Message-ID: <556FF3F8.1070507@linux.vnet.ibm.com>
Date: Thu, 04 Jun 2015 12:15:12 +0530
From: Shreyas B Prabhu <shreyas@linux.vnet.ibm.com>
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To: Michael Neuling <mikey@neuling.org>
CC: mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] powerpc: Make doorbell check preemption safe
References: <1432062014-9115-1-git-send-email-shreyas@linux.vnet.ibm.com> <1432083608.20823.19.camel@neuling.org>
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On Wednesday 20 May 2015 06:30 AM, Michael Neuling wrote:
> On Wed, 2015-05-20 at 00:30 +0530, Shreyas B. Prabhu wrote:
>> Doorbell can be used to cause ipi on cpus which are sibling threads on
>> the same core. So icp_native_cause_ipi checks if the destination cpu
>> is a sibling thread of the current cpu and uses doorbell in such cases.
>>
>> But while running with CONFIG_PREEMPT=y, since this section is
>> preemtible, we can run into issues if after we check if the destination
>> cpu is a sibling cpu, the task gets migrated from a sibling cpu to a
>> cpu on another core.
>>
>> Fix this by using get_cpu()/ put_cpu()
> 
> Thanks.  Looks good and it's boots for me.
> 
> Signed-off-by: Michael Neuling <mikey@neuling.org>
> 
mikey, Thanks!


mpe, if this looks ok, can you please pick it up?

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