From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 75534C433E0 for ; Wed, 27 May 2020 08:12:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5F3F720FC3 for ; Wed, 27 May 2020 08:12:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387803AbgE0IMf (ORCPT ); Wed, 27 May 2020 04:12:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42294 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729592AbgE0IML (ORCPT ); Wed, 27 May 2020 04:12:11 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 51BFBC061A0F; Wed, 27 May 2020 01:12:11 -0700 (PDT) Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jdrAX-0002hY-3G; Wed, 27 May 2020 10:12:09 +0200 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id E7A2E1C0837; Wed, 27 May 2020 10:12:01 +0200 (CEST) Date: Wed, 27 May 2020 08:12:01 -0000 From: "tip-bot2 for Thomas Gleixner" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/entry] rcu: Provide rcu_irq_exit_check_preempt() Cc: Thomas Gleixner , Ingo Molnar , "Paul E. McKenney" , x86 , LKML In-Reply-To: <20200521202117.089709607@linutronix.de> References: <20200521202117.089709607@linutronix.de> MIME-Version: 1.0 Message-ID: <159056712180.17951.11617155731989917506.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the x86/entry branch of tip: Commit-ID: 07325d4a90d2d84de45cc07b134fd0f023dbb971 Gitweb: https://git.kernel.org/tip/07325d4a90d2d84de45cc07b134fd0f023dbb971 Author: Thomas Gleixner AuthorDate: Thu, 21 May 2020 22:05:16 +02:00 Committer: Ingo Molnar CommitterDate: Tue, 26 May 2020 19:05:11 +02:00 rcu: Provide rcu_irq_exit_check_preempt() Provide a debug check which can be invoked from exception return to kernel mode before an attempt is made to schedule. Warn if RCU is not ready for this. Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar Cc: Paul E. McKenney Link: https://lore.kernel.org/r/20200521202117.089709607@linutronix.de --- include/linux/rcutiny.h | 1 + include/linux/rcutree.h | 6 ++++++ kernel/rcu/tree.c | 18 ++++++++++++++++++ 3 files changed, 25 insertions(+) diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h index c869fb2..8512cae 100644 --- a/include/linux/rcutiny.h +++ b/include/linux/rcutiny.h @@ -72,6 +72,7 @@ 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_preempt(void) { } +static inline void rcu_irq_exit_check_preempt(void) { } static inline void exit_rcu(void) { } static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t) { diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index 9366fa4..d5cc9d6 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -51,6 +51,12 @@ void rcu_irq_exit_preempt(void); void rcu_irq_enter_irqson(void); void rcu_irq_exit_irqson(void); +#ifdef CONFIG_PROVE_RCU +void rcu_irq_exit_check_preempt(void); +#else +static inline void rcu_irq_exit_check_preempt(void) { } +#endif + void exit_rcu(void); void rcu_scheduler_starting(void); diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index b7f8c49..d8e9dbb 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -765,6 +765,24 @@ void rcu_irq_exit_preempt(void) "RCU in extended quiescent state!"); } +#ifdef CONFIG_PROVE_RCU +/** + * rcu_irq_exit_check_preempt - Validate that scheduling is possible + */ +void rcu_irq_exit_check_preempt(void) +{ + lockdep_assert_irqs_disabled(); + + RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nesting) <= 0, + "RCU dynticks_nesting counter underflow/zero!"); + RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) != + DYNTICK_IRQ_NONIDLE, + "Bad RCU dynticks_nmi_nesting counter\n"); + RCU_LOCKDEP_WARN(rcu_dynticks_curr_cpu_in_eqs(), + "RCU in extended quiescent state!"); +} +#endif /* #ifdef CONFIG_PROVE_RCU */ + /* * Wrapper for rcu_irq_exit() where interrupts are enabled. *