Re: [PATCH 6/6] percpu: Add preemption checks to __this_cpu ops

From: Christoph Lameter
Date: Wed Oct 16 2013 - 11:55:54 EST


On Wed, 16 Oct 2013, Peter Zijlstra wrote:

> On Wed, Oct 16, 2013 at 03:09:13PM +0000, Christoph Lameter wrote:
> > On Wed, 16 Oct 2013, Peter Zijlstra wrote:
> >
> > > So I didn't understand what was wrong with:
> > >
> > > #define __this_cpu_read(pcp) \
> > > (__this_cpu_preempt_check("read"), raw_this_cpu_read(pcp))
> > >
> > > And idem for all others. This is 1) shorter to write; and 2) makes it
> > > blindingly obvious that the implementations are actually the same.
> >
> > Nothing wrong with that. It just increases the scope of this patch to
> > require modifications to arch code and I already have trouble enough
> > following through on all the issues that were raised so far.
> >
>
> But non of your raw ops touch arch code... /me confused.

Yes that is intentional to limit scope. Renaming would require arch
changes.

The __this_cpu_xxxs are defined in arch code. Look at x86 arch
implementations for example. arch/x86/include/asm/percpu.h. s390 also has
this. Not sure if other arches do.



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