linux-kernel - Re: [patch 08/13] sched: Clenaup PREEMPT

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Message-ID: <jhj8sda56so.mognet@arm.com>
Date:   Wed, 16 Sep 2020 11:56:23 +0100
From:   Valentin Schneider <valentin.schneider@....com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, linux-arch@...r.kernel.org,
        Linus Torvalds <torvalds@...uxfoundation.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Richard Henderson <rth@...ddle.net>,
        Ivan Kokshaysky <ink@...assic.park.msu.ru>,
        Matt Turner <mattst88@...il.com>, linux-alpha@...r.kernel.org,
        Jeff Dike <jdike@...toit.com>,
        Richard Weinberger <richard@....at>,
        Anton Ivanov <anton.ivanov@...bridgegreys.com>,
        linux-um@...ts.infradead.org, Brian Cain <bcain@...eaurora.org>,
        linux-hexagon@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        linux-m68k@...ts.linux-m68k.org, Ingo Molnar <mingo@...nel.org>,
        Will Deacon <will@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        Russell King <linux@...linux.org.uk>,
        linux-arm-kernel@...ts.infradead.org,
        Chris Zankel <chris@...kel.net>,
        Max Filippov <jcmvbkbc@...il.com>,
        linux-xtensa@...ux-xtensa.org,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Josh Triplett <josh@...htriplett.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Shuah Khan <shuah@...nel.org>, rcu@...r.kernel.org,
        linux-kselftest@...r.kernel.org
Subject: Re: [patch 08/13] sched: Clenaup PREEMPT_COUNT leftovers


On 14/09/20 21:42, Thomas Gleixner wrote:
> CONFIG_PREEMPT_COUNT is now unconditionally enabled and will be
> removed. Cleanup the leftovers before doing so.
>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Juri Lelli <juri.lelli@...hat.com>
> Cc: Vincent Guittot <vincent.guittot@...aro.org>
> Cc: Dietmar Eggemann <dietmar.eggemann@....com>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Cc: Ben Segall <bsegall@...gle.com>
> Cc: Mel Gorman <mgorman@...e.de>
> Cc: Daniel Bristot de Oliveira <bristot@...hat.com>

Small nit below;

Reviewed-by: Valentin Schneider <valentin.schneider@....com>

> ---
>  kernel/sched/core.c |    6 +-----
>  lib/Kconfig.debug   |    1 -
>  2 files changed, 1 insertion(+), 6 deletions(-)
>
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -3706,8 +3706,7 @@ asmlinkage __visible void schedule_tail(
>        * finish_task_switch() for details.
>        *
>        * finish_task_switch() will drop rq->lock() and lower preempt_count
> -	 * and the preempt_enable() will end up enabling preemption (on
> -	 * PREEMPT_COUNT kernels).

I suppose this wanted to be s/PREEMPT_COUNT/PREEMPT/ in the first place,
which ought to be still relevant.

> +	 * and the preempt_enable() will end up enabling preemption.
>        */
>
>       rq = finish_task_switch(prev);