Hi John, On Wed, 2011-12-21 at 11:58 -0800, John W. Linville wrote: > On Wed, Dec 21, 2011 at 07:45:00AM -0800, Guy, Wey-Yi wrote: > > Hi John, > > > > On Wed, 2011-12-21 at 08:19 -0800, John W. Linville wrote: > > > On Mon, Dec 19, 2011 at 02:00:59PM -0800, Wey-Yi Guy wrote: > > > > From: Johannes Berg <johannes.berg@xxxxxxxxx> > > > > > > > > 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@xxxxxxxxx> > > > > Cc: stable@xxxxxxxxxxxxxxx > > > > Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx> > > > > Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@xxxxxxxxx> > > > > > > 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? > > > > I understand the patch is bigger than the regular patch should be > > generated for stable kernel. Johannes can explain better, but he is on > > vacation. as what I understood, he work with community user who > > encounter issue and root cause it is PAGE SIZE cause the problem. > > > > Thanks > > Wey > > Unless someone screams, I'd be a lot more comfortable saving this > for 3.3. unless Johannes has objection, I am ok for 3.3, it is not something people will encounter everyday on common platform.. Thanks Wey -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
