check preconditions in sched

b6cac0a5 · rsc · e7a5b3c5 · b6cac0a5
--- a/proc.c
+++ b/proc.c
@@ -207,6 +207,11 @@ sched(void)
 {
  struct proc *p = curproc[cpu()];

+  if(!holding(&proc_table_lock))
+    panic("sched");
+  if(cpus[cpu()].nlock != 1)
+    panic("sched locks");
+
  if(setjmp(&p->jmpbuf) == 0)
    longjmp(&cpus[cpu()].jmpbuf);
 }