overhaul rwlocks to address several issues

[musl] / src / thread / pthread_rwlock_timedrdlock.c

diff --git a/src/thread/pthread_rwlock_timedrdlock.c b/src/thread/pthread_rwlock_timedrdlock.c
index a6f61b0..b5cb404 100644 (file)
--- a/src/thread/pthread_rwlock_timedrdlock.c
+++ b/src/thread/pthread_rwlock_timedrdlock.c
@@ -2,14 +2,15 @@
 
 int pthread_rwlock_timedrdlock(pthread_rwlock_t *rw, const struct timespec *at)
 {
-       int w=0;
-       while (pthread_rwlock_tryrdlock(rw)) {
-               if (!w) a_inc(&rw->_rw_waiters), w++;
-               if (__timedwait(&rw->_rw_wrlock, 1, CLOCK_REALTIME, at, 0, 0, 0)==ETIMEDOUT) {
-                       if (w) a_dec(&rw->_rw_waiters);
-                       return ETIMEDOUT;
-               }
+       int r, t;
+       while ((r=pthread_rwlock_tryrdlock(rw))==EBUSY) {
+               if (!(r=rw->_rw_lock) || (r&0x7fffffff)!=0x7fffffff) continue;
+               t = r | 0x80000000;
+               a_inc(&rw->_rw_waiters);
+               a_cas(&rw->_rw_lock, r, t);
+               r = __timedwait(&rw->_rw_lock, t, CLOCK_REALTIME, at, 0, 0, 0);
+               a_dec(&rw->_rw_waiters);
+               if (r && r != EINTR) return r;
        }
-       if (w) a_dec(&rw->_rw_waiters);
-       return 0;
+       return r;
 }