Commit 536ebe9c authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar

sched, fanotify: Deal with nested sleeps

As per e23738a7 ("sched, inotify: Deal with nested sleeps").

fanotify_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.
Reported-by: default avatarYuanhan Liu <yuanhan.liu@linux.intel.com>
Reported-by: default avatarSedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Paris <eparis@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Eric Paris <eparis@redhat.com>
Link: http://lkml.kernel.org/r/20141216152838.GZ3337@twins.programming.kicks-ass.netSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent b74e6278
......@@ -259,16 +259,15 @@ static ssize_t fanotify_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;
pr_debug("%s: group=%p\n", __func__, group);
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);
......@@ -289,7 +288,8 @@ static ssize_t fanotify_read(struct file *file, char __user *buf,
if (start != buf)
break;
schedule();
wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
continue;
}
......@@ -318,8 +318,8 @@ static ssize_t fanotify_read(struct file *file, char __user *buf,
buf += ret;
count -= ret;
}
remove_wait_queue(&group->notification_waitq, &wait);
finish_wait(&group->notification_waitq, &wait);
if (start != buf && ret != -EFAULT)
ret = buf - start;
return ret;
......
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