From e05a8e4d88d16e088d83ce679ac3343ac66c936b Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Tue, 21 Aug 2018 21:56:34 -0700
Subject: [PATCH] sched/wait: assert the wait_queue_head lock is held in
 __wake_up_common

Better ensure we actually hold the lock using lockdep than just commenting
on it.  Due to the various exported _locked interfaces it is far too easy
to get the locking wrong.

Link: http://lkml.kernel.org/r/20171214152344.6880-4-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 kernel/sched/wait.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
index 870f97b313e3..5dd47f1103d1 100644
--- a/kernel/sched/wait.c
+++ b/kernel/sched/wait.c
@@ -69,6 +69,8 @@ static int __wake_up_common(struct wait_queue_head *wq_head, unsigned int mode,
 	wait_queue_entry_t *curr, *next;
 	int cnt = 0;
 
+	lockdep_assert_held(&wq_head->lock);
+
 	if (bookmark && (bookmark->flags & WQ_FLAG_BOOKMARK)) {
 		curr = list_next_entry(bookmark, entry);
 
-- 
2.30.2