[Xen-devel] Re: [PATCH 09/14] xen: events: push setup of irq<->{evtchn,ipi,virq,pirq} maps into irq_info init functions

[Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>]

On Thu, 2011-03-10 at 04:56 +0000, Konrad Rzeszutek Wilk wrote:
> On Wed, Mar 09, 2011 at 05:41:21PM +0000, Ian Campbell wrote:
> > Encapsulate setup of XXX_to_irq array in the relevant
> > xen_irq_info_*_init function.
> > 
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > ---
> >  drivers/xen/events.c |   42 +++++++++++++++++++++---------------------
> >  1 files changed, 21 insertions(+), 21 deletions(-)
> > 
> > diff --git a/drivers/xen/events.c b/drivers/xen/events.c
> > index 72725fa..cf372d4 100644
> > --- a/drivers/xen/events.c
> > +++ b/drivers/xen/events.c
> > @@ -126,6 +126,7 @@ static struct irq_info *info_for_irq(unsigned irq)
> >  
> >  /* Constructors for packed IRQ information. */
> >  static void xen_irq_info_common_init(struct irq_info *info,
> > +                                unsigned irq,
> >                                  enum xen_irq_type type,
> >                                  unsigned short evtchn,
> >                                  unsigned short cpu)
> > @@ -136,6 +137,8 @@ static void xen_irq_info_common_init(struct irq_info 
> > *info,
> >     info->type = type;
> >     info->evtchn = evtchn;
> >     info->cpu = cpu;
> > +
> > +   evtchn_to_irq[evtchn] = irq;
> 
> Is there any case where this would lead to an over-write? Should we
> have an
>   WARN_ON(evtchn_to_irq[evtchn] != -1)
> 
> just to check?

This patch is pure code motion so there should be no more need for a
check than there was before.

I don't think it can happen, the callers are either running in a context
where the evtchn mapping has just been zapped (e.g. resume) or they
include an explicit check of evtchn_to_irq before getting this far (e.g.
bind_evtchn_to_irq and friends).

In any case, not much further down the series this switches to
initialising a recently allocated irq_info structure so we wouldn't
catch any errors this way.

Ian.

