linux-kernel - Re: [PATCH] irqchip/alpine-msi: Fix freeing of interrupts on allocation error path

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Message-ID: <160672672303.3588.8640979209865178403@kwain.local>
Date:   Mon, 30 Nov 2020 09:58:43 +0100
From:   Antoine Tenart <atenart@...nel.org>
To:     Marc Zyngier <maz@...nel.org>, linux-kernel@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Tsahee Zidenberg <tsahee@...apurnalabs.com>
Subject: Re: [PATCH] irqchip/alpine-msi: Fix freeing of interrupts on allocation error path

Hello Marc,

Quoting Marc Zyngier (2020-11-29 14:55:25)
> The alpine-msi driver has an interesting allocation error handling,
> where it frees the same interrupts repeatedly. Hilarity follows.

That's interesting indeed...

> This code is probably never executed, but let's fix it nonetheless.
> 
> Fixes: e6b78f2c3e14 ("irqchip: Add the Alpine MSIX interrupt controller")
> Cc: Tsahee Zidenberg <tsahee@...apurnalabs.com>
> Cc: Antoine Tenart <atenart@...nel.org>
> Signed-off-by: Marc Zyngier <maz@...nel.org>

Reviewed-by: Antoine Tenart <atenart@...nel.org>

Thanks,
Antoine

> ---
>  drivers/irqchip/irq-alpine-msi.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-alpine-msi.c b/drivers/irqchip/irq-alpine-msi.c
> index 23a3b877f7f1..ede02dc2bcd0 100644
> --- a/drivers/irqchip/irq-alpine-msi.c
> +++ b/drivers/irqchip/irq-alpine-msi.c
> @@ -165,8 +165,7 @@ static int alpine_msix_middle_domain_alloc(struct irq_domain *domain,
>         return 0;
>  
>  err_sgi:
> -       while (--i >= 0)
> -               irq_domain_free_irqs_parent(domain, virq, i);
> +       irq_domain_free_irqs_parent(domain, virq, i - 1);
>         alpine_msix_free_sgi(priv, sgi, nr_irqs);
>         return err;
>  }
> -- 
> 2.29.2
>