(= ) for @@ -173,7 +173,7 @@ void noinstr __ct_user_exit(enum ctx_state state) } EXPORT_SYMBOL_GPL(__ct_user_exit); =20 -void context_tracking_exit(enum ctx_state state) +void ct_user_exit(enum ctx_state state) { unsigned long flags; =20 @@ -184,8 +184,8 @@ void context_tracking_exit(enum ctx_state state) __ct_user_exit(state); local_irq_restore(flags); } -NOKPROBE_SYMBOL(context_tracking_exit); -EXPORT_SYMBOL_GPL(context_tracking_exit); +NOKPROBE_SYMBOL(ct_user_exit); +EXPORT_SYMBOL_GPL(ct_user_exit); =20 /** * user_exit_callable() - Unfortunate ASM callable version of user_exit() = for --=20 2.25.1 From nobody Tue Jun 23 16:12:04 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B44C4C433F5 for ; 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s=k20201202; t=1646236112; bh=sghz13J/8bJAY7L5jSCMCXvKJR3AKRsJVjaLCKwNr+s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qOf5HNzu1268TOts63/QhT6/WYeL1qBrOajum/6T8DLGBuwyrJrDT6yIW3H/ChBxJ ry6brVwSWJ+Cf6OUqEuXyxDzyB5pvAJ0/WcpfsyLdTjEnzHykYONVFvnrY36FRLFPH FoyI6Pt/dB7m6wzpHu6v8zZk/WCSCqDC/EKbF0NeJ4RxrBfA1JAyNl1BXJZblkQQMc dotLufc4/OAcdcdRTyyy3jIl0+bN5v8zVDaJiiUjqoZix27oIezjM4oj1HURcz932R n+yyRgRn61FeGycIXj8Q1Zb/zyw0+jaBhC6zY9Ij+72W8a056lFzdNw5kAWZSF9NYH smDARTytc7zYQ== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: [PATCH 04/19] context_tracking: Rename context_tracking_cpu_set() to context_tracking_cpu_track_user() Date: Wed, 2 Mar 2022 16:47:55 +0100 Message-Id: <20220302154810.42308-5-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220302154810.42308-1-frederic@kernel.org> References: <20220302154810.42308-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" context_tracking_cpu_set() is called in order to tell a CPU to track user/kernel transitions. Since context tracking is going to expand in to also track transitions from/to idle/IRQ/NMIs, the scope of this function name becomes too broad and needs to be made more specific. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits --- include/linux/context_tracking.h | 2 +- kernel/context_tracking.c | 4 ++-- kernel/time/tick-sched.c | 2 +- 3 files changed, 4 insertions(+), 4 deletions(-) diff --git a/include/linux/context_tracking.h b/include/linux/context_track= ing.h index 7a5f04ae1758..40badd62ad56 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -11,7 +11,7 @@ =20 =20 #ifdef CONFIG_CONTEXT_TRACKING -extern void context_tracking_cpu_set(int cpu); +extern void context_tracking_cpu_track_user(int cpu); =20 /* Called with interrupts disabled. */ extern void __ct_user_enter(enum ctx_state state); diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index e8e58c10f135..7b6643d2075d 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -198,7 +198,7 @@ void user_exit_callable(void) } NOKPROBE_SYMBOL(user_exit_callable); =20 -void __init context_tracking_cpu_set(int cpu) +void __init context_tracking_cpu_track_user(int cpu) { static __initdata bool initialized =3D false; =20 @@ -228,6 +228,6 @@ void __init context_tracking_init(void) int cpu; =20 for_each_possible_cpu(cpu) - context_tracking_cpu_set(cpu); + context_tracking_cpu_track_user(cpu); } #endif diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 2d76c91b85de..794410da3ee1 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -571,7 +571,7 @@ void __init tick_nohz_init(void) } =20 for_each_cpu(cpu, tick_nohz_full_mask) - context_tracking_cpu_set(cpu); + context_tracking_cpu_track_user(cpu); =20 ret =3D cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "kernel/nohz:predown", NULL, --=20 2.25.1 From nobody Tue Jun 23 16:12:04 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 939A6C4332F for ; Wed, 2 Mar 2022 15:49:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233157AbiCBPtu (ORCPT ); Wed, 2 Mar 2022 10:49:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53534 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240800AbiCBPtV (ORCPT ); Wed, 2 Mar 2022 10:49:21 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C493A245BC for ; Wed, 2 Mar 2022 07:48:36 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 5DBAF61740 for ; Wed, 2 Mar 2022 15:48:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 959AAC340F1; Wed, 2 Mar 2022 15:48:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646236115; bh=ciXcyYnIUVWExVMqLuzRBy8vgRjard065bDchEbcTs0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TbZvc5/UIWFsfc7rYEkraQyV9eKqT8MH44NZoAIjxi5PaQ0L/t/vx6oxHNVilK2Wa xKjKNsC8NryFAn1St/x9Yr0ChR15pieKzuEwV1IETbFNV0jf6RMCSX8/P7OGTTB0f3 2qaFZVlaK3RrTZ5h2kTpp6KR/VWYJ5/gvBK7KGADdMKotRfquejPzvkqUxnAu2RkId NQkMVaF2lNTlXZqNQcUrwpOu9YZiDtsXb1IQeAieU9NED+KpYRF6Q6KdJgDzhE9X2D tMyVTPHQ5uCVGNsAI30SAV0KKg6W7zS0DP5ch7o2Liw7rMxo1k7Q3rHLY9FO6MCyBA 7YZCILkzbP9CQ== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: [PATCH 05/19] context_tracking: Split user tracking Kconfig Date: Wed, 2 Mar 2022 16:47:56 +0100 Message-Id: <20220302154810.42308-6-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220302154810.42308-1-frederic@kernel.org> References: <20220302154810.42308-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Context tracking is going to be used not only to track user transitions but also idle/IRQs/NMIs. The user tracking part will then become a seperate feature. Prepare Kconfig for that. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits --- .../time/context-tracking/arch-support.txt | 6 ++--- arch/Kconfig | 4 ++-- arch/arm/Kconfig | 2 +- arch/arm/kernel/entry-common.S | 4 ++-- arch/arm/kernel/entry-header.S | 4 ++-- arch/arm64/Kconfig | 2 +- arch/csky/Kconfig | 2 +- arch/csky/kernel/entry.S | 4 ++-- arch/mips/Kconfig | 2 +- arch/powerpc/Kconfig | 2 +- arch/powerpc/include/asm/context_tracking.h | 2 +- arch/riscv/Kconfig | 2 +- arch/riscv/kernel/entry.S | 6 ++--- arch/sparc/Kconfig | 2 +- arch/sparc/kernel/rtrap_64.S | 2 +- arch/x86/Kconfig | 4 ++-- include/linux/context_tracking.h | 12 +++++----- include/linux/context_tracking_state.h | 4 ++-- init/Kconfig | 4 ++-- kernel/context_tracking.c | 6 ++++- kernel/sched/core.c | 2 +- kernel/time/Kconfig | 22 +++++++++++-------- 22 files changed, 54 insertions(+), 46 deletions(-) diff --git a/Documentation/features/time/context-tracking/arch-support.txt = b/Documentation/features/time/context-tracking/arch-support.txt index 4ed116c2ec39..0696fd08429e 100644 --- a/Documentation/features/time/context-tracking/arch-support.txt +++ b/Documentation/features/time/context-tracking/arch-support.txt @@ -1,7 +1,7 @@ # -# Feature name: context-tracking -# Kconfig: HAVE_CONTEXT_TRACKING -# description: arch supports context tracking for NO_HZ_FULL +# Feature name: user-context-tracking +# Kconfig: HAVE_CONTEXT_TRACKING_USER +# description: arch supports user context tracking for NO_HZ_FULL # ----------------------- | arch |status| diff --git a/arch/Kconfig b/arch/Kconfig index 678a80713b21..1a3b79cfc9e3 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -762,7 +762,7 @@ config HAVE_ARCH_WITHIN_STACK_FRAMES and similar) by implementing an inline arch_within_stack_frames(), which is used by CONFIG_HARDENED_USERCOPY. =20 -config HAVE_CONTEXT_TRACKING +config HAVE_CONTEXT_TRACKING_USER bool help Provide kernel/user boundaries probes necessary for subsystems @@ -773,7 +773,7 @@ config HAVE_CONTEXT_TRACKING protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on irq exit still need to be protected. =20 -config HAVE_CONTEXT_TRACKING_OFFSTACK +config HAVE_CONTEXT_TRACKING_USER_OFFSTACK bool help Architecture neither relies on exception_enter()/exception_exit() diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index fabe39169b12..2c5688f20421 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -81,7 +81,7 @@ config ARM select HAVE_ARCH_TRANSPARENT_HUGEPAGE if ARM_LPAE select HAVE_ARM_SMCCC if CPU_V7 select HAVE_EBPF_JIT if !CPU_ENDIAN_BE32 - select HAVE_CONTEXT_TRACKING + select HAVE_CONTEXT_TRACKING_USER select HAVE_C_RECORDMCOUNT select HAVE_DEBUG_KMEMLEAK if !XIP_KERNEL select HAVE_DMA_CONTIGUOUS if MMU diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index ac86c34682bb..5be34b7fe41e 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -26,7 +26,7 @@ #include "entry-header.S" =20 saved_psr .req r8 -#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING) +#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING_USER) saved_pc .req r9 #define TRACE(x...) x #else @@ -36,7 +36,7 @@ saved_pc .req lr =20 .section .entry.text,"ax",%progbits .align 5 -#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACK= ING) || \ +#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACK= ING_USER) || \ IS_ENABLED(CONFIG_DEBUG_RSEQ)) /* * This is the fast syscall return path. We do as little as possible here, diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S index 3af2a521e1d6..cd1ce0a9c652 100644 --- a/arch/arm/kernel/entry-header.S +++ b/arch/arm/kernel/entry-header.S @@ -361,7 +361,7 @@ * between user and kernel mode. */ .macro ct_user_exit, save =3D 1 -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER .if \save stmdb sp!, {r0-r3, ip, lr} bl user_exit_callable @@ -373,7 +373,7 @@ .endm =20 .macro ct_user_enter, save =3D 1 -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER .if \save stmdb sp!, {r0-r3, ip, lr} bl user_enter_callable diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 6978140edfa4..96e75d7fa0a3 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -169,7 +169,7 @@ config ARM64 select HAVE_C_RECORDMCOUNT select HAVE_CMPXCHG_DOUBLE select HAVE_CMPXCHG_LOCAL - select HAVE_CONTEXT_TRACKING + select HAVE_CONTEXT_TRACKING_USER select HAVE_DEBUG_KMEMLEAK select HAVE_DMA_CONTIGUOUS select HAVE_DYNAMIC_FTRACE diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig index 132f43f12dd8..c94cc907b828 100644 --- a/arch/csky/Kconfig +++ b/arch/csky/Kconfig @@ -42,7 +42,7 @@ config CSKY select HAVE_ARCH_AUDITSYSCALL select HAVE_ARCH_MMAP_RND_BITS select HAVE_ARCH_SECCOMP_FILTER - select HAVE_CONTEXT_TRACKING + select HAVE_CONTEXT_TRACKING_USER select HAVE_VIRT_CPU_ACCOUNTING_GEN select HAVE_DEBUG_BUGVERBOSE select HAVE_DEBUG_KMEMLEAK diff --git a/arch/csky/kernel/entry.S b/arch/csky/kernel/entry.S index bc734d17c16f..547b4cd1b24b 100644 --- a/arch/csky/kernel/entry.S +++ b/arch/csky/kernel/entry.S @@ -19,7 +19,7 @@ .endm =20 .macro context_tracking -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER mfcr a0, epsr btsti a0, 31 bt 1f @@ -159,7 +159,7 @@ ret_from_exception: and r10, r9 cmpnei r10, 0 bt exit_work -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER jbsr user_enter_callable #endif 1: diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index 058446f01487..efcab39667ea 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -55,7 +55,7 @@ config MIPS select HAVE_ARCH_TRACEHOOK select HAVE_ARCH_TRANSPARENT_HUGEPAGE if CPU_SUPPORTS_HUGEPAGES select HAVE_ASM_MODVERSIONS - select HAVE_CONTEXT_TRACKING + select HAVE_CONTEXT_TRACKING_USER select HAVE_TIF_NOHZ select HAVE_C_RECORDMCOUNT select HAVE_DEBUG_KMEMLEAK diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index b779603978e1..9a889f919fed 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -192,7 +192,7 @@ config PPC select HAVE_ARCH_SECCOMP_FILTER select HAVE_ARCH_TRACEHOOK select HAVE_ASM_MODVERSIONS - select HAVE_CONTEXT_TRACKING if PPC64 + select HAVE_CONTEXT_TRACKING_USER if PPC64 select HAVE_C_RECORDMCOUNT select HAVE_DEBUG_KMEMLEAK select HAVE_DEBUG_STACKOVERFLOW diff --git a/arch/powerpc/include/asm/context_tracking.h b/arch/powerpc/inc= lude/asm/context_tracking.h index f2682b28b050..4b63931c49e0 100644 --- a/arch/powerpc/include/asm/context_tracking.h +++ b/arch/powerpc/include/asm/context_tracking.h @@ -2,7 +2,7 @@ #ifndef _ASM_POWERPC_CONTEXT_TRACKING_H #define _ASM_POWERPC_CONTEXT_TRACKING_H =20 -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER #define SCHEDULE_USER bl schedule_user #else #define SCHEDULE_USER bl schedule diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 5adcbd9b5e88..36953ec26294 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -80,7 +80,7 @@ config RISCV select HAVE_ARCH_THREAD_STRUCT_WHITELIST select HAVE_ARCH_VMAP_STACK if MMU && 64BIT select HAVE_ASM_MODVERSIONS - select HAVE_CONTEXT_TRACKING + select HAVE_CONTEXT_TRACKING_USER select HAVE_DEBUG_KMEMLEAK select HAVE_DMA_CONTIGUOUS if MMU select HAVE_EBPF_JIT if MMU diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index 5fbaa7be18a2..a773526fb3cc 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -111,7 +111,7 @@ _save_context: call trace_hardirqs_off #endif =20 -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER /* If previous state is in user mode, call user_exit_callable(). */ li a0, SR_PP and a0, s1, a0 @@ -176,7 +176,7 @@ handle_syscall: */ csrs CSR_STATUS, SR_IE #endif -#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING) +#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING_USER) /* Recover a0 - a7 for system calls */ REG_L a0, PT_A0(sp) REG_L a1, PT_A1(sp) @@ -251,7 +251,7 @@ resume_userspace: andi s1, s0, _TIF_WORK_MASK bnez s1, work_pending =20 -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER call user_enter_callable #endif =20 diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig index 1cab1b284f1a..e736120f4333 100644 --- a/arch/sparc/Kconfig +++ b/arch/sparc/Kconfig @@ -71,7 +71,7 @@ config SPARC64 select HAVE_DYNAMIC_FTRACE select HAVE_FTRACE_MCOUNT_RECORD select HAVE_SYSCALL_TRACEPOINTS - select HAVE_CONTEXT_TRACKING + select HAVE_CONTEXT_TRACKING_USER select HAVE_TIF_NOHZ select HAVE_DEBUG_KMEMLEAK select IOMMU_HELPER diff --git a/arch/sparc/kernel/rtrap_64.S b/arch/sparc/kernel/rtrap_64.S index c5fd4b450d9b..eef102765a7e 100644 --- a/arch/sparc/kernel/rtrap_64.S +++ b/arch/sparc/kernel/rtrap_64.S @@ -15,7 +15,7 @@ #include #include =20 -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER # define SCHEDULE_USER schedule_user #else # define SCHEDULE_USER schedule diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index ebe8fc76949a..fbda20f6cf08 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -182,8 +182,8 @@ config X86 select HAVE_ASM_MODVERSIONS select HAVE_CMPXCHG_DOUBLE select HAVE_CMPXCHG_LOCAL - select HAVE_CONTEXT_TRACKING if X86_64 - select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING + select HAVE_CONTEXT_TRACKING_USER if X86_64 + select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER select HAVE_C_RECORDMCOUNT select HAVE_OBJTOOL_MCOUNT if STACK_VALIDATION select HAVE_DEBUG_KMEMLEAK diff --git a/include/linux/context_tracking.h b/include/linux/context_track= ing.h index 40badd62ad56..75738f20e111 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -10,7 +10,7 @@ #include =20 =20 -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER extern void context_tracking_cpu_track_user(int cpu); =20 /* Called with interrupts disabled. */ @@ -52,7 +52,7 @@ static inline enum ctx_state exception_enter(void) { enum ctx_state prev_ctx; =20 - if (IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK) || + if (IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK) || !context_tracking_enabled()) return 0; =20 @@ -65,7 +65,7 @@ static inline enum ctx_state exception_enter(void) =20 static inline void exception_exit(enum ctx_state prev_ctx) { - if (!IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK) && + if (!IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK) && context_tracking_enabled()) { if (prev_ctx !=3D CONTEXT_KERNEL) ct_user_enter(prev_ctx); @@ -109,14 +109,14 @@ static inline enum ctx_state ct_state(void) { return = CONTEXT_DISABLED; } static __always_inline bool context_tracking_guest_enter(void) { return fa= lse; } static inline void context_tracking_guest_exit(void) { } =20 -#endif /* !CONFIG_CONTEXT_TRACKING */ +#endif /* !CONFIG_CONTEXT_TRACKING_USER */ =20 #define CT_WARN_ON(cond) WARN_ON(context_tracking_enabled() && (cond)) =20 -#ifdef CONFIG_CONTEXT_TRACKING_FORCE +#ifdef CONFIG_CONTEXT_TRACKING_USER_FORCE extern void context_tracking_init(void); #else static inline void context_tracking_init(void) { } -#endif /* CONFIG_CONTEXT_TRACKING_FORCE */ +#endif /* CONFIG_CONTEXT_TRACKING_USER_FORCE */ =20 #endif diff --git a/include/linux/context_tracking_state.h b/include/linux/context= _tracking_state.h index 65a60d3313b0..64dbbb880378 100644 --- a/include/linux/context_tracking_state.h +++ b/include/linux/context_tracking_state.h @@ -22,7 +22,7 @@ struct context_tracking { } state; }; =20 -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER extern struct static_key_false context_tracking_key; DECLARE_PER_CPU(struct context_tracking, context_tracking); =20 @@ -50,6 +50,6 @@ static inline bool context_tracking_in_user(void) { retur= n false; } static inline bool context_tracking_enabled(void) { return false; } static inline bool context_tracking_enabled_cpu(int cpu) { return false; } static inline bool context_tracking_enabled_this_cpu(void) { return false;= } -#endif /* CONFIG_CONTEXT_TRACKING */ +#endif /* CONFIG_CONTEXT_TRACKING_USER */ =20 #endif diff --git a/init/Kconfig b/init/Kconfig index e9119bf54b1f..22525443de90 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -498,11 +498,11 @@ config VIRT_CPU_ACCOUNTING_NATIVE =20 config VIRT_CPU_ACCOUNTING_GEN bool "Full dynticks CPU time accounting" - depends on HAVE_CONTEXT_TRACKING + depends on HAVE_CONTEXT_TRACKING_USER depends on HAVE_VIRT_CPU_ACCOUNTING_GEN depends on GENERIC_CLOCKEVENTS select VIRT_CPU_ACCOUNTING - select CONTEXT_TRACKING + select CONTEXT_TRACKING_USER help Select this option to enable task and CPU time accounting on full dynticks systems. This accounting is implemented by watching every diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index 7b6643d2075d..42054841af3f 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -22,6 +22,8 @@ #include #include =20 +#ifdef CONFIG_CONTEXT_TRACKING_USER + #define CREATE_TRACE_POINTS #include =20 @@ -222,7 +224,7 @@ void __init context_tracking_cpu_track_user(int cpu) initialized =3D true; } =20 -#ifdef CONFIG_CONTEXT_TRACKING_FORCE +#ifdef CONFIG_CONTEXT_TRACKING_USER_FORCE void __init context_tracking_init(void) { int cpu; @@ -231,3 +233,5 @@ void __init context_tracking_init(void) context_tracking_cpu_track_user(cpu); } #endif + +#endif /* #ifdef CONFIG_CONTEXT_TRACKING_USER */ diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 2e4ae00e52d1..e79485afb58c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6398,7 +6398,7 @@ void __sched schedule_idle(void) } while (need_resched()); } =20 -#if defined(CONFIG_CONTEXT_TRACKING) && !defined(CONFIG_HAVE_CONTEXT_TRACK= ING_OFFSTACK) +#if defined(CONFIG_CONTEXT_TRACKING_USER) && !defined(CONFIG_HAVE_CONTEXT_= TRACKING_USER_OFFSTACK) asmlinkage __visible void __sched schedule_user(void) { /* diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig index 27b7868b5c30..aad89cc96787 100644 --- a/kernel/time/Kconfig +++ b/kernel/time/Kconfig @@ -111,7 +111,7 @@ config NO_HZ_FULL # NO_HZ_COMMON dependency # We need at least one periodic CPU for timekeeping depends on SMP - depends on HAVE_CONTEXT_TRACKING + depends on HAVE_CONTEXT_TRACKING_USER # VIRT_CPU_ACCOUNTING_GEN dependency depends on HAVE_VIRT_CPU_ACCOUNTING_GEN select NO_HZ_COMMON @@ -140,28 +140,32 @@ endchoice config CONTEXT_TRACKING bool =20 -config CONTEXT_TRACKING_FORCE - bool "Force context tracking" - depends on CONTEXT_TRACKING +config CONTEXT_TRACKING_USER + select CONTEXT_TRACKING + bool + +config CONTEXT_TRACKING_USER_FORCE + bool "Force user context tracking" + depends on CONTEXT_TRACKING_USER default y if !NO_HZ_FULL help The major pre-requirement for full dynticks to work is to - support the context tracking subsystem. But there are also + support the user context tracking subsystem. But there are also other dependencies to provide in order to make the full dynticks working. =20 This option stands for testing when an arch implements the - context tracking backend but doesn't yet fulfill all the + user context tracking backend but doesn't yet fulfill all the requirements to make the full dynticks feature working. Without the full dynticks, there is no way to test the support - for context tracking and the subsystems that rely on it: RCU + for user context tracking and the subsystems that rely on it: RCU userspace extended quiescent state and tickless cputime accounting. This option copes with the absence of the full - dynticks subsystem by forcing the context tracking on all + dynticks subsystem by forcing the user context tracking on all CPUs in the system. =20 Say Y only if you're working on the development of an - architecture backend for the context tracking. + architecture backend for the user context tracking. =20 Say N otherwise, this option brings an overhead that you don't want in production. --=20 2.25.1 From nobody Tue Jun 23 16:12:04 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 03EA3C433F5 for ; Wed, 2 Mar 2022 15:49:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237533AbiCBPt4 (ORCPT ); Wed, 2 Mar 2022 10:49:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53476 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240591AbiCBPt3 (ORCPT ); Wed, 2 Mar 2022 10:49:29 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 469652F01E for ; Wed, 2 Mar 2022 07:48:42 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id BB2B0B82082 for ; Wed, 2 Mar 2022 15:48:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 43852C340F2; Wed, 2 Mar 2022 15:48:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646236119; bh=Xy7jrcacNL5dhRBZoBp5XTvOJi/Wxwxgc/Jan99d6qY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fkx9KeA8ow3TroZLYuisk2tKNrHdtgjtEufCvJO0RCeN9JOQGK6wfJWcRDHx5X5hX uMP9MYd8tLvteEzmgOIsdbPmnsUeqP5BG1QjC+6eaiw1ng7y92/0BC6rNxGvB3L+s5 rJFJK6XIF4z9WbBNpX6aiUv783Ax7n6MJ/By40kjvTV4VOshONrWRTkOjdTsL0CixZ 9AtCRBzVmbFbh9XnkE5Rwa9sQjUWtrdhFTFpQJ+F4zSGrqgN+SIyT7TqP6qsQsIcVm 7qAova1bg99R9ZczPGml5OaXVHsBvV17c1gntiZTh3Vk3DLjpm88xqIQMwTJdOcRAS z6CPRKC2/kj+w== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: [PATCH 06/19] context_tracking: Take idle eqs entrypoints over RCU Date: Wed, 2 Mar 2022 16:47:57 +0100 Message-Id: <20220302154810.42308-7-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220302154810.42308-1-frederic@kernel.org> References: <20220302154810.42308-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The RCU dynticks counter is going to be merged into the context tracking subsystem. Start with moving the idle extended quiescent states entrypoints to RCU. For now those are dumb redirection to existing RCU calls. