4 files changed, 52 insertions, 48 deletions

diff --git a/src/internal/pthread_impl.h b/src/internal/pthread_impl.h
index 4c743d2e..63639ec2 100644
--- a/src/internal/pthread_impl.h
+++ b/src/internal/pthread_impl.h
@@ -65,11 +65,11 @@ struct __timer {
 #define _m_next __u.__p[4]
 #define _m_count __u.__i[5]
 #define _c_mutex __u.__p[0]
-#define _c_block __u.__i[2]
+#define _c_seq __u.__i[2]
 #define _c_waiters __u.__i[3]
 #define _c_clock __u.__i[4]
-#define _c_bcast __u.__i[5]
-#define _c_leavers __u.__i[6]
+#define _c_lock __u.__i[5]
+#define _c_lockwait __u.__i[6]
 #define _rw_lock __u.__i[0]
 #define _rw_waiters __u.__i[1]
 #define _b_inst __u.__p[0]
diff --git a/src/thread/pthread_cond_broadcast.c b/src/thread/pthread_cond_broadcast.c
index 7e5ea91c..bf6de048 100644
--- a/src/thread/pthread_cond_broadcast.c
+++ b/src/thread/pthread_cond_broadcast.c
@@ -1,48 +1,39 @@
 #include "pthread_impl.h"
 
-static void unlock(pthread_cond_t *c)
-{
-	a_dec(&c->_c_bcast);
-	if (c->_c_leavers) __wake(&c->_c_bcast, -1, 0);
-}
-
 int pthread_cond_broadcast(pthread_cond_t *c)
 {
 	pthread_mutex_t *m;
-	int w;
 
 	if (!c->_c_waiters) return 0;
-	a_inc(&c->_c_bcast);
-	if (!c->_c_waiters) {
-		unlock(c);
-		return 0;
-	}
 
-	a_store(&c->_c_block, 0);
+	a_inc(&c->_c_seq);
 
-	m = c->_c_mutex;
-
-	/* If mutex ptr is not available, simply wake all waiters. */
-	if (m == (void *)-1) {
-		unlock(c);
-		__wake(&c->_c_block, -1, 0);
+	/* If cond var is process-shared, simply wake all waiters. */
+	if (c->_c_mutex == (void *)-1) {
+		__wake(&c->_c_seq, -1, 0);
 		return 0;
 	}
 
+	/* Block waiters from returning so we can use the mutex. */
+	while (a_swap(&c->_c_lock, 1))
+		__wait(&c->_c_lock, &c->_c_lockwait, 1, 1);
+	if (!c->_c_waiters)
+		goto out;
+	m = c->_c_mutex;
+
 	/* Move waiter count to the mutex */
-	for (;;) {
-		w = c->_c_waiters;
-		a_fetch_add(&m->_m_waiters, w);
-		if (a_cas(&c->_c_waiters, w, 0) == w) break;
-		a_fetch_add(&m->_m_waiters, -w);
-	}
+	a_fetch_add(&m->_m_waiters, c->_c_waiters);
+	a_store(&c->_c_waiters, 0);
 
 	/* Perform the futex requeue, waking one waiter unless we know
 	 * that the calling thread holds the mutex. */
-	__syscall(SYS_futex, &c->_c_block, FUTEX_REQUEUE,
+	__syscall(SYS_futex, &c->_c_seq, FUTEX_REQUEUE,
 		!m->_m_type || (m->_m_lock&INT_MAX)!=pthread_self()->tid,
 		INT_MAX, &m->_m_lock);
 
-	unlock(c);
+out:
+	a_store(&c->_c_lock, 0);
+	if (c->_c_lockwait) __wake(&c->_c_lock, 1, 0);
+
 	return 0;
 }
diff --git a/src/thread/pthread_cond_signal.c b/src/thread/pthread_cond_signal.c
index b26b8ce5..71bcdcd9 100644
--- a/src/thread/pthread_cond_signal.c
+++ b/src/thread/pthread_cond_signal.c
@@ -2,7 +2,8 @@
 
 int pthread_cond_signal(pthread_cond_t *c)
 {
-	a_store(&c->_c_block, 0);
-	if (c->_c_waiters) __wake(&c->_c_block, 1, 0);
+	if (!c->_c_waiters) return 0;
+	a_inc(&c->_c_seq);
+	if (c->_c_waiters) __wake(&c->_c_seq, 1, 0);
 	return 0;
 }
diff --git a/src/thread/pthread_cond_timedwait.c b/src/thread/pthread_cond_timedwait.c
index 9616dd85..e9b5e2fc 100644
--- a/src/thread/pthread_cond_timedwait.c
+++ b/src/thread/pthread_cond_timedwait.c
@@ -7,17 +7,22 @@ struct cm {
 
 static void unwait(pthread_cond_t *c, pthread_mutex_t *m)
 {
-	int w;
+	/* Removing a waiter is non-trivial if we could be using requeue
+	 * based broadcast signals, due to mutex access issues, etc. */
 
-	/* Cannot leave waiting status if there are any live broadcasters
-	 * which might be inspecting/using the mutex. */
-	while ((w=c->_c_bcast)) __wait(&c->_c_bcast, &c->_c_leavers, w, 0);
+	if (c->_c_mutex == (void *)-1) {
+		a_dec(&c->_c_waiters);
+		return;
+	}
 
-	/* If the waiter count is zero, it must be the case that the
-	 * caller's count has been moved to the mutex due to bcast. */
-	do w = c->_c_waiters;
-	while (w && a_cas(&c->_c_waiters, w, w-1)!=w);
-	if (!w) a_dec(&m->_m_waiters);
+	while (a_swap(&c->_c_lock, 1))
+		__wait(&c->_c_lock, &c->_c_lockwait, 1, 1);
+
+	if (c->_c_waiters) c->_c_waiters--;
+	else a_dec(&m->_m_waiters);
+
+	a_store(&c->_c_lock, 0);
+	if (c->_c_lockwait) __wake(&c->_c_lock, 1, 1);
 }
 
 static void cleanup(void *p)
@@ -30,28 +35,35 @@ static void cleanup(void *p)
 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, tid;
+	int r, e=0, seq;
 
 	if (ts && ts->tv_nsec >= 1000000000UL)
 		return EINVAL;
 
 	pthread_testcancel();
 
-	if (c->_c_mutex != (void *)-1) c->_c_mutex = m;
+	if (c->_c_mutex == (void *)-1) {
+		a_inc(&c->_c_waiters);
+	} else {
+		c->_c_mutex = m;
+		while (a_swap(&c->_c_lock, 1))
+			__wait(&c->_c_lock, &c->_c_lockwait, 1, 1);
+		c->_c_waiters++;
+		a_store(&c->_c_lock, 0);
+		if (c->_c_lockwait) __wake(&c->_c_lock, 1, 1);
+	}
 
-	a_inc(&c->_c_waiters);
-	c->_c_block = tid = pthread_self()->tid;
+	seq = c->_c_seq;
 
 	if ((r=pthread_mutex_unlock(m))) return r;
 
-	do e = __timedwait(&c->_c_block, tid, c->_c_clock, ts, cleanup, &cm, 0);
-	while (c->_c_block == tid && (!e || e==EINTR));
+	do e = __timedwait(&c->_c_seq, seq, c->_c_clock, ts, cleanup, &cm, 0);
+	while (c->_c_seq == seq && (!e || e==EINTR));
 	if (e == EINTR) e = 0;
 
 	unwait(c, m);
 
 	if ((r=pthread_mutex_lock(m))) return r;
 
-	pthread_testcancel();
 	return e;
 }