Re: [PATCH 1/2] ahci: disable correct irq for dymmy ports

[Christoph Hellwig <hch@lst.de>]

On Thu, Aug 11, 2016 at 12:36:37PM -0400, Tejun Heo wrote:
> > diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
> > index 7461a58..dcf2c72 100644
> > --- a/drivers/ata/libahci.c
> > +++ b/drivers/ata/libahci.c
> > @@ -2524,7 +2524,7 @@ static int ahci_host_activate_multi_irqs(struct ata_host *host,
> >  
> >  		/* Do not receive interrupts sent by dummy ports */
> >  		if (!pp) {
> > -			disable_irq(irq + i);
> > +			disable_irq(irq);
> >  			continue;
> >  		}
> 
> I'm not following.  The driver at that point has irqs in the range
> [@irq, @irq + @host->n_ports - 1] and is trying to activate them and
> the above code block disables irq for a port which should be skipped.
> Why wouldn't it need to be indexed?

Because ahci_irq_vector does that indexing already.  This call changed
when Dan added ahci_irq_vector to support the MSI-X case - since
then ahci_irq_vector either does the base irq + index logic for
MSI or uses the msix_entries array for MSI-X, and irq contains the
result of that operation.