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits --- Documentation/RCU/stallwarn.rst | 4 ++-- arch/arm/mach-imx/cpuidle-imx6q.c | 5 +++-- drivers/acpi/processor_idle.c | 5 +++-- drivers/cpuidle/cpuidle.c | 9 +++++---- include/linux/context_tracking.h | 8 ++++++++ include/linux/rcupdate.h | 2 +- kernel/context_tracking.c | 12 ++++++++++++ kernel/locking/lockdep.c | 2 +- kernel/rcu/Kconfig | 2 ++ kernel/rcu/tree.c | 2 -- kernel/rcu/update.c | 2 +- kernel/sched/idle.c | 11 ++++++----- 12 files changed, 44 insertions(+), 20 deletions(-) diff --git a/Documentation/RCU/stallwarn.rst b/Documentation/RCU/stallwarn.= rst index 1d863b04727c..bdd52b40f307 100644 --- a/Documentation/RCU/stallwarn.rst +++ b/Documentation/RCU/stallwarn.rst @@ -97,8 +97,8 @@ warnings: which will include additional debugging information. =20 - A low-level kernel issue that either fails to invoke one of the - variants of rcu_user_enter(), rcu_user_exit(), rcu_idle_enter(), - rcu_idle_exit(), rcu_irq_enter(), or rcu_irq_exit() on the one + variants of rcu_user_enter(), rcu_user_exit(), ct_idle_enter(), + ct_idle_exit(), rcu_irq_enter(), or rcu_irq_exit() on the one hand, or that invokes one of them too many times on the other. Historically, the most frequent issue has been an omission of either irq_enter() or irq_exit(), which in turn invoke diff --git a/arch/arm/mach-imx/cpuidle-imx6q.c b/arch/arm/mach-imx/cpuidle-= imx6q.c index 094337dc1bc7..d086cbae09c3 100644 --- a/arch/arm/mach-imx/cpuidle-imx6q.c +++ b/arch/arm/mach-imx/cpuidle-imx6q.c @@ -3,6 +3,7 @@ * Copyright (C) 2012 Freescale Semiconductor, Inc. */ =20 +#include #include #include #include @@ -24,9 +25,9 @@ static int imx6q_enter_wait(struct cpuidle_device *dev, imx6_set_lpm(WAIT_UNCLOCKED); raw_spin_unlock(&cpuidle_lock); =20 - rcu_idle_enter(); + ct_idle_enter(); cpu_do_idle(); - rcu_idle_exit(); + ct_idle_exit(); =20 raw_spin_lock(&cpuidle_lock); if (num_idle_cpus-- =3D=3D num_online_cpus()) diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 86560a28751b..ce310c11f6ae 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -22,6 +22,7 @@ #include #include #include +#include =20 /* * Include the apic definitions for x86 to have the APIC timer related def= ines @@ -643,11 +644,11 @@ static int acpi_idle_enter_bm(struct cpuidle_driver *= drv, raw_spin_unlock(&c3_lock); } =20 - rcu_idle_enter(); + ct_idle_enter(); =20 acpi_idle_do_entry(cx); =20 - rcu_idle_exit(); + ct_idle_exit(); =20 /* Re-enable bus master arbitration */ if (dis_bm) { diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index ef2ea1b12cd8..62dd956025f3 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -23,6 +23,7 @@ #include #include #include +#include #include =20 #include "cpuidle.h" @@ -150,12 +151,12 @@ static void enter_s2idle_proper(struct cpuidle_driver= *drv, */ stop_critical_timings(); if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE)) - rcu_idle_enter(); + ct_idle_enter(); target_state->enter_s2idle(dev, drv, index); if (WARN_ON_ONCE(!irqs_disabled())) local_irq_disable(); if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE)) - rcu_idle_exit(); + ct_idle_exit(); tick_unfreeze(); start_critical_timings(); =20 @@ -233,10 +234,10 @@ int cpuidle_enter_state(struct cpuidle_device *dev, s= truct cpuidle_driver *drv, =20 stop_critical_timings(); if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE)) - rcu_idle_enter(); + ct_idle_enter(); entered_state =3D target_state->enter(dev, drv, index); if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE)) - rcu_idle_exit(); + ct_idle_exit(); start_critical_timings(); =20 sched_clock_idle_wakeup_event(); diff --git a/include/linux/context_tracking.h b/include/linux/context_track= ing.h index 75738f20e111..52a2e23d5107 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -119,4 +119,12 @@ extern void context_tracking_init(void); static inline void context_tracking_init(void) { } #endif /* CONFIG_CONTEXT_TRACKING_USER_FORCE */ =20 +#ifdef CONFIG_CONTEXT_TRACKING +extern void ct_idle_enter(void); +extern void ct_idle_exit(void); +#else +static inline void ct_idle_enter(void) { } +static inline void ct_idle_exit(void) { } +#endif /* !CONFIG_CONTEXT_TRACKING */ + #endif diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index e7c39c200e2b..38258542a6c3 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -128,7 +128,7 @@ static inline void rcu_nocb_flush_deferred_wakeup(void)= { } * @a: Code that RCU needs to pay attention to. * * RCU read-side critical sections are forbidden in the inner idle loop, - * that is, between the rcu_idle_enter() and the rcu_idle_exit() -- RCU + * that is, between the ct_idle_enter() and the ct_idle_exit() -- RCU * will happily ignore any such read-side critical sections. However, * things like powertop need tracepoints in the inner idle loop. * diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index 42054841af3f..3d479f363275 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -235,3 +235,15 @@ void __init context_tracking_init(void) #endif =20 #endif /* #ifdef CONFIG_CONTEXT_TRACKING_USER */ + +void ct_idle_enter(void) +{ + rcu_idle_enter(); +} +EXPORT_SYMBOL_GPL(ct_idle_enter); + +void ct_idle_exit(void) +{ + rcu_idle_exit(); +} +EXPORT_SYMBOL_GPL(ct_idle_exit); diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 4a882f83aeb9..c34b465ee9f5 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -6539,7 +6539,7 @@ void lockdep_rcu_suspicious(const char *file, const i= nt line, const char *s) =20 /* * If a CPU is in the RCU-free window in idle (ie: in the section - * between rcu_idle_enter() and rcu_idle_exit(), then RCU + * between ct_idle_enter() and ct_idle_exit(), then RCU * considers that CPU to be in an "extended quiescent state", * which means that RCU will be completely ignoring that CPU. * Therefore, rcu_read_lock() and friends have absolutely no diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig index bf8e341e75b4..13a49b6cbe37 100644 --- a/kernel/rcu/Kconfig +++ b/kernel/rcu/Kconfig @@ -8,6 +8,8 @@ menu "RCU Subsystem" config TREE_RCU bool default y if SMP + # Dynticks-idle tracking + select CONTEXT_TRACKING help This option selects the RCU implementation that is designed for very large SMP system with hundreds or diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 9f36bd82ffd1..57110c583767 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -664,7 +664,6 @@ void rcu_idle_enter(void) lockdep_assert_irqs_disabled(); rcu_eqs_enter(false); } -EXPORT_SYMBOL_GPL(rcu_idle_enter); =20 #ifdef CONFIG_NO_HZ_FULL =20 @@ -904,7 +903,6 @@ void rcu_idle_exit(void) rcu_eqs_exit(false); local_irq_restore(flags); } -EXPORT_SYMBOL_GPL(rcu_idle_exit); =20 #ifdef CONFIG_NO_HZ_FULL /** diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index fc7fef575606..147214b2cd68 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -85,7 +85,7 @@ module_param(rcu_normal_after_boot, int, 0444); * and while lockdep is disabled. * * Note that if the CPU is in the idle loop from an RCU point of view (ie: - * that we are in the section between rcu_idle_enter() and rcu_idle_exit()) + * that we are in the section between ct_idle_enter() and ct_idle_exit()) * then rcu_read_lock_held() sets ``*ret`` to false even if the CPU did an * rcu_read_lock(). The reason for this is that RCU ignores CPUs that are * in such a section, considering these as in extended quiescent state, diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index d17b0a5ce6ac..421341d6a74b 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -7,6 +7,7 @@ * tasks which are handled in sched/fair.c ) */ #include "sched.h" +#include =20 #include =20 @@ -56,14 +57,14 @@ static noinline int __cpuidle cpu_idle_poll(void) { trace_cpu_idle(0, smp_processor_id()); stop_critical_timings(); - rcu_idle_enter(); + ct_idle_enter(); local_irq_enable(); =20 while (!tif_need_resched() && (cpu_idle_force_poll || tick_check_broadcast_expired())) cpu_relax(); =20 - rcu_idle_exit(); + ct_idle_exit(); start_critical_timings(); trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id()); =20 @@ -101,12 +102,12 @@ void __cpuidle default_idle_call(void) * * Trace IRQs enable here, then switch off RCU, and have * arch_cpu_idle() use raw_local_irq_enable(). Note that - * rcu_idle_enter() relies on lockdep IRQ state, so switch that + * ct_idle_enter() relies on lockdep IRQ state, so switch that * last -- this is very similar to the entry code. */ trace_hardirqs_on_prepare(); lockdep_hardirqs_on_prepare(_THIS_IP_); - rcu_idle_enter(); + ct_idle_enter(); lockdep_hardirqs_on(_THIS_IP_); =20 arch_cpu_idle(); @@ -119,7 +120,7 @@ void __cpuidle default_idle_call(void) */ raw_local_irq_disable(); lockdep_hardirqs_off(_THIS_IP_); - rcu_idle_exit(); + ct_idle_exit(); lockdep_hardirqs_on(_THIS_IP_); raw_local_irq_enable(); =20 --=20 2.25.1 From nobody Tue Jun 23 16:12:04 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3B9D5C433FE for ; Wed, 2 Mar 2022 15:49:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241773AbiCBPuA (ORCPT ); Wed, 2 Mar 2022 10:50:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54550 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241237AbiCBPtc (ORCPT ); Wed, 2 Mar 2022 10:49:32 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5391632066 for ; Wed, 2 Mar 2022 07:48:44 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D575661737 for ; Wed, 2 Mar 2022 15:48:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E3E18C340F3; Wed, 2 Mar 2022 15:48:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646236123; bh=xod/I3BbXievZhy1QOy5idiuGJKwjYH4mtt5MdZpSk0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=c9Scd/MlbKd46z/H7IO207pkRo+yhMBQ1VweBdz4Wgh4ITARmCvY3yT+Yp/L7ZBCX arES+bR8Eu6TVt608MpDTbjqcye2jkFu/Zsd21wwTE9rcGCOk4qyH3SNy4Lgt7ATOt 10pa10czLT5dXB1YbSgyYhQJaatff0WY3xLqm+9nz5rjmhZky/wS+YfE9Nm4zT0qB1 oSKFdFo2EiuQ+t+JcP6SwgN5WeHwHsiDrJNLwdxcr2fGNVBu9leu3FxnMCOlZTHYPf TzltlqNphHFSXemNd8vPfsu+E3FmcZjRdDoyNWpvO/11pPXfUrEoPRwNS5evKBY0Zw +YEGMkydghU7w== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: [PATCH 07/19] context_tracking: Take IRQ eqs entrypoints over RCU Date: Wed, 2 Mar 2022 16:47:58 +0100 Message-Id: <20220302154810.42308-8-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220302154810.42308-1-frederic@kernel.org> References: <20220302154810.42308-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The RCU dynticks counter is going to be merged into the context tracking subsystem. Prepare with moving the IRQ extended quiescent states entrypoints to context tracking. For now those are dumb redirection to existing RCU calls. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits Acked-by: Paul E. McKenney --- .../RCU/Design/Requirements/Requirements.rst | 10 ++++---- Documentation/RCU/stallwarn.rst | 4 ++-- arch/Kconfig | 2 +- arch/arm64/kernel/entry-common.c | 6 ++--- arch/x86/mm/fault.c | 2 +- drivers/cpuidle/cpuidle-psci.c | 8 +++---- include/linux/context_tracking_irq.h | 17 +++++++++++++ include/linux/context_tracking_state.h | 1 + include/linux/entry-common.h | 10 ++++---- include/linux/rcupdate.h | 5 ++-- include/linux/tracepoint.h | 4 ++-- kernel/context_tracking.c | 24 +++++++++++++++++-- kernel/cpu_pm.c | 8 +++---- kernel/entry/common.c | 12 +++++----- kernel/softirq.c | 4 ++-- kernel/trace/trace.c | 6 ++--- 16 files changed, 81 insertions(+), 42 deletions(-) create mode 100644 include/linux/context_tracking_irq.h diff --git a/Documentation/RCU/Design/Requirements/Requirements.rst b/Docum= entation/RCU/Design/Requirements/Requirements.rst index ff2be1ac54c4..e3dd5d71c798 100644 --- a/Documentation/RCU/Design/Requirements/Requirements.rst +++ b/Documentation/RCU/Design/Requirements/Requirements.rst @@ -1844,10 +1844,10 @@ that meets this requirement. =20 Furthermore, NMI handlers can be interrupted by what appear to RCU to be normal interrupts. One way that this can happen is for code that -directly invokes rcu_irq_enter() and rcu_irq_exit() to be called +directly invokes ct_irq_enter() and ct_irq_exit() to be called from an NMI handler. This astonishing fact of life prompted the current -code structure, which has rcu_irq_enter() invoking -rcu_nmi_enter() and rcu_irq_exit() invoking rcu_nmi_exit(). +code structure, which has ct_irq_enter() invoking +rcu_nmi_enter() and ct_irq_exit() invoking rcu_nmi_exit(). And yes, I also learned of this requirement the hard way. =20 Loadable Modules @@ -2195,7 +2195,7 @@ scheduling-clock interrupt be enabled when RCU needs = it to be: sections, and RCU believes this CPU to be idle, no problem. This sort of thing is used by some architectures for light-weight exception handlers, which can then avoid the overhead of - rcu_irq_enter() and rcu_irq_exit() at exception entry and + ct_irq_enter() and ct_irq_exit() at exception entry and exit, respectively. Some go further and avoid the entireties of irq_enter() and irq_exit(). Just make very sure you are running some of your tests with @@ -2226,7 +2226,7 @@ scheduling-clock interrupt be enabled when RCU needs = it to be: +-----------------------------------------------------------------------+ | **Answer**: | +-----------------------------------------------------------------------+ -| One approach is to do ``rcu_irq_exit();rcu_irq_enter();`` every so | +| One approach is to do ``ct_irq_exit();ct_irq_enter();`` every so | | often. But given that long-running interrupt handlers can cause other | | problems, not least for response time, shouldn't you work to keep | | your interrupt handler's runtime within reasonable bounds? | diff --git a/Documentation/RCU/stallwarn.rst b/Documentation/RCU/stallwarn.= rst index bdd52b40f307..7858c3afa1f4 100644 --- a/Documentation/RCU/stallwarn.rst +++ b/Documentation/RCU/stallwarn.rst @@ -98,11 +98,11 @@ warnings: =20 - A low-level kernel issue that either fails to invoke one of the variants of rcu_user_enter(), rcu_user_exit(), ct_idle_enter(), - ct_idle_exit(), rcu_irq_enter(), or rcu_irq_exit() on the one + ct_idle_exit(), ct_irq_enter(), or ct_irq_exit() on the one hand, or that invokes one of them too many times on the other. Historically, the most frequent issue has been an omission of either irq_enter() or irq_exit(), which in turn invoke - rcu_irq_enter() or rcu_irq_exit(), respectively. Building your + ct_irq_enter() or ct_irq_exit(), respectively. Building your kernel with CONFIG_RCU_EQS_DEBUG=3Dy can help track down these types of issues, which sometimes arise in architecture-specific code. =20 diff --git a/arch/Kconfig b/arch/Kconfig index 1a3b79cfc9e3..66b2b6d4717b 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -770,7 +770,7 @@ config HAVE_CONTEXT_TRACKING_USER Syscalls need to be wrapped inside user_exit()-user_enter(), either optimized behind static key or through the slow path using TIF_NOHZ flag. Exceptions handlers must be wrapped as well. Irqs are already - protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal + protected inside ct_irq_enter/ct_irq_exit() but preemption or signal handling on irq exit still need to be protected. =20 config HAVE_CONTEXT_TRACKING_USER_OFFSTACK diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-com= mon.c index ef7fcefb96bd..43ca8cf4e1dd 100644 --- a/arch/arm64/kernel/entry-common.c +++ b/arch/arm64/kernel/entry-common.c @@ -40,7 +40,7 @@ static __always_inline void __enter_from_kernel_mode(stru= ct pt_regs *regs) =20 if (!IS_ENABLED(CONFIG_TINY_RCU) && is_idle_task(current)) { lockdep_hardirqs_off(CALLER_ADDR0); - rcu_irq_enter(); + ct_irq_enter(); trace_hardirqs_off_finish(); =20 regs->exit_rcu =3D true; @@ -74,7 +74,7 @@ static __always_inline void __exit_to_kernel_mode(struct = pt_regs *regs) if (regs->exit_rcu) { trace_hardirqs_on_prepare(); lockdep_hardirqs_on_prepare(CALLER_ADDR0); - rcu_irq_exit(); + ct_irq_exit(); lockdep_hardirqs_on(CALLER_ADDR0); return; } @@ -82,7 +82,7 @@ static __always_inline void __exit_to_kernel_mode(struct = pt_regs *regs) trace_hardirqs_on(); } else { if (regs->exit_rcu) - rcu_irq_exit(); + ct_irq_exit(); } } =20 diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index d0074c6ed31a..b781785b1ff3 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1526,7 +1526,7 @@ DEFINE_IDTENTRY_RAW_ERRORCODE(exc_page_fault) =20 /* * Entry handling for valid #PF from kernel mode is slightly - * different: RCU is already watching and rcu_irq_enter() must not + * different: RCU is already watching and ct_irq_enter() must not * be invoked because a kernel fault on a user space address might * sleep. * diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c index b51b5df08450..fe31b2d522b3 100644 --- a/drivers/cpuidle/cpuidle-psci.c +++ b/drivers/cpuidle/cpuidle-psci.c @@ -68,12 +68,12 @@ static int __psci_enter_domain_idle_state(struct cpuidl= e_device *dev, return -1; =20 /* Do runtime PM to manage a hierarchical CPU toplogy. */ - rcu_irq_enter_irqson(); + ct_irq_enter_irqson(); if (s2idle) dev_pm_genpd_suspend(pd_dev); else pm_runtime_put_sync_suspend(pd_dev); - rcu_irq_exit_irqson(); + ct_irq_exit_irqson(); =20 state =3D psci_get_domain_state(); if (!state) @@ -81,12 +81,12 @@ static int __psci_enter_domain_idle_state(struct cpuidl= e_device *dev, =20 ret =3D psci_cpu_suspend_enter(state) ? -1 : idx; =20 - rcu_irq_enter_irqson(); + ct_irq_enter_irqson(); if (s2idle) dev_pm_genpd_resume(pd_dev); else pm_runtime_get_sync(pd_dev); - rcu_irq_exit_irqson(); + ct_irq_exit_irqson(); =20 cpu_pm_exit(); =20 diff --git a/include/linux/context_tracking_irq.h b/include/linux/context_t= racking_irq.h new file mode 100644 index 000000000000..60e3ed15a04e --- /dev/null +++ b/include/linux/context_tracking_irq.h @@ -0,0 +1,17 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_CONTEXT_TRACKING_IRQ_H +#define _LINUX_CONTEXT_TRACKING_IRQ_H + +#ifdef CONFIG_CONTEXT_TRACKING +void ct_irq_enter(void); +void ct_irq_exit(void); +void ct_irq_enter_irqson(void); +void ct_irq_exit_irqson(void); +#else +static inline void ct_irq_enter(void) { } +static inline void ct_irq_exit(void) { } +static inline void ct_irq_enter_irqson(void) { } +static inline void ct_irq_exit_irqson(void) { } +#endif + +#endif diff --git a/include/linux/context_tracking_state.h b/include/linux/context= _tracking_state.h index 64dbbb880378..cdc692caa01d 100644 --- a/include/linux/context_tracking_state.h +++ b/include/linux/context_tracking_state.h @@ -4,6 +4,7 @@ =20 #include #include +#include =20 struct context_tracking { /* diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index 2e2b8d6140ed..7c6b1d864448 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -396,7 +396,7 @@ void irqentry_exit_to_user_mode(struct pt_regs *regs); /** * struct irqentry_state - Opaque object for exception state storage * @exit_rcu: Used exclusively in the irqentry_*() calls; signals whether = the - * exit path has to invoke rcu_irq_exit(). + * exit path has to invoke ct_irq_exit(). * @lockdep: Used exclusively in the irqentry_nmi_*() calls; ensures that * lockdep state is restored correctly on exit from nmi. * @@ -434,12 +434,12 @@ typedef struct irqentry_state { * * For kernel mode entries RCU handling is done conditional. If RCU is * watching then the only RCU requirement is to check whether the tick has - * to be restarted. If RCU is not watching then rcu_irq_enter() has to be - * invoked on entry and rcu_irq_exit() on exit. + * to be restarted. If RCU is not watching then ct_irq_enter() has to be + * invoked on entry and ct_irq_exit() on exit. * - * Avoiding the rcu_irq_enter/exit() calls is an optimization but also + * Avoiding the ct_irq_enter/exit() calls is an optimization but also * solves the problem of kernel mode pagefaults which can schedule, which - * is not possible after invoking rcu_irq_enter() without undoing it. + * is not possible after invoking ct_irq_enter() without undoing it. * * For user mode entries irqentry_enter_from_user_mode() is invoked to * establish the proper context for NOHZ_FULL. Otherwise scheduling on exit diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 38258542a6c3..5efba2bfa689 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -29,6 +29,7 @@ #include #include #include +#include =20 #define ULONG_CMP_GE(a, b) (ULONG_MAX / 2 >=3D (a) - (b)) #define ULONG_CMP_LT(a, b) (ULONG_MAX / 2 < (a) - (b)) @@ -143,9 +144,9 @@ static inline void rcu_nocb_flush_deferred_wakeup(void)= { } */ #define RCU_NONIDLE(a) \ do { \ - rcu_irq_enter_irqson(); \ + ct_irq_enter_irqson(); \ do { a; } while (0); \ - rcu_irq_exit_irqson(); \ + ct_irq_exit_irqson(); \ } while (0) =20 /* diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h index 28031b15f878..55717a2eda08 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -200,13 +200,13 @@ static inline struct tracepoint *tracepoint_ptr_deref= (tracepoint_ptr_t *p) */ \ if (rcuidle) { \ __idx =3D srcu_read_lock_notrace(&tracepoint_srcu);\ - rcu_irq_enter_irqson(); \ + ct_irq_enter_irqson(); \ } \ \ __DO_TRACE_CALL(name, TP_ARGS(args)); \ \ if (rcuidle) { \ - rcu_irq_exit_irqson(); \ + ct_irq_exit_irqson(); \ srcu_read_unlock_notrace(&tracepoint_srcu, __idx);\ } \ \ diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index 3d479f363275..b63ff851472e 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -75,7 +75,7 @@ void noinstr __ct_user_enter(enum ctx_state state) * At this stage, only low level arch entry code remains and * then we'll run in userspace. We can assume there won't be * any RCU read-side critical section until the next call to - * user_exit() or rcu_irq_enter(). Let's remove RCU's dependency + * user_exit() or ct_irq_enter(). Let's remove RCU's dependency * on the tick. */ if (state =3D=3D CONTEXT_USER) { @@ -112,7 +112,7 @@ void ct_user_enter(enum ctx_state state) /* * Some contexts may involve an exception occuring in an irq, * leading to that nesting: - * rcu_irq_enter() rcu_user_exit() rcu_user_exit() rcu_irq_exit() + * ct_irq_enter() rcu_user_exit() rcu_user_exit() ct_irq_exit() * This would mess up the dyntick_nesting count though. And rcu_irq_*() * helpers are enough to protect RCU uses inside the exception. So * just return immediately if we detect we are in an IRQ. @@ -247,3 +247,23 @@ void ct_idle_exit(void) rcu_idle_exit(); } EXPORT_SYMBOL_GPL(ct_idle_exit); + +noinstr void ct_irq_enter(void) +{ + rcu_irq_enter(); +} + +noinstr void ct_irq_exit(void) +{ + rcu_irq_exit(); +} + +void ct_irq_enter_irqson(void) +{ + rcu_irq_enter_irqson(); +} + +void ct_irq_exit_irqson(void) +{ + rcu_irq_exit_irqson(); +} diff --git a/kernel/cpu_pm.c b/kernel/cpu_pm.c index 246efc74e3f3..ba4ba71facf9 100644 --- a/kernel/cpu_pm.c +++ b/kernel/cpu_pm.c @@ -35,11 +35,11 @@ static int cpu_pm_notify(enum cpu_pm_event event) * disfunctional in cpu idle. Copy RCU_NONIDLE code to let RCU know * this. */ - rcu_irq_enter_irqson(); + ct_irq_enter_irqson(); rcu_read_lock(); ret =3D raw_notifier_call_chain(&cpu_pm_notifier.chain, event, NULL); rcu_read_unlock(); - rcu_irq_exit_irqson(); + ct_irq_exit_irqson(); =20 return notifier_to_errno(ret); } @@ -49,11 +49,11 @@ static int cpu_pm_notify_robust(enum cpu_pm_event event= _up, enum cpu_pm_event ev unsigned long flags; int ret; =20 - rcu_irq_enter_irqson(); + ct_irq_enter_irqson(); raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags); ret =3D raw_notifier_call_chain_robust(&cpu_pm_notifier.chain, event_up, = event_down, NULL); raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags); - rcu_irq_exit_irqson(); + ct_irq_exit_irqson(); =20 return notifier_to_errno(ret); } diff --git a/kernel/entry/common.c b/kernel/entry/common.c index bad713684c2e..cebc98b8adc6 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -327,7 +327,7 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs = *regs) } =20 /* - * If this entry hit the idle task invoke rcu_irq_enter() whether + * If this entry hit the idle task invoke ct_irq_enter() whether * RCU is watching or not. * * Interrupts can nest when the first interrupt invokes softirq @@ -338,12 +338,12 @@ noinstr irqentry_state_t irqentry_enter(struct pt_reg= s *regs) * not nested into another interrupt. * * Checking for rcu_is_watching() here would prevent the nesting - * interrupt to invoke rcu_irq_enter(). If that nested interrupt is + * interrupt to invoke ct_irq_enter(). If that nested interrupt is * the tick then rcu_flavor_sched_clock_irq() would wrongfully * assume that it is the first interrupt and eventually claim * quiescent state and end grace periods prematurely. * - * Unconditionally invoke rcu_irq_enter() so RCU state stays + * Unconditionally invoke ct_irq_enter() so RCU state stays * consistent. * * TINY_RCU does not support EQS, so let the compiler eliminate @@ -356,7 +356,7 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs = *regs) * as in irqentry_enter_from_user_mode(). */ lockdep_hardirqs_off(CALLER_ADDR0); - rcu_irq_enter(); + ct_irq_enter(); instrumentation_begin(); trace_hardirqs_off_finish(); instrumentation_end(); @@ -414,7 +414,7 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqent= ry_state_t state) trace_hardirqs_on_prepare(); lockdep_hardirqs_on_prepare(CALLER_ADDR0); instrumentation_end(); - rcu_irq_exit(); + ct_irq_exit(); lockdep_hardirqs_on(CALLER_ADDR0); return; } @@ -436,7 +436,7 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqent= ry_state_t state) * was not watching on entry. */ if (state.exit_rcu) - rcu_irq_exit(); + ct_irq_exit(); } } =20 diff --git a/kernel/softirq.c b/kernel/softirq.c index 41f470929e99..7b6761c1a0f3 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -607,7 +607,7 @@ void irq_enter_rcu(void) */ void irq_enter(void) { - rcu_irq_enter(); + ct_irq_enter(); irq_enter_rcu(); } =20 @@ -659,7 +659,7 @@ void irq_exit_rcu(void) void irq_exit(void) { __irq_exit_rcu(); - rcu_irq_exit(); + ct_irq_exit(); /* must be last! */ lockdep_hardirq_exit(); } diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index a569a0cb81ee..7c500c708180 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3088,15 +3088,15 @@ void __trace_stack(struct trace_array *tr, unsigned= int trace_ctx, /* * When an NMI triggers, RCU is enabled via rcu_nmi_enter(), * but if the above rcu_is_watching() failed, then the NMI - * triggered someplace critical, and rcu_irq_enter() should + * triggered someplace critical, and ct_irq_enter() should * not be called from NMI. */ if (unlikely(in_nmi())) return; =20 - rcu_irq_enter_irqson(); + ct_irq_enter_irqson(); __ftrace_trace_stack(buffer, trace_ctx, skip, NULL); - rcu_irq_exit_irqson(); + ct_irq_exit_irqson(); } =20 /** --=20 2.25.1 From nobody Tue Jun 23 16:12:04 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0FA8BC433EF for ; Wed, 2 Mar 2022 15:50:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241063AbiCBPu4 (ORCPT ); Wed, 2 Mar 2022 10:50:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53280 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240888AbiCBPti (ORCPT ); Wed, 2 Mar 2022 10:49:38 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B968B369F1 for ; Wed, 2 Mar 2022 07:48:49 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 290AEB82082 for ; Wed, 2 Mar 2022 15:48:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BC70EC340F2; Wed, 2 Mar 2022 15:48:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646236127; bh=jRx9Fwtkk7KstICJDkCl/JU8UwjeC0Xpe1Dxm4UwtqA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jcXsDEgZ+46Jzh2kikfnxwVfl3OTFREPLG1+nRtXhS8Wwhjs5ITyNVB/9+v6ORbp5 FWeWUb4ztf0xsgPyF5UG3ValcEpyx4SUMeB4DoG5AC9o5c86yyuftmrFxUxAEPI6dj FC2WJrBlpPMcdQCQaanLzUrbyO7AmO0ZDPsKLTIqRnAikIvOCWB3rq9cgcyptJKnuO AwckzEPx+LPtrCUQ4FqPIHL7EKV8JMQJzD9y7K33JIScNIY008x1zBL0EUJt6v/wPM mMgaXV85jMExTJlK9mWsgyWPXwGp2veWtRSGTjvl9EVNdblaEl0fmRrJSz+qZ4kgAC bwyUVN6mPyFgg== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: [PATCH 08/19] context_tracking: Take NMI eqs entrypoints over RCU Date: Wed, 2 Mar 2022 16:47:59 +0100 Message-Id: <20220302154810.42308-9-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220302154810.42308-1-frederic@kernel.org> References: <20220302154810.42308-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The RCU dynticks counter is going to be merged into the context tracking subsystem. Prepare with moving the NMI extended quiescent states entrypoints to context tracking. For now those are dumb redirection to existing RCU calls. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits Acked-by: Paul E. McKenney --- Documentation/RCU/Design/Requirements/Requirements.rst | 2 +- arch/Kconfig | 2 +- arch/arm64/kernel/entry-common.c | 8 ++++---- include/linux/context_tracking_irq.h | 4 ++++ include/linux/hardirq.h | 4 ++-- kernel/context_tracking.c | 10 ++++++++++ kernel/entry/common.c | 4 ++-- kernel/extable.c | 4 ++-- kernel/trace/trace.c | 2 +- 9 files changed, 27 insertions(+), 13 deletions(-) diff --git a/Documentation/RCU/Design/Requirements/Requirements.rst b/Docum= entation/RCU/Design/Requirements/Requirements.rst index e3dd5d71c798..256cf260e864 100644 --- a/Documentation/RCU/Design/Requirements/Requirements.rst +++ b/Documentation/RCU/Design/Requirements/Requirements.rst @@ -1847,7 +1847,7 @@ normal interrupts. One way that this can happen is fo= r code that directly invokes ct_irq_enter() and ct_irq_exit() to be called from an NMI handler. This astonishing fact of life prompted the current code structure, which has ct_irq_enter() invoking -rcu_nmi_enter() and ct_irq_exit() invoking rcu_nmi_exit(). +ct_nmi_enter() and ct_irq_exit() invoking ct_nmi_exit(). And yes, I also learned of this requirement the hard way. =20 Loadable Modules diff --git a/arch/Kconfig b/arch/Kconfig index 66b2b6d4717b..c22b8ca0eb01 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -785,7 +785,7 @@ config HAVE_CONTEXT_TRACKING_USER_OFFSTACK =20 - Critical entry code isn't preemptible (or better yet: not interruptible). - - No use of RCU read side critical sections, unless rcu_nmi_enter() + - No use of RCU read side critical sections, unless ct_nmi_enter() got called. - No use of instrumentation, unless instrumentation_begin() got called. diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-com= mon.c index 43ca8cf4e1dd..6a1ea28731c8 100644 --- a/arch/arm64/kernel/entry-common.c +++ b/arch/arm64/kernel/entry-common.c @@ -158,7 +158,7 @@ static void noinstr arm64_enter_nmi(struct pt_regs *reg= s) __nmi_enter(); lockdep_hardirqs_off(CALLER_ADDR0); lockdep_hardirq_enter(); - rcu_nmi_enter(); + ct_nmi_enter(); =20 trace_hardirqs_off_finish(); ftrace_nmi_enter(); @@ -179,7 +179,7 @@ static void noinstr arm64_exit_nmi(struct pt_regs *regs) lockdep_hardirqs_on_prepare(CALLER_ADDR0); } =20 - rcu_nmi_exit(); + ct_nmi_exit(); lockdep_hardirq_exit(); if (restore) lockdep_hardirqs_on(CALLER_ADDR0); @@ -196,7 +196,7 @@ static void noinstr arm64_enter_el1_dbg(struct pt_regs = *regs) regs->lockdep_hardirqs =3D lockdep_hardirqs_enabled(); =20 lockdep_hardirqs_off(CALLER_ADDR0); - rcu_nmi_enter(); + ct_nmi_enter(); =20 trace_hardirqs_off_finish(); } @@ -215,7 +215,7 @@ static void noinstr arm64_exit_el1_dbg(struct pt_regs *= regs) lockdep_hardirqs_on_prepare(CALLER_ADDR0); } =20 - rcu_nmi_exit(); + ct_nmi_exit(); if (restore) lockdep_hardirqs_on(CALLER_ADDR0); } diff --git a/include/linux/context_tracking_irq.h b/include/linux/context_t= racking_irq.h index 60e3ed15a04e..11043bf724b7 100644 --- a/include/linux/context_tracking_irq.h +++ b/include/linux/context_tracking_irq.h @@ -7,11 +7,15 @@ void ct_irq_enter(void); void ct_irq_exit(void); void ct_irq_enter_irqson(void); void ct_irq_exit_irqson(void); +void ct_nmi_enter(void); +void ct_nmi_exit(void); #else static inline void ct_irq_enter(void) { } static inline void ct_irq_exit(void) { } static inline void ct_irq_enter_irqson(void) { } static inline void ct_irq_exit_irqson(void) { } +static inline void ct_nmi_enter(void) { } +static inline void ct_nmi_exit(void) { } #endif =20 #endif diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h index 76878b357ffa..345cdbe9c1b7 100644 --- a/include/linux/hardirq.h +++ b/include/linux/hardirq.h @@ -124,7 +124,7 @@ extern void rcu_nmi_exit(void); do { \ __nmi_enter(); \ lockdep_hardirq_enter(); \ - rcu_nmi_enter(); \ + ct_nmi_enter(); \ instrumentation_begin(); \ ftrace_nmi_enter(); \ instrumentation_end(); \ @@ -143,7 +143,7 @@ extern void rcu_nmi_exit(void); instrumentation_begin(); \ ftrace_nmi_exit(); \ instrumentation_end(); \ - rcu_nmi_exit(); \ + ct_nmi_exit(); \ lockdep_hardirq_exit(); \ __nmi_exit(); \ } while (0) diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index b63ff851472e..1686cd528966 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -267,3 +267,13 @@ void ct_irq_exit_irqson(void) { rcu_irq_exit_irqson(); } + +noinstr void ct_nmi_enter(void) +{ + rcu_nmi_enter(); +} + +noinstr void ct_nmi_exit(void) +{ + rcu_nmi_exit(); +} diff --git a/kernel/entry/common.c b/kernel/entry/common.c index cebc98b8adc6..08230507793f 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -449,7 +449,7 @@ irqentry_state_t noinstr irqentry_nmi_enter(struct pt_r= egs *regs) __nmi_enter(); lockdep_hardirqs_off(CALLER_ADDR0); lockdep_hardirq_enter(); - rcu_nmi_enter(); + ct_nmi_enter(); =20 instrumentation_begin(); trace_hardirqs_off_finish(); @@ -469,7 +469,7 @@ void noinstr irqentry_nmi_exit(struct pt_regs *regs, ir= qentry_state_t irq_state) } instrumentation_end(); =20 - rcu_nmi_exit(); + ct_nmi_exit(); lockdep_hardirq_exit(); if (irq_state.lockdep) lockdep_hardirqs_on(CALLER_ADDR0); diff --git a/kernel/extable.c b/kernel/extable.c index b6f330f0fe74..88d4d739c5a1 100644 --- a/kernel/extable.c +++ b/kernel/extable.c @@ -113,7 +113,7 @@ int kernel_text_address(unsigned long addr) =20 /* Treat this like an NMI as it can happen anywhere */ if (no_rcu) - rcu_nmi_enter(); + ct_nmi_enter(); =20 if (is_module_text_address(addr)) goto out; @@ -126,7 +126,7 @@ int kernel_text_address(unsigned long addr) ret =3D 0; out: if (no_rcu) - rcu_nmi_exit(); + ct_nmi_exit(); =20 return ret; } diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 7c500c708180..9434da82af8a 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3086,7 +3086,7 @@ void __trace_stack(struct trace_array *tr, unsigned i= nt trace_ctx, } =20 /* - * When an NMI triggers, RCU is enabled via rcu_nmi_enter(), + * When an NMI triggers, RCU is enabled via ct_nmi_enter(), * but if the above rcu_is_watching() failed, then the NMI * triggered someplace critical, and ct_irq_enter() should * not be called from NMI. --=20 2.25.1 From nobody Tue Jun 23 16:12:04 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA141C433EF for ; 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d=kernel.org; s=k20201202; t=1646236130; bh=DwAg6L6aM0so0weBVmp2ThpdjHnR2WO9iHDBXGMTgKo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EzPEqow4ep8ycHt4BRkLgV9l3/hCirT+AOnieswVTFZ8F12hu7rgWuqVqlfmZcgHP JfGYeLVeeqccwq5HCPkFKwh4ICNYNhmtkyVpWpUoLF2qLAlSSbp1tnOFxcv/w9vwRM Ydx6/taTRHQ97oZaIXz5w3tl3fhz1PG+O5f+6x6znwHMWTa5hbsykqxFQn2wRzYoRF uDhnHmsp3B4s+LGtOedfDFZu7UCqSVTCN45xYR6e7nvZpZABjXTxNhVfiiLIxt6yVz M9wKyPrTnBXTFJVhdBH2PHvrZIkT55vwHlldn9p3VVnbmV7WuJ8MbeUWrsEyd0Vrzp g8uhvsYvykOgw== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: [PATCH 09/19] rcu/context-tracking: Remove rcu_irq_enter/exit() Date: Wed, 2 Mar 2022 16:48:00 +0100 Message-Id: <20220302154810.42308-10-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220302154810.42308-1-frederic@kernel.org> References: <20220302154810.42308-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Now rcu_irq_enter/exit() is an unecessary middle call between ct_irq_enter/exit() and nmi_irq_enter/exit(). Take this opportunity to remove the former functions and move the comments above them to the new entrypoints. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits --- include/linux/rcutiny.h | 4 -- include/linux/rcutree.h | 4 -- kernel/context_tracking.c | 59 ++++++++++++++++++++++++++-- kernel/rcu/tree.c | 83 --------------------------------------- 4 files changed, 55 insertions(+), 95 deletions(-) diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h index 5ebac609c984..9e07f8d9d544 100644 --- a/include/linux/rcutiny.h +++ b/include/linux/rcutiny.h @@ -98,10 +98,6 @@ static inline void rcu_cpu_stall_reset(void) { } static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; } static inline void rcu_idle_enter(void) { } static inline void rcu_idle_exit(void) { } -static inline void rcu_irq_enter(void) { } -static inline void rcu_irq_exit_irqson(void) { } -static inline void rcu_irq_enter_irqson(void) { } -static inline void rcu_irq_exit(void) { } static inline void rcu_irq_exit_check_preempt(void) { } #define rcu_is_idle_cpu(cpu) \ (is_idle_task(current) && !in_nmi() && !in_hardirq() && !in_serving_softi= rq()) diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index 127bcfb6f7e9..e05334c4c3d1 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -51,10 +51,6 @@ void cond_synchronize_rcu(unsigned long oldstate); =20 void rcu_idle_enter(void); void rcu_idle_exit(void); -void rcu_irq_enter(void); -void rcu_irq_exit(void); -void rcu_irq_enter_irqson(void); -void rcu_irq_exit_irqson(void); bool rcu_is_idle_cpu(int cpu); =20 #ifdef CONFIG_PROVE_RCU diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index 1686cd528966..ea22eb04750f 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -248,24 +248,75 @@ void ct_idle_exit(void) } EXPORT_SYMBOL_GPL(ct_idle_exit); =20 +/** + * ct_irq_enter - inform RCU that current CPU is entering irq away from id= le + * + * Enter an interrupt handler, which might possibly result in exiting + * idle mode, in other words, entering the mode in which read-side critical + * sections can occur. The caller must have disabled interrupts. + * + * Note that the Linux kernel is fully capable of entering an interrupt + * handler that it never exits, for example when doing upcalls to user mod= e! + * This code assumes that the idle loop never does upcalls to user mode. + * If your architecture's idle loop does do upcalls to user mode (or does + * anything else that results in unbalanced calls to the irq_enter() and + * irq_exit() functions), RCU will give you what you deserve, good and har= d. + * But very infrequently and irreproducibly. + * + * Use things like work queues to work around this limitation. + * + * You have been warned. + * + * If you add or remove a call to ct_irq_enter(), be sure to test with + * CONFIG_RCU_EQS_DEBUG=3Dy. + */ noinstr void ct_irq_enter(void) { - rcu_irq_enter(); + lockdep_assert_irqs_disabled(); + ct_nmi_enter(); } =20 +/** + * ct_irq_exit - inform RCU that current CPU is exiting irq towards idle + * + * Exit from an interrupt handler, which might possibly result in entering + * idle mode, in other words, leaving the mode in which read-side critical + * sections can occur. The caller must have disabled interrupts. + * + * This code assumes that the idle loop never does anything that might + * result in unbalanced calls to irq_enter() and irq_exit(). If your + * architecture's idle loop violates this assumption, RCU will give you wh= at + * you deserve, good and hard. But very infrequently and irreproducibly. + * + * Use things like work queues to work around this limitation. + * + * You have been warned. + * + * If you add or remove a call to ct_irq_exit(), be sure to test with + * CONFIG_RCU_EQS_DEBUG=3Dy. + */ noinstr void ct_irq_exit(void) { - rcu_irq_exit(); + lockdep_assert_irqs_disabled(); + ct_nmi_exit(); } =20 void ct_irq_enter_irqson(void) { - rcu_irq_enter_irqson(); + unsigned long flags; + + local_irq_save(flags); + ct_irq_enter(); + local_irq_restore(flags); } =20 void ct_irq_exit_irqson(void) { - rcu_irq_exit_irqson(); + unsigned long flags; + + local_irq_save(flags); + ct_irq_exit(); + local_irq_restore(flags); } =20 noinstr void ct_nmi_enter(void) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 57110c583767..cadf5f5a4700 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -789,31 +789,6 @@ noinstr void rcu_nmi_exit(void) rcu_dynticks_task_enter(); } =20 -/** - * rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle - * - * Exit from an interrupt handler, which might possibly result in entering - * idle mode, in other words, leaving the mode in which read-side critical - * sections can occur. The caller must have disabled interrupts. - * - * This code assumes that the idle loop never does anything that might - * result in unbalanced calls to irq_enter() and irq_exit(). If your - * architecture's idle loop violates this assumption, RCU will give you wh= at - * you deserve, good and hard. But very infrequently and irreproducibly. - * - * Use things like work queues to work around this limitation. - * - * You have been warned. - * - * If you add or remove a call to rcu_irq_exit(), be sure to test with - * CONFIG_RCU_EQS_DEBUG=3Dy. - */ -void noinstr rcu_irq_exit(void) -{ - lockdep_assert_irqs_disabled(); - rcu_nmi_exit(); -} - #ifdef CONFIG_PROVE_RCU /** * rcu_irq_exit_check_preempt - Validate that scheduling is possible @@ -832,21 +807,6 @@ void rcu_irq_exit_check_preempt(void) } #endif /* #ifdef CONFIG_PROVE_RCU */ =20 -/* - * Wrapper for rcu_irq_exit() where interrupts are enabled. - * - * If you add or remove a call to rcu_irq_exit_irqson(), be sure to test - * with CONFIG_RCU_EQS_DEBUG=3Dy. - */ -void rcu_irq_exit_irqson(void) -{ - unsigned long flags; - - local_irq_save(flags); - rcu_irq_exit(); - local_irq_restore(flags); -} - /* * Exit an RCU extended quiescent state, which can be either the * idle loop or adaptive-tickless usermode execution. @@ -1041,49 +1001,6 @@ noinstr void rcu_nmi_enter(void) barrier(); } =20 -/** - * rcu_irq_enter - inform RCU that current CPU is entering irq away from i= dle - * - * Enter an interrupt handler, which might possibly result in exiting - * idle mode, in other words, entering the mode in which read-side critical - * sections can occur. The caller must have disabled interrupts. - * - * Note that the Linux kernel is fully capable of entering an interrupt - * handler that it never exits, for example when doing upcalls to user mod= e! - * This code assumes that the idle loop never does upcalls to user mode. - * If your architecture's idle loop does do upcalls to user mode (or does - * anything else that results in unbalanced calls to the irq_enter() and - * irq_exit() functions), RCU will give you what you deserve, good and har= d. - * But very infrequently and irreproducibly. - * - * Use things like work queues to work around this limitation. - * - * You have been warned. - * - * If you add or remove a call to rcu_irq_enter(), be sure to test with - * CONFIG_RCU_EQS_DEBUG=3Dy. - */ -noinstr void rcu_irq_enter(void) -{ - lockdep_assert_irqs_disabled(); - rcu_nmi_enter(); -} - -/* - * Wrapper for rcu_irq_enter() where interrupts are enabled. - * - * If you add or remove a call to rcu_irq_enter_irqson(), be sure to test - * with CONFIG_RCU_EQS_DEBUG=3Dy. - */ -void rcu_irq_enter_irqson(void) -{ - unsigned long flags; - - local_irq_save(flags); - rcu_irq_enter(); - local_irq_restore(flags); -} - /* * Check to see if any future non-offloaded RCU-related work will need * to be done by the current CPU, even if none need be done immediately, --=20 2.25.1 From nobody Tue Jun 23 16:12:04 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 465A5C433F5 for ; Wed, 2 Mar 2022 15:50:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242517AbiCBPun (ORCPT ); Wed, 2 Mar 2022 10:50:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53776 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242036AbiCBPuK (ORCPT ); Wed, 2 Mar 2022 10:50:10 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3CD8A3E0DD for ; Wed, 2 Mar 2022 07:48:56 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 9BE58B82088 for ; Wed, 2 Mar 2022 15:48:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 19BA0C340F2; Wed, 2 Mar 2022 15:48:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646236134; bh=A5lJuMe8z5DgyT0Sqvsr43k4rr8YOnF8m07M+knzFTo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kwaKCk4dn7ZhTEbEyd8O3rxbr8MmazkpdP4byud4j6JjysAte95Rc7foN+pjCdgJI g+tNumJn9uxGr6Z7J3JI/mB1wwzLPCoF+6kQUXtG70r8xfQsq0kZ0RaqB1gTQm5Mpe rhomiJZ0L3YJV5Xtw4DXxAe4YUOLFKqZLvrFX+9dypRC3Oh9l7HRmacXZkQ4v8Y0My wH3hvh5TTNqHByz5/OyT9Bl4kf7NbqZgiSFW4QfNvoHx2Eq93AIPGlDznmjnAdb4gc +M7fJx0ibDJxA560zvdCKcPznMtpSKtbTLRpSdVOyKYvrRfvxRwhGLgvcElSPIIE3U LeRaUChojkQdA== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: [PATCH 10/19] rcu/context_tracking: Move dynticks counter to context tracking Date: Wed, 2 Mar 2022 16:48:01 +0100 Message-Id: <20220302154810.42308-11-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220302154810.42308-1-frederic@kernel.org> References: <20220302154810.42308-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" In order to prepare for merging RCU dynticks counter into the context tracking state, move the rcu_data's dynticks field to the context tracking structure. It will later be mixed within the context tracking state itself. