linux-kernel - Re: [PATCH 1/2] Revert "arm64: use cpu_online_mask when using forced irq_set

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Message-ID: <53FEFC7E.3060803@arm.com>
Date:	Thu, 28 Aug 2014 10:55:10 +0100
From:	Sudeep Holla <sudeep.holla@....com>
To:	Will Deacon <will.deacon@....com>
CC:	Sudeep Holla <sudeep.holla@....com>,
	"byungchul.park@....com" <byungchul.park@....com>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] Revert "arm64: use cpu_online_mask when using forced
 irq_set_affinity"



On 28/08/14 10:50, Will Deacon wrote:
> On Thu, Aug 28, 2014 at 10:49:54AM +0100, Sudeep Holla wrote:
>>
>>
>> On 28/08/14 10:38, Will Deacon wrote:
>>> On Wed, Aug 27, 2014 at 10:30:06AM +0100, byungchul.park@....com wrote:
>>>> From: Byungchul Park <byungchul.park@....com>
>>>>
>>>> This reverts commit 601c942176d8ad8334118bddb747e3720bed24f8.
>>>>
>>>> This patch is designed to ensure that the cpu being offlined is not
>>>> present in the affinity mask. But it is a bad idea to overwrite the
>>>> affinity variable with cpu_online_mask, even in case that the current
>>>> affinity already includes onlined cpus.
>>>>
>>>> So revert this patch to replace it with another one doing exactly
>>>> what it intends.
>>>
>>> Sudeep: what's the right way forward for this? There seems to be general
>>> agreement that the existing code is broken, but a bunch of different
>>> `fixes'. Can we just take a straight port of what tglx proposed for ARM?
>>> (changing force to false)
>>>
>>
>> Yes I agree but for that we need agreement from rmk and hence I asked to
>> wait till we hear from rmk. Main issue raised by rmk is if some other
>> interrupt controller implementation decide not to migrate away when
>> force is false(theoretically possible).
>
> Okey doke. Whatever solution we take should be the same for arm and arm64,
> so I'll leave it with you.
>

tglx just confirmed that interrupt controller implementation using force
flag must use online_cpumask. So converting to false should be fine.
So once rmk agrees for ARM, we can apply this revert and change to false
for ARM64 also.

Regards,
Sudeep

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