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

   1 #include "pthread_impl.h"
   2
   3 static int vmlock[2];
   4
   5 void __vm_lock(int inc)
   6 {
   7         for (;;) {
   8                 int v = vmlock[0];
   9                 if (inc*v < 0) __wait(vmlock, vmlock+1, v, 1);
  10                 else if (a_cas(vmlock, v, v+inc)==v) break;
  11         }
  12 }
  13
  14 void __vm_unlock(void)
  15 {
  16         int inc = vmlock[0]>0 ? -1 : 1;
  17         if (a_fetch_add(vmlock, inc)==-inc && vmlock[1])
  18                 __wake(vmlock, -1, 1);
  19 }
  20
  21 weak_alias(__vm_lock, __vm_lock_impl);
  22 weak_alias(__vm_unlock, __vm_unlock_impl);