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34 lines
1.1 KiB
34 lines
1.1 KiB
2 years ago
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commit ed8300c054cae4aeb0bbfa043f5fccc91a4adbf5
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Author: H.J. Lu <hjl.tools@gmail.com>
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Date: Thu Nov 11 06:54:01 2021 -0800
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Avoid extra load with CAS in __pthread_mutex_clocklock_common [BZ #28537]
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Replace boolean CAS with value CAS to avoid the extra load.
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Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
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(cherry picked from commit 49302b8fdf9103b6fc0a398678668a22fa19574c)
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diff --git a/nptl/pthread_mutex_timedlock.c b/nptl/pthread_mutex_timedlock.c
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index 11ad7005d07afc6e..90cede9446e33fcf 100644
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--- a/nptl/pthread_mutex_timedlock.c
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+++ b/nptl/pthread_mutex_timedlock.c
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@@ -234,12 +234,12 @@ __pthread_mutex_clocklock_common (pthread_mutex_t *mutex,
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meantime. */
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if ((oldval & FUTEX_WAITERS) == 0)
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{
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- if (atomic_compare_and_exchange_bool_acq (&mutex->__data.__lock,
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- oldval | FUTEX_WAITERS,
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- oldval)
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- != 0)
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+ int val;
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+ if ((val = atomic_compare_and_exchange_val_acq
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+ (&mutex->__data.__lock, oldval | FUTEX_WAITERS,
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+ oldval)) != oldval)
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{
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- oldval = mutex->__data.__lock;
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+ oldval = val;
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continue;
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}
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oldval |= FUTEX_WAITERS;
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