linux-kernel - Re: [BUG 4.15-rc7] IRQ matrix management errors

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Message-ID: <20180116142629.GB5643@localhost.localdomain>
Date:   Tue, 16 Jan 2018 07:26:30 -0700
From:   Keith Busch <keith.busch@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: Re: [BUG 4.15-rc7] IRQ matrix management errors

On Tue, Jan 16, 2018 at 12:20:18PM +0100, Thomas Gleixner wrote:
> What we want is s/i + 1/i/
> 
> That's correct because x86_vector_free_irqs() does:
> 
>        for (i = 0; i < nr; i++)
>        	   ....
> 
> So if we fail at the first irq, then the loop will do nothing. Failing on
> the second will free the first ....
> 
> Fix below.
> 
> Thanks,
> 
> 	tglx

Thanks! This looks much better. I'll try to verify by tomorrow, though
the hardware I was using to recreate is not available to me at the
moment. I may be able to synth the conditions on something else.

 
> 8<----------------------
> diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
> index f8b03bb8e725..3cc471beb50b 100644
> --- a/arch/x86/kernel/apic/vector.c
> +++ b/arch/x86/kernel/apic/vector.c
> @@ -542,14 +542,17 @@ static int x86_vector_alloc_irqs(struct irq_domain *domain, unsigned int virq,
>  
>  		err = assign_irq_vector_policy(irqd, info);
>  		trace_vector_setup(virq + i, false, err);
> -		if (err)
> +		if (err) {
> +			irqd->chip_data = NULL;
> +			free_apic_chip_data(apicd);
>  			goto error;
> +		}
>  	}
>  
>  	return 0;
>  
>  error:
> -	x86_vector_free_irqs(domain, virq, i + 1);
> +	x86_vector_free_irqs(domain, virq, i);
>  	return err;
>  }
>