Re: Linux 3.10-rc6

[David Daney]

On 06/17/2013 01:59 PM, Andrew Morton wrote:
> On Mon, 17 Jun 2013 13:48:16 -0700 David Daney <ddaney@xxxxxxxxxxxxxxxxxx> wrote:
>
> > On 06/17/2013 01:30 PM, Andrew Morton wrote:
> > [...]
> > > From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > > Subject: include/linux/smp.h:on_each_cpu(): switch back to a macro
> > >
> > > f21afc25f9ed4 ("smp.h: Use local_irq_{save,restore}() in !SMP version of
> > > on_each_cpu()") converted on_each_cpu() to a C function.  This required
> > > inclusion of irqflags.h, which broke ia64 and mn10300 (at least) due to
> > > header ordering hell.
> > >
> > > Switch on_each_cpu() back to a macro to fix this.
> >
> > FYI:  I have already sent a pair of patches that fix the include
> > dependencies:
> >
> > https://lkml.org/lkml/2013/6/16/113
> > https://lkml.org/lkml/2013/6/17/422
>
> I wasn't cc'ed.
>
> > Obviously, it is Linus' choice as to how best to handle the failure, but
> > I think it is important to know that there are two options (fixing ia64
> > and mn10300, or reverting the patch).
>
> I certainly prefer the inline function over a crappy macro.  The
> additional nested include is regrettable - more complexity.
>
> Also, it's good to have the SMP and non-SMP versions either both using
> macros or both using C.  Having them different can cause irritating
> unused-variable compilation warnings when using the macro version.

Although all these points are true, they are not why I wrote the patch.

The key difference, for me, between the SMP and !SMP versions is that 
the !SMP version unconditionally enables interrupts, and this enabling 
interrupts breaks my kernel

> I think switch-back-to-a-macro is simplest and safest for now.  Perhaps
> you can queue a 3.11 patch which restores the C function and fixes up
> mn10300 and ia64?

If the patch is reverted, I will do that.

David Daney

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