comment about sched() saving/restoring cpu->intena

bc8221a5 · Robert Morris · 4b2152cc · bc8221a5 · bc8221a5
--- a/proc.c
+++ b/proc.c
@@ -302,7 +302,12 @@ scheduler(void)
 }
 // Enter scheduler.  Must hold only ptable.lock
-// and have changed proc->state.
+// and have changed proc->state. Saves and restores
+// intena because intena is a property of this
+// kernel thread, not this CPU. It should
+// be proc->intena and proc->ncli, but that would
+// break in the few places where a lock is held but
+// there's no process.
 void
 sched(void)
 {

--- a/spinlock.c
+++ b/spinlock.c
@@ -102,8 +102,9 @@ pushcli(void)
  eflags = readeflags();
  cli();
-  if(cpu->ncli++ == 0)
+  if(cpu->ncli == 0)
    cpu->intena = eflags & FL_IF;
+  cpu->ncli += 1;
 }
 void