[PATCH rcu 1/3] rcu/kfree: Warn on unexpected tail state

[neeraj . upadhyay]

From: "Paul E. McKenney" <paulmck@xxxxxxxxxx>

Within the rcu_sr_normal_gp_cleanup_work() function, there is an acquire
load from rcu_state.srs_done_tail, which is expected to be non-NULL.
This commit adds a WARN_ON_ONCE() to check this expectation.

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@xxxxxxxxxx>
---
 kernel/rcu/tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index e641cc681901..0f41a81138dc 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1649,7 +1649,7 @@ static void rcu_sr_normal_gp_cleanup_work(struct work_struct *work)
 	 * the done tail list manipulations are protected here.
 	 */
 	done = smp_load_acquire(&rcu_state.srs_done_tail);
-	if (!done)
+	if (WARN_ON_ONCE(!done))
 		return;
 
 	WARN_ON_ONCE(!rcu_sr_is_wait_head(done));
-- 
2.40.1