sched/fair: Add READ_ONCE() and use existing helper function to access ->avg_irq

Use existing helper function cpu_util_irq() instead of open-coding
access to ->avg_irq.

During review it was noted that ->avg_irq could be updated by a
different CPU than the one which is trying to access it.

->avg_irq is updated with WRITE_ONCE(), use READ_ONCE to access it
in order to avoid any compiler optimizations.

Signed-off-by: Shrikanth Hegde <sshegde@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20240101154624.100981-3-sshegde@linux.vnet.ibm.com

1 files changed, 1 insertions, 1 deletions

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 001fe047bd5d..d2242679239e 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -3136,7 +3136,7 @@ static inline bool uclamp_rq_is_idle(struct rq *rq)
 #ifdef CONFIG_HAVE_SCHED_AVG_IRQ
 static inline unsigned long cpu_util_irq(struct rq *rq)
 {
-	return rq->avg_irq.util_avg;
+	return READ_ONCE(rq->avg_irq.util_avg);
 }
 
 static inline