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits Acked-by: Paul E. McKenney --- include/linux/context_tracking_state.h | 10 ++++- kernel/context_tracking.c | 9 ++-- kernel/rcu/tree.c | 59 ++++++++++++++------------ kernel/rcu/tree.h | 1 - kernel/rcu/tree_exp.h | 2 +- kernel/rcu/tree_stall.h | 4 +- 6 files changed, 48 insertions(+), 37 deletions(-) diff --git a/include/linux/context_tracking_state.h b/include/linux/context= _tracking_state.h index cdc692caa01d..5ad0e481c5a3 100644 --- a/include/linux/context_tracking_state.h +++ b/include/linux/context_tracking_state.h @@ -7,6 +7,7 @@ #include =20 struct context_tracking { +#ifdef CONFIG_CONTEXT_TRACKING_USER /* * When active is false, probes are unset in order * to minimize overhead: TIF flags are cleared @@ -21,11 +22,16 @@ struct context_tracking { CONTEXT_USER, CONTEXT_GUEST, } state; +#endif + atomic_t dynticks; /* Even value for idle, else odd. */ }; =20 -#ifdef CONFIG_CONTEXT_TRACKING_USER -extern struct static_key_false context_tracking_key; +#ifdef CONFIG_CONTEXT_TRACKING DECLARE_PER_CPU(struct context_tracking, context_tracking); +#endif + +#ifdef CONFIG_CONTEXT_TRACKING_USER +extern struct static_key_false context_tracking_key; =20 static __always_inline bool context_tracking_enabled(void) { diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index ea22eb04750f..77b61a7c9890 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -30,9 +30,6 @@ DEFINE_STATIC_KEY_FALSE(context_tracking_key); EXPORT_SYMBOL_GPL(context_tracking_key); =20 -DEFINE_PER_CPU(struct context_tracking, context_tracking); -EXPORT_SYMBOL_GPL(context_tracking); - static noinstr bool context_tracking_recursion_enter(void) { int recursion; @@ -236,6 +233,12 @@ void __init context_tracking_init(void) =20 #endif /* #ifdef CONFIG_CONTEXT_TRACKING_USER */ =20 +DEFINE_PER_CPU(struct context_tracking, context_tracking) =3D { + .dynticks =3D ATOMIC_INIT(1), +}; +EXPORT_SYMBOL_GPL(context_tracking); + + void ct_idle_enter(void) { rcu_idle_enter(); diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index cadf5f5a4700..96eb8503f28e 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -77,7 +77,6 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, rcu_data) =3D { .dynticks_nesting =3D 1, .dynticks_nmi_nesting =3D DYNTICK_IRQ_NONIDLE, - .dynticks =3D ATOMIC_INIT(1), #ifdef CONFIG_RCU_NOCB_CPU .cblist.flags =3D SEGCBLIST_RCU_CORE, #endif @@ -268,7 +267,7 @@ void rcu_softirq_qs(void) */ static noinline noinstr unsigned long rcu_dynticks_inc(int incby) { - return arch_atomic_add_return(incby, this_cpu_ptr(&rcu_data.dynticks)); + return arch_atomic_add_return(incby, this_cpu_ptr(&context_tracking.dynti= cks)); } =20 /* @@ -324,9 +323,9 @@ static noinstr void rcu_dynticks_eqs_exit(void) */ static void rcu_dynticks_eqs_online(void) { - struct rcu_data *rdp =3D this_cpu_ptr(&rcu_data); + struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); =20 - if (atomic_read(&rdp->dynticks) & 0x1) + if (atomic_read(&ct->dynticks) & 0x1) return; rcu_dynticks_inc(1); } @@ -338,17 +337,19 @@ static void rcu_dynticks_eqs_online(void) */ static __always_inline bool rcu_dynticks_curr_cpu_in_eqs(void) { - return !(arch_atomic_read(this_cpu_ptr(&rcu_data.dynticks)) & 0x1); + return !(arch_atomic_read(this_cpu_ptr(&context_tracking.dynticks)) & 0x1= ); } =20 /* * Snapshot the ->dynticks counter with full ordering so as to allow * stable comparison of this counter with past and future snapshots. */ -static int rcu_dynticks_snap(struct rcu_data *rdp) +static int rcu_dynticks_snap(int cpu) { + struct context_tracking *ct =3D per_cpu_ptr(&context_tracking, cpu); + smp_mb(); // Fundamental RCU ordering guarantee. - return atomic_read_acquire(&rdp->dynticks); + return atomic_read_acquire(&ct->dynticks); } =20 /* @@ -363,9 +364,7 @@ static bool rcu_dynticks_in_eqs(int snap) /* Return true if the specified CPU is currently idle from an RCU viewpoin= t. */ bool rcu_is_idle_cpu(int cpu) { - struct rcu_data *rdp =3D per_cpu_ptr(&rcu_data, cpu); - - return rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp)); + return rcu_dynticks_in_eqs(rcu_dynticks_snap(cpu)); } =20 /* @@ -375,7 +374,7 @@ bool rcu_is_idle_cpu(int cpu) */ static bool rcu_dynticks_in_eqs_since(struct rcu_data *rdp, int snap) { - return snap !=3D rcu_dynticks_snap(rdp); + return snap !=3D rcu_dynticks_snap(rdp->cpu); } =20 /* @@ -384,11 +383,11 @@ static bool rcu_dynticks_in_eqs_since(struct rcu_data= *rdp, int snap) */ bool rcu_dynticks_zero_in_eqs(int cpu, int *vp) { - struct rcu_data *rdp =3D per_cpu_ptr(&rcu_data, cpu); + struct context_tracking *ct =3D per_cpu_ptr(&context_tracking, cpu); int snap; =20 // If not quiescent, force back to earlier extended quiescent state. - snap =3D atomic_read(&rdp->dynticks) & ~0x1; + snap =3D atomic_read(&ct->dynticks) & ~0x1; =20 smp_rmb(); // Order ->dynticks and *vp reads. if (READ_ONCE(*vp)) @@ -396,7 +395,7 @@ bool rcu_dynticks_zero_in_eqs(int cpu, int *vp) smp_rmb(); // Order *vp read and ->dynticks re-read. =20 // If still in the same extended quiescent state, we are good! - return snap =3D=3D atomic_read(&rdp->dynticks); + return snap =3D=3D atomic_read(&ct->dynticks); } =20 /* @@ -620,6 +619,7 @@ EXPORT_SYMBOL_GPL(rcutorture_get_gp_data); static noinstr void rcu_eqs_enter(bool user) { struct rcu_data *rdp =3D this_cpu_ptr(&rcu_data); + struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); =20 WARN_ON_ONCE(rdp->dynticks_nmi_nesting !=3D DYNTICK_IRQ_NONIDLE); WRITE_ONCE(rdp->dynticks_nmi_nesting, 0); @@ -633,12 +633,12 @@ static noinstr void rcu_eqs_enter(bool user) =20 lockdep_assert_irqs_disabled(); instrumentation_begin(); - trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, atomic_read(&rd= p->dynticks)); + trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, atomic_read(&ct= ->dynticks)); WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(c= urrent)); rcu_preempt_deferred_qs(current); =20 // instrumentation for the noinstr rcu_dynticks_eqs_enter() - instrument_atomic_write(&rdp->dynticks, sizeof(rdp->dynticks)); + instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); =20 instrumentation_end(); WRITE_ONCE(rdp->dynticks_nesting, 0); /* Avoid irq-access tearing. */ @@ -740,7 +740,7 @@ noinstr void rcu_user_enter(void) * rcu_nmi_exit - inform RCU of exit from NMI context * * If we are returning from the outermost NMI handler that interrupted an - * RCU-idle period, update rdp->dynticks and rdp->dynticks_nmi_nesting + * RCU-idle period, update ct->dynticks and rdp->dynticks_nmi_nesting * to let the RCU grace-period handling know that the CPU is back to * being RCU-idle. * @@ -749,6 +749,7 @@ noinstr void rcu_user_enter(void) */ noinstr void rcu_nmi_exit(void) { + struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); struct rcu_data *rdp =3D this_cpu_ptr(&rcu_data); =20 instrumentation_begin(); @@ -766,7 +767,7 @@ noinstr void rcu_nmi_exit(void) */ if (rdp->dynticks_nmi_nesting !=3D 1) { trace_rcu_dyntick(TPS("--=3D"), rdp->dynticks_nmi_nesting, rdp->dynticks= _nmi_nesting - 2, - atomic_read(&rdp->dynticks)); + atomic_read(&ct->dynticks)); WRITE_ONCE(rdp->dynticks_nmi_nesting, /* No store tearing. */ rdp->dynticks_nmi_nesting - 2); instrumentation_end(); @@ -774,11 +775,11 @@ noinstr void rcu_nmi_exit(void) } =20 /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */ - trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nmi_nesting, 0, atomic_r= ead(&rdp->dynticks)); + trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nmi_nesting, 0, atomic_r= ead(&ct->dynticks)); WRITE_ONCE(rdp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */ =20 // instrumentation for the noinstr rcu_dynticks_eqs_enter() - instrument_atomic_write(&rdp->dynticks, sizeof(rdp->dynticks)); + instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); instrumentation_end(); =20 // RCU is watching here ... @@ -817,6 +818,7 @@ void rcu_irq_exit_check_preempt(void) */ static void noinstr rcu_eqs_exit(bool user) { + struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); struct rcu_data *rdp; long oldval; =20 @@ -836,9 +838,9 @@ static void noinstr rcu_eqs_exit(bool user) instrumentation_begin(); =20 // instrumentation for the noinstr rcu_dynticks_eqs_exit() - instrument_atomic_write(&rdp->dynticks, sizeof(rdp->dynticks)); + instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); =20 - trace_rcu_dyntick(TPS("End"), rdp->dynticks_nesting, 1, atomic_read(&rdp-= >dynticks)); + trace_rcu_dyntick(TPS("End"), rdp->dynticks_nesting, 1, atomic_read(&ct->= dynticks)); WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(c= urrent)); WRITE_ONCE(rdp->dynticks_nesting, 1); WARN_ON_ONCE(rdp->dynticks_nmi_nesting); @@ -944,7 +946,7 @@ void __rcu_irq_enter_check_tick(void) /** * rcu_nmi_enter - inform RCU of entry to NMI context * - * If the CPU was idle from RCU's viewpoint, update rdp->dynticks and + * If the CPU was idle from RCU's viewpoint, update ct->dynticks and * rdp->dynticks_nmi_nesting to let the RCU grace-period handling know * that the CPU is active. This implementation permits nested NMIs, as * long as the nesting level does not overflow an int. (You will probably @@ -957,6 +959,7 @@ noinstr void rcu_nmi_enter(void) { long incby =3D 2; struct rcu_data *rdp =3D this_cpu_ptr(&rcu_data); + struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); =20 /* Complain about underflow. */ WARN_ON_ONCE(rdp->dynticks_nmi_nesting < 0); @@ -980,9 +983,9 @@ noinstr void rcu_nmi_enter(void) =20 instrumentation_begin(); // instrumentation for the noinstr rcu_dynticks_curr_cpu_in_eqs() - instrument_atomic_read(&rdp->dynticks, sizeof(rdp->dynticks)); + instrument_atomic_read(&ct->dynticks, sizeof(ct->dynticks)); // instrumentation for the noinstr rcu_dynticks_eqs_exit() - instrument_atomic_write(&rdp->dynticks, sizeof(rdp->dynticks)); + instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); =20 incby =3D 1; } else if (!in_nmi()) { @@ -994,7 +997,7 @@ noinstr void rcu_nmi_enter(void) =20 trace_rcu_dyntick(incby =3D=3D 1 ? TPS("Endirq") : TPS("++=3D"), rdp->dynticks_nmi_nesting, - rdp->dynticks_nmi_nesting + incby, atomic_read(&rdp->dynticks)); + rdp->dynticks_nmi_nesting + incby, atomic_read(&ct->dynticks)); instrumentation_end(); WRITE_ONCE(rdp->dynticks_nmi_nesting, /* Prevent store tearing. */ rdp->dynticks_nmi_nesting + incby); @@ -1138,7 +1141,7 @@ static void rcu_gpnum_ovf(struct rcu_node *rnp, struc= t rcu_data *rdp) */ static int dyntick_save_progress_counter(struct rcu_data *rdp) { - rdp->dynticks_snap =3D rcu_dynticks_snap(rdp); + rdp->dynticks_snap =3D rcu_dynticks_snap(rdp->cpu); if (rcu_dynticks_in_eqs(rdp->dynticks_snap)) { trace_rcu_fqs(rcu_state.name, rdp->gp_seq, rdp->cpu, TPS("dti")); rcu_gpnum_ovf(rdp->mynode, rdp); @@ -4125,7 +4128,7 @@ rcu_boot_init_percpu_data(int cpu) rdp->grpmask =3D leaf_node_cpu_bit(rdp->mynode, cpu); INIT_WORK(&rdp->strict_work, strict_work_handler); WARN_ON_ONCE(rdp->dynticks_nesting !=3D 1); - WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp))); + WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(cpu))); rdp->barrier_seq_snap =3D rcu_state.barrier_sequence; rdp->rcu_ofl_gp_seq =3D rcu_state.gp_seq; rdp->rcu_ofl_gp_flags =3D RCU_GP_CLEANED; diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index b8d07bf92d29..15246a3f0734 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -188,7 +188,6 @@ struct rcu_data { int dynticks_snap; /* Per-GP tracking for dynticks. */ long dynticks_nesting; /* Track process nesting level. */ long dynticks_nmi_nesting; /* Track irq/NMI nesting level. */ - atomic_t dynticks; /* Even value for idle, else odd. */ bool rcu_need_heavy_qs; /* GP old, so heavy quiescent state! */ bool rcu_urgent_qs; /* GP old need light quiescent state. */ bool rcu_forced_tick; /* Forced tick to provide QS. */ diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index d5f30085b0cf..2210110990f4 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -358,7 +358,7 @@ static void sync_rcu_exp_select_node_cpus(struct work_s= truct *wp) !(rnp->qsmaskinitnext & mask)) { mask_ofl_test |=3D mask; } else { - snap =3D rcu_dynticks_snap(rdp); + snap =3D rcu_dynticks_snap(cpu); if (rcu_dynticks_in_eqs(snap)) mask_ofl_test |=3D mask; else diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index 84b812a3ab44..202129b1c7e4 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -448,7 +448,7 @@ static void print_cpu_stall_info(int cpu) } delta =3D rcu_seq_ctr(rdp->mynode->gp_seq - rdp->rcu_iw_gp_seq); falsepositive =3D rcu_is_gp_kthread_starving(NULL) && - rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp)); + rcu_dynticks_in_eqs(rcu_dynticks_snap(cpu)); pr_err("\t%d-%c%c%c%c: (%lu %s) idle=3D%03x/%ld/%#lx softirq=3D%u/%u fqs= =3D%ld %s\n", cpu, "O."[!!cpu_online(cpu)], @@ -458,7 +458,7 @@ static void print_cpu_stall_info(int cpu) rdp->rcu_iw_pending ? (int)min(delta, 9UL) + '0' : "!."[!delta], ticks_value, ticks_title, - rcu_dynticks_snap(rdp) & 0xfff, + rcu_dynticks_snap(cpu) & 0xfff, rdp->dynticks_nesting, rdp->dynticks_nmi_nesting, rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu), data_race(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart, --=20 2.25.1 From nobody Tue Jun 23 16:12:04 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E7292C433F5 for ; Wed, 2 Mar 2022 15:49:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241516AbiCBPuj (ORCPT ); Wed, 2 Mar 2022 10:50:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55282 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242197AbiCBPuK (ORCPT ); Wed, 2 Mar 2022 10:50:10 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EA6E340E44 for ; Wed, 2 Mar 2022 07:48:59 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 4D22BB8207F for ; Wed, 2 Mar 2022 15:48:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BAD50C340F6; Wed, 2 Mar 2022 15:48:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646236138; bh=LEEbg/tTkNBYhQGsXaeUmRgAChHsIDSgUV6Twd2J88E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fHbAze20whdP/pPGI9gRVSPjG8dxF2UCwEBpdQl0zh2mNMDpmW+Vh4XlZtnZiBjj5 4i3kgoKDCdf0zewx68YHGx6Tc9lM/jkj2V3oM/+d2LSfvb1ij6OBhUEIVFFm3fCqU/ 5tF+0SBL/nIwCXgj7fUibZ6WrZsobmVJz9XHLTToUlzGEQfB41n8xM+zXUZFLxBXG8 W8VJZmh70GBX8slwF45Vr4YjS14GCW+daAaDTB+YV4bBO0Uxc/WEnwwcBCgiCHChXF ChyN3QXsz3JQEOvp7D4/tLofiT97SW7p+ao1i/4n7BrbURUczFHb1FnIL3XB2C1kPf fEBte/UX9D18g== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: [PATCH 11/19] rcu/context_tracking: Move dynticks_nesting to context tracking Date: Wed, 2 Mar 2022 16:48:02 +0100 Message-Id: <20220302154810.42308-12-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220302154810.42308-1-frederic@kernel.org> References: <20220302154810.42308-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The RCU eqs tracking is going to be performed by the context tracking subsystem. The related nesting counters thus need to be moved to the context tracking structure. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits Acked-by: Paul E. McKenney --- include/linux/context_tracking_state.h | 1 + kernel/context_tracking.c | 1 + kernel/rcu/tree.c | 31 +++++++++++++------------- kernel/rcu/tree.h | 1 - kernel/rcu/tree_stall.h | 3 ++- 5 files changed, 20 insertions(+), 17 deletions(-) diff --git a/include/linux/context_tracking_state.h b/include/linux/context= _tracking_state.h index 5ad0e481c5a3..bcb942945265 100644 --- a/include/linux/context_tracking_state.h +++ b/include/linux/context_tracking_state.h @@ -24,6 +24,7 @@ struct context_tracking { } state; #endif atomic_t dynticks; /* Even value for idle, else odd. */ + long dynticks_nesting; /* Track process nesting level. */ }; =20 #ifdef CONFIG_CONTEXT_TRACKING diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index 77b61a7c9890..09a77884a4e3 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -234,6 +234,7 @@ void __init context_tracking_init(void) #endif /* #ifdef CONFIG_CONTEXT_TRACKING_USER */ =20 DEFINE_PER_CPU(struct context_tracking, context_tracking) =3D { + .dynticks_nesting =3D 1, .dynticks =3D ATOMIC_INIT(1), }; EXPORT_SYMBOL_GPL(context_tracking); diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 96eb8503f28e..8708d1a99565 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -75,7 +75,6 @@ /* Data structures. */ =20 static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, rcu_data) =3D { - .dynticks_nesting =3D 1, .dynticks_nmi_nesting =3D DYNTICK_IRQ_NONIDLE, #ifdef CONFIG_RCU_NOCB_CPU .cblist.flags =3D SEGCBLIST_RCU_CORE, @@ -441,7 +440,7 @@ static int rcu_is_cpu_rrupt_from_idle(void) lockdep_assert_irqs_disabled(); =20 /* Check for counter underflows */ - RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nesting) < 0, + RCU_LOCKDEP_WARN(__this_cpu_read(context_tracking.dynticks_nesting) < 0, "RCU dynticks_nesting counter underflow!"); RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) <=3D 0, "RCU dynticks_nmi_nesting counter underflow/zero!"); @@ -457,7 +456,7 @@ static int rcu_is_cpu_rrupt_from_idle(void) WARN_ON_ONCE(!nesting && !is_idle_task(current)); =20 /* Does CPU appear to be idle from an RCU standpoint? */ - return __this_cpu_read(rcu_data.dynticks_nesting) =3D=3D 0; + return __this_cpu_read(context_tracking.dynticks_nesting) =3D=3D 0; } =20 #define DEFAULT_RCU_BLIMIT (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD) ? 1= 000 : 10) @@ -624,16 +623,16 @@ static noinstr void rcu_eqs_enter(bool user) WARN_ON_ONCE(rdp->dynticks_nmi_nesting !=3D DYNTICK_IRQ_NONIDLE); WRITE_ONCE(rdp->dynticks_nmi_nesting, 0); WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && - rdp->dynticks_nesting =3D=3D 0); - if (rdp->dynticks_nesting !=3D 1) { + ct->dynticks_nesting =3D=3D 0); + if (ct->dynticks_nesting !=3D 1) { // RCU will still be watching, so just do accounting and leave. - rdp->dynticks_nesting--; + ct->dynticks_nesting--; return; } =20 lockdep_assert_irqs_disabled(); instrumentation_begin(); - trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, atomic_read(&ct= ->dynticks)); + trace_rcu_dyntick(TPS("Start"), ct->dynticks_nesting, 0, atomic_read(&ct-= >dynticks)); WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(c= urrent)); rcu_preempt_deferred_qs(current); =20 @@ -641,7 +640,7 @@ static noinstr void rcu_eqs_enter(bool user) instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); =20 instrumentation_end(); - WRITE_ONCE(rdp->dynticks_nesting, 0); /* Avoid irq-access tearing. */ + WRITE_ONCE(ct->dynticks_nesting, 0); /* Avoid irq-access tearing. */ // RCU is watching here ... rcu_dynticks_eqs_enter(); // ... but is no longer watching here. @@ -798,7 +797,7 @@ void rcu_irq_exit_check_preempt(void) { lockdep_assert_irqs_disabled(); =20 - RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nesting) <=3D 0, + RCU_LOCKDEP_WARN(__this_cpu_read(context_tracking.dynticks_nesting) <=3D = 0, "RCU dynticks_nesting counter underflow/zero!"); RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) !=3D DYNTICK_IRQ_NONIDLE, @@ -824,11 +823,11 @@ static void noinstr rcu_eqs_exit(bool user) =20 lockdep_assert_irqs_disabled(); rdp =3D this_cpu_ptr(&rcu_data); - oldval =3D rdp->dynticks_nesting; + oldval =3D ct->dynticks_nesting; WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0); if (oldval) { // RCU was already watching, so just do accounting and leave. - rdp->dynticks_nesting++; + ct->dynticks_nesting++; return; } rcu_dynticks_task_exit(); @@ -840,9 +839,9 @@ static void noinstr rcu_eqs_exit(bool user) // instrumentation for the noinstr rcu_dynticks_eqs_exit() instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); =20 - trace_rcu_dyntick(TPS("End"), rdp->dynticks_nesting, 1, atomic_read(&ct->= dynticks)); + trace_rcu_dyntick(TPS("End"), ct->dynticks_nesting, 1, atomic_read(&ct->d= ynticks)); WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(c= urrent)); - WRITE_ONCE(rdp->dynticks_nesting, 1); + WRITE_ONCE(ct->dynticks_nesting, 1); WARN_ON_ONCE(rdp->dynticks_nmi_nesting); WRITE_ONCE(rdp->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE); instrumentation_end(); @@ -4122,12 +4121,13 @@ static void rcu_init_new_rnp(struct rcu_node *rnp_l= eaf) static void __init rcu_boot_init_percpu_data(int cpu) { + struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); struct rcu_data *rdp =3D per_cpu_ptr(&rcu_data, cpu); =20 /* Set up local state, ensuring consistent view of global state. */ rdp->grpmask =3D leaf_node_cpu_bit(rdp->mynode, cpu); INIT_WORK(&rdp->strict_work, strict_work_handler); - WARN_ON_ONCE(rdp->dynticks_nesting !=3D 1); + WARN_ON_ONCE(ct->dynticks_nesting !=3D 1); WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(cpu))); rdp->barrier_seq_snap =3D rcu_state.barrier_sequence; rdp->rcu_ofl_gp_seq =3D rcu_state.gp_seq; @@ -4152,6 +4152,7 @@ rcu_boot_init_percpu_data(int cpu) int rcutree_prepare_cpu(unsigned int cpu) { unsigned long flags; + struct context_tracking *ct =3D per_cpu_ptr(&context_tracking, cpu); struct rcu_data *rdp =3D per_cpu_ptr(&rcu_data, cpu); struct rcu_node *rnp =3D rcu_get_root(); =20 @@ -4160,7 +4161,7 @@ int rcutree_prepare_cpu(unsigned int cpu) rdp->qlen_last_fqs_check =3D 0; rdp->n_force_qs_snap =3D READ_ONCE(rcu_state.n_force_qs); rdp->blimit =3D blimit; - rdp->dynticks_nesting =3D 1; /* CPU not up, no tearing. */ + ct->dynticks_nesting =3D 1; /* CPU not up, no tearing. */ raw_spin_unlock_rcu_node(rnp); /* irqs remain disabled. */ =20 /* diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 15246a3f0734..8050bab08f39 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -186,7 +186,6 @@ struct rcu_data { =20 /* 3) dynticks interface. */ int dynticks_snap; /* Per-GP tracking for dynticks. */ - long dynticks_nesting; /* Track process nesting level. */ long dynticks_nmi_nesting; /* Track irq/NMI nesting level. */ bool rcu_need_heavy_qs; /* GP old, so heavy quiescent state! */ bool rcu_urgent_qs; /* GP old need light quiescent state. */ diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index 202129b1c7e4..30a5e0a8ddb3 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -429,6 +429,7 @@ static void print_cpu_stall_info(int cpu) { unsigned long delta; bool falsepositive; + struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); struct rcu_data *rdp =3D per_cpu_ptr(&rcu_data, cpu); char *ticks_title; unsigned long ticks_value; @@ -459,7 +460,7 @@ static void print_cpu_stall_info(int cpu) "!."