snooze_loop is done often in any system which has fair bit of
idle time. So it qualifies for even micro-optimizations.
When breaking the snooze due to timeout, TIF_POLLING_NRFLAG is cleared
twice. Clearing the bit invokes atomics. Avoid double clear and thereby
avoid one atomic write.
dev->poll_time_limit indicates whether the loop was broken due to
timeout. Use that instead of defining a new variable.
Fixes: 7ded429152e8 ("cpuidle: powerpc: no memory barrier after break from
idle")
Cc: [email protected]
Reviewed-by: Mukesh Kumar Chaurasiya (IBM) <[email protected]>
Signed-off-by: Shrikanth Hegde <[email protected]>
---
v1->v2:
- Added rwb tag - Thanks to Mukesh Kumar Chaurasiya
- Added fixes tag
v1: https://lore.kernel.org/all/[email protected]/
drivers/cpuidle/cpuidle-powernv.c | 5 ++++-
drivers/cpuidle/cpuidle-pseries.c | 5 ++++-
2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/cpuidle/cpuidle-powernv.c
b/drivers/cpuidle/cpuidle-powernv.c
index 9ebedd972df0..b89e7111e7b8 100644
--- a/drivers/cpuidle/cpuidle-powernv.c
+++ b/drivers/cpuidle/cpuidle-powernv.c
@@ -95,7 +95,10 @@ static int snooze_loop(struct cpuidle_device *dev,
HMT_medium();
ppc64_runlatch_on();
- clear_thread_flag(TIF_POLLING_NRFLAG);
+
+ /* Avoid double clear when breaking */
+ if (!dev->poll_time_limit)
+ clear_thread_flag(TIF_POLLING_NRFLAG);
local_irq_disable();
diff --git a/drivers/cpuidle/cpuidle-pseries.c
b/drivers/cpuidle/cpuidle-pseries.c
index f68c65f1d023..864dd5d6e627 100644
--- a/drivers/cpuidle/cpuidle-pseries.c
+++ b/drivers/cpuidle/cpuidle-pseries.c
@@ -64,7 +64,10 @@ int snooze_loop(struct cpuidle_device *dev, struct
cpuidle_driver *drv,
}
HMT_medium();
- clear_thread_flag(TIF_POLLING_NRFLAG);
+
+ /* Avoid double clear when breaking */
+ if (!dev->poll_time_limit)
+ clear_thread_flag(TIF_POLLING_NRFLAG);
raw_local_irq_disable();
--
2.43.0
