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-rw-r--r--src/internal/pthread_impl.h6
-rw-r--r--src/thread/pthread_cond_broadcast.c45
-rw-r--r--src/thread/pthread_cond_signal.c5
-rw-r--r--src/thread/pthread_cond_timedwait.c44
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;
}