nsz Git - musl/blob - src/thread/pthread_mutex_trylock.c

   1 #include "pthread_impl.h"
   2
   3 int pthread_mutex_trylock(pthread_mutex_t *m)
   4 {
   5         if (m->__type == PTHREAD_MUTEX_RECURSIVE) {
   6                 pthread_t self = pthread_self();
   7                 if (m->__owner == self) {
   8                         if ((unsigned)m->__lock >= INT_MAX) return EAGAIN;
   9                         a_inc(&m->__lock);
  10                         return 0;
  11                 }
  12                 if (a_fetch_add(&m->__lock, 1)) {
  13                         if (a_fetch_add(&m->__lock, -1)==1 && m->__waiters)
  14                                 __wake(&m->__lock, 1, 0);
  15                         return EBUSY;
  16                 }
  17                 m->__owner = self;
  18                 return 0;
  19         }
  20
  21         if (a_xchg(&m->__lock, 1))
  22                 if (m->__type == PTHREAD_MUTEX_ERRORCHECK
  23                  && m->__owner == pthread_self()) return EDEADLK;
  24                 else return EBUSY;
  25         if (m->__type == PTHREAD_MUTEX_ERRORCHECK)
  26                 m->__owner = pthread_self();
  27         return 0;
  28 }