linux-kernel - Re: [PATCH v3 3/4] IRQ,x86: normalize return value of chip->irq_set

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Message-ID: <4F772F2A.9020903@gmail.com>
Date:	Sun, 01 Apr 2012 00:22:02 +0800
From:	Jiang Liu <liuj97@...il.com>
To:	Thomas Gleixner <tglx@...utronix.de>
CC:	Jiang Liu <jiang.liu@...wei.com>, x86@...nel.org,
	Keping Chen <chenkeping@...wei.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 3/4] IRQ,x86: normalize return value of chip->irq_set_affinity()
 method

Hi Thomas,
	Thanks for point this out. After checking related code again, I found
the method suggested by you will produce better code, so will send out another
version to remove the duplicated memory copy operations in arch specific code.
	When I was reading the comment for IRQ_SET_MASK_OK_NOCOPY, I thought
both way are ok to update the affinity mask by arch code or core logic, and
haven't realized the issue raised by you.
	Thanks!
	Gerry

On 03/31/2012 05:23 AM, Thomas Gleixner wrote:
> On Fri, 30 Mar 2012, Jiang Liu wrote:
> 
>> On x86 platforms, interrupt controller chip's irq_set_affinity() method
>> always copies affinity mask to irq_data->affinity field but still returns
> 
> Now the question here is whether it copies the mask because it
> modified the mask in some way and want to reflect the change back.
> 
> If it just copies the unmodified mask, then this patch is wrong. It
> should remove the copy from the arch code and return IRQ_SET_MASK_OK
> so the core code can take care of the copying.
> 
> Ditto for the ia64 one.
> 
> Thanks,
> 
> 	tglx

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