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authorRich Felker <dalias@aerifal.cx>2011-04-14 15:10:50 -0400
committerRich Felker <dalias@aerifal.cx>2011-04-14 15:10:50 -0400
commite983aea0aec4b77cd3eb39dabc763b08c4485395 (patch)
treea291b943275026537da847cbb0bbe9f927f03df2 /src/thread/sem_trywait.c
parentec2e50d0d78fb19c4a0b6f3e1d394408860425b4 (diff)
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change sem_trywait algorithm so it never has to call __wake
Diffstat (limited to 'src/thread/sem_trywait.c')
-rw-r--r--src/thread/sem_trywait.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/src/thread/sem_trywait.c b/src/thread/sem_trywait.c
index beb7aa5d..dd8f57e3 100644
--- a/src/thread/sem_trywait.c
+++ b/src/thread/sem_trywait.c
@@ -3,9 +3,8 @@
 
 int sem_trywait(sem_t *sem)
 {
-	if (a_fetch_add(sem->__val, -1) > 0) return 0;
-	if (!a_fetch_add(sem->__val, 1) && sem->__val[1])
-		__wake(sem->__val, 1, 0);
+	int val = sem->__val[0];
+	if (val>0 && a_cas(sem->__val, val, val-1)==val) return 0;
 	errno = EAGAIN;
 	return -1;
 }