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Commit 9573f793 authored by Jan Kara's avatar Jan Kara Committed by Linus Torvalds
Browse files

fanotify: convert access_mutex to spinlock 



access_mutex is used only to guard operations on access_list.  There's
no need for sleeping within this lock so just make a spinlock out of it.

Signed-off-by: default avatarJan Kara <jack@suse.cz>
Cc: Eric Paris <eparis@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f083441b

fs/notify/fanotify/fanotify_user.c

+7 −7
Original line number Diff line number Diff line
@@ -134,7 +134,7 @@ static struct fanotify_perm_event_info *dequeue_event( 
{

	struct fanotify_perm_event_info *event, *return_e = NULL;



	mutex_lock(&group->fanotify_data.access_mutex);

	spin_lock(&group->fanotify_data.access_lock);

	list_for_each_entry(event, &group->fanotify_data.access_list,

			    fae.fse.list) {

		if (event->fd != fd)
@@ -144,7 +144,7 @@ static struct fanotify_perm_event_info *dequeue_event( 
		return_e = event;

		break;

	}

	mutex_unlock(&group->fanotify_data.access_mutex);

	spin_unlock(&group->fanotify_data.access_lock);



	pr_debug("%s: found return_re=%p\n", __func__, return_e);
@@ -213,10 +213,10 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group, 


		pevent = FANOTIFY_PE(event);

		pevent->fd = fd;

		mutex_lock(&group->fanotify_data.access_mutex);

		spin_lock(&group->fanotify_data.access_lock);

		list_add_tail(&pevent->fae.fse.list,

			      &group->fanotify_data.access_list);

		mutex_unlock(&group->fanotify_data.access_mutex);

		spin_unlock(&group->fanotify_data.access_lock);

	}

#endif
@@ -346,7 +346,7 @@ static int fanotify_release(struct inode *ignored, struct file *file) 
#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS

	struct fanotify_perm_event_info *event, *next;



	mutex_lock(&group->fanotify_data.access_mutex);

	spin_lock(&group->fanotify_data.access_lock);



	atomic_inc(&group->fanotify_data.bypass_perm);
@@ -358,7 +358,7 @@ static int fanotify_release(struct inode *ignored, struct file *file) 
		list_del_init(&event->fae.fse.list);

		event->response = FAN_ALLOW;

	}

	mutex_unlock(&group->fanotify_data.access_mutex);

	spin_unlock(&group->fanotify_data.access_lock);



	wake_up(&group->fanotify_data.access_waitq);

#endif
@@ -700,7 +700,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 


	group->fanotify_data.f_flags = event_f_flags;

#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS

	mutex_init(&group->fanotify_data.access_mutex);

	spin_lock_init(&group->fanotify_data.access_lock);

	init_waitqueue_head(&group->fanotify_data.access_waitq);

	INIT_LIST_HEAD(&group->fanotify_data.access_list);

	atomic_set(&group->fanotify_data.bypass_perm, 0);

include/linux/fsnotify_backend.h

+1 −1
Original line number Diff line number Diff line
@@ -178,7 +178,7 @@ struct fsnotify_group { 
		struct fanotify_group_private_data {

#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS

			/* allows a group to block waiting for a userspace response */

			struct mutex access_mutex;

			spinlock_t access_lock;

			struct list_head access_list;

			wait_queue_head_t access_waitq;

			atomic_t bypass_perm;