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Date: Wed, 05 Mar 2014 17:57:25 -0500
From: Prarit Bhargava <prarit@redhat.com>
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To: David Rientjes <rientjes@google.com>
CC: linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
        x86@kernel.org, Rui Wang <rui.y.wang@intel.com>,
        Liu Ping Fan <kernelfans@gmail.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>,
        Lv Zheng <lv.zheng@intel.com>, Seiji Aguchi <seiji.aguchi@hds.com>,
        Yang Zhang <yang.z.zhang@intel.com>, Andi Kleen <ak@linux.intel.com>,
        "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>,
        Li Fei <fei.li@intel.com>, gong.chen@linux.intel.com
Subject: Re: [PATCH] x86, fix x86 fixup_irqs() error handling
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On 03/05/2014 04:09 PM, David Rientjes wrote:
> On Wed, 5 Mar 2014, Prarit Bhargava wrote:
> 
>> diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
>> index d99f31d..55fab61 100644
>> --- a/arch/x86/kernel/irq.c
>> +++ b/arch/x86/kernel/irq.c
>> @@ -351,6 +351,7 @@ void fixup_irqs(void)
>>  	struct irq_desc *desc;
>>  	struct irq_data *data;
>>  	struct irq_chip *chip;
>> +	int ret;
>>  
>>  	for_each_irq_desc(irq, desc) {
>>  		int break_affinity = 0;
>> @@ -389,8 +390,12 @@ void fixup_irqs(void)
>>  		if (!irqd_can_move_in_process_context(data) && chip->irq_mask)
>>  			chip->irq_mask(data);
>>  
>> -		if (chip->irq_set_affinity)
>> -			chip->irq_set_affinity(data, affinity, true);
>> +		if (chip->irq_set_affinity) {
>> +			ret = chip->irq_set_affinity(data, affinity, true);
>> +			WARN(ret == -ENOSPC,
>> +			     "IRQ %d set affinity failed with %d.  The device assigned to this IRQ is unstable.\n",
>> +			     irq, ret);
> 
> Should this be WARN_ON_ONCE() to avoid filling the kernel log instead?

The problem is that it could hit multiple IRQs ... maybe pr_crit might be better
here so we don't flood the log with an unnecessary stack trace; anyone with the
source can figure out what the call path is.


> 
> It doesn't make much sense to print out the negative return value, maybe 
> you meant to print -ret instead?

Heh :)  You're right.  I'll fix that too.

P.

> 
>> +		}
>>  		else if (!(warned++))
>>  			set_affinity = 0;
>>