Re: [PATCH v2] pci: fix unavailable irq number 255 reported by BIOS

[Chen Fan]

On 01/28/2016 06:32 AM, Bjorn Helgaas wrote:
> On Wed, Jan 27, 2016 at 10:13:36AM +0100, Thomas Gleixner wrote:
> > On Tue, 26 Jan 2016, Bjorn Helgaas wrote:
> > > On Tue, Jan 26, 2016 at 04:48:25PM +0100, Thomas Gleixner wrote:
> > > > Right. So we could certainly do something like this INVALID_IRQ thingy, but
> > > > that looks a bit weird. What would request_irq() return?
> > > >
> > > > If it returns success, then drivers might make the wrong decision. If it
> > > > returns an error code, then the i801 one works, but we might have to fix
> > > > others anyway.
> > > I was thinking request_irq() could return -EINVAL if the caller passed
> > > INVALID_IRQ.  That should tell drivers that this interrupt won't work.
> > >
> > > We'd be making request_irq() return -EINVAL in some cases where it
> > > currently returns success.  But even though it returns success today,
> > > I don't think the driver is getting interrupts, because the wire isn't
> > > connected.
> > Correct. What I meant is that the i801 driver can handle the -EINVAL return
> > from request_irq() today, but other drivers don't. I agree that we need to fix
> > them anyway and a failure to request the interrupt is better than a silent 'no
> > interrupts delivered' issue.
> >   
> > Though instead of returning -EINVAL I prefer an explicit error code for this
> > case. That way a driver can distinguish between the 'not connected' case and
> > other failure modes. Something like the patch below should work.
> This patch looks great to me, thanks for all your help!
>
> Chen, do you want to put all this together as formal patches with
> changelogs and post to the mailing lists?
With pleasure. I will test it on my environment first and send it out.
thank all of you for this problem.

Chen

> Bjorn
>
> > 8<------------------
> > --- a/drivers/acpi/pci_irq.c
> > +++ b/drivers/acpi/pci_irq.c
> > @@ -387,6 +387,22 @@ static inline int acpi_isa_register_gsi(
> >   }
> >   #endif
> >   
> > +static inline bool acpi_pci_irq_valid(struc pci_dev *dev)
> > +{
> > +#ifdef CONFIG_X86
> > +	/*
> > +	 * On x86 irq line 0xff means "unknown" or "no connection" (PCI 3.0,
> > +	 * Section 6.2.4, footnote on page 223).
> > +	 */
> > +	if (dev->irq == 0xff) {
> > +		dev->irq = IRQ_NOTCONNECTED;
> > +		dev_warn(&dev->dev, "PCI INT not connected\n");
> > +		return false;
> > +	}
> > +#endif
> > +	return true;
> > +}
> > +
> >   int acpi_pci_irq_enable(struct pci_dev *dev)
> >   {
> >   	struct acpi_prt_entry *entry;
> > @@ -409,6 +425,9 @@ int acpi_pci_irq_enable(struct pci_dev *
> >   	if (pci_has_managed_irq(dev))
> >   		return 0;
> >   
> > +	if (!acpi_pci_irq_valid(dev))
> > +		return 0;
> > +
> >   	entry = acpi_pci_irq_lookup(dev, pin);
> >   	if (!entry) {
> >   		/*
> > --- a/include/linux/interrupt.h
> > +++ b/include/linux/interrupt.h
> > @@ -125,6 +125,16 @@ struct irqaction {
> >   
> >   extern irqreturn_t no_action(int cpl, void *dev_id);
> >   
> > +/*
> > + * If a (PCI) device interrupt is not connected we set dev->irq to
> > + * IRQ_NOTCONNECTED. This causes request_irq() to fail with -ENOTCONN, so we
> > + * can distingiush that case from other error returns.
> > + *
> > + * 0x80000000 is guaranteed to be outside the available range of interrupts
> > + * and easy to distinguish from other possible incorrect values.
> > + */
> > +#define IRQ_NOTCONNECTED	(1U << 31)
> > +
> >   extern int __must_check
> >   request_threaded_irq(unsigned int irq, irq_handler_t handler,
> >   		     irq_handler_t thread_fn,
> > --- a/kernel/irq/manage.c
> > +++ b/kernel/irq/manage.c
> > @@ -1609,6 +1609,9 @@ int request_threaded_irq(unsigned int ir
> >   	struct irq_desc *desc;
> >   	int retval;
> >   
> > +	if (irq == IRQ_NOTCONNECTED)
> > +		return -ENOTCONN;
> > +
> >   	/*
> >   	 * Sanity-check: shared interrupts must pass in a real dev-ID,
> >   	 * otherwise we'll have trouble later trying to figure out
> > @@ -1699,9 +1702,13 @@ EXPORT_SYMBOL(request_threaded_irq);
> >   int request_any_context_irq(unsigned int irq, irq_handler_t handler,
> >   			    unsigned long flags, const char *name, void *dev_id)
> >   {
> > -	struct irq_desc *desc = irq_to_desc(irq);
> > +	struct irq_desc *desc;
> >   	int ret;
> >   
> > +	if (irq == IRQ_NOTCONNECTED)
> > +		return -ENOTCONN;
> > +
> > +	desc = irq_to_desc(irq);
> >   	if (!desc)
> >   		return -EINVAL;
> >   
> >
> >
> >
> > --
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> .