1#include "pthread_impl.h"
 2
 3int __pthread_mutex_trylock_owner(pthread_mutex_t *m)
 4{
 5	int old, own;
 6	int type = m->_m_type;
 7	pthread_t self = __pthread_self();
 8	int tid = self->tid;
 9
10	old = m->_m_lock;
11	own = old & 0x3fffffff;
12	if (own == tid) {
13		if ((type&8) && m->_m_count<0) {
14			old &= 0x40000000;
15			m->_m_count = 0;
16			goto success;
17		}
18		if ((type&3) == PTHREAD_MUTEX_RECURSIVE) {
19			if ((unsigned)m->_m_count >= INT_MAX) return EAGAIN;
20			m->_m_count++;
21			return 0;
22		}
23	}
24	if (own == 0x3fffffff) return ENOTRECOVERABLE;
25	if (own || (old && !(type & 4))) return EBUSY;
26
27	if (type & 128) {
28		if (!self->robust_list.off) {
29			self->robust_list.off = (char*)&m->_m_lock-(char *)&m->_m_next;
30			__syscall(SYS_set_robust_list, &self->robust_list, 3*sizeof(long));
31		}
32		if (m->_m_waiters) tid |= 0x80000000;
33		self->robust_list.pending = &m->_m_next;
34	}
35	tid |= old & 0x40000000;
36
37	if (a_cas(&m->_m_lock, old, tid) != old) {
38		self->robust_list.pending = 0;
39		if ((type&12)==12 && m->_m_waiters) return ENOTRECOVERABLE;
40		return EBUSY;
41	}
42
43success:
44	if ((type&8) && m->_m_waiters) {
45		int priv = (type & 128) ^ 128;
46		__syscall(SYS_futex, &m->_m_lock, FUTEX_UNLOCK_PI|priv);
47		self->robust_list.pending = 0;
48		return (type&4) ? ENOTRECOVERABLE : EBUSY;
49	}
50
51	volatile void *next = self->robust_list.head;
52	m->_m_next = next;
53	m->_m_prev = &self->robust_list.head;
54	if (next != &self->robust_list.head) *(volatile void *volatile *)
55		((char *)next - sizeof(void *)) = &m->_m_next;
56	self->robust_list.head = &m->_m_next;
57	self->robust_list.pending = 0;
58
59	if (old) {
60		m->_m_count = 0;
61		return EOWNERDEAD;
62	}
63
64	return 0;
65}
66
67int __pthread_mutex_trylock(pthread_mutex_t *m)
68{
69	if ((m->_m_type&15) == PTHREAD_MUTEX_NORMAL)
70		return a_cas(&m->_m_lock, 0, EBUSY) & EBUSY;
71	return __pthread_mutex_trylock_owner(m);
72}
73
74weak_alias(__pthread_mutex_trylock, pthread_mutex_trylock);