commit 3eb4f9edd0509bc40d38cfd3dfae08e489e0cc76
Author: Mikolaj Golub <trociny@freebsd.org>
Date:   Sun Sep 1 00:34:24 2013 +0300

    QUEUE_INSERT2/TAKE2 are used for queues that may have several
    consumers and producers, so use cv_broadcast() insted of cv_signal()
    when waiking up threads waiting on empty queue.
    
    Before the fix the following scenario was possible: 2 threads are
    waiting on empty queue, 2 threads are inserting simultaneously. The
    first inserting thread detects that the queue is empty and is going to
    send the signal, but before it sends the second thread inserts
    too. When the first sends the signal only one of the waiting threads
    receive it while the other one may wait forever.
    
    The scenario above is is beleved to be the cause of observed cases,
    when ggate_recv_thread() was getting stuck on taking free request,
    while the free queue was not empty.

diff --git a/sbin/hastd/primary.c b/sbin/hastd/primary.c
index a1cad51..83770fa 100644
--- a/sbin/hastd/primary.c
+++ b/sbin/hastd/primary.c
@@ -186,7 +186,7 @@ static pthread_mutex_t metadata_lock;
 	TAILQ_INSERT_TAIL(&hio_##name##_list, (hio), hio_##name##_next);\
 	mtx_unlock(&hio_##name##_list_lock);				\
 	if (_wakeup)							\
-		cv_signal(&hio_##name##_list_cond);			\
+		cv_broadcast(&hio_##name##_list_cond);			\
 } while (0)
 #define	QUEUE_TAKE1(hio, name, ncomp, timeout)	do {			\
 	bool _last;							\