musl/src/thread/pthread_mutex_unlock.c

#include "pthread_impl.h"

int pthread_mutex_unlock(pthread_mutex_t *m)
{
	if (m->_m_type == PTHREAD_MUTEX_RECURSIVE) {
		if (a_fetch_add(&m->_m_lock, -1)==1 && m->_m_waiters)
			__wake(&m->_m_lock, 1, 0);
		return 0;
	}

	if (m->_m_type == PTHREAD_MUTEX_ERRORCHECK
	 && m->_m_owner != pthread_self()->tid)
	 	return EPERM;

	m->_m_owner = 0;
	m->_m_lock = 0;
	if (m->_m_waiters) __wake(&m->_m_lock, 1, 0);
	return 0;
}