Re: [PATCH 3.2] iwlagn: fix (remove) use of PAGE_SIZE

["John W. Linville" <linville@tuxdriver.com>]

On Mon, Dec 19, 2011 at 02:00:59PM -0800, Wey-Yi Guy wrote:
> From: Johannes Berg <johannes.berg@intel.com>
> 
> The ICT code erroneously uses PAGE_SIZE. The bug
> is that PAGE_SIZE isn't necessarily 4096, so on
> such platforms this code will not work correctly
> as we'll try to attempt to read an index in the
> table that the device never wrote, it always has
> 4096-byte pages.
> 
> Additionally, the manual alignment code here is
> unnecessary -- Documentation/DMA-API-HOWTO.txt
> states:
>   The cpu return address and the DMA bus master address are both
>   guaranteed to be aligned to the smallest PAGE_SIZE order which
>   is greater than or equal to the requested size.  This invariant
>   exists (for example) to guarantee that if you allocate a chunk
>   which is smaller than or equal to 64 kilobytes, the extent of the
>   buffer you receive will not cross a 64K boundary.
> 
> Just use appropriate new constants and get rid of
> the alignment code.
> 
> Cc: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
> Cc: stable@vger.kernel.org
> Signed-off-by: Johannes Berg <johannes.berg@intel.com>
> Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>

This seems like a big patch.  It is a bit late in the release cycle
to rewrite all the DMA allocation code. :-)

What platforms does this affect?  Are there actual users involved?

John
-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.