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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 <jack@suse.cz>
This commit is contained in:
Jan Kara 2019-05-01 18:05:11 +02:00
parent b1da6a5187
commit 11a6f8e2db
1 changed files with 5 additions and 0 deletions
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5
fs/notify/mark.c
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@ -619,6 +619,11 @@ restart:
/* mark should be the last entry. last is the current last entry */ /* mark should be the last entry. last is the current last entry */
hlist_add_behind_rcu(&mark->obj_list, &last->obj_list); hlist_add_behind_rcu(&mark->obj_list, &last->obj_list);
added: 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); WRITE_ONCE(mark->connector, conn);
out_err: out_err:
spin_unlock(&conn->lock); spin_unlock(&conn->lock);