source: azure_iot_hub/trunk/musl-1.1.18/src/thread/pthread_mutex_unlock.c@ 390

#include "pthread_impl.h"

int __pthread_mutex_unlock(pthread_mutex_t *m)
{
        pthread_t self;
        int waiters = m->_m_waiters;
        int cont;
        int type = m->_m_type & 15;
        int priv = (m->_m_type & 128) ^ 128;

        if (type != PTHREAD_MUTEX_NORMAL) {
                self = __pthread_self();
                if ((m->_m_lock&0x7fffffff) != self->tid)
                        return EPERM;
                if ((type&3) == PTHREAD_MUTEX_RECURSIVE && m->_m_count)
                        return m->_m_count--, 0;
                if (!priv) {
                        self->robust_list.pending = &m->_m_next;
                        __vm_lock();
                }
                volatile void *prev = m->_m_prev;
                volatile void *next = m->_m_next;
                *(volatile void *volatile *)prev = next;
                if (next != &self->robust_list.head) *(volatile void *volatile *)
                        ((char *)next - sizeof(void *)) = prev;
        }
        cont = a_swap(&m->_m_lock, (type & 8) ? 0x7fffffff : 0);
        if (type != PTHREAD_MUTEX_NORMAL && !priv) {
                self->robust_list.pending = 0;
                __vm_unlock();
        }
        if (waiters || cont<0)
                __wake(&m->_m_lock, 1, priv);
        return 0;
}

weak_alias(__pthread_mutex_unlock, pthread_mutex_unlock);