cpuidle: Use a lighter barrier in snooze_loop()

RFC PATCH New Pranith Kumar 1 participant 1 message Nov 16, 2014

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PowerPC CPU idle time management framework

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Pranith Kumar

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2014-11-16 02:00 UTC #0 lore raw

RFC PATCH 1/1 cpuidle: Use a lighter barrier in snooze_loop()

Using smp_mb() here so that the bit clear is not reordered is an overkill.

It is more appropriate to use smp_mb__after_atomic() which ensures that the bit clear is not reordered.

Signed-off-by Pranith Kumar <[email protected]>

---
 drivers/cpuidle/cpuidle-powernv.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

drivers/cpuidle/cpuidle-powernv.c +2 -1

index 7d3a349..b0bfcbe 100644
@@ -48,7 +48,8 @@ static int snooze_loop(struct cpuidle_device *dev,
 	HMT_medium();
 	ppc64_runlatch_on();
 	clear_thread_flag(TIF_POLLING_NRFLAG);
-	smp_mb();
+	/* ensure bit clear is not reordered */
+	smp_mb__after_atomic();
 	return index;
 }

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