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    Subject[PATCH 05/11] 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.

    Cc: Robert Love <rlove@rlove.org>
    Cc: Eric Paris <eparis@parisplace.org>
    Cc: John McCutchan <john@johnmccutchan.com>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@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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