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#include "pthread_impl.h"
int pthread_mutex_trylock(pthread_mutex_t *m)
{
int tid, old, own;
pthread_t self;
if (m->_m_type == PTHREAD_MUTEX_NORMAL)
return a_cas(&m->_m_lock, 0, EBUSY) & EBUSY;
self = __pthread_self();
tid = self->tid;
if (m->_m_type >= 4) {
if (!self->robust_list.off)
__syscall(SYS_set_robust_list,
&self->robust_list, 3*sizeof(long));
self->robust_list.off = (char*)&m->_m_lock-(char *)&m->_m_next;
self->robust_list.pending = &m->_m_next;
}
old = m->_m_lock;
own = old & 0x7fffffff;
if (own == tid && (m->_m_type&3) == PTHREAD_MUTEX_RECURSIVE) {
if ((unsigned)m->_m_count >= INT_MAX) return EAGAIN;
m->_m_count++;
return 0;
}
if ((own && !(own & 0x40000000)) || a_cas(&m->_m_lock, old, tid)!=old)
return EBUSY;
if (m->_m_type < 4) return 0;
if (m->_m_type >= 8) {
m->_m_lock = 0;
return ENOTRECOVERABLE;
}
m->_m_next = self->robust_list.head;
m->_m_prev = &self->robust_list.head;
if (self->robust_list.head)
self->robust_list.head[-1] = &m->_m_next;
self->robust_list.head = &m->_m_next;
self->robust_list.pending = 0;
if (own) {
m->_m_count = 0;
m->_m_type += 8;
return EOWNERDEAD;
}
return 0;
}
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