I don't think this one needs nested sleeps.
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index cc423a3..1ca5888 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -233,15 +233,16 @@ static ssize_t inotify_read(struct file *file, char
__user *buf,
group = file->private_data;
while (1) {
+ mutex_lock(&group->notification_mutex);
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);
pr_debug("%s: group=%p kevent=%p\n", __func__, group, kevent);
if (kevent) {
+ __set_current_state(TASK_RUNNING);
ret = PTR_ERR(kevent);
if (IS_ERR(kevent))
break;
On 08/04/2014 06:30 PM, Peter Zijlstra wrote:
> 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: Eric Paris <epa...@parisplace.org>
> Cc: John McCutchan <j...@johnmccutchan.com>
> Cc: Robert Love <rl...@rlove.org>
> Signed-off-by: Peter Zijlstra <pet...@infradead.org>
> ---
> 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;
>
>
> --
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