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Re: [PATCH] x86/apic: Avoid infinite loop in io_apic_level_ack_pending()
- To: Jason Andryuk <jason.andryuk@xxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Fri, 5 Sep 2025 09:39:34 +0200
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- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Fri, 05 Sep 2025 07:39:44 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 04.09.2025 23:51, Jason Andryuk wrote:
> io_apic_level_ack_pending() will end up in an infinite loop if
> entry->pin == -1. entry does not change, so it will keep reading -1.
>
> Switched to breaking out of the loop.
>
> Fixes: f821102450a1 ("x86: IRQ Migration logic enhancement.")
> Signed-off-by: Jason Andryuk <jason.andryuk@xxxxxxx>
> ---
> Noticed during code inspection.
Well spotted, just that ...
> --- a/xen/arch/x86/io_apic.c
> +++ b/xen/arch/x86/io_apic.c
> @@ -1715,7 +1715,7 @@ static bool io_apic_level_ack_pending(unsigned int irq)
>
> pin = entry->pin;
> if (pin == -1)
> - continue;
> + break;
... we shouldn't terminate the loop here, but rather continue with the next
entry in the list (if any). Hence presumably why "continue" was used, without
achieving the intended effect.
Jan
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