Re: [PATCH] rmap : tidy the code

[Nikita Danilov <danilov@gmail.com>]

2009/9/28 Hugh Dickins <hugh.dickins@tiscali.co.uk>:
> On Mon, 28 Sep 2009, Huang Shijie wrote:
>
>> Introduce is_page_mapped_in_vma() to merge the vma_address() and
>> page_check_address().
>>
>> Make the rmap codes more simple.
>
> There is indeed a recurring pattern there; but personally, I prefer
> that recurring pattern, to introducing another multi-argument layer.
>
> I think it would make more sense to do the vma_address() inside (a
> differently named) page_check_address(); but that would still have
> to return the address, so I'll probably prefer what we have now.
>
> (And that seems to have been Nikita's preference when he introduced
> page_check_address(), to keep the vma_address() part of it separate.)
>

Indeed, I tried to minimize the number of parameters and to avoid
making "address" an output parameter. But on the other hand, there
were only 2 page_check_address() call-sites back then. Now there are 5
of them, so adding a parameter is more justifiable.

> Other opinions?

I agree that adding EFAULT check into page_check_address() is better.
The only call-site that does not call vma_address() before
page_check_address() is __xip_unmap() and it explicitly BUG_ON()s on
the same condition.

>
> Hugh
>

Nikita.

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