map_domain_pirq(): pirq already mapped?

[Jason Andryuk <jason.andryuk@amd.com>]

Hi,

Early in map_domain_pirq(), we have this block:

     old_irq = domain_pirq_to_irq(d, pirq);
     old_pirq = domain_irq_to_pirq(d, irq);

     if ( (old_irq > 0 && (old_irq != irq) ) ||
          (old_pirq && (old_pirq != pirq)) )
     {
         dprintk(XENLOG_G_WARNING,
                 "dom%d: pirq %d or irq %d already mapped (%d,%d)\n",
                 d->domain_id, pirq, irq, old_pirq, old_irq);
         return 0;
     }

Why do we return 0 instead of -EEXIST?  Since the pirq is not updated, 
the caller doesn't know that pirq won't fire - only old_pirq.  For 
allocate_and_map_gsi_pirq(), the new pirq is still returned to the 
caller.  I would expect old_pirq to be returned so the caller knows what 
to use.  Am I missing something?

Thanks,
Jason