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authorRich Felker <dalias@aerifal.cx>2011-03-17 12:14:40 -0400
committerRich Felker <dalias@aerifal.cx>2011-03-17 12:14:40 -0400
commite914f8b7ec79f622fa3b017af434642f61d45ce8 (patch)
treedfba95ae52b2a5998269f7296bef97aa9fce47c4
parent1d59f1eddbcca03063cf080ded6df13170adcb23 (diff)
downloadmusl-e914f8b7ec79f622fa3b017af434642f61d45ce8.tar.gz
optimize contended normal mutex case; add int compare-and-swap atomic
-rw-r--r--arch/i386/atomic.h7
-rw-r--r--arch/x86_64/atomic.h7
-rw-r--r--src/thread/pthread_mutex_trylock.c2
3 files changed, 15 insertions, 1 deletions
diff --git a/arch/i386/atomic.h b/arch/i386/atomic.h
index e74e4535..bf3c336e 100644
--- a/arch/i386/atomic.h
+++ b/arch/i386/atomic.h
@@ -49,6 +49,13 @@ static inline long a_cas_l(volatile void *p, long t, long s)
return t;
}
+static inline int a_cas(volatile int *p, int t, int s)
+{
+ __asm__( "lock ; cmpxchg %3, %1"
+ : "=a"(t), "=m"(*p) : "a"(t), "r"(s) : "memory" );
+ return t;
+}
+
static inline void *a_swap_p(void *volatile *x, void *v)
{
__asm__( "xchg %0, %1" : "=r"(v), "=m"(*(void **)x) : "0"(v) : "memory" );
diff --git a/arch/x86_64/atomic.h b/arch/x86_64/atomic.h
index 7a665c1b..04f6c28d 100644
--- a/arch/x86_64/atomic.h
+++ b/arch/x86_64/atomic.h
@@ -48,6 +48,13 @@ static inline long a_cas_l(volatile void *p, long t, long s)
return t;
}
+static inline int a_cas(volatile int *p, int t, int s)
+{
+ __asm__( "lock ; cmpxchgl %3, %1"
+ : "=a"(t), "=m"(*p) : "a"(t), "r"(s) : "memory" );
+ return t;
+}
+
static inline void *a_swap_p(void *volatile *x, void *v)
{
__asm__( "xchg %0, %1" : "=r"(v), "=m"(*(void **)x) : "0"(v) : "memory" );
diff --git a/src/thread/pthread_mutex_trylock.c b/src/thread/pthread_mutex_trylock.c
index af421472..6fc604fe 100644
--- a/src/thread/pthread_mutex_trylock.c
+++ b/src/thread/pthread_mutex_trylock.c
@@ -5,7 +5,7 @@ int pthread_mutex_trylock(pthread_mutex_t *m)
int tid;
if (m->_m_type == PTHREAD_MUTEX_NORMAL)
- return -a_xchg(&m->_m_lock, 1) & EBUSY;
+ return (m->_m_lock || a_swap(&m->_m_lock, 1)) ? EBUSY : 0;
tid = pthread_self()->tid;