linux-kernel - Re: [PATCH 1/1] ahci: Do not receive interrupts sent by dummy ports

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Message-ID: <5350147A.10403@redhat.com>
Date:	Thu, 17 Apr 2014 12:50:50 -0500
From:	David Milburn <dmilburn@...hat.com>
To:	Tejun Heo <tj@...nel.org>
CC:	Alexander Gordeev <agordeev@...hat.com>,
	linux-kernel@...r.kernel.org, linux-ide@...r.kernel.org
Subject: Re: [PATCH 1/1] ahci: Do not receive interrupts sent by dummy ports

On 04/17/2014 12:06 PM, Tejun Heo wrote:
> On Thu, Apr 17, 2014 at 06:06:15PM +0200, Alexander Gordeev wrote:
>> In multiple MSI mode all AHCI ports (including dummy) get
>> assigned separate MSI vectors and (as result of execution
>> pci_enable_msi_exact() function) separate IRQ numbers,
>> (mapped to the MSI vectors).
>>
>> Therefore, although interrupts from dummy ports are not
>> desired they are still enabled. We do not request IRQs
>> for dummy ports, but that only means we do not assign
>> AHCI-specific ISRs to corresponding IRQ numbers.
>>
>> As result, dummy port interrupts still could come and
>> traverse all the way from the PCI device to the kernel,
>> causing unnecessary overhead.
>>
>> This update disables IRQs for dummy ports and prevents
>> the described issue.
>>
>> Signed-off-by: Alexander Gordeev <agordeev@...hat.com>
>> Cc: Tejun Heo <tj@...nel.org>
>> Cc: David Milburn <dmilburn@...hat.com>
>> Cc: linux-ide@...r.kernel.org
>
> David, can you please test the patch?
>


Hi,

I have re-tested successfully, this patch prevents the crash
when using kdump, and I boot tested a system that boots off
ahci and has dummy ports present, no problems seen.

Thanks,
David


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