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authorEric Wong <normalperson@yhbt.net>2013-04-30 15:27:40 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-04-30 17:04:04 -0700
commitddf676c38b56a8641c8eb9fb856fa304018ff390 (patch)
tree1c4aed96cc3f07c2f740929811156e16126f04f6 /fs
parenteea1d585917c538d90bc26fda5d8e53796feada2 (diff)
downloadlinux-ddf676c38b56a8641c8eb9fb856fa304018ff390.tar.gz
epoll: lock ep->mtx in ep_free to silence lockdep
Technically we do not need to hold ep->mtx during ep_free since we are certain there are no other users of ep at that point. However, lockdep complains with a "suspicious rcu_dereference_check() usage!" message; so lock the mutex before ep_remove to silence the warning. Signed-off-by: Eric Wong <normalperson@yhbt.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Arve Hjønnevåg <arve@android.com> Cc: Davide Libenzi <davidel@xmailserver.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: NeilBrown <neilb@suse.de>, Cc: Rafael J. Wysocki <rjw@sisk.pl> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/eventpoll.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index a3acf936c72..5744a7f0187 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -745,11 +745,15 @@ static void ep_free(struct eventpoll *ep)
* point we are sure no poll callbacks will be lingering around, and also by
* holding "epmutex" we can be sure that no file cleanup code will hit
* us during this operation. So we can avoid the lock on "ep->lock".
+ * We do not need to lock ep->mtx, either, we only do it to prevent
+ * a lockdep warning.
*/
+ mutex_lock(&ep->mtx);
while ((rbp = rb_first(&ep->rbr)) != NULL) {
epi = rb_entry(rbp, struct epitem, rbn);
ep_remove(ep, epi);
}
+ mutex_unlock(&ep->mtx);
mutex_unlock(&epmutex);
mutex_destroy(&ep->mtx);