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Subject: Re: [PATCH v2 2/2] mm: prevent gup_fast from racing with COW during
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To:     "Ahmed S. Darwish" <a.darwish@linutronix.de>,
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From:   John Hubbard <jhubbard@nvidia.com>
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On 11/2/20 4:41 PM, Ahmed S. Darwish wrote:
> On Mon, Nov 02, 2020 at 08:25:32PM -0400, Jason Gunthorpe wrote:
>> On Tue, Nov 03, 2020 at 01:17:12AM +0100, Ahmed S. Darwish wrote:
>>
>>> Please stick with the official exported API: raw_write_seqcount_begin().
>>
>> How did you know this was 'offical exported API' ??
>>
> 
> All the official exported seqlock.h APIs are marked with verbose
> kernel-doc annotations on top. The rest are internal...
> 

OK, but no one here was able to deduce that, probably because there is not
enough consistency throughout the kernel to be able to assume such things--even
though your seqlock project is internally consistent. It's just not *quite*
enough communication.

I think if we added the following it would be very nice:

a) Short comments to the "unofficial and internal" routines, identifying them as
such, and

b) Short comments to the "official API for general use", also identifying
those as such.

c) A comment about what makes "raw" actually raw, for seqlock.


Since I'm proposing new work, I'll also offer to help, perhaps by putting together
a small patch to get it kicked off, if you approve of the idea.

thanks,
-- 
John Hubbard
NVIDIA