From: Paul E. McKenney <paulmck@kernel.org>
Date: Tue, 18 Jun 2024 17:40:30 +0000 (-0700)
Subject: rcu/kfree: Warn on unexpected tail state
X-Git-Tag: v6.12-rc1~166^2^8~2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=3471e96bcf53731639587580fd02e5a297940b91;p=thirdparty%2Flinux.git

rcu/kfree: Warn on unexpected tail state

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@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
---

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index e641cc681901a..0f41a81138dce 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));