fix deadlock in condition wait whenever there are multiple waiters

it's amazing none of the conformance tests i've run even bothered to
check whether something so basic works...

1 files changed, 13 insertions, 3 deletions

diff --git a/src/thread/pthread_cond_timedwait.c b/src/thread/pthread_cond_timedwait.c
index ee874a36..ec5aa6f4 100644
--- a/src/thread/pthread_cond_timedwait.c
+++ b/src/thread/pthread_cond_timedwait.c
@@ -1,12 +1,20 @@
 #include "pthread_impl.h"
 
-static void relock(void *m)
+struct cm {
+	pthread_cond_t *c;
+	pthread_mutex_t *m;
+};
+
+static void cleanup(void *p)
 {
-	pthread_mutex_lock(m);
+	struct cm *cm = p;
+	a_dec(&cm->c->_c_waiters);
+	pthread_mutex_lock(cm->m);
 }
 
 int pthread_cond_timedwait(pthread_cond_t *c, pthread_mutex_t *m, const struct timespec *ts)
 {
+	struct cm cm = { .c=c, .m=m };
 	int r, e=0;
 
 	if (ts && ts->tv_nsec >= 1000000000UL)
@@ -17,8 +25,10 @@ int pthread_cond_timedwait(pthread_cond_t *c, pthread_mutex_t *m, const struct t
 	c->_c_block = 1;
 	if ((r=pthread_mutex_unlock(m))) return r;
 
-	do e = __timedwait(&c->_c_block, 1, c->_c_clock, ts, relock, m, 0);
+	a_inc(&c->_c_waiters);
+	do e = __timedwait(&c->_c_block, 1, c->_c_clock, ts, cleanup, &cm, 0);
 	while (e == EINTR);
+	a_dec(&c->_c_waiters);
 
 	if ((r=pthread_mutex_lock(m))) return r;