Re: range operation of outer cache when start >= end?

From	Masahiro Yamada <yamada.masahiro@socionext.com>
Newsgroups	linux.kernel
Subject	Re: range operation of outer cache when start >= end?
Date	2016-01-08 17:10 +0100
Message-ID	<qOHM0-DI-51@gated-at.bofh.it> (permalink)
References	<qOvrs-f2-3@gated-at.bofh.it> <qOGPU-8rM-37@gated-at.bofh.it>
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Hi Russell,


2016-01-09 0:06 GMT+09:00 Russell King - ARM Linux <linux@arm.linux.org.uk>:
> On Fri, Jan 08, 2016 at 11:54:30AM +0900, Masahiro Yamada wrote:
>> I know I am nitpicking.  Forgive me if I am asking a silly question.
>>
>>
>> How should the outer-cache handle such an insane case like  start >= end?
>
> Passing start >= end isn't defined, code should not pass start >= end.
>
>> Assumed answers are:
>>
>> [1] Do not care about that.  It should never happen.  If it does, fix
>> the caller.
>
> This applies.  What situation are you seeing start >= end?

I never see such a case at all.
When I saw l2c210_inv_range(), I just wondered whether it should be
cared or not.


> What you will get with the existing code is potentially some cache
> cleaning and a sync, but nothing apart from that.  __l2c210_op_pa_range()
> becomes a no-op of start >= end.  However, that behaviour is not
> guaranteed.

Thanks for your explanation!

-- 
Best Regards
Masahiro Yamada

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range operation of outer cache when start >= end? Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-01-08 04:00 +0100
  Re: range operation of outer cache when start >= end? Russell King - ARM Linux <linux@arm.linux.org.uk> - 2016-01-08 16:10 +0100
    Re: range operation of outer cache when start >= end? Masahiro Yamada <yamada.masahiro@socionext.com> - 2016-01-08 17:10 +0100

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