xref: /aosp_15_r20/external/musl/src/thread/pthread_mutex_unlock.c (revision c9945492fdd68bbe62686c5b452b4dc1be3f8453)
1*c9945492SAndroid Build Coastguard Worker #include "pthread_impl.h"
2*c9945492SAndroid Build Coastguard Worker 
__pthread_mutex_unlock(pthread_mutex_t * m)3*c9945492SAndroid Build Coastguard Worker int __pthread_mutex_unlock(pthread_mutex_t *m)
4*c9945492SAndroid Build Coastguard Worker {
5*c9945492SAndroid Build Coastguard Worker 	pthread_t self;
6*c9945492SAndroid Build Coastguard Worker 	int waiters = m->_m_waiters;
7*c9945492SAndroid Build Coastguard Worker 	int cont;
8*c9945492SAndroid Build Coastguard Worker 	int type = m->_m_type & 15;
9*c9945492SAndroid Build Coastguard Worker 	int priv = (m->_m_type & 128) ^ 128;
10*c9945492SAndroid Build Coastguard Worker 	int new = 0;
11*c9945492SAndroid Build Coastguard Worker 	int old;
12*c9945492SAndroid Build Coastguard Worker 
13*c9945492SAndroid Build Coastguard Worker 	if (type != PTHREAD_MUTEX_NORMAL) {
14*c9945492SAndroid Build Coastguard Worker 		self = __pthread_self();
15*c9945492SAndroid Build Coastguard Worker 		old = m->_m_lock;
16*c9945492SAndroid Build Coastguard Worker 		int own = old & 0x3fffffff;
17*c9945492SAndroid Build Coastguard Worker 		if (own != self->tid)
18*c9945492SAndroid Build Coastguard Worker 			return EPERM;
19*c9945492SAndroid Build Coastguard Worker 		if ((type&3) == PTHREAD_MUTEX_RECURSIVE && m->_m_count)
20*c9945492SAndroid Build Coastguard Worker 			return m->_m_count--, 0;
21*c9945492SAndroid Build Coastguard Worker 		if ((type&4) && (old&0x40000000))
22*c9945492SAndroid Build Coastguard Worker 			new = 0x7fffffff;
23*c9945492SAndroid Build Coastguard Worker 		if (!priv) {
24*c9945492SAndroid Build Coastguard Worker 			self->robust_list.pending = &m->_m_next;
25*c9945492SAndroid Build Coastguard Worker 			__vm_lock();
26*c9945492SAndroid Build Coastguard Worker 		}
27*c9945492SAndroid Build Coastguard Worker 		volatile void *prev = m->_m_prev;
28*c9945492SAndroid Build Coastguard Worker 		volatile void *next = m->_m_next;
29*c9945492SAndroid Build Coastguard Worker 		*(volatile void *volatile *)prev = next;
30*c9945492SAndroid Build Coastguard Worker 		if (next != &self->robust_list.head) *(volatile void *volatile *)
31*c9945492SAndroid Build Coastguard Worker 			((char *)next - sizeof(void *)) = prev;
32*c9945492SAndroid Build Coastguard Worker 	}
33*c9945492SAndroid Build Coastguard Worker 	if (type&8) {
34*c9945492SAndroid Build Coastguard Worker 		if (old<0 || a_cas(&m->_m_lock, old, new)!=old) {
35*c9945492SAndroid Build Coastguard Worker 			if (new) a_store(&m->_m_waiters, -1);
36*c9945492SAndroid Build Coastguard Worker 			__syscall(SYS_futex, &m->_m_lock, FUTEX_UNLOCK_PI|priv);
37*c9945492SAndroid Build Coastguard Worker 		}
38*c9945492SAndroid Build Coastguard Worker 		cont = 0;
39*c9945492SAndroid Build Coastguard Worker 		waiters = 0;
40*c9945492SAndroid Build Coastguard Worker 	} else {
41*c9945492SAndroid Build Coastguard Worker 		cont = a_swap(&m->_m_lock, new);
42*c9945492SAndroid Build Coastguard Worker 	}
43*c9945492SAndroid Build Coastguard Worker 	if (type != PTHREAD_MUTEX_NORMAL && !priv) {
44*c9945492SAndroid Build Coastguard Worker 		self->robust_list.pending = 0;
45*c9945492SAndroid Build Coastguard Worker 		__vm_unlock();
46*c9945492SAndroid Build Coastguard Worker 	}
47*c9945492SAndroid Build Coastguard Worker 	if (waiters || cont<0)
48*c9945492SAndroid Build Coastguard Worker 		__wake(&m->_m_lock, 1, priv);
49*c9945492SAndroid Build Coastguard Worker 	return 0;
50*c9945492SAndroid Build Coastguard Worker }
51*c9945492SAndroid Build Coastguard Worker 
52*c9945492SAndroid Build Coastguard Worker weak_alias(__pthread_mutex_unlock, pthread_mutex_unlock);
53