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=-11.8 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 4517DC352A3 for ; Tue, 11 Feb 2020 12:49:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 26C86214DB for ; Tue, 11 Feb 2020 12:49:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729132AbgBKMtO (ORCPT ); Tue, 11 Feb 2020 07:49:14 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:46088 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728617AbgBKMs3 (ORCPT ); Tue, 11 Feb 2020 07:48:29 -0500 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 1j1Uxi-0007kU-Nn; Tue, 11 Feb 2020 13:48:22 +0100 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id 67AF91C2018; Tue, 11 Feb 2020 13:48:22 +0100 (CET) Date: Tue, 11 Feb 2020 12:48:22 -0000 From: "tip-bot2 for Davidlohr Bueso" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: locking/core] locking/percpu-rwsem: Fold __percpu_up_read() Cc: Davidlohr Bueso , "Peter Zijlstra (Intel)" , Ingo Molnar , Will Deacon , Waiman Long , x86 , LKML In-Reply-To: <20200131151540.212415454@infradead.org> References: <20200131151540.212415454@infradead.org> MIME-Version: 1.0 Message-ID: <158142530217.411.5840640700611865076.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 locking/core branch of tip: Commit-ID: ac8dec420970f5cbaf2f6eda39153a60ec5b257b Gitweb: https://git.kernel.org/tip/ac8dec420970f5cbaf2f6eda39153a60ec5b257b Author: Davidlohr Bueso AuthorDate: Mon, 18 Nov 2019 15:19:35 -08:00 Committer: Ingo Molnar CommitterDate: Tue, 11 Feb 2020 13:10:58 +01:00 locking/percpu-rwsem: Fold __percpu_up_read() Now that __percpu_up_read() is only ever used from percpu_up_read() merge them, it's a small function. Signed-off-by: Davidlohr Bueso Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Acked-by: Will Deacon Acked-by: Waiman Long Link: https://lkml.kernel.org/r/20200131151540.212415454@infradead.org --- include/linux/percpu-rwsem.h | 19 +++++++++++++++---- kernel/exit.c | 1 + kernel/locking/percpu-rwsem.c | 15 --------------- 3 files changed, 16 insertions(+), 19 deletions(-) diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h index f5ecf6a..5e033fe 100644 --- a/include/linux/percpu-rwsem.h +++ b/include/linux/percpu-rwsem.h @@ -43,7 +43,6 @@ is_static struct percpu_rw_semaphore name = { \ __DEFINE_PERCPU_RWSEM(name, static) extern bool __percpu_down_read(struct percpu_rw_semaphore *, bool); -extern void __percpu_up_read(struct percpu_rw_semaphore *); static inline void percpu_down_read(struct percpu_rw_semaphore *sem) { @@ -103,10 +102,22 @@ static inline void percpu_up_read(struct percpu_rw_semaphore *sem) /* * Same as in percpu_down_read(). */ - if (likely(rcu_sync_is_idle(&sem->rss))) + if (likely(rcu_sync_is_idle(&sem->rss))) { __this_cpu_dec(*sem->read_count); - else - __percpu_up_read(sem); /* Unconditional memory barrier */ + } else { + /* + * slowpath; reader will only ever wake a single blocked + * writer. + */ + smp_mb(); /* B matches C */ + /* + * In other words, if they see our decrement (presumably to + * aggregate zero, as that is the only time it matters) they + * will also see our critical section. + */ + __this_cpu_dec(*sem->read_count); + rcuwait_wake_up(&sem->writer); + } preempt_enable(); } diff --git a/kernel/exit.c b/kernel/exit.c index 2833ffb..f64a8f9 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -258,6 +258,7 @@ void rcuwait_wake_up(struct rcuwait *w) wake_up_process(task); rcu_read_unlock(); } +EXPORT_SYMBOL_GPL(rcuwait_wake_up); /* * Determine if a process group is "orphaned", according to the POSIX diff --git a/kernel/locking/percpu-rwsem.c b/kernel/locking/percpu-rwsem.c index a136677..8048a9a 100644 --- a/kernel/locking/percpu-rwsem.c +++ b/kernel/locking/percpu-rwsem.c @@ -177,21 +177,6 @@ bool __percpu_down_read(struct percpu_rw_semaphore *sem, bool try) } EXPORT_SYMBOL_GPL(__percpu_down_read); -void __percpu_up_read(struct percpu_rw_semaphore *sem) -{ - smp_mb(); /* B matches C */ - /* - * In other words, if they see our decrement (presumably to aggregate - * zero, as that is the only time it matters) they will also see our - * critical section. - */ - __this_cpu_dec(*sem->read_count); - - /* Prod writer to re-evaluate readers_active_check() */ - rcuwait_wake_up(&sem->writer); -} -EXPORT_SYMBOL_GPL(__percpu_up_read); - #define per_cpu_sum(var) \ ({ \ typeof(var) __sum = 0; \