1 #include "pthread_impl.h"
2
__pthread_mutex_trylock_owner(pthread_mutex_t * m)3 int __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
43 success:
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
__pthread_mutex_trylock(pthread_mutex_t * m)67 int __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
74 weak_alias(__pthread_mutex_trylock, pthread_mutex_trylock);
75