From afbcac6826988d12d9a874359cab735049c17500 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Wed, 22 Apr 2015 03:24:37 -0400 Subject: [PATCH] minor optimization to pthread_spin_trylock use CAS instead of swap since it's lighter for most archs, and keep EBUSY in the lock value so that the old value obtained by CAS can be used directly as the return value for pthread_spin_trylock. --- src/thread/pthread_spin_lock.c | 3 ++- src/thread/pthread_spin_trylock.c | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/src/thread/pthread_spin_lock.c b/src/thread/pthread_spin_lock.c index 0462e0f3..ded2b653 100644 --- a/src/thread/pthread_spin_lock.c +++ b/src/thread/pthread_spin_lock.c @@ -1,7 +1,8 @@ #include "pthread_impl.h" +#include int pthread_spin_lock(pthread_spinlock_t *s) { - while (*(volatile int *)s || a_cas(s, 0, 1)) a_spin(); + while (*(volatile int *)s || a_cas(s, 0, EBUSY)) a_spin(); return 0; } diff --git a/src/thread/pthread_spin_trylock.c b/src/thread/pthread_spin_trylock.c index 59de695d..5284fdac 100644 --- a/src/thread/pthread_spin_trylock.c +++ b/src/thread/pthread_spin_trylock.c @@ -1,6 +1,7 @@ #include "pthread_impl.h" +#include int pthread_spin_trylock(pthread_spinlock_t *s) { - return -a_swap(s, 1) & EBUSY; + return a_cas(s, 0, EBUSY); } -- 2.25.1