simplify cond var code now that cleanup handler is not needed

diff --git a/src/thread/pthread_cond_timedwait.c b/src/thread/pthread_cond_timedwait.c
index 5f29a249b44018d378bfdf22510716fcbb2eca29..d28b478ee2f4c5fd753bcd9205383817971faadf 100644 (file)
--- a/src/thread/pthread_cond_timedwait.c
+++ b/src/thread/pthread_cond_timedwait.c
@@ -3,6 +3,7 @@
 void __pthread_testcancel(void);
 int __pthread_mutex_lock(pthread_mutex_t *);
 int __pthread_mutex_unlock(pthread_mutex_t *);
+int __pthread_setcancelstate(int, int *);
 
 /*
  * struct waiter
@@ -28,11 +29,8 @@ int __pthread_mutex_unlock(pthread_mutex_t *);
 
 struct waiter {
        struct waiter *prev, *next;
-       int state, barrier, mutex_ret;
+       int state, barrier;
        int *notify;
-       pthread_mutex_t *mutex;
-       pthread_cond_t *cond;
-       int shared, err;
 };
 
 /* Self-synchronized-destruction-safe lock functions */
@@ -66,83 +64,14 @@ enum {
        LEAVING,
 };
 
-static void unwait(void *arg)
-{
-       struct waiter *node = arg;
-
-       if (node->shared) {
-               pthread_cond_t *c = node->cond;
-               pthread_mutex_t *m = node->mutex;
-               /* Suppress cancellation if a signal was potentially
-                * consumed; this is a legitimate form of spurious
-                * wake even if not. */
-               if (node->err == ECANCELED && c->_c_seq != node->state)
-                       node->err = 0;
-               if (a_fetch_add(&c->_c_waiters, -1) == -0x7fffffff)
-                       __wake(&c->_c_waiters, 1, 0);
-               node->mutex_ret = pthread_mutex_lock(m);
-               return;
-       }
-
-       int oldstate = a_cas(&node->state, WAITING, LEAVING);
-
-       if (oldstate == WAITING) {
-               /* Access to cv object is valid because this waiter was not
-                * yet signaled and a new signal/broadcast cannot return
-                * after seeing a LEAVING waiter without getting notified
-                * via the futex notify below. */
-
-               pthread_cond_t *c = node->cond;
-               lock(&c->_c_lock);
-               
-               if (c->_c_head == node) c->_c_head = node->next;
-               else if (node->prev) node->prev->next = node->next;
-               if (c->_c_tail == node) c->_c_tail = node->prev;
-               else if (node->next) node->next->prev = node->prev;
-               
-               unlock(&c->_c_lock);
-
-               if (node->notify) {
-                       if (a_fetch_add(node->notify, -1)==1)
-                               __wake(node->notify, 1, 1);
-               }
-       } else {
-               /* Lock barrier first to control wake order. */
-               lock(&node->barrier);
-       }
-
-       node->mutex_ret = pthread_mutex_lock(node->mutex);
-
-       if (oldstate == WAITING) return;
-
-       if (!node->next) a_inc(&node->mutex->_m_waiters);
-
-       /* Unlock the barrier that's holding back the next waiter, and
-        * either wake it or requeue it to the mutex. */
-       if (node->prev) {
-               unlock_requeue(&node->prev->barrier,
-                       &node->mutex->_m_lock,
-                       node->mutex->_m_type & 128);
-       } else {
-               a_dec(&node->mutex->_m_waiters);
-       }
-
-       /* Since a signal was consumed, acting on cancellation is not
-        * permitted. The only other error possible at this stage,
-        * ETIMEDOUT, is permitted even if a signal was consumed. */
-       if (node->err = ECANCELED) node->err = 0;
-}
-
 static void dummy(void *arg)
 {
 }
 