[!delta], ticks_value, ticks_title, rcu_dynticks_snap(cpu) & 0xfff, - rdp->dynticks_nesting, rdp->dynticks_nmi_nesting, + ct->dynticks_nesting, rdp->dynticks_nmi_nesting, rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu), data_race(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart, falsepositive ? " (false positive?)" : ""); --=20 2.25.1 From nobody Tue Jun 23 16:12:04 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C8B23C433F5 for ; Wed, 2 Mar 2022 15:49:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238562AbiCBPuZ (ORCPT ); Wed, 2 Mar 2022 10:50:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54400 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242325AbiCBPuL (ORCPT ); Wed, 2 Mar 2022 10:50:11 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 47DE345534 for ; Wed, 2 Mar 2022 07:49:04 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id EF432B82084 for ; Wed, 2 Mar 2022 15:49:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 66F47C340ED; Wed, 2 Mar 2022 15:48:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646236141; bh=t7Pzx0Xf/nV+xH5b2ZqaWHa4MALVOK7avXOtaFWndOo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EFRQA145ScZMggAtcH758SmtEmqfqQLp7lmDzIUX/b0qTy9kHF7gU3Sbb6F9n3PlF KRGLJpEdUYIjMfaAFZUvzp/rw1yWftW5gsO5kXIExAt1OpPRVR6XuApa7HMQhRm5Vr gTPszVmtii6IOl/iCKE/B4D4VsXrfkzZJcnxzeqSrd9ps2MSTkHVd5Lvyx93z05A4u ock7SdcNL4daO67NwDA3mbkpUDdfD9nmqySb1UDI+ByHwKJZZTwUyBk1GtK1J/4NSA EOaXc5/00C3vp9kPR6EYd9kKICbkGSXorhS8q6jWVQDqrIvJesif6oYRnUwCZ9tMH4 1gTx0u/0n3d2Q== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: [PATCH 12/19] rcu/context_tracking: Move dynticks_nmi_nesting to context tracking Date: Wed, 2 Mar 2022 16:48:03 +0100 Message-Id: <20220302154810.42308-13-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220302154810.42308-1-frederic@kernel.org> References: <20220302154810.42308-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The RCU eqs tracking is going to be performed by the context tracking subsystem. The related nesting counters thus need to be moved to the context tracking structure. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits Acked-by: Paul E. McKenney --- include/linux/context_tracking_state.h | 4 +++ kernel/context_tracking.c | 1 + kernel/rcu/rcu.h | 4 --- kernel/rcu/tree.c | 48 +++++++++++--------------- kernel/rcu/tree.h | 1 - kernel/rcu/tree_stall.h | 2 +- 6 files changed, 27 insertions(+), 33 deletions(-) diff --git a/include/linux/context_tracking_state.h b/include/linux/context= _tracking_state.h index bcb942945265..4efb97fe6518 100644 --- a/include/linux/context_tracking_state.h +++ b/include/linux/context_tracking_state.h @@ -6,6 +6,9 @@ #include #include =20 +/* Offset to allow distinguishing irq vs. task-based idle entry/exit. */ +#define DYNTICK_IRQ_NONIDLE ((LONG_MAX / 2) + 1) + struct context_tracking { #ifdef CONFIG_CONTEXT_TRACKING_USER /* @@ -25,6 +28,7 @@ struct context_tracking { #endif atomic_t dynticks; /* Even value for idle, else odd. */ long dynticks_nesting; /* Track process nesting level. */ + long dynticks_nmi_nesting; /* Track irq/NMI nesting level. */ }; =20 #ifdef CONFIG_CONTEXT_TRACKING diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index 09a77884a4e3..155534c409fc 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -234,6 +234,7 @@ void __init context_tracking_init(void) #endif /* #ifdef CONFIG_CONTEXT_TRACKING_USER */ =20 DEFINE_PER_CPU(struct context_tracking, context_tracking) =3D { + .dynticks_nmi_nesting =3D DYNTICK_IRQ_NONIDLE, .dynticks_nesting =3D 1, .dynticks =3D ATOMIC_INIT(1), }; diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index eccbdbdaa02e..d3cd9e7d11fa 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -12,10 +12,6 @@ =20 #include =20 -/* Offset to allow distinguishing irq vs. task-based idle entry/exit. */ -#define DYNTICK_IRQ_NONIDLE ((LONG_MAX / 2) + 1) - - /* * Grace-period counter management. */ diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 8708d1a99565..c2528e65de0c 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -75,7 +75,6 @@ /* Data structures. */ =20 static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, rcu_data) =3D { - .dynticks_nmi_nesting =3D DYNTICK_IRQ_NONIDLE, #ifdef CONFIG_RCU_NOCB_CPU .cblist.flags =3D SEGCBLIST_RCU_CORE, #endif @@ -442,11 +441,11 @@ static int rcu_is_cpu_rrupt_from_idle(void) /* Check for counter underflows */ RCU_LOCKDEP_WARN(__this_cpu_read(context_tracking.dynticks_nesting) < 0, "RCU dynticks_nesting counter underflow!"); - RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) <=3D 0, + RCU_LOCKDEP_WARN(__this_cpu_read(context_tracking.dynticks_nmi_nesting) <= =3D 0, "RCU dynticks_nmi_nesting counter underflow/zero!"); =20 /* Are we at first interrupt nesting level? */ - nesting =3D __this_cpu_read(rcu_data.dynticks_nmi_nesting); + nesting =3D __this_cpu_read(context_tracking.dynticks_nmi_nesting); if (nesting > 1) return false; =20 @@ -617,11 +616,10 @@ EXPORT_SYMBOL_GPL(rcutorture_get_gp_data); */ static noinstr void rcu_eqs_enter(bool user) { - struct rcu_data *rdp =3D this_cpu_ptr(&rcu_data); struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); =20 - WARN_ON_ONCE(rdp->dynticks_nmi_nesting !=3D DYNTICK_IRQ_NONIDLE); - WRITE_ONCE(rdp->dynticks_nmi_nesting, 0); + WARN_ON_ONCE(ct->dynticks_nmi_nesting !=3D DYNTICK_IRQ_NONIDLE); + WRITE_ONCE(ct->dynticks_nmi_nesting, 0); WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && ct->dynticks_nesting =3D=3D 0); if (ct->dynticks_nesting !=3D 1) { @@ -739,7 +737,7 @@ noinstr void rcu_user_enter(void) * rcu_nmi_exit - inform RCU of exit from NMI context * * If we are returning from the outermost NMI handler that interrupted an - * RCU-idle period, update ct->dynticks and rdp->dynticks_nmi_nesting + * RCU-idle period, update ct->dynticks and ct->dynticks_nmi_nesting * to let the RCU grace-period handling know that the CPU is back to * being RCU-idle. * @@ -749,7 +747,6 @@ noinstr void rcu_user_enter(void) noinstr void rcu_nmi_exit(void) { struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); - struct rcu_data *rdp =3D this_cpu_ptr(&rcu_data); =20 instrumentation_begin(); /* @@ -757,25 +754,25 @@ noinstr void rcu_nmi_exit(void) * (We are exiting an NMI handler, so RCU better be paying attention * to us!) */ - WARN_ON_ONCE(rdp->dynticks_nmi_nesting <=3D 0); + WARN_ON_ONCE(ct->dynticks_nmi_nesting <=3D 0); WARN_ON_ONCE(rcu_dynticks_curr_cpu_in_eqs()); =20 /* * If the nesting level is not 1, the CPU wasn't RCU-idle, so * leave it in non-RCU-idle state. */ - if (rdp->dynticks_nmi_nesting !=3D 1) { - trace_rcu_dyntick(TPS("--=3D"), rdp->dynticks_nmi_nesting, rdp->dynticks= _nmi_nesting - 2, + if (ct->dynticks_nmi_nesting !=3D 1) { + trace_rcu_dyntick(TPS("--=3D"), ct->dynticks_nmi_nesting, ct->dynticks_n= mi_nesting - 2, atomic_read(&ct->dynticks)); - WRITE_ONCE(rdp->dynticks_nmi_nesting, /* No store tearing. */ - rdp->dynticks_nmi_nesting - 2); + WRITE_ONCE(ct->dynticks_nmi_nesting, /* No store tearing. */ + ct->dynticks_nmi_nesting - 2); instrumentation_end(); return; } =20 /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */ - trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nmi_nesting, 0, atomic_r= ead(&ct->dynticks)); - WRITE_ONCE(rdp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */ + trace_rcu_dyntick(TPS("Startirq"), ct->dynticks_nmi_nesting, 0, atomic_re= ad(&ct->dynticks)); + WRITE_ONCE(ct->dynticks_nmi_nesting, 0); /* Avoid store tearing. */ =20 // instrumentation for the noinstr rcu_dynticks_eqs_enter() instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); @@ -799,7 +796,7 @@ void rcu_irq_exit_check_preempt(void) =20 RCU_LOCKDEP_WARN(__this_cpu_read(context_tracking.dynticks_nesting) <=3D = 0, "RCU dynticks_nesting counter underflow/zero!"); - RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) !=3D + RCU_LOCKDEP_WARN(__this_cpu_read(context_tracking.dynticks_nmi_nesting) != =3D DYNTICK_IRQ_NONIDLE, "Bad RCU dynticks_nmi_nesting counter\n"); RCU_LOCKDEP_WARN(rcu_dynticks_curr_cpu_in_eqs(), @@ -818,11 +815,9 @@ void rcu_irq_exit_check_preempt(void) static void noinstr rcu_eqs_exit(bool user) { struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); - struct rcu_data *rdp; long oldval; =20 lockdep_assert_irqs_disabled(); - rdp =3D this_cpu_ptr(&rcu_data); oldval =3D ct->dynticks_nesting; WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0); if (oldval) { @@ -842,8 +837,8 @@ static void noinstr rcu_eqs_exit(bool user) trace_rcu_dyntick(TPS("End"), ct->dynticks_nesting, 1, atomic_read(&ct->d= ynticks)); WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(c= urrent)); WRITE_ONCE(ct->dynticks_nesting, 1); - WARN_ON_ONCE(rdp->dynticks_nmi_nesting); - WRITE_ONCE(rdp->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE); + WARN_ON_ONCE(ct->dynticks_nmi_nesting); + WRITE_ONCE(ct->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE); instrumentation_end(); } =20 @@ -946,7 +941,7 @@ void __rcu_irq_enter_check_tick(void) * rcu_nmi_enter - inform RCU of entry to NMI context * * If the CPU was idle from RCU's viewpoint, update ct->dynticks and - * rdp->dynticks_nmi_nesting to let the RCU grace-period handling know + * ct->dynticks_nmi_nesting to let the RCU grace-period handling know * that the CPU is active. This implementation permits nested NMIs, as * long as the nesting level does not overflow an int. (You will probably * run out of stack space first.) @@ -957,11 +952,10 @@ void __rcu_irq_enter_check_tick(void) noinstr void rcu_nmi_enter(void) { long incby =3D 2; - struct rcu_data *rdp =3D this_cpu_ptr(&rcu_data); struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); =20 /* Complain about underflow. */ - WARN_ON_ONCE(rdp->dynticks_nmi_nesting < 0); + WARN_ON_ONCE(ct->dynticks_nmi_nesting < 0); =20 /* * If idle from RCU viewpoint, atomically increment ->dynticks @@ -995,11 +989,11 @@ noinstr void rcu_nmi_enter(void) } =20 trace_rcu_dyntick(incby =3D=3D 1 ? TPS("Endirq") : TPS("++=3D"), - rdp->dynticks_nmi_nesting, - rdp->dynticks_nmi_nesting + incby, atomic_read(&ct->dynticks)); + ct->dynticks_nmi_nesting, + ct->dynticks_nmi_nesting + incby, atomic_read(&ct->dynticks)); instrumentation_end(); - WRITE_ONCE(rdp->dynticks_nmi_nesting, /* Prevent store tearing. */ - rdp->dynticks_nmi_nesting + incby); + WRITE_ONCE(ct->dynticks_nmi_nesting, /* Prevent store tearing. */ + ct->dynticks_nmi_nesting + incby); barrier(); } =20 diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 8050bab08f39..56d38568292b 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -186,7 +186,6 @@ struct rcu_data { =20 /* 3) dynticks interface. */ int dynticks_snap; /* Per-GP tracking for dynticks. */ - long dynticks_nmi_nesting; /* Track irq/NMI nesting level. */ bool rcu_need_heavy_qs; /* GP old, so heavy quiescent state! */ bool rcu_urgent_qs; /* GP old need light quiescent state. */ bool rcu_forced_tick; /* Forced tick to provide QS. */ diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index 30a5e0a8ddb3..9bf5cc79d5eb 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -460,7 +460,7 @@ static void print_cpu_stall_info(int cpu) "!."[!delta], ticks_value, ticks_title, rcu_dynticks_snap(cpu) & 0xfff, - ct->dynticks_nesting, rdp->dynticks_nmi_nesting, + ct->dynticks_nesting, ct->dynticks_nmi_nesting, rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu), data_race(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart, falsepositive ? " (false positive?)" : ""); --=20 2.25.1 From nobody Tue Jun 23 16:12:04 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0F7B0C433F5 for ; Wed, 2 Mar 2022 15:49:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241112AbiCBPuf (ORCPT ); Wed, 2 Mar 2022 10:50:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54472 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242436AbiCBPuL (ORCPT ); Wed, 2 Mar 2022 10:50:11 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DCD3E48E66 for ; Wed, 2 Mar 2022 07:49:06 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D75DB61735 for ; Wed, 2 Mar 2022 15:49:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A09CC004E1; Wed, 2 Mar 2022 15:49:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646236145; bh=2VDUvcEwCsllnDBe7ipIo2e+Ud0/ufJ0n1ICl+dEAtM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VsG2+xVCpCoAVWqgWfvgs7rkNLIx+ua/P3troHf6UzPuLYrUGUTv01nH0qyWDjCif YUvWJtqKWLvAD39h9qgVSS99CErge3C9+Hz8Wt67w5tjtc2IVsjla4WnU+4x6/dxbP dv5lkptgABolUNEcSMtFduKji1D+g+P0yxRFf9CbkFawDPHlUBKk77lT0Dc95m0TEr Ovaojr9ieZVfkbuvcBNssBTwUXHPXSMV4udB6RsCiMN62/cYkn1+Hr6uqNCMaIYe2s vfi0PAaziTlubAlcAmNAJ6yexRags+h5/c+Fl5x9OAQuY4cGm/Zy6Id4pee+6aXCbW 4ABOkFaPlMnUw== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: [PATCH 13/19] rcu/context-tracking: Move deferred nocb resched to context tracking Date: Wed, 2 Mar 2022 16:48:04 +0100 Message-Id: <20220302154810.42308-14-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220302154810.42308-1-frederic@kernel.org> References: <20220302154810.42308-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" To prepare for migrating the RCU eqs accounting code to context tracking, split the last-resort deferred nocb resched from rcu_user_enter() and move it into a separate call from context tracking. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits Acked-by: Paul E. McKenney --- include/linux/rcutree.h | 6 ++++++ kernel/context_tracking.c | 8 ++++++++ kernel/rcu/tree.c | 15 ++------------- 3 files changed, 16 insertions(+), 13 deletions(-) diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index e05334c4c3d1..6d111a3c0cc0 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -78,4 +78,10 @@ int rcutree_dead_cpu(unsigned int cpu); int rcutree_dying_cpu(unsigned int cpu); void rcu_cpu_starting(unsigned int cpu); =20 +#if defined(CONFIG_NO_HZ_FULL) && (!defined(CONFIG_GENERIC_ENTRY) || !defi= ned(CONFIG_KVM_XFER_TO_GUEST_WORK)) +void rcu_irq_work_resched(void); +#else +static inline void rcu_irq_work_resched(void) { } +#endif + #endif /* __LINUX_RCUTREE_H */ diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index 155534c409fc..7be7a2044d3a 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -60,6 +60,8 @@ static __always_inline void context_tracking_recursion_ex= it(void) */ void noinstr __ct_user_enter(enum ctx_state state) { + lockdep_assert_irqs_disabled(); + /* Kernel threads aren't supposed to go to userspace */ WARN_ON_ONCE(!current->mm); =20 @@ -81,6 +83,12 @@ void noinstr __ct_user_enter(enum ctx_state state) vtime_user_enter(current); instrumentation_end(); } + /* + * Other than generic entry implementation, we may be past the last + * rescheduling opportunity in the entry code. Trigger a self IPI + * that will fire and reschedule once we resume in user/guest mode. + */ + rcu_irq_work_resched(); rcu_user_enter(); } /* diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index c2528e65de0c..938537958c27 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -686,7 +686,7 @@ static DEFINE_PER_CPU(struct irq_work, late_wakeup_work= ) =3D * last resort is to fire a local irq_work that will trigger a reschedule = once IRQs * get re-enabled again. */ -noinstr static void rcu_irq_work_resched(void) +noinstr void rcu_irq_work_resched(void) { struct rcu_data *rdp =3D this_cpu_ptr(&rcu_data); =20 @@ -702,10 +702,7 @@ noinstr static void rcu_irq_work_resched(void) } instrumentation_end(); } - -#else -static inline void rcu_irq_work_resched(void) { } -#endif +#endif /* #if !defined(CONFIG_GENERIC_ENTRY) || !defined(CONFIG_KVM_XFER_T= O_GUEST_WORK) */ =20 /** * rcu_user_enter - inform RCU that we are resuming userspace. @@ -720,14 +717,6 @@ static inline void rcu_irq_work_resched(void) { } */ noinstr void rcu_user_enter(void) { - lockdep_assert_irqs_disabled(); - - /* - * Other than generic entry implementation, we may be past the last - * rescheduling opportunity in the entry code. Trigger a self IPI - * that will fire and reschedule once we resume in user/guest mode. - */ - rcu_irq_work_resched(); rcu_eqs_enter(true); } =20 --=20 2.25.1 From nobody Tue Jun 23 16:12:04 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AFBDAC433FE for ; Wed, 2 Mar 2022 15:49:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240271AbiCBPub (ORCPT ); Wed, 2 Mar 2022 10:50:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57852 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242513AbiCBPuL (ORCPT ); Wed, 2 Mar 2022 10:50:11 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 493E54C406 for ; Wed, 2 Mar 2022 07:49:09 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 801E961729 for ; Wed, 2 Mar 2022 15:49:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B9AB5C340F2; Wed, 2 Mar 2022 15:49:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646236148; bh=7gBvhA6lrIdtZSAOppL+ZBogD5zkwFsHRazqfS0lyDE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fqnHc6bfUexak1x4irpU1niXD8goQrqh8vfN2e3xy+Pj4zGOR7dSnVAxcfF0a1u8b Xtu2WBjcuVbDsaUQWrkdjeDJVHRj130b+eqMlxyJrUhn3yf6niz8NZJWfHz6elMKyP YLq1+yiOKPtHrORP0ZUzhbjY4h0R3QmaIEhAhsYsrZROoNcegu2h8R/quYaz32usKn YqjUq2e1RY7T6BSbS6ONeO9lWhpV3r4DwSH8NMeDoOHjCu0OpkD7lPMfe3+4g+2922 aBtjr4Eerxio7O3i/tYWFzy3cQepfrw+YZZPjO4RFmpAkyMOPnMjArqp8+i0urGjlc WwxbTstEbaYRg== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: [PATCH 14/19] rcu/context-tracking: Move RCU-dynticks internal functions to context_tracking Date: Wed, 2 Mar 2022 16:48:05 +0100 Message-Id: <20220302154810.42308-15-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220302154810.42308-1-frederic@kernel.org> References: <20220302154810.42308-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Move the core RCU eqs/dynticks functions to context tracking so that we can later merge all that code within context tracking. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits Acked-by: Paul E. McKenney --- include/linux/context_tracking.h | 12 ++ include/linux/rcutree.h | 3 + kernel/context_tracking.c | 347 +++++++++++++++++++++++++++++++ kernel/rcu/tree.c | 326 +---------------------------- kernel/rcu/tree.h | 5 - kernel/rcu/tree_plugin.h | 36 +--- 6 files changed, 366 insertions(+), 363 deletions(-) diff --git a/include/linux/context_tracking.h b/include/linux/context_track= ing.h index 52a2e23d5107..086546569d14 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -122,6 +122,18 @@ static inline void context_tracking_init(void) { } #ifdef CONFIG_CONTEXT_TRACKING extern void ct_idle_enter(void); extern void ct_idle_exit(void); +extern unsigned long rcu_dynticks_inc(int incby); + +/* + * Is the current CPU in an extended quiescent state? + * + * No ordering, as we are sampling CPU-local information. + */ +static __always_inline bool rcu_dynticks_curr_cpu_in_eqs(void) +{ + return !(arch_atomic_read(this_cpu_ptr(&context_tracking.dynticks)) & 0x1= ); +} + #else static inline void ct_idle_enter(void) { } static inline void ct_idle_exit(void) { } diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index 6d111a3c0cc0..408435ff7a06 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -59,6 +59,9 @@ void rcu_irq_exit_check_preempt(void); static inline void rcu_irq_exit_check_preempt(void) { } #endif =20 +struct task_struct; +void rcu_preempt_deferred_qs(struct task_struct *t); + void exit_rcu(void); =20 void rcu_scheduler_starting(void); diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index 7be7a2044d3a..dc24a9782bbd 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -21,6 +21,353 @@ #include #include #include +#include + +#define TPS(x) tracepoint_string(x) + +/* Record the current task on dyntick-idle entry. */ +static __always_inline void rcu_dynticks_task_enter(void) +{ +#if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) + WRITE_ONCE(current->rcu_tasks_idle_cpu, smp_processor_id()); +#endif /* #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) */ +} + +/* Record no current task on dyntick-idle exit. */ +static __always_inline void rcu_dynticks_task_exit(void) +{ +#if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) + WRITE_ONCE(current->rcu_tasks_idle_cpu, -1); +#endif /* #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) */ +} + +/* Turn on heavyweight RCU tasks trace readers on idle/user entry. */ +static __always_inline void rcu_dynticks_task_trace_enter(void) +{ +#ifdef CONFIG_TASKS_TRACE_RCU + if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB)) + current->trc_reader_special.b.need_mb =3D true; +#endif /* #ifdef CONFIG_TASKS_TRACE_RCU */ +} + +/* Turn off heavyweight RCU tasks trace readers on idle/user exit. */ +static __always_inline void rcu_dynticks_task_trace_exit(void) +{ +#ifdef CONFIG_TASKS_TRACE_RCU + if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB)) + current->trc_reader_special.b.need_mb =3D false; +#endif /* #ifdef CONFIG_TASKS_TRACE_RCU */ +} + +/* + * Increment the current CPU's context_tracking structure's ->dynticks fie= ld + * with ordering. Return the new value. + */ +noinstr unsigned long rcu_dynticks_inc(int incby) +{ + return arch_atomic_add_return(incby, this_cpu_ptr(&context_tracking.dynti= cks)); +} + +/* + * Record entry into an extended quiescent state. This is only to be + * called when not already in an extended quiescent state, that is, + * RCU is watching prior to the call to this function and is no longer + * watching upon return. + */ +static noinstr void rcu_dynticks_eqs_enter(void) +{ + int seq; + + /* + * CPUs seeing atomic_add_return() must see prior RCU read-side + * critical sections, and we also must force ordering with the + * next idle sojourn. + */ + rcu_dynticks_task_trace_enter(); // Before ->dynticks update! + seq =3D rcu_dynticks_inc(1); + // RCU is no longer watching. Better be in extended quiescent state! + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && (seq & 0x1)); +} + +/* + * Record exit from an extended quiescent state. This is only to be + * called from an extended quiescent state, that is, RCU is not watching + * prior to the call to this function and is watching upon return. + */ +static noinstr void rcu_dynticks_eqs_exit(void) +{ + int seq; + + /* + * CPUs seeing atomic_add_return() must see prior idle sojourns, + * and we also must force ordering with the next RCU read-side + * critical section. + */ + seq =3D rcu_dynticks_inc(1); + // RCU is now watching. Better not be in an extended quiescent state! + rcu_dynticks_task_trace_exit(); // After ->dynticks update! + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !(seq & 0x1)); +} + +/* + * Enter an RCU extended quiescent state, which can be either the + * idle loop or adaptive-tickless usermode execution. + * + * We crowbar the ->dynticks_nmi_nesting field to zero to allow for + * the possibility of usermode upcalls having messed up our count + * of interrupt nesting level during the prior busy period. + */ +static noinstr void rcu_eqs_enter(bool user) +{ + struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); + + WARN_ON_ONCE(ct->dynticks_nmi_nesting !=3D DYNTICK_IRQ_NONIDLE); + WRITE_ONCE(ct->dynticks_nmi_nesting, 0); + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && + ct->dynticks_nesting =3D=3D 0); + if (ct->dynticks_nesting !