sched: add READ_ONCE to task_on_rq_queued

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 <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Phil Auld <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

Author: Harshit Agarwal

kernel/sched/sched.h

@@ -2271,7 +2271,7 @@ 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)