[PATCH] schedstat: fix schedule() statistics

The number of times schedule() left the processor idle in the
/proc/schedstat (runqueue.sched_goidle) seems to be wrong.

The schedule() statistics should satisfy the equation:
	sched_cnt == sched_noswitch + sched_switch + sched_goidle

(http://eaglet.rain.com/rick/linux/schedstat/v10/format-10.html)

The below patch fix this, and I have confirmed to be fixed with:
	# grep ^cpu /proc/schedstat | awk '{print $6+$7+$9, $8}'
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

kernel/sched.c

@@ -2574,7 +2574,6 @@ asmlinkage void __sched schedule(void)
 		}
 	} else {
 		if (dependent_sleeper(cpu, rq)) {
-			schedstat_inc(rq, sched_goidle);
 			next = rq->idle;
 			goto switch_tasks;
 		}
@@ -2618,6 +2617,8 @@ asmlinkage void __sched schedule(void)
 	}
 	next->activated = 0;
 switch_tasks:
+	if (next == rq->idle)
+		schedstat_inc(rq, sched_goidle);
 	prefetch(next);
 	clear_tsk_need_resched(prev);
 	rcu_qsctr_inc(task_cpu(prev));