fix and optimize non-default-type mutex behavior

problem 1: mutex type from the attribute was being ignored by
pthread_mutex_init, so recursive/errorchecking mutexes were never
being used at all.

problem 2: ownership of recursive mutexes was not being enforced at
unlock time.

src/internal/pthread_impl.h

@@ -47,6 +47,7 @@ struct pthread {
 #define _m_lock __u.__i[1]
 #define _m_waiters __u.__i[2]
 #define _m_owner __u.__i[3]
+#define _m_count __u.__i[4]
 #define _c_block __u.__i[0]
 #define _c_clock __u.__i[1]
 #define _rw_wrlock __u.__i[0]

src/thread/pthread_mutex_init.c

@@ -3,7 +3,6 @@
 int pthread_mutex_init(pthread_mutex_t *m, const pthread_mutexattr_t *a)
 {
 	memset(m, 0, sizeof *m);
-	if (a) {
-	}
+	if (a) m->_m_type = *a & 3;
 	return 0;
 }

src/thread/pthread_mutex_trylock.c

@@ -2,27 +2,24 @@
 
 int pthread_mutex_trylock(pthread_mutex_t *m)
 {
-	if (m->_m_type == PTHREAD_MUTEX_RECURSIVE) {
-		pthread_t self = pthread_self();
-		if (m->_m_owner == self->tid) {
-			if ((unsigned)m->_m_lock >= INT_MAX) return EAGAIN;
-			a_inc(&m->_m_lock);
+	pthread_t self;
+	if (m->_m_type != PTHREAD_MUTEX_NORMAL) {
+		self = pthread_self();
+		if (m->_m_type == PTHREAD_MUTEX_RECURSIVE
+		 && m->_m_owner == self->tid) {
+			if ((unsigned)m->_m_count >= INT_MAX) return EAGAIN;
+			m->_m_count++;
 			return 0;
 		}
-		if (a_fetch_add(&m->_m_lock, 1)) {
-			if (a_fetch_add(&m->_m_lock, -1)==1 && m->_m_waiters)
-				__wake(&m->_m_lock, 1, 0);
-			return EBUSY;
-		}
-		m->_m_owner = self->tid;
-		return 0;
 	}
 
 	if (a_xchg(&m->_m_lock, 1))
 		if (m->_m_type == PTHREAD_MUTEX_ERRORCHECK
-		 && m->_m_owner == pthread_self()->tid) return EDEADLK;
+		 && m->_m_owner == self->tid) return EDEADLK;
 		else return EBUSY;
-	if (m->_m_type == PTHREAD_MUTEX_ERRORCHECK)
-		m->_m_owner = pthread_self()->tid;
+	if (m->_m_type != PTHREAD_MUTEX_NORMAL) {
+		m->_m_owner = self->tid;
+		m->_m_count = 1;
+	}
 	return 0;
 }

src/thread/pthread_mutex_unlock.c

@@ -2,16 +2,13 @@
 
 int pthread_mutex_unlock(pthread_mutex_t *m)
 {
-	if (m->_m_type == PTHREAD_MUTEX_RECURSIVE) {
-		if (a_fetch_add(&m->_m_lock, -1)==1 && m->_m_waiters)
-			__wake(&m->_m_lock, 1, 0);
-		return 0;
+	if (m->_m_type != PTHREAD_MUTEX_NORMAL) {
+		if (m->_m_owner != pthread_self()->tid)
+		 	return EPERM;
+		if (m->_m_type == PTHREAD_MUTEX_RECURSIVE && --m->_m_count)
+			return 0;
 	}
 
-	if (m->_m_type == PTHREAD_MUTEX_ERRORCHECK
-	 && m->_m_owner != pthread_self()->tid)
-	 	return EPERM;
-
 	m->_m_owner = 0;
 	m->_m_lock = 0;
 	if (m->_m_waiters) __wake(&m->_m_lock, 1, 0);