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-rw-r--r--src/thread/__lock.c33
1 files changed, 27 insertions, 6 deletions
diff --git a/src/thread/__lock.c b/src/thread/__lock.c
index d1717956..d1734096 100644
--- a/src/thread/__lock.c
+++ b/src/thread/__lock.c
@@ -1,11 +1,32 @@
#include "pthread_impl.h"
+void __lock_2(volatile int *l)
+{
+ if (!__syscall(SYS_futex, l, FUTEX_LOCK_PI, 0, 0))
+ return;
+ int old, tid = __pthread_self()->tid;
+ while ((old = a_cas(l, 0, tid))) {
+ a_cas(l, old, old|INT_MIN);
+ __syscall(SYS_futex, l, FUTEX_WAIT, old|INT_MIN, 0);
+ }
+}
+
void __lock(volatile int *l)
{
- int spins=10000;
- /* Do not use futexes because we insist that unlocking is a simple
- * assignment to optimize non-pathological code with no contention. */
- while (a_swap(l, 1))
- if (spins) spins--, a_spin();
- else __syscall(SYS_sched_yield);
+ if (a_cas(l, 0, __pthread_self()->tid)) __lock_2(l);
+}
+
+void __unlock_2(volatile int *l)
+{
+ if (__syscall(SYS_futex, l, FUTEX_UNLOCK_PI)) {
+ *l = 0;
+ __syscall(SYS_futex, l, FUTEX_WAKE, 1);
+ }
+}
+
+void __unlock(volatile int *l)
+{
+ int old = *l;
+ if (!(old & INT_MIN) && a_cas(l, old, 0)==old) return;
+ __unlock_2(l);
}