Re: PATCH 2.4.23-pre6 add kmap_types.h for CONFIG_CRYPTO

From: Bjorn Helgaas <>
Date: 2003-10-24 08:15:56
On Thursday 23 October 2003 3:04 pm, Keith Owens wrote:
> I disagree with this fix.  All uses of KM_ variables are restricted to
> headers that make their use conditional on CONFIG_HIGHMEM.

It's not true that all uses of KM_ variables are restricted to headers.
As one counter-example, file_read_actor() in mm/filemap.c does this:

	kaddr = kmap_atomic(page, KM_USER0);

I guess your argument is that KM_ variables should *only* be
used in places where they'll never be evaluated, i.e., as
arguments to kmap_atomic() and kunmap_atomic().

I think that if you can pass KM_USER0 to a function, you ought
to be able to copy KM_USER0 somewhere and pass the copy to
the function.  Otherwise we'll just have to keep explaining
this funny wart on the kmap interface.

> crypto is
> the only expection and the correct fix is to change crypto to test
> CONFIG_HIGHMEM, not to change every architecture.

I only changed so many architectures because the whole point was to
avoid requiring a dummy kmap_types.h file if you don't use highmem.
So I just removed the now-unnecessary kmap_types.h files, and I
assume you would do the same.  (Although you didn't mention changes
to include/linux/highmem.h and fs/aio.c to remove generic knowledge
of <asm/kmap_types.h>, so I could be misunderstanding your proposal.)


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Received on Thu Oct 23 18:16:16 2003

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