[PATCH v2] sched: add READ_ONCE to task_on_rq_queued

[Jon Kohler <jon@nutanix.com>]

From: Harshit Agarwal <harshit@nutanix.com>

task_on_rq_queued read p->on_rq without READ_ONCE, though p->on_rq is
set with WRITE_ONCE in {activate|deactivate}_task and smp_store_release
in __block_task, and also read with READ_ONCE in task_on_rq_migrating.

Make all of these accesses pair together by adding READ_ONCE in the
task_on_rq_queued.

Signed-off-by: Harshit Agarwal <harshit@nutanix.com>
Reviewed-by: Phil Auld <pauld@redhat.com>
Cc: Jon Kohler <jon@nutanix.com>
---
 kernel/sched/sched.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c03b3d7b320e..dbbe5ce0dd96 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2277,7 +2277,7 @@ static inline int task_on_cpu(struct rq *rq, struct task_struct *p)
 
 static inline int task_on_rq_queued(struct task_struct *p)
 {
-	return p->on_rq == TASK_ON_RQ_QUEUED;
+	return READ_ONCE(p->on_rq) == TASK_ON_RQ_QUEUED;
 }
 
 static inline int task_on_rq_migrating(struct task_struct *p)
-- 
2.43.0