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 228f61f..c71edc9 100644 (file)
--- a/src/thread/pthread_cond_timedwait.c
+++ b/src/thread/pthread_cond_timedwait.c
@@ -1,26 +1,40 @@
 #include "pthread_impl.h"
 
-static void relock(void *m)
+struct cm {
+       pthread_cond_t *c;
+       pthread_mutex_t *m;
+};
+
+static void cleanup(void *p)
 {
-       pthread_mutex_lock(m);
+       struct cm *cm = p;
+       a_dec(&cm->c->_c_waiters);
+       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(0);
+       struct cm cm = { .c=c, .m=m };
+       int r, e, tid;
+
+       if (ts && ts->tv_nsec >= 1000000000UL)
+               return EINVAL;
+
+       pthread_testcancel();
+
+       a_inc(&c->_c_waiters);
+       c->_c_block = tid = pthread_self()->tid;
 
-       pthread_cleanup_push(relock, m);
-       c->_c_block = 1;
        if ((r=pthread_mutex_unlock(m))) return r;
 
-       CANCELPT(1);
-       e = __timedwait(&c->_c_block, 1, c->_c_clock, ts, 0);
-       CANCELPT(0);
+       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);
 
-       pthread_cleanup_pop(0);
        if ((r=pthread_mutex_lock(m))) return r;
 
-       CANCELPT(0);
+       pthread_testcancel();
        return e;
 }