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

jiraiyew · Sep 2, 2016 · bc8221a · bc8221a
1 parent 4b2152c
commit bc8221a
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Showing 2 changed files with 8 additions and 2 deletions.
diff --git 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)
 {

diff --git 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