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https://github.com/torvalds/linux
synced 2024-09-06 18:01:05 +00:00
fsnotify: convert notification_mutex to a spinlock
notification_mutex is used to protect the list of pending events. As such there's no reason to use a sleeping lock for it. Convert it to a spinlock. [jack@suse.cz: fixed version] Link: http://lkml.kernel.org/r/1474031567-1831-1-git-send-email-jack@suse.cz Link: http://lkml.kernel.org/r/1473797711-14111-5-git-send-email-jack@suse.cz Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Lino Sanfilippo <LinoSanfilippo@gmx.de> Tested-by: Guenter Roeck <linux@roeck-us.net> Cc: Miklos Szeredi <mszeredi@redhat.com> Cc: Eric Paris <eparis@redhat.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c21dbe20f6
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@ -49,12 +49,13 @@ struct kmem_cache *fanotify_perm_event_cachep __read_mostly;
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* enough to fit in "count". Return an error pointer if the count
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* is not large enough.
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*
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* Called with the group->notification_mutex held.
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* Called with the group->notification_lock held.
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*/
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static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
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size_t count)
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{
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BUG_ON(!mutex_is_locked(&group->notification_mutex));
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BUG_ON(IS_ENABLED(CONFIG_SMP) &&
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!spin_is_locked(&group->notification_lock));
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pr_debug("%s: group=%p count=%zd\n", __func__, group, count);
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@ -64,7 +65,7 @@ static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
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if (FAN_EVENT_METADATA_LEN > count)
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return ERR_PTR(-EINVAL);
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/* held the notification_mutex the whole time, so this is the
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/* held the notification_lock the whole time, so this is the
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* same event we peeked above */
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return fsnotify_remove_first_event(group);
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}
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@ -244,10 +245,10 @@ static unsigned int fanotify_poll(struct file *file, poll_table *wait)
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int ret = 0;
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poll_wait(file, &group->notification_waitq, wait);
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mutex_lock(&group->notification_mutex);
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spin_lock(&group->notification_lock);
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if (!fsnotify_notify_queue_is_empty(group))
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ret = POLLIN | POLLRDNORM;
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mutex_unlock(&group->notification_mutex);
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spin_unlock(&group->notification_lock);
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return ret;
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}
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@ -268,9 +269,9 @@ static ssize_t fanotify_read(struct file *file, char __user *buf,
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add_wait_queue(&group->notification_waitq, &wait);
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while (1) {
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mutex_lock(&group->notification_mutex);
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spin_lock(&group->notification_lock);
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kevent = get_one_event(group, count);
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mutex_unlock(&group->notification_mutex);
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spin_unlock(&group->notification_lock);
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if (IS_ERR(kevent)) {
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ret = PTR_ERR(kevent);
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@ -387,17 +388,17 @@ static int fanotify_release(struct inode *ignored, struct file *file)
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* dequeue them and set the response. They will be freed once the
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* response is consumed and fanotify_get_response() returns.
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*/
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mutex_lock(&group->notification_mutex);
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spin_lock(&group->notification_lock);
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while (!fsnotify_notify_queue_is_empty(group)) {
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fsn_event = fsnotify_remove_first_event(group);
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if (!(fsn_event->mask & FAN_ALL_PERM_EVENTS)) {
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mutex_unlock(&group->notification_mutex);
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spin_unlock(&group->notification_lock);
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fsnotify_destroy_event(group, fsn_event);
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mutex_lock(&group->notification_mutex);
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spin_lock(&group->notification_lock);
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} else
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FANOTIFY_PE(fsn_event)->response = FAN_ALLOW;
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}
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mutex_unlock(&group->notification_mutex);
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spin_unlock(&group->notification_lock);
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/* Response for all permission events it set, wakeup waiters */
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wake_up(&group->fanotify_data.access_waitq);
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@ -423,10 +424,10 @@ static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long ar
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switch (cmd) {
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case FIONREAD:
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mutex_lock(&group->notification_mutex);
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spin_lock(&group->notification_lock);
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list_for_each_entry(fsn_event, &group->notification_list, list)
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send_len += FAN_EVENT_METADATA_LEN;
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mutex_unlock(&group->notification_mutex);
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spin_unlock(&group->notification_lock);
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ret = put_user(send_len, (int __user *) p);
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break;
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}
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@ -45,9 +45,9 @@ static void fsnotify_final_destroy_group(struct fsnotify_group *group)
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*/
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void fsnotify_group_stop_queueing(struct fsnotify_group *group)
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{
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mutex_lock(&group->notification_mutex);
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spin_lock(&group->notification_lock);
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group->shutdown = true;
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mutex_unlock(&group->notification_mutex);
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spin_unlock(&group->notification_lock);
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}
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/*
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@ -125,7 +125,7 @@ struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops)
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atomic_set(&group->refcnt, 1);
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atomic_set(&group->num_marks, 0);
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mutex_init(&group->notification_mutex);
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spin_lock_init(&group->notification_lock);
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INIT_LIST_HEAD(&group->notification_list);
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init_waitqueue_head(&group->notification_waitq);
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group->max_events = UINT_MAX;
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@ -115,10 +115,10 @@ static unsigned int inotify_poll(struct file *file, poll_table *wait)
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int ret = 0;
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poll_wait(file, &group->notification_waitq, wait);
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mutex_lock(&group->notification_mutex);
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spin_lock(&group->notification_lock);
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if (!fsnotify_notify_queue_is_empty(group))
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ret = POLLIN | POLLRDNORM;
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mutex_unlock(&group->notification_mutex);
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spin_unlock(&group->notification_lock);
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return ret;
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}
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@ -138,7 +138,7 @@ static int round_event_name_len(struct fsnotify_event *fsn_event)
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* enough to fit in "count". Return an error pointer if
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* not large enough.
