-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)
-{
- if (vmlock[0]>0) a_dec(vmlock);
- else a_inc(vmlock);
- if (vmlock[1]) __wake(vmlock, 1, 1);
-}