From nobody Mon Apr 27 07:26:20 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 16FA7C433EF for ; Wed, 15 Jun 2022 19:56:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350403AbiFOTz7 (ORCPT ); Wed, 15 Jun 2022 15:55:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55564 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346674AbiFOTz5 (ORCPT ); Wed, 15 Jun 2022 15:55:57 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DD99A2B271; Wed, 15 Jun 2022 12:55:56 -0700 (PDT) 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 51C02612FD; Wed, 15 Jun 2022 19:55:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 37C94C3411E; Wed, 15 Jun 2022 19:55:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1655322955; bh=cMGsN4lRnGRmSyfnqRXMyxUoMSPApeamTo6HJshVyk4=; h=Date:From:To:Cc:Subject:From; b=M7iI3RVSbP2HWUf1YznMNt7xWNiObefPzcnXlOJtlM/GgXUEVprDkuBC18mC1ncxy FS42zDYk71g1I6IJzHVVL1HeyLlImlLu2jcoSezMnhChcP+O3IGxCz4WHxErqcC1jw tkcwwv3tMrZfuOrY+BRdy1OW/YSNg/DpV+EBleRxHBSS156J25mpQSROmfouXLzKne EU5tuPlzqOIV2AVkGWDB/XtRLmibSzAtTY8LXVIRozVtKlYaFwJ1UD4el7iuSwZX4G oh5gsV/lgaY9jR7sLZn3wF495IPL0PfauOgL6PzpmLf0Dmqer19etrD6n/H879kKdE yiJCDyOvTwNfQ== Date: Wed, 15 Jun 2022 12:55:53 -0700 From: Nathan Chancellor To: Stephen Rothwell , "Paul E. McKenney" , Frederic Weisbecker , Sami Tolvanen , Kees Cook Cc: llvm@lists.linux.dev, linux-kernel@vger.kernel.org, linux-next@vger.kernel.org Subject: Contextual conflict between kspp and rcu trees Message-ID: MIME-Version: 1.0 Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Hi Stephen et al., There is a contextual conflict between commit e1d337335207 ("cfi: Fix __cfi_slowpath_diag RCU usage with cpuidle") in the kspp tree and commit dcc0c11aa87b ("rcu/context-tracking: Remove rcu_irq_enter/exit()") in the rcu tree, which is visible when building ARCH=3Darm64 defconfig + CONFIG_LTO_CLANG_THIN=3Dy + CONFIG_CFI_CLANG=3Dy with clang: kernel/cfi.c:298:3: error: call to undeclared function 'rcu_irq_enter'; I= SO C99 and later do not support implicit function declarations [-Wimplicit-= function-declaration] rcu_irq_enter(); ^ kernel/cfi.c:298:3: note: did you mean 'ct_irq_enter'? ./include/linux/context_tracking_irq.h:6:6: note: 'ct_irq_enter' declared= here void ct_irq_enter(void); ^ kernel/cfi.c:307:3: error: call to undeclared function 'rcu_irq_exit'; IS= O C99 and later do not support implicit function declarations [-Wimplicit-f= unction-declaration] rcu_irq_exit(); ^ kernel/cfi.c:307:3: note: did you mean 'ct_irq_exit'? ./include/linux/context_tracking_irq.h:7:6: note: 'ct_irq_exit' declared = here void ct_irq_exit(void); ^ 2 errors generated. Per the above RCU commit and commit 6c5218715286 ("context_tracking: Take IRQ eqs entrypoints over RCU"), it appears that the following diff is the proper fix up. Would you mind applying it to the merge of whichever tree comes second if possible? I did build and boot test it but it would not be a bad idea for Sami and Frederic to verify that it is correct so that Kees/Paul can mention it to Linus :) Cheers, Nathan diff --git a/kernel/cfi.c b/kernel/cfi.c index 08102d19ec15..2046276ee234 100644 --- a/kernel/cfi.c +++ b/kernel/cfi.c @@ -295,7 +295,7 @@ static inline cfi_check_fn find_check_fn(unsigned long = ptr) rcu_idle =3D !rcu_is_watching(); if (rcu_idle) { local_irq_save(flags); - rcu_irq_enter(); + ct_irq_enter(); } =20 if (IS_ENABLED(CONFIG_CFI_CLANG_SHADOW)) @@ -304,7 +304,7 @@ static inline cfi_check_fn find_check_fn(unsigned long = ptr) fn =3D find_module_check_fn(ptr); =20 if (rcu_idle) { - rcu_irq_exit(); + ct_irq_exit(); local_irq_restore(flags); }