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

[Greg KH <greg@xxxxxxxxx>]

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.)

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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