1 files changed, 13 insertions, 11 deletions

diff --git a/src/thread/pthread_barrier_wait.c b/src/thread/pthread_barrier_wait.c
index 9b1edbf9..71f7b5fe 100644
--- a/src/thread/pthread_barrier_wait.c
+++ b/src/thread/pthread_barrier_wait.c
@@ -21,7 +21,6 @@ void __vm_unlock(void)
 static int pshared_barrier_wait(pthread_barrier_t *b)
 {
 	int limit = (b->_b_limit & INT_MAX) + 1;
-	int seq;
 	int ret = 0;
 	int v, w;
 
@@ -30,33 +29,36 @@ static int pshared_barrier_wait(pthread_barrier_t *b)
 	while ((v=a_cas(&b->_b_lock, 0, limit)))
 		__wait(&b->_b_lock, &b->_b_waiters, v, 0);
 
-	seq = b->_b_seq;
-
+	/* Wait for <limit> threads to get to the barrier */
 	if (++b->_b_count == limit) {
+		a_store(&b->_b_count, 0);
 		ret = PTHREAD_BARRIER_SERIAL_THREAD;
-		b->_b_seq++;
-		__wake(&b->_b_seq, -1, 0);
+		if (b->_b_waiters2) __wake(&b->_b_count, -1, 0);
 	} else {
 		a_store(&b->_b_lock, 0);
 		if (b->_b_waiters) __wake(&b->_b_lock, 1, 0);
-		__wait(&b->_b_seq, 0, seq, 0);
+		while ((v=b->_b_count)>0)
+			__wait(&b->_b_count, &b->_b_waiters2, v, 0);
 	}
 
 	__vm_lock(+1);
 
-	if (a_fetch_add(&b->_b_count, -1)==1) {
-		b->_b_seq++;
-		__wake(&b->_b_seq, -1, 0);
+	/* Ensure all threads have a vm lock before proceeding */
+	if (a_fetch_add(&b->_b_count, -1)==1-limit) {
+		a_store(&b->_b_count, 0);
+		if (b->_b_waiters2) __wake(&b->_b_count, -1, 0);
 	} else {
-		__wait(&b->_b_seq, 0, seq+1, 0);
+		while ((v=b->_b_count))
+			__wait(&b->_b_count, &b->_b_waiters2, v, 0);
 	}
 	
 	/* Perform a recursive unlock suitable for self-sync'd destruction */
 	do {
 		v = b->_b_lock;
 		w = b->_b_waiters;
-	} while (a_cas(&b->_b_lock, v, v-1 & INT_MAX) != v);
+	} while (a_cas(&b->_b_lock, v, v==INT_MIN+1 ? 0 : v-1) != v);
 
+	/* Wake a thread waiting to reuse or destroy the barrier */
 	if (v==INT_MIN+1 || (v==1 && w))
 		__wake(&b->_b_lock, 1, 0);