-int __pthread_setcancelstate(int, int *);
-
 int __pthread_cond_timedwait(pthread_cond_t *restrict c, pthread_mutex_t *restrict m, const struct timespec *restrict ts)
 {
-       struct waiter node = { .cond = c, .mutex = m };
-       int e, seq, *fut, clock = c->_c_clock, cs;
+       struct waiter node = { 0 };
+       int e, seq, *fut, clock = c->_c_clock, cs, shared=0, oldstate, tmp;
 
        if ((m->_m_type&15) && (m->_m_lock&INT_MAX) != __pthread_self()->tid)
                return EPERM;
@@ -153,9 +82,9 @@ int __pthread_cond_timedwait(pthread_cond_t *restrict c, pthread_mutex_t *restri
        __pthread_testcancel();
 
        if (c->_c_shared) {
-               node.shared = 1;
+               shared = 1;
                fut = &c->_c_seq;
-               seq = node.state = c->_c_seq;
+               seq = c->_c_seq;
                a_inc(&c->_c_waiters);
        } else {
                lock(&c->_c_lock);
@@ -175,20 +104,68 @@ int __pthread_cond_timedwait(pthread_cond_t *restrict c, pthread_mutex_t *restri
 
        __pthread_setcancelstate(PTHREAD_CANCEL_MASKED, &cs);
 
-       do e = __timedwait(fut, seq, clock, ts, dummy, 0, !node.shared);
+       do e = __timedwait(fut, seq, clock, ts, dummy, 0, !shared);
        while (*fut==seq && (!e || e==EINTR));
        if (e == EINTR) e = 0;
 
-       node.err = e;
-       unwait(&node);
-       e = node.err;
+       if (shared) {
+               /* Suppress cancellation if a signal was potentially
+                * consumed; this is a legitimate form of spurious
+                * wake even if not. */
+               if (e == ECANCELED && c->_c_seq != seq) e = 0;
+               if (a_fetch_add(&c->_c_waiters, -1) == -0x7fffffff)
+                       __wake(&c->_c_waiters, 1, 0);
+               oldstate = WAITING;
+               goto relock;
+       }
+
+       oldstate = a_cas(&node.state, WAITING, LEAVING);
+
+       if (oldstate == WAITING) {
+               /* Access to cv object is valid because this waiter was not
+                * yet signaled and a new signal/broadcast cannot return
+                * after seeing a LEAVING waiter without getting notified
+                * via the futex notify below. */
+
+               lock(&c->_c_lock);
+               
+               if (c->_c_head == &node) c->_c_head = node.next;
+               else if (node.prev) node.prev->next = node.next;
+               if (c->_c_tail == &node) c->_c_tail = node.prev;
+               else if (node.next) node.next->prev = node.prev;
+               
+               unlock(&c->_c_lock);
+
+               if (node.notify) {
+                       if (a_fetch_add(node.notify, -1)==1)
+                               __wake(node.notify, 1, 1);
+               }
+       } else {
+               /* Lock barrier first to control wake order. */
+               lock(&node.barrier);
+       }
+
+relock:
+       /* Errors locking the mutex override any existing error or
+        * cancellation, since the caller must see them to know the
+        * state of the mutex. */
+       if ((tmp = pthread_mutex_lock(m))) e = tmp;
+
+       if (oldstate == WAITING) goto done;
+
+       if (!node.next) a_inc(&m->_m_waiters);
+
+       /* Unlock the barrier that's holding back the next waiter, and
+        * either wake it or requeue it to the mutex. */
+       if (node.prev)
+               unlock_requeue(&node.prev->barrier, &m->_m_lock, m->_m_type & 128);
+       else
+               a_dec(&m->_m_waiters);
 
-       /* Suppress cancellation if there was an error locking the mutex,
-        * since the contract for cancellation requires the mutex to be
-        * locked when the cleanup handler is called, and there is no
-        * way to report an error. */
-       if (node.mutex_ret) e = node.mutex_ret;
+       /* Since a signal was consumed, cancellation is not permitted. */
+       if (e = ECANCELED) e = 0;
 
+done:
        __pthread_setcancelstate(cs, 0);
 
        if (e == ECANCELED) {