From patchwork Mon Jun 20 23:10:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Paul E. McKenney" X-Patchwork-Id: 12888516 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 A8545C43334 for ; Mon, 20 Jun 2022 23:12:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347002AbiFTXMk (ORCPT ); Mon, 20 Jun 2022 19:12:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53632 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347046AbiFTXME (ORCPT ); Mon, 20 Jun 2022 19:12:04 -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 23FFE1ADA2; Mon, 20 Jun 2022 16:10:44 -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 F2DF761503; Mon, 20 Jun 2022 23:10:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 155FFC36AEA; Mon, 20 Jun 2022 23:10:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1655766632; bh=xsKKjIRCTs+MYTIZQulQGrFw/Klyh+WfPxCeTxp4NpA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OCEWw2VQTwNZzAlOV5mtXQ9uJL086ovj3jehUe8+Y/yVJ+bGcnjBpCSl7mNY0SYe/ BwL2PO01qHOxJwvoYwFMdETev9aXAOO+T/ypDUWiYc/ysvgF/VmiHgbxw7fzF7JA41 H8jtZOZcwSTTaZUwQ9LJbgT8t3+b8SLAithhwWLlx/NQPXqrGJmFUd9fwKjsNBEPEA ZWbYEAi2gBX0loyUqMv5hdIrAXzc51fshU6LzdeNB2GgNHn/SSaPuN3N1wWOLEGuv8 P4toCMvx0GEb47ynw6IJhH49Flb8pnA1dDeeV51jYGYhQYmIXlDlNYOLNvp6DUFcUN KYHJk+HPS6sLA== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 650A15C0E42; Mon, 20 Jun 2022 16:10:31 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, rostedt@goodmis.org, Frederic Weisbecker , Peter Zijlstra , Thomas Gleixner , Neeraj Upadhyay , Uladzislau Rezki , Joel Fernandes , Boqun Feng , Nicolas Saenz Julienne , Marcelo Tosatti , Xiongfeng Wang , Yu Liao , Phil Auld , Paul Gortmaker , Alex Belits , "Paul E . McKenney" Subject: [PATCH rcu 13/23] rcu/context-tracking: Remove rcu_irq_enter/exit() Date: Mon, 20 Jun 2022 16:10:19 -0700 Message-Id: <20220620231029.3844583-13-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20220620231027.GA3844372@paulmck-ThinkPad-P17-Gen-1> References: <20220620231027.GA3844372@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org From: Frederic Weisbecker 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: 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 Signed-off-by: Paul E. McKenney --- include/linux/rcutiny.h | 4 -- include/linux/rcutree.h | 4 -- kernel/context_tracking.c | 71 +++++++++++++++++++++++++++++++-- kernel/rcu/tree.c | 83 --------------------------------------- 4 files changed, 67 insertions(+), 95 deletions(-) diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h index 5fed476f977f6..591119413cf1d 100644 --- a/include/linux/rcutiny.h +++ b/include/linux/rcutiny.h @@ -78,10 +78,6 @@ 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_softirq()) diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index 9c6cfb742504f..4522b6a7cc42f 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -47,10 +47,6 @@ void cond_synchronize_rcu(unsigned long oldstate); 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); #ifdef CONFIG_PROVE_RCU diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index afb4451c26a25..96406daf5f54b 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -36,24 +36,87 @@ void ct_idle_exit(void) } EXPORT_SYMBOL_GPL(ct_idle_exit); +/** + * ct_irq_enter - inform RCU that current CPU is entering irq away from idle + * + * 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 mode! + * 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 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_enter(), be sure to test with + * CONFIG_RCU_EQS_DEBUG=y. + */ noinstr void ct_irq_enter(void) { - rcu_irq_enter(); + lockdep_assert_irqs_disabled(); + ct_nmi_enter(); } +/** + * 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 what + * 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=y. + */ noinstr void ct_irq_exit(void) { - rcu_irq_exit(); + lockdep_assert_irqs_disabled(); + ct_nmi_exit(); } +/* + * Wrapper for ct_irq_enter() where interrupts are enabled. + * + * If you add or remove a call to ct_irq_enter_irqson(), be sure to test + * with CONFIG_RCU_EQS_DEBUG=y. + */ void ct_irq_enter_irqson(void) { - rcu_irq_enter_irqson(); + unsigned long flags; + + local_irq_save(flags); + ct_irq_enter(); + local_irq_restore(flags); } +/* + * Wrapper for ct_irq_exit() where interrupts are enabled. + * + * If you add or remove a call to ct_irq_exit_irqson(), be sure to test + * with CONFIG_RCU_EQS_DEBUG=y. + */ void ct_irq_exit_irqson(void) { - rcu_irq_exit_irqson(); + unsigned long flags; + + local_irq_save(flags); + ct_irq_exit(); + local_irq_restore(flags); } noinstr void ct_nmi_enter(void) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 051fed0844b67..75b433dba4276 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(); } -/** - * 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 what - * 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=y. - */ -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 */ -/* - * 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=y. - */ -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(); } -/** - * rcu_irq_enter - inform RCU that current CPU is entering irq away from idle - * - * 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 mode! - * 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 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_enter(), be sure to test with - * CONFIG_RCU_EQS_DEBUG=y. - */ -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=y. - */ -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,