Re: [Stable-review] [12/28] x86, cpu: Clean up AMD erratum 400workaround

[Ben Hutchings]

On Tue, 2011-04-19 at 20:11 -0700, Greg KH wrote:
> On Wed, Apr 20, 2011 at 03:17:42AM +0100, Ben Hutchings wrote:
> > On Tue, 2011-04-19 at 19:01 -0700, Greg KH wrote:
> > > On Wed, Apr 20, 2011 at 02:40:53AM +0100, Ben Hutchings wrote:
> > > > On Tue, 2011-04-19 at 13:30 -0700, Greg KH wrote:
> > > > > 2.6.32-longterm review patch.  If anyone has any objections, please let us know.
> > > > > 
> > > > > ------------------
> > > > > 
> > > > > From: Hans Rosenfeld <hans.rosenfeld@xxxxxxx>
> > > > > 
> > > > > commit 9d8888c2a214aece2494a49e699a097c2ba9498b upstream.
> > > > > 
> > > > > Remove check_c1e_idle() and use the new AMD errata checking framework
> > > > > instead.
> > > > 
> > > > Clean-up patches are generally not candidates for longterm updates.
> > > 
> > > This was added because a follow-on patch required it.
> > 
> > Ah yes, 'x86, AMD: Set ARAT feature on AMD processors' is using the same
> > condition.
> > 
> > Of course, that could have been backported by referring to the function
> > that this removes, rather than pulling in a load of other changes with
> > consequent risk of regressions.
> 
> I prefer to take original patches for stable, it makes it easier in the
> end.

It makes what easier, when?  What I see here is a bug fix that is much
larger than necessary, with a consequent risk of regression that seems
way out of proportion to the benefit.  (What actually *is* the benefit
of these AMD changes?)  And we have had several serious regressions in
the 2.6.32.y series recently, so I really don't think we are getting the
trade-off right.

Ben.

-- 
Ben Hutchings
Once a job is fouled up, anything done to improve it makes it worse.

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