Re: [Xen-devel] A suggestion about processing irq

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2013-08-19 at 02:29 +0000, êìë wrote:
> Hello,
> While I was reading gic handling part of xen arm, I noticed that, in 
> gic_set_guest_irq function, 
> if lr_pending is not empty, the arrival irq is also stored into pending list.
> I think although lr_pending is not empty, there maybe empty slots in lr, and 
> if so, we can insert 
> IRQ immediately. Since I'd like to keep the IRQ in priority order, how about 
> checking the 
> highest priority in lr_pending list rather than emptiness?
> Here goes the simple patch:

Julien & Stefano know about this stuff -- guys?

Julien was planning to rework a bunch of the interrupt handling stuff, I
don't know if that was orthogonal to this or not.

>  
> Signed-off-by: Jaemin Kim <jmkim.kim@xxxxxxxxxxx>
> ---
> diff -urN xen/arch/arm/gic.c xen2/arch/arm/gic.c
> --- xen/arch/arm/gic.c  2013-07-30 10:16:45.076382483 +0900
> +++ xen2/arch/arm/gic.c 2013-07-31 11:19:28.094799335 +0900
> @@ -587,12 +587,17 @@
>          unsigned int state, unsigned int priority)
>  {
>      int i;
> -    struct pending_irq *iter, *n;
> +    struct pending_irq *iter, *n, *first_item;
>      unsigned long flags;
>      spin_lock_irqsave(&gic.lock, flags);
> +
> +   first_item = list_entry( (&v->arch.vgic.lr_pending)->next,
> +                           typeof(*iter), lr_queue );
> -    if (( v == current ) &&  (list_empty(&v->arch.vgic.lr_pending) ))
> +    if ( ( v == current ) &&
> +         ( list_empty(&v->arch.vgic.lr_pending) ||
> +           ( priority > first_item->priority ) ) )
>      {
>          i = find_first_zero_bit(&this_cpu(lr_mask), nr_lrs);
>          if (i < nr_lrs) {
> --- 
> Thanks.
> Best Regards.
> Jaemin Kim
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> http://lists.xen.org/xen-devel



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