Hi Andrew,
On 5/10/07, Andrew Morton <[EMAIL PROTECTED]> 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.
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?
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.
Hmmm. How about:
1. Introduce some CONFIG_WANTS_HARD_IRQ_DISABLE that is #defined (or
left undefined) by the arch/.../defconfig (depending upon whether or
not that arch implements a hard_irq_disable() for itself or not)
2. Then pull-in that code into include/linux/interrupt.h somehow
(through some known / fixed header file, or through asm/system.h, or
anyhow -- it doesn't really matter)
3. And:
#ifndef CONFIG_WANTS_HARD_IRQ_DISABLE
#define hard_irq_disable() do { } while(0)
#endif
We don't need to standardize on some particular arch-specific header
filename in this case.
Comments?
Satyam
-
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/
