Re: spin_lock behavior with ARM64 big.Little/HMP

From	Sudeep Holla <sudeep.holla@arm.com>
Newsgroups	linux.kernel
Subject	Re: spin_lock behavior with ARM64 big.Little/HMP
Date	2017-03-30 12:30 +0200
Message-ID	<tqFv4-4UX-5@gated-at.bofh.it> (permalink)
References	<sEH69-RN-3@gated-at.bofh.it> <sEOKm-5WQ-9@gated-at.bofh.it> <sEXXk-3vd-13@gated-at.bofh.it> <sFYHJ-2Tm-17@gated-at.bofh.it> <tqzJ0-HD-7@gated-at.bofh.it>
Organization	ARM

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On 30/03/17 05:12, Vikram Mulukutla wrote:
> 
> Hi Sudeep,
> 
>>
>> Interesting. Just curious if this is r0p0/p1 A53 ? If so, is the errata
>> 819472 enabled ?
> 
> Sorry for bringing this up after the loo-ong delay, but I've been
> assured that the A53 involved is > r0p1. I've also confirmed this
> problem on multiple internal platforms, and I'm pretty sure that it
> occurs on any b.L out there today. Also, we found the same problematic
> lock design used in the workqueue code in the kernel, causing the same
> livelock. It's very very rare and requires a perfect set of circumstances.
> 
> If it would help I can provide a unit test if you folks would be
> generous enough to test it on the latest Juno or something b.L that's
> also upstream.
> 

Sure, please do share the unit test. I will give that a try on Juno.

-- 
Regards,
Sudeep

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Re: spin_lock behavior with ARM64 big.Little/HMP Vikram Mulukutla <markivx@codeaurora.org> - 2017-03-30 06:20 +0200
  Re: spin_lock behavior with ARM64 big.Little/HMP Sudeep Holla <sudeep.holla@arm.com> - 2017-03-30 12:30 +0200

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