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implement robust mutexes

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some of this code should be cleaned up, e.g. using macros for some of
the bit flags, masks, etc. nonetheless, the code is believed to be
working and correct at this point.
This commit is contained in:
Rich Felker 2011-03-17 20:41:37 -04:00
commit 047e434ef5
10 changed files with 84 additions and 10 deletions
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38
src/thread/pthread_mutex_trylock.c
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@ -3,19 +3,51 @@
int pthread_mutex_trylock(pthread_mutex_t *m)
{
int tid;
int own;
pthread_t self;
if (m->_m_type == PTHREAD_MUTEX_NORMAL)
return (m->_m_lock || a_swap(&m->_m_lock, 1)) ? EBUSY : 0;
tid = pthread_self()->tid;
self = pthread_self();
tid = self->tid | 0x80000000;
if (m->_m_lock == tid && m->_m_type == PTHREAD_MUTEX_RECURSIVE) {
if (m->_m_type >= 4) {
if (!self->robust_list.off)
syscall2(__NR_set_robust_list,
(long)&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;
}
if (m->_m_lock == tid && (m->_m_type&3) == PTHREAD_MUTEX_RECURSIVE) {
if ((unsigned)m->_m_count >= INT_MAX) return EAGAIN;
m->_m_count++;
return 0;
}
if (m->_m_lock || a_cas(&m->_m_lock, 0, tid)) return EBUSY;
own = m->_m_lock;
if ((own && !(own & 0x40000000)) || a_cas(&m->_m_lock, own, tid)!=own)
return EBUSY;
m->_m_count = 1;
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_type += 8;
return EOWNERDEAD;
}
return 0;
}