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SubjectRe: [PATCH] percpu,lockdep: implement and use is_static_percpu_address()
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On Tue, 2010-03-09 at 20:42 +0900, Tejun Heo wrote:
> Hello, Peter.
>
> On 03/09/2010 08:25 PM, Peter Zijlstra wrote:
> >> +/* can't distinguish from other static vars, always false */
> >> +static inline bool is_static_percpu_address(unsigned long addr)
> >> +{
> >> + return false;
> >> +}
> >
> > At this point it might make sense to simply fail to compile if lockdep
> > is enabled as well.
> >
> > I'm not sure if there's many SMP archs that don't have this and do have
> > lockdep, but simply failing this test isn't really an option.
>
> That might be better. Returning %false isn't that bad tho. There
> really is no distinction between percpu and !percpu variable on UP and
> static variable address match will catch both.

Ah, if this is UP only then yes, no complaints ;-)

> >> /**
> >> + * is_static_percpu_address - test whether address is from static percpu area
> >> + * @addr: address to test
> >> + *
> >> + * Test whether @addr belongs to static percpu area. Module static
> >> + * percpu areas allocated via __alloc_reserved_percpu() is not
> >> + * considered. Use is_module_address() for those.
> >> + *
> >> + * RETURNS:
> >> + * %true if @addr is from static percpu area, %false otherwise.
> >> + */
> >
> > So is_module_address() will only return true for static per-cpu module
> > storage, right?
>
> Right, got confused there. I'll update is_static_percpu_address() to
> test for reserved regions too.

Or as per your other email, make the above be true, and have
is_module_address() be true for its static per-cpu regions.


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