[lkml]   [2019]   [Jul]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] unaligned: delete 1-byte accessors
On Mon, 2019-07-22 at 08:22 +0300, Alexey Dobriyan wrote:
> On Mon, Jul 22, 2019 at 08:08:33AM +0900, James Bottomley wrote:
> > On Mon, 2019-07-22 at 00:52 +0300, Alexey Dobriyan wrote:
> > > Each and every 1-byte access is aligned!
> >
> > The design idea of this is for parsing descriptors. We simply
> > chunk up the describing structure using get_unaligned for
> > everything. The reason is because a lot of these structures come
> > with reserved areas which we may make use of later. If we're using
> > get_unaligned for everything we can simply change a u8 to a u16 in
> > the structure absorbing the reserved padding. With your change now
> > I'd have to chase down every byte access and replace it with
> > get_unaligned instead of simply changing the structure.
> >
> > What's the significant advantage of this change that compensates
> > for the problems the above causes?
> HW descriptors have fixed endianness, you're supposed to use
> get_unaligned_be32() and friends.

Not if this is an internal descriptor format, which is what this is
mostly used for.

> For that matter, drivers/scsi/ has exactly 2 get_unaligned() calls
> one of which can be changed to get_unaligned_be32().

You haven't answered the "what is the benefit of this change" question.
I mean sure we can do it, but it won't make anything more efficient
and it does help with the descriptor format to treat every structure
field the same.


 \ /
  Last update: 2019-07-22 07:49    [W:0.066 / U:6.788 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site