[Xen-devel] Re: Patch Upstream: genirq: Add IRQF_RESUME_EARLY and resume such IRQs earlier

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

Hi Greg,

On Tue, 2011-11-01 at 19:09 -0400, Greg KH wrote:
> If someone wants this in .32-stable, can they provide me a backported
> version, as this doesn't backport very easily (i.e. I tried and failed.)

Please see <1318859710.16132.15.camel@xxxxxxxxxxxxxxxxxxxxxx> which
contains a backported version of the patch.

Stefan Bader reported that he was still having some issues even with
this patch which I haven't had a chance to investigate fully, however I
think the patch is correct in its own right.

Ian.

> 
> thanks,
> 
> greg k-h
> 
> On Wed, Oct 26, 2011 at 05:05:39PM -0400, Gregs git-bot wrote:
> > commit: 9bab0b7fbaceec47d32db51cd9e59c82fb071f5a
> > From: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > Date: Mon, 3 Oct 2011 15:37:00 +0100
> > Subject: genirq: Add IRQF_RESUME_EARLY and resume such IRQs earlier
> > 
> > This adds a mechanism to resume selected IRQs during syscore_resume
> > instead of dpm_resume_noirq.
> > 
> > Under Xen we need to resume IRQs associated with IPIs early enough
> > that the resched IPI is unmasked and we can therefore schedule
> > ourselves out of the stop_machine where the suspend/resume takes
> > place.
> > 
> > This issue was introduced by 676dc3cf5bc3 "xen: Use IRQF_FORCE_RESUME".
> > 
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > Cc: Rafael J. Wysocki <rjw@xxxxxxx>
> > Cc: Jeremy Fitzhardinge <Jeremy.Fitzhardinge@xxxxxxxxxx>
> > Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
> > Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> > Link: 
> > http://lkml.kernel.org/r/1318713254.11016.52.camel@xxxxxxxxxxxxxxxxxxxx
> > Cc: stable@xxxxxxxxxx (at least to 2.6.32.y)
> > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > ---
> >  drivers/xen/events.c      |    2 +-
> >  include/linux/interrupt.h |    3 ++
> >  kernel/irq/pm.c           |   48 
> > ++++++++++++++++++++++++++++++++++++++------
> >  3 files changed, 45 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/xen/events.c b/drivers/xen/events.c
> > index da70f5c..a758bc1 100644
> > --- a/drivers/xen/events.c
> > +++ b/drivers/xen/events.c
> > @@ -1021,7 +1021,7 @@ int bind_ipi_to_irqhandler(enum ipi_vector ipi,
> >     if (irq < 0)
> >             return irq;
> >  
> > -   irqflags |= IRQF_NO_SUSPEND | IRQF_FORCE_RESUME;
> > +   irqflags |= IRQF_NO_SUSPEND | IRQF_FORCE_RESUME | IRQF_EARLY_RESUME;
> >     retval = request_irq(irq, handler, irqflags, devname, dev_id);
> >     if (retval != 0) {
> >             unbind_from_irq(irq);
> > diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
> > index 664544f..a64b00e 100644
> > --- a/include/linux/interrupt.h
> > +++ b/include/linux/interrupt.h
> > @@ -59,6 +59,8 @@
> >   * IRQF_NO_SUSPEND - Do not disable this IRQ during suspend
> >   * IRQF_FORCE_RESUME - Force enable it on resume even if IRQF_NO_SUSPEND 
> > is set
> >   * IRQF_NO_THREAD - Interrupt cannot be threaded
> > + * IRQF_EARLY_RESUME - Resume IRQ early during syscore instead of at device
> > + *                resume time.
> >   */
> >  #define IRQF_DISABLED              0x00000020
> >  #define IRQF_SAMPLE_RANDOM 0x00000040
> > @@ -72,6 +74,7 @@
> >  #define IRQF_NO_SUSPEND            0x00004000
> >  #define IRQF_FORCE_RESUME  0x00008000
> >  #define IRQF_NO_THREAD             0x00010000
> > +#define IRQF_EARLY_RESUME  0x00020000
> >  
> >  #define IRQF_TIMER         (__IRQF_TIMER | IRQF_NO_SUSPEND | 
> > IRQF_NO_THREAD)
> >  
> > diff --git a/kernel/irq/pm.c b/kernel/irq/pm.c
> > index f76fc00..15e53b1 100644
> > --- a/kernel/irq/pm.c
> > +++ b/kernel/irq/pm.c
> > @@ -9,6 +9,7 @@
> >  #include <linux/irq.h>
> >  #include <linux/module.h>
> >  #include <linux/interrupt.h>
> > +#include <linux/syscore_ops.h>
> >  
> >  #include "internals.h"
> >  
> > @@ -39,25 +40,58 @@ void suspend_device_irqs(void)
> >  }
> >  EXPORT_SYMBOL_GPL(suspend_device_irqs);
> >  
> > -/**
> > - * resume_device_irqs - enable interrupt lines disabled by 
> > suspend_device_irqs()
> > - *
> > - * Enable all interrupt lines previously disabled by suspend_device_irqs() 
> > that
> > - * have the IRQS_SUSPENDED flag set.
> > - */
> > -void resume_device_irqs(void)
> > +static void resume_irqs(bool want_early)
> >  {
> >     struct irq_desc *desc;
> >     int irq;
> >  
> >     for_each_irq_desc(irq, desc) {
> >             unsigned long flags;
> > +           bool is_early = desc->action &&
> > +                   desc->action->flags & IRQF_EARLY_RESUME;
> > +
> > +           if (is_early != want_early)
> > +                   continue;
> >  
> >             raw_spin_lock_irqsave(&desc->lock, flags);
> >             __enable_irq(desc, irq, true);
> >             raw_spin_unlock_irqrestore(&desc->lock, flags);
> >     }
> >  }
> > +
> > +/**
> > + * irq_pm_syscore_ops - enable interrupt lines early
> > + *
> > + * Enable all interrupt lines with %IRQF_EARLY_RESUME set.
> > + */
> > +static void irq_pm_syscore_resume(void)
> > +{
> > +   resume_irqs(true);
> > +}
> > +
> > +static struct syscore_ops irq_pm_syscore_ops = {
> > +   .resume         = irq_pm_syscore_resume,
> > +};
> > +
> > +static int __init irq_pm_init_ops(void)
> > +{
> > +   register_syscore_ops(&irq_pm_syscore_ops);
> > +   return 0;
> > +}
> > +
> > +device_initcall(irq_pm_init_ops);
> > +
> > +/**
> > + * resume_device_irqs - enable interrupt lines disabled by 
> > suspend_device_irqs()
> > + *
> > + * Enable all non-%IRQF_EARLY_RESUME interrupt lines previously
> > + * disabled by suspend_device_irqs() that have the IRQS_SUSPENDED flag
> > + * set as well as those with %IRQF_FORCE_RESUME.
> > + */
> > +void resume_device_irqs(void)
> > +{
> > +   resume_irqs(false);
> > +}
> >  EXPORT_SYMBOL_GPL(resume_device_irqs);
> >  
> >  /**
> > -- 
> > 1.7.3.4



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