cheap trick to further optimize locking normal mutexes

[musl] / src / thread / pthread_mutex_lock.c

diff --git a/src/thread/pthread_mutex_lock.c b/src/thread/pthread_mutex_lock.c
index 8255614..99c15bd 100644 (file)
--- a/src/thread/pthread_mutex_lock.c
+++ b/src/thread/pthread_mutex_lock.c
@@ -3,11 +3,16 @@
 int pthread_mutex_lock(pthread_mutex_t *m)
 {
        int r;
+
+       if (m->_m_type == PTHREAD_MUTEX_NORMAL && !a_swap(&m->_m_lock, EBUSY))
+               return 0;
+
        while ((r=pthread_mutex_trylock(m)) == EBUSY) {
-               if (m->_m_type == PTHREAD_MUTEX_ERRORCHECK
-                && m->_m_owner == pthread_self()->tid)
+               if (!(r=m->_m_lock) || (r&0x40000000)) continue;
+               if ((m->_m_type&3) == PTHREAD_MUTEX_ERRORCHECK
+                && (r&0x1fffffff) == pthread_self()->tid)
                        return EDEADLK;
-               __wait(&m->_m_lock, &m->_m_waiters, 1, 0);
+               __wait(&m->_m_lock, &m->_m_waiters, r, 0);
        }
        return r;
 }