From nobody Fri Jun 19 09:49:49 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 E62C3C35280 for ; Tue, 5 Apr 2022 10:50:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346027AbiDEKmi (ORCPT ); Tue, 5 Apr 2022 06:42:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33834 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241197AbiDEIcy (ORCPT ); Tue, 5 Apr 2022 04:32:54 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 358C917A86; Tue, 5 Apr 2022 01:29:24 -0700 (PDT) Date: Tue, 05 Apr 2022 08:29:21 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1649147362; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=weL/Y/0bLbSr89Udbwco2BymGNu3H+Z73Jcjq6NeTuI=; b=PPDV1NnBtSFLvt+bcYKiG4rGphZi2oyC3AxUFgeFR9azd2m3bY5YILSwXRH9zUEYevKbSf 6TgHUz7gPyC36Cul2Lh5ecKuM5r5ro/ZQdDhljRgq9DFCZzp4G9O0ZtvACwMc3D68gyiz8 h7XSSH5vUz69vCQP90l9SjYJu2ZntIk/exYEPgyxhE0EFT3tGlfcGtBWovfZ68oqhoC9sN JZmu52rUUAzhG/CzCo6u7t9Am9nNhfynUJHeG1wCDLmzQZUhig/dncBKOaGJmS2ExxdcY3 Oxa6g5ZnL0jwIHJmCgXwttzUvo8aSzXjrGEd8ZeRxFI7S+Bs+TgntsMNBwzpJA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1649147362; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=weL/Y/0bLbSr89Udbwco2BymGNu3H+Z73Jcjq6NeTuI=; b=f3PzWIp1F/sCFHuDCAPpTCS7V1P+VizleOlgVky2nSdFgu4dQLNEi8ZWjVFAk0V9bgVqmO ElUnO1IoQ+aBq1AQ== From: "tip-bot2 for Valentin Schneider" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/core] preempt/dynamic: Introduce preemption model accessors Cc: Marco Elver , Valentin Schneider , "Peter Zijlstra (Intel)" , Frederic Weisbecker , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20211112185203.280040-3-valentin.schneider@arm.com> References: <20211112185203.280040-3-valentin.schneider@arm.com> MIME-Version: 1.0 Message-ID: <164914736184.389.17168803226310097171.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the sched/core branch of tip: Commit-ID: cfe43f478b79ba45573ca22d52d0d8823be068fa Gitweb: https://git.kernel.org/tip/cfe43f478b79ba45573ca22d52d0d8823= be068fa Author: Valentin Schneider AuthorDate: Fri, 12 Nov 2021 18:52:01=20 Committer: Peter Zijlstra CommitterDate: Tue, 05 Apr 2022 10:24:42 +02:00 preempt/dynamic: Introduce preemption model accessors CONFIG_PREEMPT{_NONE, _VOLUNTARY} designate either: o The build-time preemption model when !PREEMPT_DYNAMIC o The default boot-time preemption model when PREEMPT_DYNAMIC IOW, using those on PREEMPT_DYNAMIC kernels is meaningless - the actual model could have been set to something else by the "preempt=3Dfoo" cmdline parameter. Same problem applies to CONFIG_PREEMPTION. Introduce a set of helpers to determine the actual preemption model used by the live kernel. Suggested-by: Marco Elver Signed-off-by: Valentin Schneider Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Marco Elver Acked-by: Frederic Weisbecker Link: https://lore.kernel.org/r/20211112185203.280040-3-valentin.schneider@= arm.com --- include/linux/sched.h | 41 +++++++++++++++++++++++++++++++++++++++++ kernel/sched/core.c | 12 ++++++++++++ 2 files changed, 53 insertions(+) diff --git a/include/linux/sched.h b/include/linux/sched.h index d5e3c00..67f06f7 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2117,6 +2117,47 @@ static inline void cond_resched_rcu(void) #endif } =20 +#ifdef CONFIG_PREEMPT_DYNAMIC + +extern bool preempt_model_none(void); +extern bool preempt_model_voluntary(void); +extern bool preempt_model_full(void); + +#else + +static inline bool preempt_model_none(void) +{ + return IS_ENABLED(CONFIG_PREEMPT_NONE); +} +static inline bool preempt_model_voluntary(void) +{ + return IS_ENABLED(CONFIG_PREEMPT_VOLUNTARY); +} +static inline bool preempt_model_full(void) +{ + return IS_ENABLED(CONFIG_PREEMPT); +} + +#endif + +static inline bool preempt_model_rt(void) +{ + return IS_ENABLED(CONFIG_PREEMPT_RT); +} + +/* + * Does the preemption model allow non-cooperative preemption? + * + * For !CONFIG_PREEMPT_DYNAMIC kernels this is an exact match with + * CONFIG_PREEMPTION; for CONFIG_PREEMPT_DYNAMIC this doesn't work as the + * kernel is *built* with CONFIG_PREEMPTION=3Dy but may run with e.g. the + * PREEMPT_NONE model. + */ +static inline bool preempt_model_preemptible(void) +{ + return preempt_model_full() || preempt_model_rt(); +} + /* * Does a critical section need to be broken due to another * task waiting?: (technically does not depend on CONFIG_PREEMPTION, diff --git a/kernel/sched/core.c b/kernel/sched/core.c index d575b49..068c088 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8409,6 +8409,18 @@ static void __init preempt_dynamic_init(void) } } =20 +#define PREEMPT_MODEL_ACCESSOR(mode) \ + bool preempt_model_##mode(void) \ + { \ + WARN_ON_ONCE(preempt_dynamic_mode =3D=3D preempt_dynamic_undefined); \ + return preempt_dynamic_mode =3D=3D preempt_dynamic_##mode; \ + } \ + EXPORT_SYMBOL_GPL(preempt_model_##mode) + +PREEMPT_MODEL_ACCESSOR(none); +PREEMPT_MODEL_ACCESSOR(voluntary); +PREEMPT_MODEL_ACCESSOR(full); + #else /* !CONFIG_PREEMPT_DYNAMIC */ =20 static inline void preempt_dynamic_init(void) { }