From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751267AbdAVKPE (ORCPT ); Sun, 22 Jan 2017 05:15:04 -0500 Received: from terminus.zytor.com ([65.50.211.136]:60510 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750770AbdAVKPD (ORCPT ); Sun, 22 Jan 2017 05:15:03 -0500 Date: Sun, 22 Jan 2017 02:14:19 -0800 From: tip-bot for Waiman Long Message-ID: Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, paulmck@linux.vnet.ibm.com, hpa@zytor.com, dave@stgolabs.net, torvalds@linux-foundation.org, peterz@infradead.org, mingo@kernel.org, longman@redhat.com Reply-To: dave@stgolabs.net, hpa@zytor.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, paulmck@linux.vnet.ibm.com, longman@redhat.com, mingo@kernel.org, peterz@infradead.org, torvalds@linux-foundation.org In-Reply-To: <1485052415-9611-1-git-send-email-longman@redhat.com> References: <1485052415-9611-1-git-send-email-longman@redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:locking/core] locking/rwsem: Reinit wake_q after use Git-Commit-ID: bcc9a76d5ac426bc45c9e863b1830347827ca77a X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: bcc9a76d5ac426bc45c9e863b1830347827ca77a Gitweb: http://git.kernel.org/tip/bcc9a76d5ac426bc45c9e863b1830347827ca77a Author: Waiman Long AuthorDate: Sat, 21 Jan 2017 21:33:35 -0500 Committer: Ingo Molnar CommitDate: Sun, 22 Jan 2017 09:54:00 +0100 locking/rwsem: Reinit wake_q after use In __rwsem_down_write_failed_common(), the same wake_q variable name is defined twice, with the inner wake_q hiding the one in outer scope. We can either use different names for the two wake_q's. Even better, we can use the same wake_q twice, if necessary. To enable the latter change, we need to define a new helper function wake_q_init() to enable reinitalization of wake_q after use. Signed-off-by: Waiman Long Cc: Andrew Morton Cc: Davidlohr Bueso Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1485052415-9611-1-git-send-email-longman@redhat.com Signed-off-by: Ingo Molnar --- include/linux/sched.h | 6 ++++++ kernel/locking/rwsem-xadd.c | 7 +++++-- 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index f4f9d32..4e62b37 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1021,6 +1021,12 @@ struct wake_q_head { #define DEFINE_WAKE_Q(name) \ struct wake_q_head name = { WAKE_Q_TAIL, &name.first } +static inline void wake_q_init(struct wake_q_head *head) +{ + head->first = WAKE_Q_TAIL; + head->lastp = &head->first; +} + extern void wake_q_add(struct wake_q_head *head, struct task_struct *task); extern void wake_up_q(struct wake_q_head *head); diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c index a3a381a..2ad8d8d 100644 --- a/kernel/locking/rwsem-xadd.c +++ b/kernel/locking/rwsem-xadd.c @@ -502,8 +502,6 @@ __rwsem_down_write_failed_common(struct rw_semaphore *sem, int state) * wake any read locks that were queued ahead of us. */ if (count > RWSEM_WAITING_BIAS) { - DEFINE_WAKE_Q(wake_q); - __rwsem_mark_wake(sem, RWSEM_WAKE_READERS, &wake_q); /* * The wakeup is normally called _after_ the wait_lock @@ -513,6 +511,11 @@ __rwsem_down_write_failed_common(struct rw_semaphore *sem, int state) * for attempting rwsem_try_write_lock(). */ wake_up_q(&wake_q); + + /* + * Reinitialize wake_q after use. + */ + wake_q_init(&wake_q); } } else