From e0339f036ef4beb9b20f0b6532a1e0ece7f594c6 Mon Sep 17 00:00:00 2001
From: David Howells <dhowells@redhat.com>
Date: Thu, 28 Jul 2022 10:31:06 +0100
Subject: [PATCH] watch_queue: Fix missing rcu annotation
Git-commit: e0339f036ef4beb9b20f0b6532a1e0ece7f594c6
Patch-mainline: v5.19
References: git-fixes

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>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 kernel/watch_queue.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/watch_queue.c
+++ b/kernel/watch_queue.c
@@ -494,7 +494,7 @@ int add_watch_to_object(struct watch *wa
 		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);