linux-kernel - Re: [PATCH 8/8] stop_machine: cleanup the usage of preemption counter in cpu_stopper

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Message-ID: <20151116191007.GL18894@mtj.duckdns.org>
Date:	Mon, 16 Nov 2015 14:10:07 -0500
From:	Tejun Heo <tj@...nel.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Milos Vyletel <milos@...hat.com>,
	Prarit Bhargava <prarit@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 8/8] stop_machine: cleanup the usage of preemption
 counter in cpu_stopper_thread()

On Sun, Nov 15, 2015 at 08:33:32PM +0100, Oleg Nesterov wrote:
> 1. Change this code to use preempt_count_inc/preempt_count_dec; this way
>    it works even if CONFIG_PREEMPT_COUNT=n, and we avoid the unnecessary
>    __preempt_schedule() check (stop_sched_class is not preemptible).
> 
>    And this makes clear that we only want to make preempt_count() != 0
>    for __might_sleep() / schedule_debug().
> 
> 2. Change WARN_ONCE() to use %pf to print the function name and remove
>    kallsyms_lookup/ksym_buf.
> 
> 3. Move "int ret" into the "if (work)" block, this looks more consistent.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>

The entire series looks good to me.  Please feel free to add

Acked-by: Tejun Heo <tj@...nel.org>

Thanks.

-- 
tejun
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