linux-kernel - [PATCH 2/3] nohz: Remove ts->inidle checks before restarting the tick

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Date:	Tue, 24 Jan 2012 18:59:43 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	John Stultz <john.stultz@...aro.org>
Subject: [PATCH 2/3] nohz: Remove ts->inidle checks before restarting the tick

ts->inidle is set by tick_nohz_idle_enter() and unset by
tick_nohz_idle_exit(). However These two calls are assumed
to be always paired. This means that by the time we call
tick_nohz_idle_exit(), ts->inidle is supposed to be always
set to 1.

Remove the checks for ts->inidle in tick_nohz_idle_exit().
This simplifies a bit the code and improves its debuggability
(ie: ensure the call is paired with a tick_nohz_idle_enter()
call).

Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
Reviewed-by: Yong Zhang <yong.zhang0@...il.com>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: John Stultz <john.stultz@...aro.org>
---
 kernel/time/tick-sched.c |   11 ++++++-----
 1 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 85a67e8..6aecf74 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -560,20 +560,21 @@ void tick_nohz_idle_exit(void)
 
 	local_irq_disable();
 
-	if (ts->idle_active || (ts->inidle && ts->tick_stopped))
+	WARN_ON_ONCE(!ts->inidle);
+
+	ts->inidle = 0;
+
+	if (ts->idle_active || ts->tick_stopped)
 		now = ktime_get();
 
 	if (ts->idle_active)
 		tick_nohz_stop_idle(cpu, now);
 
-	if (!ts->inidle || !ts->tick_stopped) {
-		ts->inidle = 0;
+	if (!ts->tick_stopped) {
 		local_irq_enable();
 		return;
 	}
 
-	ts->inidle = 0;
-
 	/* Update jiffies first */
 	select_nohz_load_balancer(0);
 	tick_do_update_jiffies64(now);
-- 
1.7.5.4

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