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-rw-r--r--src/internal/pthread_impl.h1
-rw-r--r--src/thread/pthread_cond_broadcast.c8
-rw-r--r--src/thread/pthread_cond_timedwait.c22
3 files changed, 17 insertions, 14 deletions
diff --git a/src/internal/pthread_impl.h b/src/internal/pthread_impl.h
index 63639ec2..bbb4502f 100644
--- a/src/internal/pthread_impl.h
+++ b/src/internal/pthread_impl.h
@@ -70,6 +70,7 @@ struct __timer {
#define _c_clock __u.__i[4]
#define _c_lock __u.__i[5]
#define _c_lockwait __u.__i[6]
+#define _c_waiters2 __u.__i[7]
#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 bf6de048..9c6a462b 100644
--- a/src/thread/pthread_cond_broadcast.c
+++ b/src/thread/pthread_cond_broadcast.c
@@ -22,8 +22,12 @@ int pthread_cond_broadcast(pthread_cond_t *c)
m = c->_c_mutex;
/* Move waiter count to the mutex */
- a_fetch_add(&m->_m_waiters, c->_c_waiters);
- a_store(&c->_c_waiters, 0);
+ for (;;) {
+ int w = c->_c_waiters2;
+ a_fetch_add(&m->_m_waiters, w);
+ if (a_cas(&c->_c_waiters2, w, 0) == w) break;
+ a_fetch_add(&m->_m_waiters, -w);
+ }
/* Perform the futex requeue, waking one waiter unless we know
* that the calling thread holds the mutex. */
diff --git a/src/thread/pthread_cond_timedwait.c b/src/thread/pthread_cond_timedwait.c
index e9b5e2fc..e3dc8147 100644
--- a/src/thread/pthread_cond_timedwait.c
+++ b/src/thread/pthread_cond_timedwait.c
@@ -7,6 +7,8 @@ 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. */
@@ -18,8 +20,10 @@ static void unwait(pthread_cond_t *c, pthread_mutex_t *m)
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);
+ /* Atomically decrement waiters2 if positive, else mutex waiters. */
+ do w = c->_c_waiters2;
+ while (w && a_cas(&c->_c_waiters2, w, w-1)!=w);
+ if (!w) a_dec(&m->_m_waiters);
a_store(&c->_c_lock, 0);
if (c->_c_lockwait) __wake(&c->_c_lock, 1, 1);
@@ -42,16 +46,10 @@ int pthread_cond_timedwait(pthread_cond_t *c, pthread_mutex_t *m, const struct t
pthread_testcancel();
- 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);
- }
+ if (c->_c_mutex != (void *)-1) c->_c_mutex = m;
+
+ a_inc(&c->_c_waiters);
+ a_inc(&c->_c_waiters2);
seq = c->_c_seq;