From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756175AbaJ1LLj (ORCPT ); Tue, 28 Oct 2014 07:11:39 -0400 Received: from terminus.zytor.com ([198.137.202.10]:51264 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756129AbaJ1LLh (ORCPT ); Tue, 28 Oct 2014 07:11:37 -0400 Date: Tue, 28 Oct 2014 04:10:33 -0700 From: tip-bot for Peter Zijlstra Message-ID: Cc: torvalds@linux-foundation.org, peterz@infradead.org, hpa@zytor.com, john@johnmccutchan.com, eparis@parisplace.org, rlove@rlove.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@kernel.org, oleg@redhat.com, viro@zeniv.linux.org.uk Reply-To: viro@zeniv.linux.org.uk, oleg@redhat.com, mingo@kernel.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, rlove@rlove.org, eparis@parisplace.org, john@johnmccutchan.com, hpa@zytor.com, peterz@infradead.org, torvalds@linux-foundation.org In-Reply-To: <20140924082242.254858080@infradead.org> References: <20140924082242.254858080@infradead.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched, inotify: Deal with nested sleeps Git-Commit-ID: e23738a7300a7591a57a22f47b813fd1b53ec404 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: e23738a7300a7591a57a22f47b813fd1b53ec404 Gitweb: http://git.kernel.org/tip/e23738a7300a7591a57a22f47b813fd1b53ec404 Author: Peter Zijlstra AuthorDate: Wed, 24 Sep 2014 10:18:50 +0200 Committer: Ingo Molnar CommitDate: Tue, 28 Oct 2014 10:55:37 +0100 sched, inotify: Deal with nested sleeps inotify_read is a wait loop with sleeps in. Wait loops rely on task_struct::state and sleeps do too, since that's the only means of actually sleeping. Therefore the nested sleeps destroy the wait loop state and the wait loop breaks the sleep functions that assume TASK_RUNNING (mutex_lock). Fix this by using the new woken_wake_function and wait_woken() stuff, which registers wakeups in wait and thereby allows shrinking the task_state::state changes to the actual sleep part. Signed-off-by: Peter Zijlstra (Intel) Cc: Al Viro Cc: Linus Torvalds Cc: tglx@linutronix.de Cc: ilya.dryomov@inktank.com Cc: umgwanakikbuti@gmail.com Cc: Robert Love Cc: Eric Paris Cc: John McCutchan Cc: Robert Love Cc: Oleg Nesterov Link: http://lkml.kernel.org/r/20140924082242.254858080@infradead.org Signed-off-by: Ingo Molnar --- fs/notify/inotify/inotify_user.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c index daf7665..283aa31 100644 --- a/fs/notify/inotify/inotify_user.c +++ b/fs/notify/inotify/inotify_user.c @@ -227,14 +227,13 @@ static ssize_t inotify_read(struct file *file, char __user *buf, struct fsnotify_event *kevent; char __user *start; int ret; - DEFINE_WAIT(wait); + DEFINE_WAIT_FUNC(wait, woken_wake_function); start = buf; group = file->private_data; + add_wait_queue(&group->notification_waitq, &wait); while (1) { - prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE); - mutex_lock(&group->notification_mutex); kevent = get_one_event(group, count); mutex_unlock(&group->notification_mutex); @@ -264,10 +263,10 @@ static ssize_t inotify_read(struct file *file, char __user *buf, if (start != buf) break; - schedule(); + wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); } + remove_wait_queue(&group->notification_waitq, &wait); - finish_wait(&group->notification_waitq, &wait); if (start != buf && ret != -EFAULT) ret = buf - start; return ret;