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Re: [PREEMPT-RT] [Xen-devel] [PATCH] xen: Add comment for missing FROZEN notifier transitions

From Anna-Maria Gleixner <anna-maria@linutronix.de>
Newsgroups linux.kernel
Subject Re: [PREEMPT-RT] [Xen-devel] [PATCH] xen: Add comment for missing FROZEN notifier transitions
Date 2016-04-06 16:10 +0200
Message-ID <rkWjE-52m-35@gated-at.bofh.it> (permalink)
References <rkbXs-31q-17@gated-at.bofh.it> <rkVxh-4kN-35@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Wed, 6 Apr 2016, David Vrabel wrote:

> 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.

Ok. Should the frozen transitions be handled the same way than the
corresponding non frozen transitions? If yes and if it doesn't matter
to mask action with ~CPU_TASKS_FROZEN in arch/x86/xen/enlighten.c and
drivers/xen/events/events_fifo.c like Juergen sugessts, I could change
the patch by masking action.

Anna-Maria

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[PATCH] xen: Add comment for missing FROZEN notifier transitions Anna-Maria Gleixner <anna-maria@linutronix.de> - 2016-04-04 14:40 +0200
  Re: [Xen-devel] [PATCH] xen: Add comment for missing FROZEN notifier  transitions Julien Grall <julien.grall@arm.com> - 2016-04-04 18:30 +0200
    Re: [Xen-devel] [PATCH] xen: Add comment for missing FROZEN notifier  transitions David Vrabel <david.vrabel@citrix.com> - 2016-04-04 18:40 +0200
      Re: [Xen-devel] [PATCH] xen: Add comment for missing FROZEN notifier  transitions Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-04-04 18:50 +0200
        Re: [Xen-devel] [PATCH] xen: Add comment for missing FROZEN notifier  transitions Juergen Gross <jgross@suse.com> - 2016-04-05 06:30 +0200
          Re: [Xen-devel] [PATCH] xen: Add comment for missing FROZEN notifier  transitions Stefano Stabellini <sstabellini@kernel.org> - 2016-04-07 02:00 +0200
  Re: [Xen-devel] [PATCH] xen: Add comment for missing FROZEN notifier  transitions David Vrabel <dvrabel@cantab.net> - 2016-04-06 15:20 +0200
    Re: [PREEMPT-RT] [Xen-devel] [PATCH] xen: Add comment for missing  FROZEN notifier transitions Anna-Maria Gleixner <anna-maria@linutronix.de> - 2016-04-06 16:10 +0200
    Re: [Xen-devel] [PATCH] xen: Add comment for missing FROZEN notifier  transitions Stefano Stabellini <sstabellini@kernel.org> - 2016-04-07 02:00 +0200

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