Re: linux-next: percpu tree build warning

Rusty Russell
2009-11-28T09:51:52Z

On Fri, 27 Nov 2009 04:11:28 pm Ingo Molnar wrote:
>
> * Rusty Russell <rusty@rustcorp.com.au> wrote:
>
> > On Thu, 26 Nov 2009 12:10:58 am Ingo Molnar wrote:
> > > While a percpu variable is defined and used in completely different
> > > ways:
> > >
> > > DEFINE_PER_CPU(unsigned long, dr7);
> > >
> > > and is used via:
> > >
> > > __get_cpu_var(dr7); [[Fixed -- RR]]
> >
> > The entire point of Tejun's per-cpu work is that &dr7 is now valid. A
> > per-cpu pointer as if it were allocated by the dynamic per-cpu
> > allocator.
> >
> > Your arguments are fine, but out-of-date.
>
> But allowing &dr7 is outright dangerous - and not particularly clean
> either.

That's foolish. We can now have generic per-cpu function for counters
and the like.

> Nothing tells us that it's a percpu variable

__percpu. Again, I'm explaining what you should already know before sending
email about this stuff.

> and it blends into the
> regular namespace while most of the operators on it are special
> (__get_cpu_var(), per_cpu(), __this_cpu(), etc.).

OK, you convince Linus to change __user vars to use a prefix. Then I'll
agree that per_cpu_## is more kernely.

Stupidest debate ever.
Rusty.