Re: [Xen-devel] [PATCH 03/12] xen/events: remove unnecessary init_evtchn_cpu_bindings()

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 19.03.13 at 22:04, David Vrabel <david.vrabel@xxxxxxxxxx> wrote:
> From: David Vrabel <david.vrabel@xxxxxxxxxx>
> 
> Event channels are always explicitly bound to a specific VCPU before
> they are first enabled.  There is no need to initialize all possible
> events as bound to VCPU 0 at start of day or after a resume.

That part may indeed be safe to do, but ...

> --- a/drivers/xen/events.c
> +++ b/drivers/xen/events.c
> @@ -333,24 +333,6 @@ static void bind_evtchn_to_cpu(unsigned int chn, 
> unsigned int cpu)
>       info_for_irq(irq)->cpu = cpu;
>  }
>  
> -static void init_evtchn_cpu_bindings(void)
> -{
> -     int i;
> -#ifdef CONFIG_SMP
> -     struct irq_info *info;
> -
> -     /* By default all event channels notify CPU#0. */
> -     list_for_each_entry(info, &xen_irq_list_head, list) {
> -             struct irq_desc *desc = irq_to_desc(info->irq);
> -             cpumask_copy(desc->irq_data.affinity, cpumask_of(0));
> -     }
> -#endif
> -
> -     for_each_possible_cpu(i)
> -             memset(per_cpu(cpu_evtchn_mask, i),
> -                    (i == 0) ? ~0 : 0, sizeof(*per_cpu(cpu_evtchn_mask, i)));

... you also remove the initialization of the mask bits here. If
that was intended, a sentence about the safety of this would
certainly be good to add to the description.

Jan


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