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.

diff --git a/src/thread/pthread_spin_lock.c b/src/thread/pthread_spin_lock.c
index 0462e0f3a4004ca469cf6f99f7c24566f383a423..ded2b653c4751db88f288af6b84f92a7341263b3 100644 (file)
--- a/src/thread/pthread_spin_lock.c
+++ b/src/thread/pthread_spin_lock.c
@@ -1,7 +1,8 @@
 #include "pthread_impl.h"
+#include <errno.h>
 
 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 59de695ddad9ebb4ad941574681829513fe321db..5284fdac24d4ae70eb06242131dff16a33c61d90 100644 (file)
--- a/src/thread/pthread_spin_trylock.c
+++ b/src/thread/pthread_spin_trylock.c
@@ -1,6 +1,7 @@
 #include "pthread_impl.h"
+#include <errno.h>
 
 int pthread_spin_trylock(pthread_spinlock_t *s)
 {
-       return -a_swap(s, 1) & EBUSY;
+       return a_cas(s, 0, EBUSY);
 }