synchronize cond var destruction with exiting waits

[musl] / src / thread / pthread_cond_timedwait.c

diff --git a/src/thread/pthread_cond_timedwait.c b/src/thread/pthread_cond_timedwait.c
index 1439aac..1d0f578 100644 (file)
--- a/src/thread/pthread_cond_timedwait.c
+++ b/src/thread/pthread_cond_timedwait.c
@@ -1,28 +1,76 @@
 #include "pthread_impl.h"
 
-static void relock(void *m)
+struct cm {
+       pthread_cond_t *c;
+       pthread_mutex_t *m;
+};
+
+static void unwait(pthread_cond_t *c, pthread_mutex_t *m)
+{
+       /* Removing a waiter is non-trivial if we could be using requeue
+        * based broadcast signals, due to mutex access issues, etc. */
+
+       if (c->_c_mutex == (void *)-1) {
+               a_dec(&c->_c_waiters);
+               if (c->_c_destroy) __wake(&c->_c_waiters, 1, 0);
+               return;
+       }
+
+       while (a_swap(&c->_c_lock, 1))
+               __wait(&c->_c_lock, &c->_c_lockwait, 1, 1);
+
+       if (c->_c_waiters2) c->_c_waiters2--;
+       else a_dec(&m->_m_waiters);
+
+       a_store(&c->_c_lock, 0);
+       if (c->_c_lockwait) __wake(&c->_c_lock, 1, 1);
+
+       a_dec(&c->_c_waiters);
+       if (c->_c_destroy) __wake(&c->_c_waiters, 1, 1);
+}
+
+static void cleanup(void *p)
 {
-       pthread_mutex_lock(m);
+       struct cm *cm = p;
+       unwait(cm->c, cm->m);
+       pthread_mutex_lock(cm->m);
 }
 
 int pthread_cond_timedwait(pthread_cond_t *c, pthread_mutex_t *m, const struct timespec *ts)
 {
-       int r, e=0;
-       CANCELPT_BEGIN;
-       CANCELPT_END;
+       struct cm cm = { .c=c, .m=m };
+       int r, e=0, seq;
+
+       if (m->_m_type && (m->_m_lock&INT_MAX) != pthread_self()->tid)
+               return EPERM;
+
+       if (ts && ts->tv_nsec >= 1000000000UL)
+               return EINVAL;
+
+       pthread_testcancel();
+
+       a_inc(&c->_c_waiters);
+
+       if (c->_c_mutex != (void *)-1) {
+               c->_c_mutex = m;
+               while (a_swap(&c->_c_lock, 1))
+                       __wait(&c->_c_lock, &c->_c_lockwait, 1, 1);
+               c->_c_waiters2++;
+               a_store(&c->_c_lock, 0);
+               if (c->_c_lockwait) __wake(&c->_c_lock, 1, 1);
+       }
+
+       seq = c->_c_seq;
+
+       pthread_mutex_unlock(m);
 
-       pthread_cleanup_push(relock, m);
-       c->_c_block = 1;
-       if ((r=pthread_mutex_unlock(m))) return r;
+       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;
 
-       CANCELPT_BEGIN;
-       e = __timedwait(&c->_c_block, 1, c->_c_clock, ts, 0);
-       CANCELPT_END;
+       unwait(c, m);
 
-       pthread_cleanup_pop(0);
        if ((r=pthread_mutex_lock(m))) return r;
 
-       CANCELPT_BEGIN;
-       CANCELPT_END;
        return e;
 }