Re: linux-next: manual merge of the tip tree with the sparc tree

[Daniel Hellstrom]

Peter Zijlstra wrote:

> On Thu, 2011-05-19 at 15:37 +0200, Daniel Hellstrom wrote:
>
>
>  
>
> > diff --git a/arch/sparc/kernel/smp_32.c b/arch/sparc/kernel/smp_32.c
> > index 41102c5..d5b3958 100644
> > --- a/arch/sparc/kernel/smp_32.c
> > +++ b/arch/sparc/kernel/smp_32.c
> > @@ -156,11 +156,11 @@ void arch_send_call_function_ipi_mask(const struct 
> > cpumask *mask)
> >
> > void smp_resched_interrupt(void)
> > {
> > +       irq_enter();
> > +       scheduler_ipi();
> >        local_cpu_data().irq_resched_count++;
> > -       /*
> > -        * do nothing, since it all was about calling re-schedule
> > -        * routine called by interrupt return code.
> > -        */
> > +       irq_exit();
> > +       /* re-schedule routine called by interrupt return code. */
> > }
> >    
>
> That doesn't look like an IPI, that looks like its calls the function on
> the local cpu, which is completely pointless.
>  
The above function is one of the IPI interrupt handlers.

The smp_send_reschedule() is called by the generic code, it is 
responsible for sending an IRQ to the target CPU, that CPU comes into 
smp_resched_interrupt above from the IRQ trap handler. So yes, the 
scheduler_ipi() is called on the local CPU, but on the CPU taking the 
IPI not the CPU sending the IPI.

Daniel
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/