Re: [GIT] Sparc

[Steve Capper]

On Mon, Oct 27, 2014 at 06:43:27PM -0400, David Miller wrote:
> From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Date: Mon, 27 Oct 2014 14:09:38 -0700
> 
> > Perhaps sparc should be defining CONFIG_HAVE_GENERIC_RCU_GUP.
> > 
> > We really should switch x86 to the generic version - from a quick read
> > it looks like it will work without needing any changes.
> > 
> > Steve, thoughts?
> 
> We need to add the necessary hooks to the generic code so that x86
> doesn't so specualtive gets and instead do direct increments,
> otherwise it's a performance regression, and then sparc can make use
> of that as well.

Agreed, I think x86 may require a helper to read 64-bit ptes (as it
can't do that atomically). Also I think there's some subtlety in the
way access_ok works that should be checked.

The overall structure of the code looks the same to me, and I think it
would be beneficial to extend then use the generic version for x86.

Cheers,
-- 
Steve
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