libc-top-half/musl/src/thread/pthread_mutexattr_setprotocol.c

   1 #include "pthread_impl.h"
   2 #include "syscall.h"
   3
   4 static volatile int check_pi_result = -1;
   5
   6 int pthread_mutexattr_setprotocol(pthread_mutexattr_t *a, int protocol)
   7 {
   8         int r;
   9         switch (protocol) {
  10         case PTHREAD_PRIO_NONE:
  11                 a->__attr &= ~8;
  12                 return 0;
  13         case PTHREAD_PRIO_INHERIT:
  14 #ifdef __wasilibc_unmodified_upstream
  15                 r = check_pi_result;
  16                 if (r < 0) {
  17                         volatile int lk = 0;
  18                         r = -__syscall(SYS_futex, &lk, FUTEX_LOCK_PI, 0, 0);
  19                         a_store(&check_pi_result, r);
  20                 }
  21                 if (r) return r;
  22                 a->__attr |= 8;
  23                 return 0;
  24 #else
  25                 return ENOTSUP;
  26 #endif
  27         case PTHREAD_PRIO_PROTECT:
  28                 return ENOTSUP;
  29         default:
  30                 return EINVAL;
  31         }
  32 }