Re: [PATCH] x86/xen: resume timer irqs early

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 08/07/2014 01:16 PM, David Vrabel wrote:
> If the timer irqs are resumed during device resume it is possible in
> certain circumstances for the resume to hang early on, before device
> interrupts are resumed.
>
> It is not entirely clear what is occuring the point of the hang but I
> think a task necessary for the resume calls schedule_timeout(),
> waiting for a timer interrupt (which never arrives).  This failure may
> require specific tasks to be running on the other VCPUs to trigger
> (processes are not frozen during a suspend/resume if PREEMPT is
> disabled).
>
> Add IRQF_EARLY_RESUME to the timer interrupts so they are resumed in
> syscore_resume().
>
> Also add IRQF_NO_SUSPEND as it is not necessary to suspend the timer
> interrupts and IRQF_FORCE_RESUME was already set.


IRQF_NO_SUSPEND is a component of IRQF_TIMER.


-boris



>
> Signed-off-by: David Vrabel <david.vrabel@citrix.com>
> ---
>   arch/x86/xen/time.c |    6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
> index 7b78f88..90dd311 100644
> --- a/arch/x86/xen/time.c
> +++ b/arch/x86/xen/time.c
> @@ -443,8 +443,10 @@ void xen_setup_timer(int cpu)
>   		name = "<timer kasprintf failed>";
>   
>   	irq = bind_virq_to_irqhandler(VIRQ_TIMER, cpu, xen_timer_interrupt,
> -				      IRQF_PERCPU|IRQF_NOBALANCING|IRQF_TIMER|
> -				      IRQF_FORCE_RESUME,
> +				      IRQF_PERCPU | IRQF_NOBALANCING
> +				      | IRQF_TIMER
> +				      | IRQF_NO_SUSPEND | IRQF_FORCE_RESUME
> +				      | IRQF_EARLY_RESUME,
>   				      name, NULL);
>   	(void)xen_set_irq_priority(irq, XEN_IRQ_PRIORITY_MAX);
>