fix failure-to-wake in rwlock unlock

a reader unlocking the lock need only wake one waiter (necessarily a
writer, but a writer unlocking the lock must wake all waiters
(necessarily readers). if it only wakes one, the remainder can remain
blocked indefinitely, or at least until the first reader unlocks (in
which case the whole lock becomes serialized and behaves as a mutex
rather than a read lock).

1 files changed, 1 insertions, 1 deletions

diff --git a/src/thread/pthread_rwlock_unlock.c b/src/thread/pthread_rwlock_unlock.c
index 5edca634..a6d20854 100644
--- a/src/thread/pthread_rwlock_unlock.c
+++ b/src/thread/pthread_rwlock_unlock.c
@@ -12,7 +12,7 @@ int pthread_rwlock_unlock(pthread_rwlock_t *rw)
 	} while (a_cas(&rw->_rw_lock, val, new) != val);
 
 	if (!new && (waiters || val<0))
-		__wake(&rw->_rw_lock, 1, 0);
+		__wake(&rw->_rw_lock, cnt, 0);
 
 	return 0;
 }