Re: [Xen-devel] [PATCH 10/14] xen: events: maintain a list of Xen interrupts

[Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>]

On Thu, 2011-03-10 at 05:22 +0000, Konrad Rzeszutek Wilk wrote:
> On Wed, Mar 09, 2011 at 05:41:22PM +0000, Ian Campbell wrote:
> > In a PVHVM kernel not all interrupts are Xen interrupts (APIC interrupts 
> > can also be present).
> > 
> > Currently we get away with walking over all interrupts because the
> > lookup in the irq_info array simply returns IRQT_UNBOUND and we ignore
> > it. However this array will be going away in a future patch so we need
> > to manually track which interrupts have been allocated by the Xen
> > events infrastructure.
> > 
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > ---
> >  drivers/xen/events.c |   59 
> > +++++++++++++++++++++++++++++++++++++------------
> >  1 files changed, 44 insertions(+), 15 deletions(-)
> > 
> > diff --git a/drivers/xen/events.c b/drivers/xen/events.c
> > index cf372d4..e119989 100644
> > --- a/drivers/xen/events.c
> > +++ b/drivers/xen/events.c
> > @@ -56,6 +56,8 @@
> >   */
> >  static DEFINE_SPINLOCK(irq_mapping_update_lock);
> >  
> > +static LIST_HEAD(xen_irq_list_head);
> > +
> >  /* IRQ <-> VIRQ mapping. */
> >  static DEFINE_PER_CPU(int [NR_VIRQS], virq_to_irq) = {[0 ... NR_VIRQS-1] = 
> > -1};
> >  
> > @@ -85,7 +87,9 @@ enum xen_irq_type {
> >   */
> >  struct irq_info
> >  {
> > +   struct list_head list;
> >     enum xen_irq_type type; /* type */
> > +   unsigned irq;
> >     unsigned short evtchn;  /* event channel */
> >     unsigned short cpu;     /* cpu bound */
> >  
> > @@ -135,6 +139,7 @@ static void xen_irq_info_common_init(struct irq_info 
> > *info,
> >     BUG_ON(info->type != IRQT_UNBOUND && info->type != type);
> >  
> >     info->type = type;
> > +   info->irq = irq;
> >     info->evtchn = evtchn;
> >     info->cpu = cpu;
> >  
> > @@ -311,10 +316,11 @@ static void init_evtchn_cpu_bindings(void)
> >  {
> >     int i;
> >  #ifdef CONFIG_SMP
> > -   struct irq_desc *desc;
> > +   struct irq_info *info;
> >  
> >     /* By default all event channels notify CPU#0. */
> > -   for_each_irq_desc(i, desc) {
> > +   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
> > @@ -397,6 +403,21 @@ static void unmask_evtchn(int port)
> >     put_cpu();
> >  }
> >  
> > +static void xen_irq_init(unsigned irq)
> > +{
> > +   struct irq_info *info;
> > +   struct irq_desc *desc = irq_to_desc(irq);
> > +
> > +   /* By default all event channels notify CPU#0. */
> > +   cpumask_copy(desc->irq_data.affinity, cpumask_of(0));
> > +
> > +   info = &irq_info[irq];
> > +
> > +   info->type = IRQT_UNBOUND;
> > +
> > +   list_add_tail(&info->list, &xen_irq_list_head);
> 
> Should we use some form of spinlock lock? Just in case
> there are two drivers that are being unloaded?

The callers are xen_allocate_irq_dynamic and xen_allocate_irq_gsi both
of which expect to be protected by irq_mapping_update_lock already.


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