src/thread/pthread_mutex_unlock.c

   1 #include "pthread_impl.h"
   2
   3 int __pthread_mutex_unlock(pthread_mutex_t *m)
   4 {
   5         pthread_t self;
   6         int waiters = m->_m_waiters;
   7         int cont;
   8         int type = m->_m_type & 15;
   9         int priv = (m->_m_type & 128) ^ 128;
  10         int new = 0;
  11         int old;
  12
  13         if (type != PTHREAD_MUTEX_NORMAL) {
  14                 self = __pthread_self();
  15                 old = m->_m_lock;
  16                 int own = old & 0x3fffffff;
  17                 if (own != self->tid)
  18                         return EPERM;
  19                 if ((type&3) == PTHREAD_MUTEX_RECURSIVE && m->_m_count)
  20                         return m->_m_count--, 0;
  21                 if ((type&4) && (old&0x40000000))
  22                         new = 0x7fffffff;
  23                 if (!priv) {
  24                         self->robust_list.pending = &m->_m_next;
  25                         __vm_lock();
  26                 }
  27                 volatile void *prev = m->_m_prev;
  28                 volatile void *next = m->_m_next;
  29                 *(volatile void *volatile *)prev = next;
  30                 if (next != &self->robust_list.head) *(volatile void *volatile *)
  31                         ((char *)next - sizeof(void *)) = prev;
  32         }
  33         if (type&8) {
  34                 if (old<0 || a_cas(&m->_m_lock, old, new)!=old) {
  35                         if (new) a_store(&m->_m_waiters, -1);
  36                         __syscall(SYS_futex, &m->_m_lock, FUTEX_UNLOCK_PI|priv);
  37                 }
  38                 cont = 0;
  39                 waiters = 0;
  40         } else {
  41                 cont = a_swap(&m->_m_lock, new);
  42         }
  43         if (type != PTHREAD_MUTEX_NORMAL && !priv) {
  44                 self->robust_list.pending = 0;
  45                 __vm_unlock();
  46         }
  47         if (waiters || cont<0)
  48                 __wake(&m->_m_lock, 1, priv);
  49         return 0;
  50 }
  51
  52 weak_alias(__pthread_mutex_unlock, pthread_mutex_unlock);