linux-kernel - Re: [patch 00/14] x86/irq: Plug various vector cleanup races

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Date:	Thu, 14 Jan 2016 11:33:26 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Joe Lawrence <joe.lawrence@...atus.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>, Peter Anvin <hpa@...or.com>,
	Jiang Liu <jiang.liu@...ux.intel.com>,
	Jeremiah Mahler <jmmahler@...il.com>,
	andy.shevchenko@...il.com, Guenter Roeck <linux@...ck-us.net>
Subject: Re: [patch 00/14] x86/irq: Plug various vector cleanup races

On Thu, Jan 14, 2016 at 09:24:35AM +0100, Thomas Gleixner wrote:
> On Mon, 4 Jan 2016, Joe Lawrence wrote:
> > No issues running the same PCI device removal and stress tests against
> > the patchset.
> 
> Thanks for testing!
> 
> Though there is yet another long standing bug in that area. Fix below.
> 
> Thanks,
> 
> 	tglx
> 
> 8<--------------------
> 
> Subject: x86/irq: Call chip->irq_set_affinity in proper context
> From: Thomas Gleixner <tglx@...utronix.de>
> Date: Thu, 14 Jan 2016 08:43:38 +0100
> 
> setup_ioapic_dest() calls irqchip->irq_set_affinity() completely
> unprotected. That's wrong in several aspects:
> 
>  - it triggers a lockdep splat because vector lock is taken with interrupts
>    enabled.
> 
>  - it opens a race window where irq_set_affinity() can be interrupted and the
>    irq chip left in unconsistent state.
> 
> The proper calling convention is irq descriptor lock held and interrupts
> disabled.
> 
> Reported-by: Borislav Petkov <bp@...en8.de>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Cc: stable@...r.kernel.org
> ---
>  arch/x86/kernel/apic/io_apic.c |    6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> --- a/arch/x86/kernel/apic/io_apic.c
> +++ b/arch/x86/kernel/apic/io_apic.c
> @@ -2521,6 +2521,7 @@ void __init setup_ioapic_dest(void)
>  {
>  	int pin, ioapic, irq, irq_entry;
>  	const struct cpumask *mask;
> +	struct irq_desc *desc;
>  	struct irq_data *idata;
>  	struct irq_chip *chip;
>  
> @@ -2536,7 +2537,9 @@ void __init setup_ioapic_dest(void)
>  		if (irq < 0 || !mp_init_irq_at_boot(ioapic, irq))
>  			continue;
>  
> -		idata = irq_get_irq_data(irq);
> +		desc = irq_to_desc(irq);
> +		raw_spin_lock_irq(d&desc->lock);

s/d//

> +		idata = irq_desc_get_irq_data(desc);
>  
>  		/*
>  		 * Honour affinities which have been set in early boot
> @@ -2550,6 +2553,7 @@ void __init setup_ioapic_dest(void)
>  		/* Might be lapic_chip for irq 0 */
>  		if (chip->irq_set_affinity)
>  			chip->irq_set_affinity(idata, mask, false);
> +		raw_spin_unlock_irq(d&desc->lock);

s/d//

With those micro-changes:

Tested-by: Borislav Petkov <bp@...e.de>

:-)

-- 
Regards/Gruss,
    Boris.

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