musl/src/thread/pthread_mutex_lock.c

#include "pthread_impl.h"

int pthread_mutex_lock(pthread_mutex_t *m)
{
	if ((m->_m_type&15) == PTHREAD_MUTEX_NORMAL
	    && !a_cas(&m->_m_lock, 0, EBUSY))
		return 0;

	return pthread_mutex_timedlock(m, 0);
}