From 11a6f8e2db26519b6468686411deafab81c14741 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Wed, 1 May 2019 18:05:11 +0200 Subject: [PATCH] fsnotify: Clarify connector assignment in fsnotify_add_mark_list() Add a comment explaining why WRITE_ONCE() is enough when setting mark->connector which can get dereferenced by RCU protected readers. Signed-off-by: Jan Kara --- fs/notify/mark.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/notify/mark.c b/fs/notify/mark.c index 22acb0a79b53..b251105f646f 100644 --- a/fs/notify/mark.c +++ b/fs/notify/mark.c @@ -619,6 +619,11 @@ restart: /* mark should be the last entry. last is the current last entry */ hlist_add_behind_rcu(&mark->obj_list, &last->obj_list); added: + /* + * Since connector is attached to object using cmpxchg() we are + * guaranteed that connector initialization is fully visible by anyone + * seeing mark->connector set. + */ WRITE_ONCE(mark->connector, conn); out_err: spin_unlock(&conn->lock);