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40 lines
1.2 KiB
40 lines
1.2 KiB
7 months ago
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From 0b82747dc48d5bf0871bdc6da8cb6eec1256355f Mon Sep 17 00:00:00 2001
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From: "H.J. Lu" <hjl.tools@gmail.com>
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Date: Thu, 11 Nov 2021 06:31:51 -0800
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Subject: [PATCH] Avoid extra load with CAS in __pthread_mutex_lock_full [BZ
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#28537]
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Content-type: text/plain; charset=UTF-8
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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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---
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nptl/pthread_mutex_lock.c | 10 +++++-----
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1 file changed, 5 insertions(+), 5 deletions(-)
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diff --git a/nptl/pthread_mutex_lock.c b/nptl/pthread_mutex_lock.c
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index 29cc143e..60ada70d 100644
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--- a/nptl/pthread_mutex_lock.c
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+++ b/nptl/pthread_mutex_lock.c
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@@ -292,12 +292,12 @@ __pthread_mutex_lock_full (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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--
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GitLab
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