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*
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* Called with the group->notification_mutex held.
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* Called with the group->notification_lock held.
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*/
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static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
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size_t count)
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@ -157,7 +157,7 @@ static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
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if (event_size > count)
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return ERR_PTR(-EINVAL);
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/* held the notification_mutex the whole time, so this is the
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/* held the notification_lock the whole time, so this is the
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* same event we peeked above */
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fsnotify_remove_first_event(group);
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@ -234,9 +234,9 @@ static ssize_t inotify_read(struct file *file, char __user *buf,
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add_wait_queue(&group->notification_waitq, &wait);
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while (1) {
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mutex_lock(&group->notification_mutex);
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spin_lock(&group->notification_lock);
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kevent = get_one_event(group, count);
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mutex_unlock(&group->notification_mutex);
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spin_unlock(&group->notification_lock);
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pr_debug("%s: group=%p kevent=%p\n", __func__, group, kevent);
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@ -300,13 +300,13 @@ static long inotify_ioctl(struct file *file, unsigned int cmd,
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switch (cmd) {
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case FIONREAD:
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mutex_lock(&group->notification_mutex);
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spin_lock(&group->notification_lock);
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list_for_each_entry(fsn_event, &group->notification_list,
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list) {
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send_len += sizeof(struct inotify_event);
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send_len += round_event_name_len(fsn_event);
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}
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mutex_unlock(&group->notification_mutex);
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spin_unlock(&group->notification_lock);
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ret = put_user(send_len, (int __user *) p);
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break;
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}
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@ -63,7 +63,8 @@ EXPORT_SYMBOL_GPL(fsnotify_get_cookie);
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/* return true if the notify queue is empty, false otherwise */
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bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group)
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{
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BUG_ON(!mutex_is_locked(&group->notification_mutex));
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BUG_ON(IS_ENABLED(CONFIG_SMP) &&
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!spin_is_locked(&group->notification_lock));
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return list_empty(&group->notification_list) ? true : false;
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}
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@ -95,10 +96,10 @@ int fsnotify_add_event(struct fsnotify_group *group,
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pr_debug("%s: group=%p event=%p\n", __func__, group, event);
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mutex_lock(&group->notification_mutex);
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spin_lock(&group->notification_lock);
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if (group->shutdown) {
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mutex_unlock(&group->notification_mutex);
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spin_unlock(&group->notification_lock);
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return 2;
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}
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@ -106,7 +107,7 @@ int fsnotify_add_event(struct fsnotify_group *group,
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ret = 2;
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/* Queue overflow event only if it isn't already queued */
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if (!list_empty(&group->overflow_event->list)) {
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mutex_unlock(&group->notification_mutex);
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spin_unlock(&group->notification_lock);
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return ret;
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}
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event = group->overflow_event;
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@ -116,7 +117,7 @@ int fsnotify_add_event(struct fsnotify_group *group,
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if (!list_empty(list) && merge) {
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ret = merge(list, event);
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if (ret) {
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mutex_unlock(&group->notification_mutex);
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spin_unlock(&group->notification_lock);
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return ret;
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}
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}
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@ -124,7 +125,7 @@ int fsnotify_add_event(struct fsnotify_group *group,
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queue:
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group->q_len++;
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list_add_tail(&event->list, list);
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mutex_unlock(&group->notification_mutex);
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spin_unlock(&group->notification_lock);
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wake_up(&group->notification_waitq);
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kill_fasync(&group->fsn_fa, SIGIO, POLL_IN);
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@ -139,7 +140,8 @@ struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group)
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{
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struct fsnotify_event *event;
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BUG_ON(!mutex_is_locked(&group->notification_mutex));
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BUG_ON(IS_ENABLED(CONFIG_SMP) &&
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!spin_is_locked(&group->notification_lock));
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pr_debug("%s: group=%p\n", __func__, group);
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@ -161,7 +163,8 @@ struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group)
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*/
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struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group)
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{
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BUG_ON(!mutex_is_locked(&group->notification_mutex));
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BUG_ON(IS_ENABLED(CONFIG_SMP) &&
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!spin_is_locked(&group->notification_lock));
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return list_first_entry(&group->notification_list,
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struct fsnotify_event, list);
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@ -175,14 +178,14 @@ void fsnotify_flush_notify(struct fsnotify_group *group)
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{
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struct fsnotify_event *event;
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mutex_lock(&group->notification_mutex);
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spin_lock(&group->notification_lock);
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while (!fsnotify_notify_queue_is_empty(group)) {
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event = fsnotify_remove_first_event(group);
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mutex_unlock(&group->notification_mutex);
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spin_unlock(&group->notification_lock);
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fsnotify_destroy_event(group, event);
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mutex_lock(&group->notification_mutex);
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spin_lock(&group->notification_lock);
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}
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mutex_unlock(&group->notification_mutex);
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spin_unlock(&group->notification_lock);
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}
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/*
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@ -135,7 +135,7 @@ struct fsnotify_group {
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const struct fsnotify_ops *ops; /* how this group handles things */
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/* needed to send notification to userspace */
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struct mutex notification_mutex; /* protect the notification_list */
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spinlock_t notification_lock; /* protect the notification_list */
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struct list_head notification_list; /* list of event_holder this group needs to send to userspace */
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wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */
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unsigned int q_len; /* events on the queue */
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