From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754159AbaIXIal (ORCPT ); Wed, 24 Sep 2014 04:30:41 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:57000 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753028AbaIXI1U (ORCPT ); Wed, 24 Sep 2014 04:27:20 -0400 Message-Id: <20140924082242.254858080@infradead.org> User-Agent: quilt/0.60-1 Date: Wed, 24 Sep 2014 10:18:50 +0200 From: Peter Zijlstra To: mingo@kernel.org, oleg@redhat.com, torvalds@linux-foundation.org Cc: tglx@linutronix.de, ilya.dryomov@inktank.com, umgwanakikbuti@gmail.com, linux-kernel@vger.kernel.org, Peter Zijlstra , Robert Love , Eric Paris , John McCutchan Subject: [PATCH 05/11] inotify: Deal with nested sleeps References: <20140924081845.572814794@infradead.org> Content-Disposition: inline; filename=peterz-might_sleep-inotify.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Cc: Robert Love Cc: Eric Paris Cc: John McCutchan Signed-off-by: Peter Zijlstra (Intel) --- fs/notify/inotify/inotify_user.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) --- 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 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 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;