fanotify: fix possible false warning when freeing events
authorJan Kara <jack@suse.cz>
Fri, 7 Oct 2016 23:56:58 +0000 (16:56 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sat, 8 Oct 2016 01:46:26 +0000 (18:46 -0700)
commit0b1b86527df4b1f398266c23e926dd788925bb69
tree04d4ba30ad9e2e17a9e68b344964fe06bcfcfd88
parent073f65522aeb23e46fc8a809d69513132d3acc81
fanotify: fix possible false warning when freeing events

When freeing permission events by fsnotify_destroy_event(), the warning
WARN_ON(!list_empty(&event->list)); may falsely hit.

This is because although fanotify_get_response() saw event->response
set, there is nothing to make sure the current CPU also sees the removal
of the event from the list.  Add proper locking around the WARN_ON() to
avoid the false warning.

Link: http://lkml.kernel.org/r/1473797711-14111-7-git-send-email-jack@suse.cz
Reported-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
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>
fs/notify/notification.c