[PATCH 2/3] Add hard_irq_disable()

[Satyam Sharma]

On 5/10/07, Benjamin Herrenschmidt <benh at kernel.crashing.org> wrote:
>
> > So you're saying that this mechanism forces the arch (that really
> > wants hard_irq_disable) to _#define_ hard_irq_disable (as a macro),
> > and if it implements it as an inline function, for example, then we're
> > screwed?
>
> No. The idea is to do like we did for a few other things already
> (according to Linus request in fact), which is to write
>
> static inline void hard_irq_disable(void)
> {
>         .../...
> }
> #define hard_irq_disable hard_irq_disable
>
> This is nicer than having an ARCH_HAS_xxx

Ok, that's reasonable, we don't want to end up with zillions of
ARCH_HAS_THIS and ARCH_HAS_THAT.

But then, what _is_ the problem with your approach above? An arch that
wants (and implements) hard_irq_disable will also #define that dummy
macro, so we just need to pull in the appropriate header (directly,
indirectly, anyhow -- we don't really care) into
include/linux/interrupt.h and then just do the exact same "#ifndef
hard_irq_disable" check that you're doing right now. I must be missing
something trivial (either that or I need to go and have a coffee :-)
because I don't see the possibility of hitting multiple _different_
definitions with the approach you mentioned just now.