=3D 1) { + // RCU will still be watching, so just do accounting and leave. + ct->dynticks_nesting--; + return; + } + + lockdep_assert_irqs_disabled(); + instrumentation_begin(); + trace_rcu_dyntick(TPS("Start"), ct->dynticks_nesting, 0, atomic_read(&ct-= >dynticks)); + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(c= urrent)); + rcu_preempt_deferred_qs(current); + + // instrumentation for the noinstr rcu_dynticks_eqs_enter() + instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); + + instrumentation_end(); + WRITE_ONCE(ct->dynticks_nesting, 0); /* Avoid irq-access tearing. */ + // RCU is watching here ... + rcu_dynticks_eqs_enter(); + // ... but is no longer watching here. + rcu_dynticks_task_enter(); +} + +/** + * rcu_idle_enter - inform RCU that current CPU is entering idle + * + * Enter idle mode, in other words, -leave- the mode in which RCU + * read-side critical sections can occur. (Though RCU read-side + * critical sections can occur in irq handlers in idle, a possibility + * handled by irq_enter() and irq_exit().) + * + * If you add or remove a call to rcu_idle_enter(), be sure to test with + * CONFIG_RCU_EQS_DEBUG=3Dy. + */ +void rcu_idle_enter(void) +{ + lockdep_assert_irqs_disabled(); + rcu_eqs_enter(false); +} + +#ifdef CONFIG_NO_HZ_FULL +/** + * rcu_user_enter - inform RCU that we are resuming userspace. + * + * Enter RCU idle mode right before resuming userspace. No use of RCU + * is permitted between this call and rcu_user_exit(). This way the + * CPU doesn't need to maintain the tick for RCU maintenance purposes + * when the CPU runs in userspace. + * + * If you add or remove a call to rcu_user_enter(), be sure to test with + * CONFIG_RCU_EQS_DEBUG=3Dy. + */ +noinstr void rcu_user_enter(void) +{ + rcu_eqs_enter(true); +} +#endif /* CONFIG_NO_HZ_FULL */ + +/** + * rcu_nmi_exit - inform RCU of exit from NMI context + * + * If we are returning from the outermost NMI handler that interrupted an + * RCU-idle period, update ct->dynticks and ct->dynticks_nmi_nesting + * to let the RCU grace-period handling know that the CPU is back to + * being RCU-idle. + * + * If you add or remove a call to rcu_nmi_exit(), be sure to test + * with CONFIG_RCU_EQS_DEBUG=3Dy. + */ +noinstr void rcu_nmi_exit(void) +{ + struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); + + instrumentation_begin(); + /* + * Check for ->dynticks_nmi_nesting underflow and bad ->dynticks. + * (We are exiting an NMI handler, so RCU better be paying attention + * to us!) + */ + WARN_ON_ONCE(ct->dynticks_nmi_nesting <=3D 0); + WARN_ON_ONCE(rcu_dynticks_curr_cpu_in_eqs()); + + /* + * If the nesting level is not 1, the CPU wasn't RCU-idle, so + * leave it in non-RCU-idle state. + */ + if (ct->dynticks_nmi_nesting !=3D 1) { + trace_rcu_dyntick(TPS("--=3D"), ct->dynticks_nmi_nesting, ct->dynticks_n= mi_nesting - 2, + atomic_read(&ct->dynticks)); + WRITE_ONCE(ct->dynticks_nmi_nesting, /* No store tearing. */ + ct->dynticks_nmi_nesting - 2); + instrumentation_end(); + return; + } + + /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */ + trace_rcu_dyntick(TPS("Startirq"), ct->dynticks_nmi_nesting, 0, atomic_re= ad(&ct->dynticks)); + WRITE_ONCE(ct->dynticks_nmi_nesting, 0); /* Avoid store tearing. */ + + // instrumentation for the noinstr rcu_dynticks_eqs_enter() + instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); + instrumentation_end(); + + // RCU is watching here ... + rcu_dynticks_eqs_enter(); + // ... but is no longer watching here. + + if (!in_nmi()) + rcu_dynticks_task_enter(); +} + +/* + * Exit an RCU extended quiescent state, which can be either the + * idle loop or adaptive-tickless usermode execution. + * + * We crowbar the ->dynticks_nmi_nesting field to DYNTICK_IRQ_NONIDLE to + * allow for the possibility of usermode upcalls messing up our count of + * interrupt nesting level during the busy period that is just now startin= g. + */ +static void noinstr rcu_eqs_exit(bool user) +{ + struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); + long oldval; + + lockdep_assert_irqs_disabled(); + oldval =3D ct->dynticks_nesting; + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0); + if (oldval) { + // RCU was already watching, so just do accounting and leave. + ct->dynticks_nesting++; + return; + } + rcu_dynticks_task_exit(); + // RCU is not watching here ... + rcu_dynticks_eqs_exit(); + // ... but is watching here. + instrumentation_begin(); + + // instrumentation for the noinstr rcu_dynticks_eqs_exit() + instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); + + trace_rcu_dyntick(TPS("End"), ct->dynticks_nesting, 1, atomic_read(&ct->d= ynticks)); + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(c= urrent)); + WRITE_ONCE(ct->dynticks_nesting, 1); + WARN_ON_ONCE(ct->dynticks_nmi_nesting); + WRITE_ONCE(ct->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE); + instrumentation_end(); +} + +/** + * rcu_idle_exit - inform RCU that current CPU is leaving idle + * + * Exit idle mode, in other words, -enter- the mode in which RCU + * read-side critical sections can occur. + * + * If you add or remove a call to rcu_idle_exit(), be sure to test with + * CONFIG_RCU_EQS_DEBUG=3Dy. + */ +void rcu_idle_exit(void) +{ + unsigned long flags; + + local_irq_save(flags); + rcu_eqs_exit(false); + local_irq_restore(flags); +} +EXPORT_SYMBOL_GPL(rcu_idle_exit); + +#ifdef CONFIG_NO_HZ_FULL +/** + * rcu_user_exit - inform RCU that we are exiting userspace. + * + * Exit RCU idle mode while entering the kernel because it can + * run a RCU read side critical section anytime. + * + * If you add or remove a call to rcu_user_exit(), be sure to test with + * CONFIG_RCU_EQS_DEBUG=3Dy. + */ +void noinstr rcu_user_exit(void) +{ + rcu_eqs_exit(true); +} +#endif /* ifdef CONFIG_NO_HZ_FULL */ + +/** + * rcu_nmi_enter - inform RCU of entry to NMI context + * + * If the CPU was idle from RCU's viewpoint, update ct->dynticks and + * ct->dynticks_nmi_nesting to let the RCU grace-period handling know + * that the CPU is active. This implementation permits nested NMIs, as + * long as the nesting level does not overflow an int. (You will probably + * run out of stack space first.) + * + * If you add or remove a call to rcu_nmi_enter(), be sure to test + * with CONFIG_RCU_EQS_DEBUG=3Dy. + */ +noinstr void rcu_nmi_enter(void) +{ + long incby =3D 2; + struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); + + /* Complain about underflow. */ + WARN_ON_ONCE(ct->dynticks_nmi_nesting < 0); + + /* + * If idle from RCU viewpoint, atomically increment ->dynticks + * to mark non-idle and increment ->dynticks_nmi_nesting by one. + * Otherwise, increment ->dynticks_nmi_nesting by two. This means + * if ->dynticks_nmi_nesting is equal to one, we are guaranteed + * to be in the outermost NMI handler that interrupted an RCU-idle + * period (observation due to Andy Lutomirski). + */ + if (rcu_dynticks_curr_cpu_in_eqs()) { + + if (!in_nmi()) + rcu_dynticks_task_exit(); + + // RCU is not watching here ... + rcu_dynticks_eqs_exit(); + // ... but is watching here. + + instrumentation_begin(); + // instrumentation for the noinstr rcu_dynticks_curr_cpu_in_eqs() + instrument_atomic_read(&ct->dynticks, sizeof(ct->dynticks)); + // instrumentation for the noinstr rcu_dynticks_eqs_exit() + instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); + + incby =3D 1; + } else if (!in_nmi()) { + instrumentation_begin(); + rcu_irq_enter_check_tick(); + } else { + instrumentation_begin(); + } + + trace_rcu_dyntick(incby =3D=3D 1 ? TPS("Endirq") : TPS("++=3D"), + ct->dynticks_nmi_nesting, + ct->dynticks_nmi_nesting + incby, atomic_read(&ct->dynticks)); + instrumentation_end(); + WRITE_ONCE(ct->dynticks_nmi_nesting, /* Prevent store tearing. */ + ct->dynticks_nmi_nesting + incby); + barrier(); +} =20 #ifdef CONFIG_CONTEXT_TRACKING_USER =20 diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 938537958c27..e55a44ed19b6 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -62,6 +62,7 @@ #include #include #include +#include #include "../time/tick-internal.h" =20 #include "tree.h" @@ -259,56 +260,6 @@ void rcu_softirq_qs(void) rcu_tasks_qs(current, false); } =20 -/* - * Increment the current CPU's rcu_data structure's ->dynticks field - * with ordering. Return the new value. - */ -static noinline noinstr unsigned long rcu_dynticks_inc(int incby) -{ - return arch_atomic_add_return(incby, this_cpu_ptr(&context_tracking.dynti= cks)); -} - -/* - * Record entry into an extended quiescent state. This is only to be - * called when not already in an extended quiescent state, that is, - * RCU is watching prior to the call to this function and is no longer - * watching upon return. - */ -static noinstr void rcu_dynticks_eqs_enter(void) -{ - int seq; - - /* - * CPUs seeing atomic_add_return() must see prior RCU read-side - * critical sections, and we also must force ordering with the - * next idle sojourn. - */ - rcu_dynticks_task_trace_enter(); // Before ->dynticks update! - seq =3D rcu_dynticks_inc(1); - // RCU is no longer watching. Better be in extended quiescent state! - WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && (seq & 0x1)); -} - -/* - * Record exit from an extended quiescent state. This is only to be - * called from an extended quiescent state, that is, RCU is not watching - * prior to the call to this function and is watching upon return. - */ -static noinstr void rcu_dynticks_eqs_exit(void) -{ - int seq; - - /* - * CPUs seeing atomic_add_return() must see prior idle sojourns, - * and we also must force ordering with the next RCU read-side - * critical section. - */ - seq =3D rcu_dynticks_inc(1); - // RCU is now watching. Better not be in an extended quiescent state! - rcu_dynticks_task_trace_exit(); // After ->dynticks update! - WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !(seq & 0x1)); -} - /* * Reset the current CPU's ->dynticks counter to indicate that the * newly onlined CPU is no longer in an extended quiescent state. @@ -328,16 +279,6 @@ static void rcu_dynticks_eqs_online(void) rcu_dynticks_inc(1); } =20 -/* - * Is the current CPU in an extended quiescent state? - * - * No ordering, as we are sampling CPU-local information. - */ -static __always_inline bool rcu_dynticks_curr_cpu_in_eqs(void) -{ - return !(arch_atomic_read(this_cpu_ptr(&context_tracking.dynticks)) & 0x1= ); -} - /* * Snapshot the ->dynticks counter with full ordering so as to allow * stable comparison of this counter with past and future snapshots. @@ -606,65 +547,7 @@ void rcutorture_get_gp_data(enum rcutorture_type test_= type, int *flags, } EXPORT_SYMBOL_GPL(rcutorture_get_gp_data); =20 -/* - * Enter an RCU extended quiescent state, which can be either the - * idle loop or adaptive-tickless usermode execution. - * - * We crowbar the ->dynticks_nmi_nesting field to zero to allow for - * the possibility of usermode upcalls having messed up our count - * of interrupt nesting level during the prior busy period. - */ -static noinstr void rcu_eqs_enter(bool user) -{ - struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); - - WARN_ON_ONCE(ct->dynticks_nmi_nesting !=3D DYNTICK_IRQ_NONIDLE); - WRITE_ONCE(ct->dynticks_nmi_nesting, 0); - WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && - ct->dynticks_nesting =3D=3D 0); - if (ct->dynticks_nesting !=3D 1) { - // RCU will still be watching, so just do accounting and leave. - ct->dynticks_nesting--; - return; - } - - lockdep_assert_irqs_disabled(); - instrumentation_begin(); - trace_rcu_dyntick(TPS("Start"), ct->dynticks_nesting, 0, atomic_read(&ct-= >dynticks)); - WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(c= urrent)); - rcu_preempt_deferred_qs(current); - - // instrumentation for the noinstr rcu_dynticks_eqs_enter() - instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); - - instrumentation_end(); - WRITE_ONCE(ct->dynticks_nesting, 0); /* Avoid irq-access tearing. */ - // RCU is watching here ... - rcu_dynticks_eqs_enter(); - // ... but is no longer watching here. - rcu_dynticks_task_enter(); -} - -/** - * rcu_idle_enter - inform RCU that current CPU is entering idle - * - * Enter idle mode, in other words, -leave- the mode in which RCU - * read-side critical sections can occur. (Though RCU read-side - * critical sections can occur in irq handlers in idle, a possibility - * handled by irq_enter() and irq_exit().) - * - * If you add or remove a call to rcu_idle_enter(), be sure to test with - * CONFIG_RCU_EQS_DEBUG=3Dy. - */ -void rcu_idle_enter(void) -{ - lockdep_assert_irqs_disabled(); - rcu_eqs_enter(false); -} - -#ifdef CONFIG_NO_HZ_FULL - -#if !defined(CONFIG_GENERIC_ENTRY) || !defined(CONFIG_KVM_XFER_TO_GUEST_WO= RK) +#if defined(CONFIG_NO_HZ_FULL) && (!defined(CONFIG_GENERIC_ENTRY) || !defi= ned(CONFIG_KVM_XFER_TO_GUEST_WORK)) /* * An empty function that will trigger a reschedule on * IRQ tail once IRQs get re-enabled on userspace/guest resume. @@ -702,78 +585,7 @@ noinstr void rcu_irq_work_resched(void) } instrumentation_end(); } -#endif /* #if !defined(CONFIG_GENERIC_ENTRY) || !defined(CONFIG_KVM_XFER_T= O_GUEST_WORK) */ - -/** - * rcu_user_enter - inform RCU that we are resuming userspace. - * - * Enter RCU idle mode right before resuming userspace. No use of RCU - * is permitted between this call and rcu_user_exit(). This way the - * CPU doesn't need to maintain the tick for RCU maintenance purposes - * when the CPU runs in userspace. - * - * If you add or remove a call to rcu_user_enter(), be sure to test with - * CONFIG_RCU_EQS_DEBUG=3Dy. - */ -noinstr void rcu_user_enter(void) -{ - rcu_eqs_enter(true); -} - -#endif /* CONFIG_NO_HZ_FULL */ - -/** - * rcu_nmi_exit - inform RCU of exit from NMI context - * - * If we are returning from the outermost NMI handler that interrupted an - * RCU-idle period, update ct->dynticks and ct->dynticks_nmi_nesting - * to let the RCU grace-period handling know that the CPU is back to - * being RCU-idle. - * - * If you add or remove a call to rcu_nmi_exit(), be sure to test - * with CONFIG_RCU_EQS_DEBUG=3Dy. - */ -noinstr void rcu_nmi_exit(void) -{ - struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); - - instrumentation_begin(); - /* - * Check for ->dynticks_nmi_nesting underflow and bad ->dynticks. - * (We are exiting an NMI handler, so RCU better be paying attention - * to us!) - */ - WARN_ON_ONCE(ct->dynticks_nmi_nesting <=3D 0); - WARN_ON_ONCE(rcu_dynticks_curr_cpu_in_eqs()); - - /* - * If the nesting level is not 1, the CPU wasn't RCU-idle, so - * leave it in non-RCU-idle state. - */ - if (ct->dynticks_nmi_nesting !=3D 1) { - trace_rcu_dyntick(TPS("--=3D"), ct->dynticks_nmi_nesting, ct->dynticks_n= mi_nesting - 2, - atomic_read(&ct->dynticks)); - WRITE_ONCE(ct->dynticks_nmi_nesting, /* No store tearing. */ - ct->dynticks_nmi_nesting - 2); - instrumentation_end(); - return; - } - - /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */ - trace_rcu_dyntick(TPS("Startirq"), ct->dynticks_nmi_nesting, 0, atomic_re= ad(&ct->dynticks)); - WRITE_ONCE(ct->dynticks_nmi_nesting, 0); /* Avoid store tearing. */ - - // instrumentation for the noinstr rcu_dynticks_eqs_enter() - instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); - instrumentation_end(); - - // RCU is watching here ... - rcu_dynticks_eqs_enter(); - // ... but is no longer watching here. - - if (!in_nmi()) - rcu_dynticks_task_enter(); -} +#endif /* #if defined(CONFIG_NO_HZ_FULL) && (!defined(CONFIG_GENERIC_ENTRY= ) || !defined(CONFIG_KVM_XFER_TO_GUEST_WORK)) */ =20 #ifdef CONFIG_PROVE_RCU /** @@ -793,77 +605,6 @@ void rcu_irq_exit_check_preempt(void) } #endif /* #ifdef CONFIG_PROVE_RCU */ =20 -/* - * Exit an RCU extended quiescent state, which can be either the - * idle loop or adaptive-tickless usermode execution. - * - * We crowbar the ->dynticks_nmi_nesting field to DYNTICK_IRQ_NONIDLE to - * allow for the possibility of usermode upcalls messing up our count of - * interrupt nesting level during the busy period that is just now startin= g. - */ -static void noinstr rcu_eqs_exit(bool user) -{ - struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); - long oldval; - - lockdep_assert_irqs_disabled(); - oldval =3D ct->dynticks_nesting; - WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0); - if (oldval) { - // RCU was already watching, so just do accounting and leave. - ct->dynticks_nesting++; - return; - } - rcu_dynticks_task_exit(); - // RCU is not watching here ... - rcu_dynticks_eqs_exit(); - // ... but is watching here. - instrumentation_begin(); - - // instrumentation for the noinstr rcu_dynticks_eqs_exit() - instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); - - trace_rcu_dyntick(TPS("End"), ct->dynticks_nesting, 1, atomic_read(&ct->d= ynticks)); - WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(c= urrent)); - WRITE_ONCE(ct->dynticks_nesting, 1); - WARN_ON_ONCE(ct->dynticks_nmi_nesting); - WRITE_ONCE(ct->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE); - instrumentation_end(); -} - -/** - * rcu_idle_exit - inform RCU that current CPU is leaving idle - * - * Exit idle mode, in other words, -enter- the mode in which RCU - * read-side critical sections can occur. - * - * If you add or remove a call to rcu_idle_exit(), be sure to test with - * CONFIG_RCU_EQS_DEBUG=3Dy. - */ -void rcu_idle_exit(void) -{ - unsigned long flags; - - local_irq_save(flags); - rcu_eqs_exit(false); - local_irq_restore(flags); -} - -#ifdef CONFIG_NO_HZ_FULL -/** - * rcu_user_exit - inform RCU that we are exiting userspace. - * - * Exit RCU idle mode while entering the kernel because it can - * run a RCU read side critical section anytime. - * - * If you add or remove a call to rcu_user_exit(), be sure to test with - * CONFIG_RCU_EQS_DEBUG=3Dy. - */ -void noinstr rcu_user_exit(void) -{ - rcu_eqs_exit(true); -} - /** * __rcu_irq_enter_check_tick - Enable scheduler tick on CPU if RCU needs = it. * @@ -924,67 +665,6 @@ void __rcu_irq_enter_check_tick(void) } raw_spin_unlock_rcu_node(rdp->mynode); } -#endif /* CONFIG_NO_HZ_FULL */ - -/** - * rcu_nmi_enter - inform RCU of entry to NMI context - * - * If the CPU was idle from RCU's viewpoint, update ct->dynticks and - * ct->dynticks_nmi_nesting to let the RCU grace-period handling know - * that the CPU is active. This implementation permits nested NMIs, as - * long as the nesting level does not overflow an int. (You will probably - * run out of stack space first.) - * - * If you add or remove a call to rcu_nmi_enter(), be sure to test - * with CONFIG_RCU_EQS_DEBUG=3Dy. - */ -noinstr void rcu_nmi_enter(void) -{ - long incby =3D 2; - struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); - - /* Complain about underflow. */ - WARN_ON_ONCE(ct->dynticks_nmi_nesting < 0); - - /* - * If idle from RCU viewpoint, atomically increment ->dynticks - * to mark non-idle and increment ->dynticks_nmi_nesting by one. - * Otherwise, increment ->dynticks_nmi_nesting by two. This means - * if ->dynticks_nmi_nesting is equal to one, we are guaranteed - * to be in the outermost NMI handler that interrupted an RCU-idle - * period (observation due to Andy Lutomirski). - */ - if (rcu_dynticks_curr_cpu_in_eqs()) { - - if (!in_nmi()) - rcu_dynticks_task_exit(); - - // RCU is not watching here ... - rcu_dynticks_eqs_exit(); - // ... but is watching here. - - instrumentation_begin(); - // instrumentation for the noinstr rcu_dynticks_curr_cpu_in_eqs() - instrument_atomic_read(&ct->dynticks, sizeof(ct->dynticks)); - // instrumentation for the noinstr rcu_dynticks_eqs_exit() - instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); - - incby =3D 1; - } else if (!in_nmi()) { - instrumentation_begin(); - rcu_irq_enter_check_tick(); - } else { - instrumentation_begin(); - } - - trace_rcu_dyntick(incby =3D=3D 1 ? TPS("Endirq") : TPS("++=3D"), - ct->dynticks_nmi_nesting, - ct->dynticks_nmi_nesting + incby, atomic_read(&ct->dynticks)); - instrumentation_end(); - WRITE_ONCE(ct->dynticks_nmi_nesting, /* Prevent store tearing. */ - ct->dynticks_nmi_nesting + incby); - barrier(); -} =20 /* * Check to see if any future non-offloaded RCU-related work will need diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 56d38568292b..a42c2a737e24 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -426,7 +426,6 @@ static void rcu_cpu_kthread_setup(unsigned int cpu); static void rcu_spawn_one_boost_kthread(struct rcu_node *rnp); static bool rcu_preempt_has_tasks(struct rcu_node *rnp); static bool rcu_preempt_need_deferred_qs(struct task_struct *t); -static void rcu_preempt_deferred_qs(struct task_struct *t); static void zero_cpu_stall_ticks(struct rcu_data *rdp); static struct swait_queue_head *rcu_nocb_gp_get(struct rcu_node *rnp); static void rcu_nocb_gp_cleanup(struct swait_queue_head *sq); @@ -466,10 +465,6 @@ do { \ =20 static void rcu_bind_gp_kthread(void); static bool rcu_nohz_full_cpu(void); -static void rcu_dynticks_task_enter(void); -static void rcu_dynticks_task_exit(void); -static void rcu_dynticks_task_trace_enter(void); -static void rcu_dynticks_task_trace_exit(void); =20 /* Forward declarations for tree_stall.h */ static void record_gp_stall_check_time(void); diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 6b9bcd45c7b2..be4b74b46109 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -595,7 +595,7 @@ static bool rcu_preempt_need_deferred_qs(struct task_st= ruct *t) * evaluate safety in terms of interrupt, softirq, and preemption * disabling. */ -static void rcu_preempt_deferred_qs(struct task_struct *t) +void rcu_preempt_deferred_qs(struct task_struct *t) { unsigned long flags; =20 @@ -1283,37 +1283,3 @@ static void rcu_bind_gp_kthread(void) return; housekeeping_affine(current, HK_FLAG_RCU); } - -/* Record the current task on dyntick-idle entry. */ -static __always_inline void rcu_dynticks_task_enter(void) -{ -#if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) - WRITE_ONCE(current->rcu_tasks_idle_cpu, smp_processor_id()); -#endif /* #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) */ -} - -/* Record no current task on dyntick-idle exit. */ -static __always_inline void rcu_dynticks_task_exit(void) -{ -#if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) - WRITE_ONCE(current->rcu_tasks_idle_cpu, -1); -#endif /* #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) */ -} - -/* Turn on heavyweight RCU tasks trace readers on idle/user entry. */ -static __always_inline void rcu_dynticks_task_trace_enter(void) -{ -#ifdef CONFIG_TASKS_TRACE_RCU - if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB)) - current->trc_reader_special.b.need_mb =3D true; -#endif /* #ifdef CONFIG_TASKS_TRACE_RCU */ -} - -/* Turn off heavyweight RCU tasks trace readers on idle/user exit. */ -static __always_inline void rcu_dynticks_task_trace_exit(void) -{ -#ifdef CONFIG_TASKS_TRACE_RCU - if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB)) - current->trc_reader_special.b.need_mb =3D false; -#endif /* #ifdef CONFIG_TASKS_TRACE_RCU */ -} --=20 2.25.1 From nobody Tue Jun 23 16:12:04 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4EDD0C433F5 for ; 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s=k20201202; t=1646236152; bh=Br4pxY4VoxIw0HBPSrXMfPZc3KO2Yla/93cf3653wX8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uFkKbokVY/Oyqzit1B8DwKOEtjHoXU+zhwvmWFR1RYNPx9cqToo6/mp+5UvA/wM5O N9igwo89Eiucs+3idowV1I8fmdWkWEaEkpMmKwpkP/w2H6YpnmeU5i2XGU53u/o1BW u+DjYC5EBKBwMrGU9d0Q29qqNUwFzDSXzzlDOMtLvr3XycKx9VkA4yxu/USWnLvP6f 13MIId5sXGucGyhhl2mo/FlS8xu+1XfHeLkli3Q22P0E3qpQMp/SyzTG56t7V8hMTW YmXx3zG54cOyee0q7GTUnPjKIiUh+gKd50dFxsdY30hSz4sy1Iq0BXTWZFjDaU2d8Z Y0N1IYxz0pV/A== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: [PATCH 15/19] rcu/context-tracking: Remove unused and/or unecessary middle functions Date: Wed, 2 Mar 2022 16:48:06 +0100 Message-Id: <20220302154810.42308-16-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220302154810.42308-1-frederic@kernel.org> References: <20220302154810.42308-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Some eqs functions are now only used internally by context tracking, so their public declarations can be removed. Also middle functions such as rcu_user_*() and rcu_idle_*() which now directly call to rcu_eqs_enter() and rcu_eqs_exit() can be wiped out as well. