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musl/src/thread/pthread_mutex_timedlock.c

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initial check-in, version 0.5.0
15 years ago
#include "pthread_impl.h"
int pthread_mutex_timedlock(pthread_mutex_t *m, const struct timespec *at)
{
avoid accessing mutex memory after atomic unlock this change is needed to fix a race condition and ensure that it's possible to unlock and destroy or unmap the mutex as soon as pthread_mutex_lock succeeds. POSIX explicitly gives such an example in the rationale and requires an implementation to allow such usage.
15 years ago
int r, t;
if (m->_m_type == PTHREAD_MUTEX_NORMAL && !a_cas(&m->_m_lock, 0, EBUSY))
return 0;
initial check-in, version 0.5.0
15 years ago
while ((r=pthread_mutex_trylock(m)) == EBUSY) {
implement robust mutexes 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.
15 years ago
if (!(r=m->_m_lock) || (r&0x40000000)) continue;
avoid accessing mutex memory after atomic unlock this change is needed to fix a race condition and ensure that it's possible to unlock and destroy or unmap the mutex as soon as pthread_mutex_lock succeeds. POSIX explicitly gives such an example in the rationale and requires an implementation to allow such usage.
15 years ago
if ((m->_m_type&3) == PTHREAD_MUTEX_ERRORCHECK
&& (r&0x1fffffff) == pthread_self()->tid)
return EDEADLK;
a_inc(&m->_m_waiters);
t = r | 0x80000000;
a_cas(&m->_m_lock, r, t);
r = __timedwait(&m->_m_lock, t, CLOCK_REALTIME, at, 0);
a_dec(&m->_m_waiters);
if (r && r != EINTR) break;
initial check-in, version 0.5.0
15 years ago
}
return r;
}