fix ABA race in cond vars, improve them overall

[musl] / src / thread / pthread_cond_timedwait.c

diff --git a/src/thread/pthread_cond_timedwait.c b/src/thread/pthread_cond_timedwait.c
index ec5aa6f..c71edc9 100644 (file)
--- a/src/thread/pthread_cond_timedwait.c
+++ b/src/thread/pthread_cond_timedwait.c
@@ -15,19 +15,22 @@ 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 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=0;
+       int r, e, tid;

 
        if (ts && ts->tv_nsec >= 1000000000UL)
                return EINVAL;
 
        pthread_testcancel();
 
 
        if (ts && ts->tv_nsec >= 1000000000UL)
                return EINVAL;
 
        pthread_testcancel();
 

-       c->_c_block = 1;
+       a_inc(&c->_c_waiters);
+       c->_c_block = tid = pthread_self()->tid;
+

        if ((r=pthread_mutex_unlock(m))) return r;
 
        if ((r=pthread_mutex_unlock(m))) return r;
 

-       a_inc(&c->_c_waiters);
-       do e = __timedwait(&c->_c_block, 1, c->_c_clock, ts, cleanup, &cm, 0);
-       while (e == EINTR);
+       do e = __timedwait(&c->_c_block, tid, c->_c_clock, ts, cleanup, &cm, 0);
+       while (c->_c_block == tid && (!e || e==EINTR));
+       if (e == EINTR) e = 0;
+

        a_dec(&c->_c_waiters);
 
        if ((r=pthread_mutex_lock(m))) return r;
        a_dec(&c->_c_waiters);
 
        if ((r=pthread_mutex_lock(m))) return r;