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cpuidle: powerpc: avoid double clear when breaking snooze

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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: 7ded429152 ("cpuidle: powerpc: no memory barrier after break from idle")
Cc: stable@vger.kernel.org
Reviewed-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260311061709.1230440-1-sshegde@linux.ibm.com
This commit is contained in:
Shrikanth Hegde
2026-03-11 11:47:09 +05:30
committed by Madhavan Srinivasan
parent 26d76caac4
commit 64ed1e3e72
2 changed files with 8 additions and 2 deletions
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5
drivers/cpuidle/cpuidle-powernv.c
View File

@@ -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();

5
drivers/cpuidle/cpuidle-pseries.c
View File

@@ -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();