Re: [RFC v2 PATCH 03/14] irq: add new struct ipi_mask

[Qais Yousef]

On 10/13/2015 02:26 PM, Thomas Gleixner wrote:
> On Tue, 13 Oct 2015, Qais Yousef wrote:
> > cpumask is limited to NR_CPUS. introduce ipi_mask which allows us to address
> > cpu range that is higher than NR_CPUS which is required for drivers to send
> > IPIs for coprocessor that are outside Linux CPU range.
> >
> > Signed-off-by: Qais Yousef <qais.yousef@xxxxxxxxxx>
> > ---
> >   include/linux/irq.h | 15 +++++++++++++++
> >   1 file changed, 15 insertions(+)
> >
> > diff --git a/include/linux/irq.h b/include/linux/irq.h
> > index 11bf09288ddb..4b537e4d393b 100644
> > --- a/include/linux/irq.h
> > +++ b/include/linux/irq.h
> > @@ -125,6 +125,21 @@ enum {
> >   struct msi_desc;
> >   struct irq_domain;
> >   
> > + /**
> > + * struct ipi_mask - IPI mask information
> > + * @cpumask: bitmap of cpumasks
> > + * @nbits: number of bits in cpumask
> > + * @global: whether the mask is SMP IPI ie: subset of cpu_possible_mask or not
> > + *
> > + * ipi_mask is similar to cpumask, but it provides nbits that's configurable
> > + * rather than fixed to NR_CPUS.
> > + */
> > +struct ipi_mask {
> > +	unsigned long	*cpumask;
> > +	unsigned int	nbits;
> > +	bool		global;
> > +};
> Can you make that:
>
> struct ipi_mask {
> 	unsigned int	nbits;
> 	bool		global;
> 	unsigned long	cpu_bitmap[];
> };
>
> That allows you to allocate the data structure in one go. So the
> ipi_mask in irq_data_common becomes a pointer which is only filled in
> when ipi_mask is actually used.
>
> Note, I renamed cpumask to cpu_bitmap to avoid confusion with
> cpumasks.
>
> We also want a helper function
>
>     struct cpumask *irq_data_get_ipi_mask(struct irq_data *data);
>
> so we can use normal cpumask operations for the majority of cases.

Will do.

Thanks,
Qais
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