-static int vmlock[2];
-
-void __vm_lock(int inc)
-{
- for (;;) {
- int v = vmlock[0];
- if (inc*v < 0) __wait(vmlock, vmlock+1, v, 1);
- else if (a_cas(vmlock, v, v+inc)==v) break;
- }
-}
-
-void __vm_unlock(void)
-{
- int inc = vmlock[0]>0 ? -1 : 1;
- if (a_fetch_add(vmlock, inc)==-inc && vmlock[1])
- __wake(vmlock, -1, 1);
-}