> >  }
> >  
> >  static void xen_irq_info_evtchn_init(unsigned irq,
> > @@ -143,29 +146,35 @@ static void xen_irq_info_evtchn_init(unsigned irq,
> >  {
> >     struct irq_info *info = info_for_irq(irq);
> >  
> > -   xen_irq_info_common_init(info, IRQT_EVTCHN, evtchn, 0);
> > +   xen_irq_info_common_init(info, irq, IRQT_EVTCHN, evtchn, 0);
> >  }
> >  
> > -static void xen_irq_info_ipi_init(unsigned irq,
> > +static void xen_irq_info_ipi_init(unsigned cpu,
> > +                             unsigned irq,
> >                               unsigned short evtchn,
> >                               enum ipi_vector ipi)
> >  {
> >     struct irq_info *info = info_for_irq(irq);
> >  
> > -   xen_irq_info_common_init(info, IRQT_IPI, evtchn, 0);
> > +   xen_irq_info_common_init(info, irq, IRQT_IPI, evtchn, 0);
> >  
> >     info->u.ipi = ipi;
> > +
> > +   per_cpu(ipi_to_irq, cpu)[ipi] = irq;
> 
> Ditto. Should we do a check first to see if we are overwritting anything
> but the default value of -1?
> >  }
> >  
> > -static void xen_irq_info_virq_init(unsigned irq,
> > +static void xen_irq_info_virq_init(unsigned cpu,
> > +                              unsigned irq,
> >                                unsigned short evtchn,
> >                                unsigned short virq)
> >  {
> >     struct irq_info *info = info_for_irq(irq);
> >  
> > -   xen_irq_info_common_init(info, IRQT_VIRQ, evtchn, 0);
> > +   xen_irq_info_common_init(info, irq, IRQT_VIRQ, evtchn, 0);
> >  
> >     info->u.virq = virq;
> > +
> > +   per_cpu(virq_to_irq, cpu)[virq] = irq;
> >  }
> >  
> >  static void xen_irq_info_pirq_init(unsigned irq,
> > @@ -177,12 +186,14 @@ static void xen_irq_info_pirq_init(unsigned irq,
> >  {
> >     struct irq_info *info = info_for_irq(irq);
> >  
> > -   xen_irq_info_common_init(info, IRQT_PIRQ, evtchn, 0);
> > +   xen_irq_info_common_init(info, irq, IRQT_PIRQ, evtchn, 0);
> >  
> >     info->u.pirq.pirq = pirq;
> >     info->u.pirq.gsi = gsi;
> >     info->u.pirq.vector = vector;
> >     info->u.pirq.flags = flags;
> > +
> > +   pirq_to_irq[pirq] = irq;
> >  }
> >  
> >  /*
> > @@ -644,7 +655,6 @@ int xen_bind_pirq_gsi_to_irq(unsigned gsi,
> >  
> >     xen_irq_info_pirq_init(irq, 0, pirq, gsi, irq_op.vector,
> >                            shareable ? PIRQ_SHAREABLE : 0);
> > -   pirq_to_irq[pirq] = irq;
> >  
> >  out:
> >     spin_unlock(&irq_mapping_update_lock);
> > @@ -682,7 +692,6 @@ int xen_bind_pirq_msi_to_irq(struct pci_dev *dev, 
> > struct msi_desc *msidesc,
> >                                   handle_level_irq, name);
> >  
> >     xen_irq_info_pirq_init(irq, 0, pirq, 0, vector, 0);
> > -   pirq_to_irq[pirq] = irq;
> >     ret = set_irq_msi(irq, msidesc);
> >     if (ret < 0)
> >             goto error_irq;
> > @@ -746,7 +755,6 @@ int bind_evtchn_to_irq(unsigned int evtchn)
> >             set_irq_chip_and_handler_name(irq, &xen_dynamic_chip,
> >                                           handle_fasteoi_irq, "event");
> >  
> > -           evtchn_to_irq[evtchn] = irq;
> >             xen_irq_info_evtchn_init(irq, evtchn);
> >     }
> >  
> > @@ -779,9 +787,7 @@ static int bind_ipi_to_irq(unsigned int ipi, unsigned 
> > int cpu)
> >                     BUG();
> >             evtchn = bind_ipi.port;
> >  
> > -           evtchn_to_irq[evtchn] = irq;
> > -           xen_irq_info_ipi_init(irq, evtchn, ipi);
> > -           per_cpu(ipi_to_irq, cpu)[ipi] = irq;
> > +           xen_irq_info_ipi_init(cpu, irq, evtchn, ipi);
> >  
> >             bind_evtchn_to_cpu(evtchn, cpu);
> >     }
> > @@ -814,10 +820,7 @@ int bind_virq_to_irq(unsigned int virq, unsigned int 
> > cpu)
> >                     BUG();
> >             evtchn = bind_virq.port;
> >  
> > -           evtchn_to_irq[evtchn] = irq;
> > -           xen_irq_info_virq_init(irq, evtchn, virq);
> > -
> > -           per_cpu(virq_to_irq, cpu)[virq] = irq;
> > +           xen_irq_info_virq_init(cpu, irq, evtchn, virq);
> >  
> >             bind_evtchn_to_cpu(evtchn, cpu);
> >     }
> > @@ -1120,7 +1123,6 @@ void rebind_evtchn_irq(int evtchn, int irq)
> >        so there should be a proper type */
> >     BUG_ON(info->type == IRQT_UNBOUND);
> >  
> > -   evtchn_to_irq[evtchn] = irq;
> >     xen_irq_info_evtchn_init(irq, evtchn);
> >  
> >     spin_unlock(&irq_mapping_update_lock);
> > @@ -1288,8 +1290,7 @@ static void restore_cpu_virqs(unsigned int cpu)
> >             evtchn = bind_virq.port;
> >  
> >             /* Record the new mapping. */
> > -           evtchn_to_irq[evtchn] = irq;
> > -           xen_irq_info_virq_init(irq, evtchn, virq);
> > +           xen_irq_info_virq_init(cpu, irq, evtchn, virq);
> >             bind_evtchn_to_cpu(evtchn, cpu);
> >     }
> >  }
> > @@ -1313,8 +1314,7 @@ static void restore_cpu_ipis(unsigned int cpu)
> >             evtchn = bind_ipi.port;
> >  
> >             /* Record the new mapping. */
> > -           evtchn_to_irq[evtchn] = irq;
> > -           xen_irq_info_ipi_init(irq, evtchn, ipi);
> > +           xen_irq_info_ipi_init(cpu, irq, evtchn, ipi);
> >             bind_evtchn_to_cpu(evtchn, cpu);
> >     }
> >  }
> > -- 
> > 1.5.6.5



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