Re: [Xen-devel] [RFC 11/16] irq: skip action avalability check for guest's IRQ

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andrii,

On 28/11/2018 21:32, Andrii Anisov wrote:
> From: Andrii Anisov <andrii_anisov@xxxxxxxx>
>
> An IRQ assigned to guest always has an action. This removes
> another odd check on guest IRQ path.
And you can't see any potential race in that code happening in the future?

> Also getting an unknown
> interrupt is very unlikely on a non-debug platform.
I am tempted to keep the code at the same place but protect with an #ifndef 
NDEBUG. What do you think?
Like patch #5, feel free to resend the patch alone for Xen 4.12.

Cheers,

> Signed-off-by: Andrii Anisov <andrii_anisov@xxxxxxxx>
> ---
>   xen/arch/arm/irq.c | 14 +++++++-------
>   1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/xen/arch/arm/irq.c b/xen/arch/arm/irq.c
> index 596a8b8..5debfc5 100644
> --- a/xen/arch/arm/irq.c
> +++ b/xen/arch/arm/irq.c
> @@ -205,13 +205,6 @@ void do_IRQ(struct cpu_user_regs *regs, unsigned int irq, 
> int is_fiq)
>       spin_lock(&desc->lock);
>       desc->handler->ack(desc);
>   
> -    if ( !desc->action )
> -    {
> -        printk("Unknown %s %#3.3x\n",
> -               is_fiq ? "FIQ" : "IRQ", irq);
> -        goto out;
> -    }
> -
>       if ( test_bit(_IRQ_GUEST, &desc->status) )
>       {
>           struct irq_guest *info = irq_get_guest_info(desc);
> @@ -229,6 +222,13 @@ void do_IRQ(struct cpu_user_regs *regs, unsigned int irq, 
> int is_fiq)
>           goto out_no_end;
>       }
>   
> +    if ( unlikely(!desc->action) )
> +    {
> +        printk("Unknown %s %#3.3x\n",
> +               is_fiq ? "FIQ" : "IRQ", irq);
> +        goto out;
> +    }
> +
>       set_bit(_IRQ_PENDING, &desc->status);
>   
>       /*
--
Julien Grall

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