use count=0 instead of 1 for recursive mutex with only one lock reference

this simplifies the code paths slightly, but perhaps what's nicer is
that it makes recursive mutexes fully reentrant, i.e. locking and
unlocking from a signal handler works even if the interrupted code was
in the middle of locking or unlocking.

diff --git a/src/thread/pthread_mutex_trylock.c b/src/thread/pthread_mutex_trylock.c
index 4a424bc91a4217e869fe29c55f6ddd681eb85e63..fb2779706e75a9fa7e9e6769021174a30e7f31b5 100644 (file)
--- a/src/thread/pthread_mutex_trylock.c
+++ b/src/thread/pthread_mutex_trylock.c
@@ -30,8 +30,6 @@ int pthread_mutex_trylock(pthread_mutex_t *m)
        if ((own && !(own & 0x40000000)) || a_cas(&m->_m_lock, old, tid)!=old)
                return EBUSY;
 
-       m->_m_count = 1;
-
        if (m->_m_type < 4) return 0;
 
        if (m->_m_type >= 8) {

diff --git a/src/thread/pthread_mutex_unlock.c b/src/thread/pthread_mutex_unlock.c
index 0f4a5e6cccc036e03d3bd0feb2f928517dfc0851..05baec18dd13a3c5ac8e43077f082f2671526b90 100644 (file)
--- a/src/thread/pthread_mutex_unlock.c
+++ b/src/thread/pthread_mutex_unlock.c
@@ -12,8 +12,8 @@ int pthread_mutex_unlock(pthread_mutex_t *m)
                self = __pthread_self();
                if ((m->_m_lock&0x1fffffff) != self->tid)
                        return EPERM;
-               if ((m->_m_type&3) == PTHREAD_MUTEX_RECURSIVE && --m->_m_count)
-                       return 0;
+               if ((m->_m_type&3) == PTHREAD_MUTEX_RECURSIVE && m->_m_count)
+                       return m->_m_count--, 0;
                if (m->_m_type >= 4) {
                        self->robust_list.pending = &m->_m_next;
                        *(void **)m->_m_prev = m->_m_next;