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits --- include/linux/hardirq.h | 8 --- include/linux/rcutiny.h | 2 - include/linux/rcutree.h | 2 - kernel/context_tracking.c | 137 ++++++++++++-------------------------- 4 files changed, 44 insertions(+), 105 deletions(-) diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h index 345cdbe9c1b7..d57cab4d4c06 100644 --- a/include/linux/hardirq.h +++ b/include/linux/hardirq.h @@ -92,14 +92,6 @@ void irq_exit_rcu(void); #define arch_nmi_exit() do { } while (0) #endif =20 -#ifdef CONFIG_TINY_RCU -static inline void rcu_nmi_enter(void) { } -static inline void rcu_nmi_exit(void) { } -#else -extern void rcu_nmi_enter(void); -extern void rcu_nmi_exit(void); -#endif - /* * NMI vs Tracing * -------------- diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h index 9e07f8d9d544..f3326d88693a 100644 --- a/include/linux/rcutiny.h +++ b/include/linux/rcutiny.h @@ -96,8 +96,6 @@ static inline int rcu_needs_cpu(void) static inline void rcu_virt_note_context_switch(int cpu) { } static inline void rcu_cpu_stall_reset(void) { } static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; } -static inline void rcu_idle_enter(void) { } -static inline void rcu_idle_exit(void) { } static inline void rcu_irq_exit_check_preempt(void) { } #define rcu_is_idle_cpu(cpu) \ (is_idle_task(current) && !in_nmi() && !in_hardirq() && !in_serving_softi= rq()) diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index 408435ff7a06..54e84020e7e0 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -49,8 +49,6 @@ unsigned long start_poll_synchronize_rcu(void); bool poll_state_synchronize_rcu(unsigned long oldstate); void cond_synchronize_rcu(unsigned long oldstate); =20 -void rcu_idle_enter(void); -void rcu_idle_exit(void); bool rcu_is_idle_cpu(int cpu); =20 #ifdef CONFIG_PROVE_RCU diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index dc24a9782bbd..de247e758767 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -149,52 +149,17 @@ static noinstr void rcu_eqs_enter(bool user) } =20 /** - * rcu_idle_enter - inform RCU that current CPU is entering idle - * - * Enter idle mode, in other words, -leave- the mode in which RCU - * read-side critical sections can occur. (Though RCU read-side - * critical sections can occur in irq handlers in idle, a possibility - * handled by irq_enter() and irq_exit().) - * - * If you add or remove a call to rcu_idle_enter(), be sure to test with - * CONFIG_RCU_EQS_DEBUG=3Dy. - */ -void rcu_idle_enter(void) -{ - lockdep_assert_irqs_disabled(); - rcu_eqs_enter(false); -} - -#ifdef CONFIG_NO_HZ_FULL -/** - * rcu_user_enter - inform RCU that we are resuming userspace. - * - * Enter RCU idle mode right before resuming userspace. No use of RCU - * is permitted between this call and rcu_user_exit(). This way the - * CPU doesn't need to maintain the tick for RCU maintenance purposes - * when the CPU runs in userspace. - * - * If you add or remove a call to rcu_user_enter(), be sure to test with - * CONFIG_RCU_EQS_DEBUG=3Dy. - */ -noinstr void rcu_user_enter(void) -{ - rcu_eqs_enter(true); -} -#endif /* CONFIG_NO_HZ_FULL */ - -/** - * rcu_nmi_exit - inform RCU of exit from NMI context + * ct_nmi_exit - inform RCU of exit from NMI context * * If we are returning from the outermost NMI handler that interrupted an * RCU-idle period, update ct->dynticks and ct->dynticks_nmi_nesting * to let the RCU grace-period handling know that the CPU is back to * being RCU-idle. * - * If you add or remove a call to rcu_nmi_exit(), be sure to test + * If you add or remove a call to ct_nmi_exit(), be sure to test * with CONFIG_RCU_EQS_DEBUG=3Dy. */ -noinstr void rcu_nmi_exit(void) +noinstr void ct_nmi_exit(void) { struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); =20 @@ -275,42 +240,7 @@ static void noinstr rcu_eqs_exit(bool user) } =20 /** - * rcu_idle_exit - inform RCU that current CPU is leaving idle - * - * Exit idle mode, in other words, -enter- the mode in which RCU - * read-side critical sections can occur. - * - * If you add or remove a call to rcu_idle_exit(), be sure to test with - * CONFIG_RCU_EQS_DEBUG=3Dy. - */ -void rcu_idle_exit(void) -{ - unsigned long flags; - - local_irq_save(flags); - rcu_eqs_exit(false); - local_irq_restore(flags); -} -EXPORT_SYMBOL_GPL(rcu_idle_exit); - -#ifdef CONFIG_NO_HZ_FULL -/** - * rcu_user_exit - inform RCU that we are exiting userspace. - * - * Exit RCU idle mode while entering the kernel because it can - * run a RCU read side critical section anytime. - * - * If you add or remove a call to rcu_user_exit(), be sure to test with - * CONFIG_RCU_EQS_DEBUG=3Dy. - */ -void noinstr rcu_user_exit(void) -{ - rcu_eqs_exit(true); -} -#endif /* ifdef CONFIG_NO_HZ_FULL */ - -/** - * rcu_nmi_enter - inform RCU of entry to NMI context + * ct_nmi_enter - inform RCU of entry to NMI context * * If the CPU was idle from RCU's viewpoint, update ct->dynticks and * ct->dynticks_nmi_nesting to let the RCU grace-period handling know @@ -318,10 +248,10 @@ void noinstr rcu_user_exit(void) * long as the nesting level does not overflow an int. (You will probably * run out of stack space first.) * - * If you add or remove a call to rcu_nmi_enter(), be sure to test + * If you add or remove a call to ct_nmi_enter(), be sure to test * with CONFIG_RCU_EQS_DEBUG=3Dy. */ -noinstr void rcu_nmi_enter(void) +noinstr void ct_nmi_enter(void) { long incby =3D 2; struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); @@ -436,7 +366,13 @@ void noinstr __ct_user_enter(enum ctx_state state) * that will fire and reschedule once we resume in user/guest mode. */ rcu_irq_work_resched(); - rcu_user_enter(); + /* + * Enter RCU idle mode right before resuming userspace. No use of RCU + * is permitted between this call and rcu_eqs_exit(). This way the + * CPU doesn't need to maintain the tick for RCU maintenance purposes + * when the CPU runs in userspace. + */ + rcu_eqs_enter(true); } /* * Even if context tracking is disabled on this CPU, because it's outside @@ -510,10 +446,10 @@ void noinstr __ct_user_exit(enum ctx_state state) if (__this_cpu_read(context_tracking.state) =3D=3D state) { if (__this_cpu_read(context_tracking.active)) { /* - * We are going to run code that may use RCU. Inform - * RCU core about that (ie: we may need the tick again). + * Exit RCU idle mode while entering the kernel because it can + * run a RCU read side critical section anytime. */ - rcu_user_exit(); + rcu_eqs_exit(true); if (state =3D=3D CONTEXT_USER) { instrumentation_begin(); vtime_user_exit(current); @@ -595,16 +531,41 @@ DEFINE_PER_CPU(struct context_tracking, context_track= ing) =3D { }; EXPORT_SYMBOL_GPL(context_tracking); =20 - +/** + * ct_idle_enter - inform RCU that current CPU is entering idle + * + * Enter idle mode, in other words, -leave- the mode in which RCU + * read-side critical sections can occur. (Though RCU read-side + * critical sections can occur in irq handlers in idle, a possibility + * handled by irq_enter() and irq_exit().) + * + * If you add or remove a call to ct_idle_enter(), be sure to test with + * CONFIG_RCU_EQS_DEBUG=3Dy. + */ void ct_idle_enter(void) { - rcu_idle_enter(); + lockdep_assert_irqs_disabled(); + rcu_eqs_enter(false); } EXPORT_SYMBOL_GPL(ct_idle_enter); =20 +/** + * ct_idle_exit - inform RCU that current CPU is leaving idle + * + * Exit idle mode, in other words, -enter- the mode in which RCU + * read-side critical sections can occur. + * + * If you add or remove a call to ct_idle_exit(), be sure to test with + * CONFIG_RCU_EQS_DEBUG=3Dy. + */ void ct_idle_exit(void) { - rcu_idle_exit(); + unsigned long flags; + + local_irq_save(flags); + rcu_eqs_exit(false); + local_irq_restore(flags); + } EXPORT_SYMBOL_GPL(ct_idle_exit); =20 @@ -678,13 +639,3 @@ void ct_irq_exit_irqson(void) ct_irq_exit(); local_irq_restore(flags); } - -noinstr void ct_nmi_enter(void) -{ - rcu_nmi_enter(); -} - -noinstr void ct_nmi_exit(void) -{ - rcu_nmi_exit(); -} --=20 2.25.1 From nobody Tue Jun 23 16:12:04 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8FA72C433F5 for ; Wed, 2 Mar 2022 15:50:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235732AbiCBPvU (ORCPT ); Wed, 2 Mar 2022 10:51:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58732 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242415AbiCBPuX (ORCPT ); Wed, 2 Mar 2022 10:50:23 -0500 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 700F158E55 for ; Wed, 2 Mar 2022 07:49:19 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id D412ECE2189 for ; Wed, 2 Mar 2022 15:49:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1321EC340F1; Wed, 2 Mar 2022 15:49:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646236156; bh=gZi+CrUhT+iAU5seHENLkIn+v+3EqQ+aMPe1Xaq/+2E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=URMHZj4PS6XkbGAyr/CSCcrtqunr94F9hlGp6C3Z+wWSswDU/90ksVNbipPCgMOID KIA9KwdCMzXqhnmLbVPFUBUE0+ScTuP/gtnWMjnf10X+jnGPCwZvn/+1NGUc067VV+ vJxu2oV+jAmeIUMAeJUu/ROCiYriksQY0VhhNZqOh4kut/JbDW4eSr0qW4xUCFbg7F F7ylaURzj+CAo5c331wu+kVVa0cymsbHpcjREtXBsfGgiXvQ8rb8SI/gI3oiyDsdYZ tUUrj+VP8Yp+F1BM9f0il9sdf/Md0fJsBbkurT3oppIVlTlMbnX6JEZb0m8P3OF+F2 hE4Gw0in4Jr1Q== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: [PATCH 16/19] context_tracking: Convert state to atomic_t Date: Wed, 2 Mar 2022 16:48:07 +0100 Message-Id: <20220302154810.42308-17-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220302154810.42308-1-frederic@kernel.org> References: <20220302154810.42308-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Context tracking's state and dynticks counter are going to be merged in a single field so that both updates can happen atomically and at the same time. Prepare for that with converting the state into an atomic_t. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits --- include/linux/context_tracking.h | 18 ++--------- include/linux/context_tracking_state.h | 42 +++++++++++++++++++++----- kernel/context_tracking.c | 15 +++++---- 3 files changed, 47 insertions(+), 28 deletions(-) diff --git a/include/linux/context_tracking.h b/include/linux/context_track= ing.h index 086546569d14..63343c34ab4e 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -56,7 +56,7 @@ static inline enum ctx_state exception_enter(void) !context_tracking_enabled()) return 0; =20 - prev_ctx =3D this_cpu_read(context_tracking.state); + prev_ctx =3D __ct_state(); if (prev_ctx !=3D CONTEXT_KERNEL) ct_user_exit(prev_ctx); =20 @@ -86,26 +86,14 @@ static __always_inline void context_tracking_guest_exit= (void) __ct_user_exit(CONTEXT_GUEST); } =20 -/** - * ct_state() - return the current context tracking state if known - * - * Returns the current cpu's context tracking state if context tracking - * is enabled. If context tracking is disabled, returns - * CONTEXT_DISABLED. This should be used primarily for debugging. - */ -static __always_inline enum ctx_state ct_state(void) -{ - return context_tracking_enabled() ? - this_cpu_read(context_tracking.state) : CONTEXT_DISABLED; -} #else static inline void user_enter(void) { } static inline void user_exit(void) { } static inline void user_enter_irqoff(void) { } static inline void user_exit_irqoff(void) { } -static inline enum ctx_state exception_enter(void) { return 0; } +static inline int exception_enter(void) { return 0; } static inline void exception_exit(enum ctx_state prev_ctx) { } -static inline enum ctx_state ct_state(void) { return CONTEXT_DISABLED; } +static inline int ct_state(void) { return -1; } static __always_inline bool context_tracking_guest_enter(void) { return fa= lse; } static inline void context_tracking_guest_exit(void) { } =20 diff --git a/include/linux/context_tracking_state.h b/include/linux/context= _tracking_state.h index 4efb97fe6518..3da44987dc71 100644 --- a/include/linux/context_tracking_state.h +++ b/include/linux/context_tracking_state.h @@ -9,6 +9,13 @@ /* Offset to allow distinguishing irq vs. task-based idle entry/exit. */ #define DYNTICK_IRQ_NONIDLE ((LONG_MAX / 2) + 1) =20 +enum ctx_state { + CONTEXT_DISABLED =3D -1, /* returned by ct_state() if unknown */ + CONTEXT_KERNEL =3D 0, + CONTEXT_USER, + CONTEXT_GUEST, +}; + struct context_tracking { #ifdef CONFIG_CONTEXT_TRACKING_USER /* @@ -19,12 +26,7 @@ struct context_tracking { */ bool active; int recursion; - enum ctx_state { - CONTEXT_DISABLED =3D -1, /* returned by ct_state() if unknown */ - CONTEXT_KERNEL =3D 0, - CONTEXT_USER, - CONTEXT_GUEST, - } state; + atomic_t state; #endif atomic_t dynticks; /* Even value for idle, else odd. */ long dynticks_nesting; /* Track process nesting level. */ @@ -33,6 +35,11 @@ struct context_tracking { =20 #ifdef CONFIG_CONTEXT_TRACKING DECLARE_PER_CPU(struct context_tracking, context_tracking); + +static __always_inline int __ct_state(void) +{ + return atomic_read(this_cpu_ptr(&context_tracking.state)); +} #endif =20 #ifdef CONFIG_CONTEXT_TRACKING_USER @@ -53,9 +60,30 @@ static inline bool context_tracking_enabled_this_cpu(voi= d) return context_tracking_enabled() && __this_cpu_read(context_tracking.act= ive); } =20 +/** + * ct_state() - return the current context tracking state if known + * + * Returns the current cpu's context tracking state if context tracking + * is enabled. If context tracking is disabled, returns + * CONTEXT_DISABLED. This should be used primarily for debugging. + */ +static __always_inline int ct_state(void) +{ + int ret; + + if (!context_tracking_enabled()) + return CONTEXT_DISABLED; + + preempt_disable(); + ret =3D __ct_state(); + preempt_enable(); + + return ret; +} + static __always_inline bool context_tracking_in_user(void) { - return __this_cpu_read(context_tracking.state) =3D=3D CONTEXT_USER; + return __ct_state() =3D=3D CONTEXT_USER; } #else static inline bool context_tracking_in_user(void) { return false; } diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index de247e758767..69db43548768 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -337,6 +337,7 @@ static __always_inline void context_tracking_recursion_= exit(void) */ void noinstr __ct_user_enter(enum ctx_state state) { + struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); lockdep_assert_irqs_disabled(); =20 /* Kernel threads aren't supposed to go to userspace */ @@ -345,8 +346,8 @@ void noinstr __ct_user_enter(enum ctx_state state) if (!context_tracking_recursion_enter()) return; =20 - if ( __this_cpu_read(context_tracking.state) !=3D state) { - if (__this_cpu_read(context_tracking.active)) { + if (__ct_state() !=3D state) { + if (ct->active) { /* * At this stage, only low level arch entry code remains and * then we'll run in userspace. We can assume there won't be @@ -387,7 +388,7 @@ void noinstr __ct_user_enter(enum ctx_state state) * OTOH we can spare the calls to vtime and RCU when context_tracking.ac= tive * is false because we know that CPU is not tickless. */ - __this_cpu_write(context_tracking.state, state); + atomic_set(&ct->state, state); } context_tracking_recursion_exit(); } @@ -440,11 +441,13 @@ NOKPROBE_SYMBOL(user_enter_callable); */ void noinstr __ct_user_exit(enum ctx_state state) { + struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); + if (!context_tracking_recursion_enter()) return; =20 - if (__this_cpu_read(context_tracking.state) =3D=3D state) { - if (__this_cpu_read(context_tracking.active)) { + if (__ct_state() =3D=3D state) { + if (ct->active) { /* * Exit RCU idle mode while entering the kernel because it can * run a RCU read side critical section anytime. @@ -457,7 +460,7 @@ void noinstr __ct_user_exit(enum ctx_state state) instrumentation_end(); } } - __this_cpu_write(context_tracking.state, CONTEXT_KERNEL); + atomic_set(&ct->state, CONTEXT_KERNEL); } context_tracking_recursion_exit(); } --=20 2.25.1 From nobody Tue Jun 23 16:12:04 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5228CC433F5 for ; Wed, 2 Mar 2022 15:50:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242331AbiCBPvQ (ORCPT ); Wed, 2 Mar 2022 10:51:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53766 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242080AbiCBPu0 (ORCPT ); Wed, 2 Mar 2022 10:50:26 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EE5DF49F0A for ; Wed, 2 Mar 2022 07:49:20 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 80F4961756 for ; Wed, 2 Mar 2022 15:49:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B2DCBC36AE3; Wed, 2 Mar 2022 15:49:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646236159; bh=Zc2Ger41MT5AQkcTRwCrjz5QqdHbkGcSl486vW7t/34=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Js1fEjlWLiURECtMXJ6bP5aFqWjYUNKA/M+cRAdfcTDwasKhJKJO/MqaEhIoSjdWY zc8+EcMt6AEIoDbMQZhpTsRIOnQYZhRYa93LQbDWgCKBqervSTq970y2/S0KGgK2Si ELKPZzfwze6wfvT7sPMZbG/sJHlj8fqRE5gQAUzl+2ErKGI5yfQJReYs+8wBrfYAI1 Bk1x4txI9iAdd9Ac3y0NoIpPjFYyzvZ9/Qziccul2LAAA7YHSrHM+5tsWGHLwwUssk ZiASTw5lHJzkI34ciSPaDrfxO/D0fSdJPJIT1X+XBDOZgKh65cfldb9BuBJL/2NMR0 adH1j0CjBYqzA== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: [PATCH 17/19] rcu/context-tracking: Use accessor for dynticks counter value Date: Wed, 2 Mar 2022 16:48:08 +0100 Message-Id: <20220302154810.42308-18-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220302154810.42308-1-frederic@kernel.org> References: <20220302154810.42308-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The dynticks counter value is going to join the context tracking state in a single field. Use an accessor for this value to make the transition easier for all readers. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits Acked-by: Paul E. McKenney --- include/linux/context_tracking_state.h | 17 +++++++++++++++++ kernel/context_tracking.c | 10 +++++----- kernel/rcu/tree.c | 13 ++++--------- 3 files changed, 26 insertions(+), 14 deletions(-) diff --git a/include/linux/context_tracking_state.h b/include/linux/context= _tracking_state.h index 3da44987dc71..bca0d3e0bd3d 100644 --- a/include/linux/context_tracking_state.h +++ b/include/linux/context_tracking_state.h @@ -40,6 +40,23 @@ static __always_inline int __ct_state(void) { return atomic_read(this_cpu_ptr(&context_tracking.state)); } + +static __always_inline int ct_dynticks(void) +{ + return atomic_read(this_cpu_ptr(&context_tracking.dynticks)); +} + +static __always_inline int ct_dynticks_cpu(int cpu) +{ + struct context_tracking *ct =3D per_cpu_ptr(&context_tracking, cpu); + return atomic_read(&ct->dynticks); +} + +static __always_inline int ct_dynticks_cpu_acquire(int cpu) +{ + struct context_tracking *ct =3D per_cpu_ptr(&context_tracking, cpu); + return atomic_read_acquire(&ct->state); +} #endif =20 #ifdef CONFIG_CONTEXT_TRACKING_USER diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index 69db43548768..fe9066fdfaab 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -133,7 +133,7 @@ static noinstr void rcu_eqs_enter(bool user) =20 lockdep_assert_irqs_disabled(); instrumentation_begin(); - trace_rcu_dyntick(TPS("Start"), ct->dynticks_nesting, 0, atomic_read(&ct-= >dynticks)); + trace_rcu_dyntick(TPS("Start"), ct->dynticks_nesting, 0, ct_dynticks()); WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(c= urrent)); rcu_preempt_deferred_qs(current); =20 @@ -178,7 +178,7 @@ noinstr void ct_nmi_exit(void) */ if (ct->dynticks_nmi_nesting !