/* return true if the notify queue is empty, false otherwise */
bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group)
{
- BUG_ON(!mutex_is_locked(&group->notification_mutex));
+ assert_spin_locked(&group->notification_lock);
return list_empty(&group->notification_list) ? true : false;
}
/* Overflow events are per-group and we don't want to free them */
if (!event || event->mask == FS_Q_OVERFLOW)
return;
- /* If the event is still queued, we have a problem... */
- WARN_ON(!list_empty(&event->list));
+ /*
+ * If the event is still queued, we have a problem... Do an unreliable
+ * lockless check first to avoid locking in the common case. The
+ * locking may be necessary for permission events which got removed
+ * from the list by a different CPU than the one freeing the event.
+ */
+ if (!list_empty(&event->list)) {
+ spin_lock(&group->notification_lock);
+ WARN_ON(!list_empty(&event->list));
+ spin_unlock(&group->notification_lock);
+ }
group->ops->free_event(event);
}
pr_debug("%s: group=%p event=%p\n", __func__, group, event);
- mutex_lock(&group->notification_mutex);
+ spin_lock(&group->notification_lock);
if (group->shutdown) {
- mutex_unlock(&group->notification_mutex);
+ spin_unlock(&group->notification_lock);
return 2;
}
ret = 2;
/* Queue overflow event only if it isn't already queued */
if (!list_empty(&group->overflow_event->list)) {
- mutex_unlock(&group->notification_mutex);
+ spin_unlock(&group->notification_lock);
return ret;
}
event = group->overflow_event;
if (!list_empty(list) && merge) {
ret = merge(list, event);
if (ret) {
- mutex_unlock(&group->notification_mutex);
+ spin_unlock(&group->notification_lock);
return ret;
}
}
queue:
group->q_len++;
list_add_tail(&event->list, list);
- mutex_unlock(&group->notification_mutex);
+ spin_unlock(&group->notification_lock);
wake_up(&group->notification_waitq);
kill_fasync(&group->fsn_fa, SIGIO, POLL_IN);
{
struct fsnotify_event *event;
- BUG_ON(!mutex_is_locked(&group->notification_mutex));
+ assert_spin_locked(&group->notification_lock);
pr_debug("%s: group=%p\n", __func__, group);
*/
struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group)
{
- BUG_ON(!mutex_is_locked(&group->notification_mutex));
+ assert_spin_locked(&group->notification_lock);
return list_first_entry(&group->notification_list,
struct fsnotify_event, list);
{
struct fsnotify_event *event;
- mutex_lock(&group->notification_mutex);
+ spin_lock(&group->notification_lock);
while (!fsnotify_notify_queue_is_empty(group)) {
event = fsnotify_remove_first_event(group);
+ spin_unlock(&group->notification_lock);
fsnotify_destroy_event(group, event);
+ spin_lock(&group->notification_lock);
}
- mutex_unlock(&group->notification_mutex);
+ spin_unlock(&group->notification_lock);
}
/*