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 4a424bc..fb27797 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;
 
        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) {
        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 0f4a5e6..05baec1 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;
                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;
                if (m->_m_type >= 4) {
                        self->robust_list.pending = &m->_m_next;
                        *(void **)m->_m_prev = m->_m_next;