workqueue: Add RCU annotation for pwq list walk

[ Upstream commit 49e9d1a9faf2f71fdfd80a30697ee9a15070626d ]

An additional check has been recently added to ensure that a RCU related lock
is held while the RCU list is iterated.
The `pwqs' are sometimes iterated without a RCU lock but with the &wq->mutex
acquired leading to a warning.

Teach list_for_each_entry_rcu() that the RCU usage is okay if &wq->mutex
is acquired during the list traversal.

Fixes: 28875945ba98d ("rcu: Add support for consolidated-RCU reader checking")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 6496876..e9c63b7 100644 (file)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -425,7 +425,8 @@ static void workqueue_sysfs_unregister(struct workqueue_struct *wq);
  * ignored.
  */
 #define for_each_pwq(pwq, wq)                                          \
-       list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node)          \
+       list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node,          \
+                               lockdep_is_held(&wq->mutex))            \
                if (({ assert_rcu_or_wq_mutex(wq); false; })) { }       \
                else