watch_queue: Fix missing rcu annotation

commit e0339f036ef4beb9b20f0b6532a1e0ece7f594c6 upstream.

Since __post_watch_notification() walks wlist->watchers with only the
RCU read lock held, we need to use RCU methods to add to the list (we
already use RCU methods to remove from the list).

Fix add_watch_to_object() to use hlist_add_head_rcu() instead of
hlist_add_head() for that list.

Fixes: c73be61cede5 ("pipe: Add general notification queue support")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/watch_queue.c b/kernel/watch_queue.c
index e5d22af43fa0b26b9e8855ccc133ae9a421ee905..f78f90910398f09f503c4b63a89361186ee185ab 100644 (file)
--- a/kernel/watch_queue.c
+++ b/kernel/watch_queue.c
@@ -497,7 +497,7 @@ int add_watch_to_object(struct watch *watch, struct watch_list *wlist)
                unlock_wqueue(wqueue);
        }
 
-       hlist_add_head(&watch->list_node, &wlist->watchers);
+       hlist_add_head_rcu(&watch->list_node, &wlist->watchers);
        return 0;
 }
 EXPORT_SYMBOL(add_watch_to_object);