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

   1 #include "pthread_impl.h"
   2 #include "syscall.h"
   3
   4 static pthread_once_t check_pi_once;
   5 static int check_pi_result;
   6
   7 static void check_pi()
   8 {
   9         volatile int lk = 0;
  10         check_pi_result = -__syscall(SYS_futex, &lk, FUTEX_LOCK_PI, 0, 0);
  11 }
  12
  13 int pthread_mutexattr_setprotocol(pthread_mutexattr_t *a, int protocol)
  14 {
  15         switch (protocol) {
  16         case PTHREAD_PRIO_NONE:
  17                 a->__attr &= ~8;
  18                 return 0;
  19         case PTHREAD_PRIO_INHERIT:
  20                 pthread_once(&check_pi_once, check_pi);
  21                 if (check_pi_result) return check_pi_result;
  22                 a->__attr |= 8;
  23                 return 0;
  24         case PTHREAD_PRIO_PROTECT:
  25                 return ENOTSUP;
  26         default:
  27                 return EINVAL;
  28         }
  29 }