diff options
| -rw-r--r-- | src/internal/pthread_impl.h | 6 | ||||
| -rw-r--r-- | src/thread/pthread_cond_broadcast.c | 45 | ||||
| -rw-r--r-- | src/thread/pthread_cond_signal.c | 5 | ||||
| -rw-r--r-- | src/thread/pthread_cond_timedwait.c | 44 |
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; } |