diff options
| -rw-r--r-- | src/internal/pthread_impl.h | 1 | ||||
| -rw-r--r-- | src/thread/pthread_cond_broadcast.c | 8 | ||||
| -rw-r--r-- | src/thread/pthread_cond_timedwait.c | 22 |
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; |