[PATCH v3 7/7] cpuidle/poll_state: replace cpu_relax with smp_cond_load_relaxed

[Mihai Carabas]

cpu_relax on ARM64 does a simple "yield". Thus we replace it with
smp_cond_load_relaxed which basically does a "wfe".

Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Mihai Carabas <mihai.carabas@xxxxxxxxxx>
---
 drivers/cpuidle/poll_state.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/cpuidle/poll_state.c b/drivers/cpuidle/poll_state.c
index 9b6d90a72601..440cd713e39a 100644
--- a/drivers/cpuidle/poll_state.c
+++ b/drivers/cpuidle/poll_state.c
@@ -26,12 +26,16 @@ static int __cpuidle poll_idle(struct cpuidle_device *dev,
 
 		limit = cpuidle_poll_time(drv, dev);
 
-		while (!need_resched()) {
-			cpu_relax();
-			if (loop_count++ < POLL_IDLE_RELAX_COUNT)
-				continue;
-
+		for (;;) {
 			loop_count = 0;
+
+			smp_cond_load_relaxed(&current_thread_info()->flags,
+					      (VAL & _TIF_NEED_RESCHED) ||
+					      (loop_count++ >= POLL_IDLE_RELAX_COUNT));
+
+			if (loop_count < POLL_IDLE_RELAX_COUNT)
+				break;
+
 			if (local_clock_noinstr() - time_start > limit) {
 				dev->poll_time_limit = true;
 				break;
-- 
1.8.3.1