On Wed, 2007-05-09 at 22:41 -0700, Andrew Morton wrote:
> On Thu, 10 May 2007 15:25:58 +1000 Benjamin Herrenschmidt <[EMAIL PROTECTED]>
> wrote:
>
> > --- linux-cell.orig/include/linux/interrupt.h 2007-05-10
> > 14:51:22.000000000 +1000
> > +++ linux-cell/include/linux/interrupt.h 2007-05-10 15:18:04.000000000
> > +1000
> > @@ -241,6 +241,16 @@ static inline void __deprecated save_and
> > #define save_and_cli(x) save_and_cli(&x)
> > #endif /* CONFIG_SMP */
> >
> > +/* Some architectures might implement lazy enabling/disabling of
> > + * interrupts. In some cases, such as stop_machine, we might want
> > + * to ensure that after a local_irq_disable(), interrupts have
> > + * really been disabled in hardware. Such architectures need to
> > + * implement the following hook.
> > + */
> > +#ifndef hard_irq_disable
> > +#define hard_irq_disable() do { } while(0)
> > +#endif
>
> We absolutely require that the architecture's hard_irq_disable() be defined
> when we do this. If it happens that the definition of hard_irq_disable()
> is implemented three levels deep in nested includes then we risk getting
> into a situation where different .c files see different implementations of
> hard_irq_disable(), which could lead to confusing results, to say the least.
Yes, I'm indeed a bit worried about that... I've been wondering what's
the best include path here... I tried to follow who gets to hw_irq.h and
didn't come to any conclusive results.
powerpc gets it from asm/system.h but I haven't verified other arch
(though it only matters on arch that have their own here).
I've verified that a #error on ppc up there will not trigger thus it's
fine on powerpc, but I agree it's a bit fragile.
> Your implementation comes via the inclusion of system.h which then includes
> hw_irq.h. That's perhaps a little fragile and it would be better to
>
> a) include in the comment the name of the arch file which must implement
> hard_irq_disable() and
>
> b) include that file directly from this one.
Fair enough. I was just worried that including hw_irq.h here might cause
trouble for some archs though (as I said, we get it indirectly on
powerpc via some other asm thingy, not via some linux/*.h). I've looked
around and seen all sort of horrors in arch include dependencies
(including some circular stuff that must work by mere luck).
> Oh, and your comment layout style is wrong ;)
What about my comment layout style ? I've been using that forever ... Or
do you mean I should use a function documentation style layout there ?
Cheers,
Ben.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
