Subject: Re: [Xen-devel] [PATCH] xen: Add comment for missing FROZEN notifier
 transitions
To: Anna-Maria Gleixner <anna-maria@linutronix.de>,
        linux-kernel@vger.kernel.org
References: <1459773140-43707-1-git-send-email-anna-maria@linutronix.de>
Cc: xen-devel@lists.xenproject.org,
        Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
        rt@linutronix.de, David Vrabel <david.vrabel@citrix.com>
From: David Vrabel <dvrabel@cantab.net>
Message-ID: <57050A98.80901@cantab.net>
Date: Wed, 6 Apr 2016 14:09:44 +0100
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On 04/04/16 13:32, Anna-Maria Gleixner wrote:
> Xen guests do not offline/online CPUs during suspend/resume and
> therefore FROZEN notifier transitions are not required. Add this
> explanation as a comment in the code to get not confused why
> CPU_TASKS_FROZEN masked transitions are not considered.
> 
> Cc: David Vrabel <david.vrabel@citrix.com>
> Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> Cc: xen-devel@lists.xenproject.org 
> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
> ---
>  arch/arm/xen/enlighten.c         |    6 ++++++
>  arch/x86/xen/enlighten.c         |    7 +++++++
>  drivers/xen/events/events_fifo.c |    6 ++++++
>  3 files changed, 19 insertions(+)
> 
> --- a/arch/arm/xen/enlighten.c
> +++ b/arch/arm/xen/enlighten.c
> @@ -213,6 +213,12 @@ static int xen_cpu_notification(struct n
>  				unsigned long action,
>  				void *hcpu)
>  {
> +	/*
> +	 * Xen guests do not offline/online CPUs during
> +	 * suspend/resume, thus CPU_TASKS_FROZEN masked transitions
> +	 * are not considered.
> +	 */

This may not be true for arm guests.

David