=3D 1) { trace_rcu_dyntick(TPS("--=3D"), ct->dynticks_nmi_nesting, ct->dynticks_n= mi_nesting - 2, - atomic_read(&ct->dynticks)); + ct_dynticks()); WRITE_ONCE(ct->dynticks_nmi_nesting, /* No store tearing. */ ct->dynticks_nmi_nesting - 2); instrumentation_end(); @@ -186,7 +186,7 @@ noinstr void ct_nmi_exit(void) } =20 /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */ - trace_rcu_dyntick(TPS("Startirq"), ct->dynticks_nmi_nesting, 0, atomic_re= ad(&ct->dynticks)); + trace_rcu_dyntick(TPS("Startirq"), ct->dynticks_nmi_nesting, 0, ct_dyntic= ks()); WRITE_ONCE(ct->dynticks_nmi_nesting, 0); /* Avoid store tearing. */ =20 // instrumentation for the noinstr rcu_dynticks_eqs_enter() @@ -231,7 +231,7 @@ static void noinstr rcu_eqs_exit(bool user) // instrumentation for the noinstr rcu_dynticks_eqs_exit() instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); =20 - trace_rcu_dyntick(TPS("End"), ct->dynticks_nesting, 1, atomic_read(&ct->d= ynticks)); + trace_rcu_dyntick(TPS("End"), ct->dynticks_nesting, 1, ct_dynticks()); WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(c= urrent)); WRITE_ONCE(ct->dynticks_nesting, 1); WARN_ON_ONCE(ct->dynticks_nmi_nesting); @@ -292,7 +292,7 @@ noinstr void ct_nmi_enter(void) =20 trace_rcu_dyntick(incby =3D=3D 1 ? TPS("Endirq") : TPS("++=3D"), ct->dynticks_nmi_nesting, - ct->dynticks_nmi_nesting + incby, atomic_read(&ct->dynticks)); + ct->dynticks_nmi_nesting + incby, ct_dynticks()); instrumentation_end(); WRITE_ONCE(ct->dynticks_nmi_nesting, /* Prevent store tearing. */ ct->dynticks_nmi_nesting + incby); diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index e55a44ed19b6..90a22dd2189d 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -272,9 +272,7 @@ void rcu_softirq_qs(void) */ static void rcu_dynticks_eqs_online(void) { - struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); - - if (atomic_read(&ct->dynticks) & 0x1) + if (ct_dynticks() & 0x1) return; rcu_dynticks_inc(1); } @@ -285,10 +283,8 @@ static void rcu_dynticks_eqs_online(void) */ static int rcu_dynticks_snap(int cpu) { - struct context_tracking *ct =3D per_cpu_ptr(&context_tracking, cpu); - smp_mb(); // Fundamental RCU ordering guarantee. - return atomic_read_acquire(&ct->dynticks); + return ct_dynticks_cpu_acquire(cpu); } =20 /* @@ -322,11 +318,10 @@ static bool rcu_dynticks_in_eqs_since(struct rcu_data= *rdp, int snap) */ bool rcu_dynticks_zero_in_eqs(int cpu, int *vp) { - struct context_tracking *ct =3D per_cpu_ptr(&context_tracking, cpu); int snap; =20 // If not quiescent, force back to earlier extended quiescent state. - snap =3D atomic_read(&ct->dynticks) & ~0x1; + snap =3D ct_dynticks_cpu(cpu) & ~0x1; =20 smp_rmb(); // Order ->dynticks and *vp reads. if (READ_ONCE(*vp)) @@ -334,7 +329,7 @@ bool rcu_dynticks_zero_in_eqs(int cpu, int *vp) smp_rmb(); // Order *vp read and ->dynticks re-read. =20 // If still in the same extended quiescent state, we are good! - return snap =3D=3D atomic_read(&ct->dynticks); + return snap =3D=3D ct_dynticks_cpu(cpu); } =20 /* --=20 2.25.1 From nobody Tue Jun 23 16:12:04 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 41694C433EF for ; Wed, 2 Mar 2022 15:50:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241668AbiCBPu7 (ORCPT ); Wed, 2 Mar 2022 10:50:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59216 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241651AbiCBPu3 (ORCPT ); Wed, 2 Mar 2022 10:50:29 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B95C95AEFA for ; Wed, 2 Mar 2022 07:49:24 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 2D3FD61738 for ; Wed, 2 Mar 2022 15:49:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 635E9C36AE5; Wed, 2 Mar 2022 15:49:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646236163; bh=Z+gcfayBIvkyDX+8C5q29ZIotRNA7uEePF1v8HDUZGE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dThnWHLsi8M2t3evEqDNe4g8mV725xzM5uYP3yg/1Sta2raThHe0I8iamAsQ5DxGn tdv2VjRP646x76OkYa4yxLtSHipDzqIwiV+2Lv9kvs+ubf9/Qj1kir/H6PcxvL4T9B sNFaa8IjttbSpwHg/V/pXhFlb4p6UR1/H/cA+Dkx2ymd4OFRAjdtdZyU/uNLcWBkbj k6ad1FMOtlvXJNBs0X0PEDVB2BpbVq9WIpkkevY4C7NQCQT2Cx1wDIEgu72iNAJHZI P/XBHuRdIdlDpek5f6bT0sgS/j4ZLvdhLKJQa2GbA29xqHCNo6paxrFkZF3hdmfBGL WsFtkpZQ/Qrfg== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: [PATCH 18/19] rcu/context_tracking: Merge dynticks counter and context tracking states Date: Wed, 2 Mar 2022 16:48:09 +0100 Message-Id: <20220302154810.42308-19-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220302154810.42308-1-frederic@kernel.org> References: <20220302154810.42308-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Updating the context tracking state and the RCU dynticks counter atomically in a single operation is a first step towards improving CPU isolation. This makes the context tracking state updates fully ordered and therefore allow for later enhancements such as postponing some work while a task is running isolated in userspace until it ever comes back to the kernel. The state field becomes divided in two parts: 1) Lower bits for context tracking state: CONTEXT_IDLE =3D 1, CONTEXT_USER =3D 2, CONTEXT_GUEST =3D 4, A value of 0 means we are in CONTEXT_KERNEL. 2) Higher bits for RCU eqs dynticks counting: RCU_DYNTICKS_IDX =3D 8 The dynticks counting is always incremented by this value. (state & RCU_DYNTICKS_IDX) means we are NOT in an extended quiescent state. This makes the chance for a collision more likely between two RCU dynticks snapshots but wrapping up 24 bits of eqs dynticks increments still takes some bad luck (also rdp.dynticks_snap could be converted from int to long?) Some RCU eqs functions have been renamed to better reflect their broader scope that now include context tracking state. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits --- include/linux/context_tracking.h | 4 +- include/linux/context_tracking_state.h | 33 ++++++--- kernel/context_tracking.c | 92 +++++++++++++------------- kernel/rcu/tree.c | 13 ++-- kernel/rcu/tree_stall.h | 2 +- 5 files changed, 81 insertions(+), 63 deletions(-) diff --git a/include/linux/context_tracking.h b/include/linux/context_track= ing.h index 63343c34ab4e..aa0e6fbf6946 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -110,7 +110,7 @@ static inline void context_tracking_init(void) { } #ifdef CONFIG_CONTEXT_TRACKING extern void ct_idle_enter(void); extern void ct_idle_exit(void); -extern unsigned long rcu_dynticks_inc(int incby); +extern unsigned long ct_state_inc(int incby); =20 /* * Is the current CPU in an extended quiescent state? @@ -119,7 +119,7 @@ extern unsigned long rcu_dynticks_inc(int incby); */ static __always_inline bool rcu_dynticks_curr_cpu_in_eqs(void) { - return !(arch_atomic_read(this_cpu_ptr(&context_tracking.dynticks)) & 0x1= ); + return !(arch_atomic_read(this_cpu_ptr(&context_tracking.state)) & RCU_DY= NTICKS_IDX); } =20 #else diff --git a/include/linux/context_tracking_state.h b/include/linux/context= _tracking_state.h index bca0d3e0bd3d..b8a309532c18 100644 --- a/include/linux/context_tracking_state.h +++ b/include/linux/context_tracking_state.h @@ -9,13 +9,29 @@ /* Offset to allow distinguishing irq vs. task-based idle entry/exit. */ #define DYNTICK_IRQ_NONIDLE ((LONG_MAX / 2) + 1) =20 +enum { + CONTEXT_IDLE_OFFSET =3D 0, + CONTEXT_USER_OFFSET, + CONTEXT_GUEST_OFFSET, + CONTEXT_MAX_OFFSET, +}; + enum ctx_state { CONTEXT_DISABLED =3D -1, /* returned by ct_state() if unknown */ CONTEXT_KERNEL =3D 0, - CONTEXT_USER, - CONTEXT_GUEST, + CONTEXT_IDLE =3D BIT(CONTEXT_IDLE_OFFSET), + CONTEXT_USER =3D BIT(CONTEXT_USER_OFFSET), + CONTEXT_GUEST =3D BIT(CONTEXT_GUEST_OFFSET), + CONTEXT_MAX =3D BIT(CONTEXT_MAX_OFFSET), }; =20 +/* Even value for idle, else odd. */ +#define RCU_DYNTICKS_SHIFT CONTEXT_MAX_OFFSET +#define RCU_DYNTICKS_IDX CONTEXT_MAX + +#define CT_STATE_MASK (CONTEXT_MAX - 1) +#define CT_DYNTICKS_MASK (~CT_STATE_MASK) + struct context_tracking { #ifdef CONFIG_CONTEXT_TRACKING_USER /* @@ -26,9 +42,8 @@ struct context_tracking { */ bool active; int recursion; +#endif atomic_t state; -#endif - atomic_t dynticks; /* Even value for idle, else odd. */ long dynticks_nesting; /* Track process nesting level. */ long dynticks_nmi_nesting; /* Track irq/NMI nesting level. */ }; @@ -38,24 +53,26 @@ DECLARE_PER_CPU(struct context_tracking, context_tracki= ng); =20 static __always_inline int __ct_state(void) { - return atomic_read(this_cpu_ptr(&context_tracking.state)); + return atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_STATE_MASK; } =20 static __always_inline int ct_dynticks(void) { - return atomic_read(this_cpu_ptr(&context_tracking.dynticks)); + return atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_DYNTICKS_M= ASK; } =20 static __always_inline int ct_dynticks_cpu(int cpu) { struct context_tracking *ct =3D per_cpu_ptr(&context_tracking, cpu); - return atomic_read(&ct->dynticks); + + return atomic_read(&ct->state) & CT_DYNTICKS_MASK; } =20 static __always_inline int ct_dynticks_cpu_acquire(int cpu) { struct context_tracking *ct =3D per_cpu_ptr(&context_tracking, cpu); - return atomic_read_acquire(&ct->state); + + return atomic_read_acquire(&ct->state) & CT_DYNTICKS_MASK; } #endif =20 diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index fe9066fdfaab..87e7b748791c 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -63,9 +63,9 @@ static __always_inline void rcu_dynticks_task_trace_exit(= void) * Increment the current CPU's context_tracking structure's ->dynticks fie= ld * with ordering. Return the new value. */ -noinstr unsigned long rcu_dynticks_inc(int incby) +noinstr unsigned long ct_state_inc(int incby) { - return arch_atomic_add_return(incby, this_cpu_ptr(&context_tracking.dynti= cks)); + return arch_atomic_add_return(incby, this_cpu_ptr(&context_tracking.state= )); } =20 /* @@ -74,7 +74,7 @@ noinstr unsigned long rcu_dynticks_inc(int incby) * RCU is watching prior to the call to this function and is no longer * watching upon return. */ -static noinstr void rcu_dynticks_eqs_enter(void) +static noinstr void ct_kernel_exit_state(int offset) { int seq; =20 @@ -84,9 +84,9 @@ static noinstr void rcu_dynticks_eqs_enter(void) * next idle sojourn. */ rcu_dynticks_task_trace_enter(); // Before ->dynticks update! - seq =3D rcu_dynticks_inc(1); + seq =3D ct_state_inc(offset); // RCU is no longer watching. Better be in extended quiescent state! - WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && (seq & 0x1)); + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && (seq & RCU_DYNTICKS_IDX)= ); } =20 /* @@ -94,7 +94,7 @@ static noinstr void rcu_dynticks_eqs_enter(void) * called from an extended quiescent state, that is, RCU is not watching * prior to the call to this function and is watching upon return. */ -static noinstr void rcu_dynticks_eqs_exit(void) +static noinstr void ct_kernel_enter_state(int offset) { int seq; =20 @@ -103,10 +103,10 @@ static noinstr void rcu_dynticks_eqs_exit(void) * and we also must force ordering with the next RCU read-side * critical section. */ - seq =3D rcu_dynticks_inc(1); + seq =3D ct_state_inc(offset); // RCU is now watching. Better not be in an extended quiescent state! rcu_dynticks_task_trace_exit(); // After ->dynticks update! - WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !(seq & 0x1)); + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !(seq & RCU_DYNTICKS_IDX= )); } =20 /* @@ -117,7 +117,7 @@ static noinstr void rcu_dynticks_eqs_exit(void) * the possibility of usermode upcalls having messed up our count * of interrupt nesting level during the prior busy period. */ -static noinstr void rcu_eqs_enter(bool user) +static noinstr void ct_kernel_exit(bool user, int offset) { struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); =20 @@ -137,13 +137,13 @@ static noinstr void rcu_eqs_enter(bool user) WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(c= urrent)); rcu_preempt_deferred_qs(current); =20 - // instrumentation for the noinstr rcu_dynticks_eqs_enter() - instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); + // instrumentation for the noinstr ct_kernel_exit_state() + instrument_atomic_write(&ct->state, sizeof(ct->state)); =20 instrumentation_end(); WRITE_ONCE(ct->dynticks_nesting, 0); /* Avoid irq-access tearing. */ // RCU is watching here ... - rcu_dynticks_eqs_enter(); + ct_kernel_exit_state(offset); // ... but is no longer watching here. rcu_dynticks_task_enter(); } @@ -152,7 +152,7 @@ static noinstr void rcu_eqs_enter(bool user) * ct_nmi_exit - inform RCU of exit from NMI context * * If we are returning from the outermost NMI handler that interrupted an - * RCU-idle period, update ct->dynticks and ct->dynticks_nmi_nesting + * RCU-idle period, update ct->state and ct->dynticks_nmi_nesting * to let the RCU grace-period handling know that the CPU is back to * being RCU-idle. * @@ -189,12 +189,12 @@ noinstr void ct_nmi_exit(void) trace_rcu_dyntick(TPS("Startirq"), ct->dynticks_nmi_nesting, 0, ct_dyntic= ks()); WRITE_ONCE(ct->dynticks_nmi_nesting, 0); /* Avoid store tearing. */ =20 - // instrumentation for the noinstr rcu_dynticks_eqs_enter() - instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); + // instrumentation for the noinstr ct_kernel_exit_state() + instrument_atomic_write(&ct->state, sizeof(ct->state)); instrumentation_end(); =20 // RCU is watching here ... - rcu_dynticks_eqs_enter(); + ct_kernel_exit_state(RCU_DYNTICKS_IDX); // ... but is no longer watching here. =20 if (!in_nmi()) @@ -209,7 +209,7 @@ noinstr void ct_nmi_exit(void) * allow for the possibility of usermode upcalls messing up our count of * interrupt nesting level during the busy period that is just now startin= g. */ -static void noinstr rcu_eqs_exit(bool user) +static void noinstr ct_kernel_enter(bool user, int offset) { struct context_tracking *ct =3D this_cpu_ptr(&context_tracking); long oldval; @@ -224,12 +224,12 @@ static void noinstr rcu_eqs_exit(bool user) } rcu_dynticks_task_exit(); // RCU is not watching here ... - rcu_dynticks_eqs_exit(); + ct_kernel_enter_state(offset); // ... but is watching here. instrumentation_begin(); =20 - // instrumentation for the noinstr rcu_dynticks_eqs_exit() - instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); + // instrumentation for the noinstr ct_kernel_enter_state() + instrument_atomic_write(&ct->state, sizeof(ct->state)); =20 trace_rcu_dyntick(TPS("End"), ct->dynticks_nesting, 1, ct_dynticks()); WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(c= urrent)); @@ -242,7 +242,7 @@ static void noinstr rcu_eqs_exit(bool user) /** * ct_nmi_enter - inform RCU of entry to NMI context * - * If the CPU was idle from RCU's viewpoint, update ct->dynticks and + * If the CPU was idle from RCU's viewpoint, update ct->state and * ct->dynticks_nmi_nesting to let the RCU grace-period handling know * that the CPU is active. This implementation permits nested NMIs, as * long as the nesting level does not overflow an int. (You will probably @@ -273,14 +273,14 @@ noinstr void ct_nmi_enter(void) rcu_dynticks_task_exit(); =20 // RCU is not watching here ... - rcu_dynticks_eqs_exit(); + ct_kernel_enter_state(RCU_DYNTICKS_IDX); // ... but is watching here. =20 instrumentation_begin(); // instrumentation for the noinstr rcu_dynticks_curr_cpu_in_eqs() - instrument_atomic_read(&ct->dynticks, sizeof(ct->dynticks)); - // instrumentation for the noinstr rcu_dynticks_eqs_exit() - instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks)); + instrument_atomic_read(&ct->state, sizeof(ct->state)); + // instrumentation for the noinstr ct_kernel_enter_state() + instrument_atomic_write(&ct->state, sizeof(ct->state)); =20 incby =3D 1; } else if (!in_nmi()) { @@ -373,22 +373,23 @@ void noinstr __ct_user_enter(enum ctx_state state) * CPU doesn't need to maintain the tick for RCU maintenance purposes * when the CPU runs in userspace. */ - rcu_eqs_enter(true); + ct_kernel_exit(true, RCU_DYNTICKS_IDX + state); + } else { + /* + * Even if context tracking is disabled on this CPU, because it's outsi= de + * the full dynticks mask for example, we still have to keep track of t= he + * context transitions and states to prevent inconsistency on those of + * other CPUs. + * If a task triggers an exception in userspace, sleep on the exception + * handler and then migrate to another CPU, that new CPU must know where + * the exception returns by the time we call exception_exit(). + * This information can only be provided by the previous CPU when it ca= lled + * exception_enter(). + * OTOH we can spare the calls to vtime and RCU when context_tracking.a= ctive + * is false because we know that CPU is not tickless. + */ + atomic_add(state, &ct->state); } - /* - * Even if context tracking is disabled on this CPU, because it's outside - * the full dynticks mask for example, we still have to keep track of the - * context transitions and states to prevent inconsistency on those of - * other CPUs. - * If a task triggers an exception in userspace, sleep on the exception - * handler and then migrate to another CPU, that new CPU must know where - * the exception returns by the time we call exception_exit(). - * This information can only be provided by the previous CPU when it cal= led - * exception_enter(). - * OTOH we can spare the calls to vtime and RCU when context_tracking.ac= tive - * is false because we know that CPU is not tickless. - */ - atomic_set(&ct->state, state); } context_tracking_recursion_exit(); } @@ -452,15 +453,16 @@ void noinstr __ct_user_exit(enum ctx_state state) * Exit RCU idle mode while entering the kernel because it can * run a RCU read side critical section anytime. */ - rcu_eqs_exit(true); + ct_kernel_enter(true, RCU_DYNTICKS_IDX - state); if (state =3D=3D CONTEXT_USER) { instrumentation_begin(); vtime_user_exit(current); trace_user_exit(0); instrumentation_end(); } + } else { + atomic_sub(state, &ct->state); } - atomic_set(&ct->state, CONTEXT_KERNEL); } context_tracking_recursion_exit(); } @@ -530,7 +532,7 @@ void __init context_tracking_init(void) DEFINE_PER_CPU(struct context_tracking, context_tracking) =3D { .dynticks_nmi_nesting =3D DYNTICK_IRQ_NONIDLE, .dynticks_nesting =3D 1, - .dynticks =3D ATOMIC_INIT(1), + .state =3D ATOMIC_INIT(RCU_DYNTICKS_IDX), }; EXPORT_SYMBOL_GPL(context_tracking); =20 @@ -548,7 +550,7 @@ EXPORT_SYMBOL_GPL(context_tracking); void ct_idle_enter(void) { lockdep_assert_irqs_disabled(); - rcu_eqs_enter(false); + ct_kernel_exit(false, RCU_DYNTICKS_IDX + CONTEXT_IDLE); } EXPORT_SYMBOL_GPL(ct_idle_enter); =20 @@ -566,7 +568,7 @@ void ct_idle_exit(void) unsigned long flags; =20 local_irq_save(flags); - rcu_eqs_exit(false); + ct_kernel_enter(false, RCU_DYNTICKS_IDX - CONTEXT_IDLE); local_irq_restore(flags); =20 } diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 90a22dd2189d..98fac3d327c9 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -272,9 +272,9 @@ void rcu_softirq_qs(void) */ static void rcu_dynticks_eqs_online(void) { - if (ct_dynticks() & 0x1) + if (ct_dynticks() & RCU_DYNTICKS_IDX) return; - rcu_dynticks_inc(1); + ct_state_inc(RCU_DYNTICKS_IDX); } =20 /* @@ -293,7 +293,7 @@ static int rcu_dynticks_snap(int cpu) */ static bool rcu_dynticks_in_eqs(int snap) { - return !(snap & 0x1); + return !(snap & RCU_DYNTICKS_IDX); } =20 /* Return true if the specified CPU is currently idle from an RCU viewpoin= t. */ @@ -321,8 +321,7 @@ bool rcu_dynticks_zero_in_eqs(int cpu, int *vp) int snap; =20 // If not quiescent, force back to earlier extended quiescent state. - snap =3D ct_dynticks_cpu(cpu) & ~0x1; - + snap =3D ct_dynticks_cpu(cpu) & ~RCU_DYNTICKS_IDX; smp_rmb(); // Order ->dynticks and *vp reads. if (READ_ONCE(*vp)) return false; // Non-zero, so report failure; @@ -348,9 +347,9 @@ notrace void rcu_momentary_dyntick_idle(void) int seq; =20 raw_cpu_write(rcu_data.rcu_need_heavy_qs, false); - seq =3D rcu_dynticks_inc(2); + seq =3D ct_state_inc(2 * RCU_DYNTICKS_IDX); /* It is illegal to call this from idle state. */ - WARN_ON_ONCE(!(seq & 0x1)); + WARN_ON_ONCE(!(seq & RCU_DYNTICKS_IDX)); rcu_preempt_deferred_qs(current); } EXPORT_SYMBOL_GPL(rcu_momentary_dyntick_idle); diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index 9bf5cc79d5eb..1ac48c804006 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -459,7 +459,7 @@ static void print_cpu_stall_info(int cpu) rdp->rcu_iw_pending ? (int)min(delta, 9UL) + '0' : "!."[!delta], ticks_value, ticks_title, - rcu_dynticks_snap(cpu) & 0xfff, + (rcu_dynticks_snap(cpu) >> RCU_DYNTICKS_SHIFT) & 0xfff , ct->dynticks_nesting, ct->dynticks_nmi_nesting, rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu), data_race(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart, --=20 2.25.1 From nobody Tue Jun 23 16:12:04 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 09EC3C433F5 for ; Wed, 2 Mar 2022 15:50:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238096AbiCBPvJ (ORCPT ); Wed, 2 Mar 2022 10:51:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55092 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241074AbiCBPuf (ORCPT ); Wed, 2 Mar 2022 10:50:35 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C73844DF7C for ; Wed, 2 Mar 2022 07:49:29 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 779CBB82082 for ; Wed, 2 Mar 2022 15:49:28 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0F526C340F3; Wed, 2 Mar 2022 15:49:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646236167; bh=GOoi6g4ctUqUHDqZeFC0Osd59H+sK7UFUWiNfmdM4sc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GchxLgCOMc3ImfFguBtOgg8lb1eEi7ABmXlwkU1UgNt42MTVFrg2bshW/EJY5NwHu wiUXvSY6skQRiyPs1Qb930sLXBoYI1Py+hIzCF8qPDLmk0kVK8nkkc1RCSgKE5By7f 6L8+W8oV0kOelAm1817ns08dR24m92Fz1K6EaJ0YzNHJEIwJBPs1F10/71qkETpqCB zjMJR8oDA690r7PnFK5yj6h8uDyKjgs3agKwkH1bIZrYYwN+uzthqdy4N/RT0jTdVx EAt0co2bf16ftUAo6txovtwjvY/67uRf1+nlKsu9u99gcqTVX7Q3B9TqywPsoXl4jj xxG0ZagQi+2Zg== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Peter Zijlstra , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: [PATCH 19/19] context_tracking: Exempt CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK from non-active tracking Date: Wed, 2 Mar 2022 16:48:10 +0100 Message-Id: <20220302154810.42308-20-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220302154810.42308-1-frederic@kernel.org> References: <20220302154810.42308-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Since a CPU may save the state of the context tracking using exception_enter() before calling into schedule(), we need all CPUs in the system to track user <-> kernel transitions and not just those that really need it (nohz_full CPUs). The following illustrates the issue that could otherwise happen: CPU 0 (not tracking) CPU 1 (tracking) ------------------- -------------------- // we are past user_enter() // but this CPU is always in // CONTEXT_KERNEL // because it doesn't track user <-> kernel ctx =3D exception_enter(); //ctx =3D=3D CONTEXT_KERNEL schedule(); =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D> return from schedule(); exception_exit(ctx); //go to user in CONTEXT_KERN= EL However CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK doesn't play those games because schedule() can't be called between user_enter() and user_exit() under such config. In this situation we can spare context tracking on the CPUs that don't need it. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits --- kernel/context_tracking.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index 87e7b748791c..b1934264f77f 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -374,7 +374,7 @@ void noinstr __ct_user_enter(enum ctx_state state) * when the CPU runs in userspace. */ ct_kernel_exit(true, RCU_DYNTICKS_IDX + state); - } else { + } else if (!IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK)) { /* * Even if context tracking is disabled on this CPU, because it's outsi= de * the full dynticks mask for example, we still have to keep track of t= he @@ -384,7 +384,8 @@ void noinstr __ct_user_enter(enum ctx_state state) * handler and then migrate to another CPU, that new CPU must know where * the exception returns by the time we call exception_exit(). * This information can only be provided by the previous CPU when it ca= lled - * exception_enter(). + * exception_enter(). CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK is + * excused though because it doesn't use exception_enter(). * OTOH we can spare the calls to vtime and RCU when context_tracking.a= ctive * is false because we know that CPU is not tickless. */ @@ -460,7 +461,7 @@ void noinstr __ct_user_exit(enum ctx_state state) trace_user_exit(0); instrumentation_end(); } - } else { + } else if (!IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK)) { atomic_sub(state, &ct->state); } } --=20 2.25.1