linux-kernel - [Query]: tick-sched: can idle_active be false in tick_nohz_idle

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Message-ID: <CAKohpon3vJzL51V9aOBcXKJC4nr3K-0q77HsxFi+=ACUqNqhcA@mail.gmail.com>
Date:	Wed, 9 Apr 2014 17:28:57 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Frédéric Weisbecker <fweisbec@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Lists linaro-kernel <linaro-kernel@...ts.linaro.org>
Subject: [Query]: tick-sched: can idle_active be false in tick_nohz_idle_exit()?

Hi Guys,

File: kernel/time/tick-sched.c
function: tick_nohz_idle_exit()

We are checking here if idle_active is true or not and then
do some stuff. But is it possible that idle_active be false
here?

The sequence as far as I understood is:
idle-loop:

tick_nohz_idle_enter(), i.e. idle_active = true;
local_irq_disable()

IDLE
.
.

wake up due to IPI ??

local_irq_enable()
    tick_nohz_irq_enter(), i.e. idle_active = false;
    tick_nohz_irq_exit(), i.e. idle_active = true;

tick_nohz_idle_exit()

How can idle_active be false here?

--
viresh
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