Re: [GIT PULL] Btrfs

Josh Boyer
2013-09-13T15:06:23Z

On Fri, Sep 13, 2013 at 8:15 AM, Russell King <rmk@arm.linux.org.uk> wrote:
> On Fri, Sep 13, 2013 at 07:53:21AM -0400, Josh Boyer wrote:
>> I'm not an ARM expert, so I don't know if ARM should use the
>> asm-generic implementations, or just use __get_user/__put_user in all
>> cases. I've CC'd rmk.
>
> Why do we have uaccess-unaligned.h ? Normally, these kinds of things
> are spawned by architectures which have problems with unaligned accesses,
> ARM being one of them, but afaik we've never need this.
>
> With the kernel-side trapping of unaligned accesses on older hardware,
> we've always dealt with the normal accessor faulting.
>
> From what I can tell in the git history, these unaligned put_user and
> get_user have existed all the way back to the dawn of git use.
>
> Can someone enlighten me why we have them?

So while that gets sorted out, would it be safe to just do as Geert
did on m68k and put:

#define __put_user_unaligned(x, ptr) __put_user((x), (ptr))

in arch/arm/include/asm/uaccess.h, and let the normal accessors and
kernel-side trapping deal with things? I'm thinking that's a local
fix until something gets sorted upstream, but I don't want to do it if
it's going to break things.

josh