[PATCH AUTOSEL 6.3 1/3] refscale: Move shutdown from wait_event() to wait_event_idle()

Sasha Levin
2023-07-02T19:41:05Z

From: "Paul E. McKenney" <paulmck@kernel.org>

[ Upstream commit 6bc6e6b27524304aadb9c04611ddb1c84dd7617a ]

The ref_scale_shutdown() kthread/function uses wait_event() to wait for
the refscale test to complete. However, although the read-side tests
are normally extremely fast, there is no law against specifying a very
large value for the refscale.loops module parameter or against having
a slow read-side primitive. Either way, this might well trigger the
hung-task timeout.

This commit therefore replaces those wait_event() calls with calls to
wait_event_idle(), which do not trigger the hung-task timeout.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/rcu/refscale.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c
index afa3e1a2f6902..1970ce5f22d40 100644
--- a/kernel/rcu/refscale.c
+++ b/kernel/rcu/refscale.c
@@ -1031,7 +1031,7 @@ ref_scale_cleanup(void)
static int
ref_scale_shutdown(void *arg)
{
- wait_event(shutdown_wq, shutdown_start);
+ wait_event_idle(shutdown_wq, shutdown_start);

smp_mb(); // Wake before output.
ref_scale_cleanup();
--
2.39.2