linux-kernel - Re: [PATCH] x86, irq, fix logical AND/OR error in check_irq_vectors_for_cpu

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Message-ID: <52B989CD.6060403@redhat.com>
Date:	Tue, 24 Dec 2013 08:19:09 -0500
From:	Prarit Bhargava <prarit@...hat.com>
To:	linux-kernel@...r.kernel.org,
	Michel Lespinasse <walken@...gle.com>,
	Seiji Aguchi <seiji.aguchi@....com>,
	Yang Zhang <yang.z.zhang@...el.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Janet Morgan <janet.morgan@...el.com>,
	Tony Luck <tony.luck@...el.com>,
	Ruiv Wang <ruiv.wang@...il.com>,
	Andi Kleen <ak@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...ux.intel.com>, x86@...nel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH] x86, irq, fix logical AND/OR error in check_irq_vectors_for_cpu_disable()



On 12/23/2013 09:51 PM, Chen, Gong wrote:
> On Mon, Dec 23, 2013 at 09:39:12AM -0500, Prarit Bhargava wrote:
>> diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
>> index 7d40698..aed7acc 100644
>> --- a/arch/x86/kernel/irq.c
>> +++ b/arch/x86/kernel/irq.c
>> @@ -281,7 +281,7 @@ int check_irq_vectors_for_cpu_disable(void)
>>  			desc = irq_to_desc(irq);
>>  			data = irq_desc_get_irq_data(desc);
>>  			affinity = data->affinity;
>> -			if (irq_has_action(irq) || !irqd_is_per_cpu(data) ||
>> +			if (irq_has_action(irq) && !irqd_is_per_cpu(data) &&
>>  			    !cpumask_subset(affinity, cpu_online_mask))
>>  				this_count++;
> Hi, Prarit
> 
> I noticed that you don't mention another question I asked in last mail.
> 
> "It looks like cpu_online_mask will be updated until cpu_disable_common
> is called, but your check_vectors is called before that."

Oh, I'm sorry ... Yes, check_irq_vectors_for_cpu_disable() is called before we
remove the CPU from the maps.  If there is an error then we have to do much less
clean up of the code.  I explicitly take into account the cpu that is being
downed into the check vectors code.


> 
> native_cpu_disable		
>         cpu_disable_common
>                 remove_cpu_from_maps
>                         /*
>                          * until here, cpu_online_mask/cpu_online_bits
>                          * is cleared
>                          */
>                         set_cpu_online(cpu, false);
> 
> Something I missed?

No -- are you pointing out a bug?

P.
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