Re: [REGRESSION] Failed network caused by: xhci: switch to pci_alloc_irq_vectors

[Christoph Hellwig]

On Fri, May 19, 2017 at 08:37:21AM -0400, Steven Rostedt wrote:
> ktest config bisect ended with:
> 
> ***************************************
> Found bad config: CONFIG_PCI_MSI
> ***************************************

Oh, that's interesting.  I think there's been a bug in the !CONFIG_PCI_MSI
fallback for pci_alloc_irq_vectors since the very beginning.  And it
didn't matter for any driver so far, but xhci has a very odd way
to set MSI(-X) vs legacy interrupts.

Can you try the patch below?


diff --git a/include/linux/pci.h b/include/linux/pci.h
index 33c2b0b77429..5a7fd3b6a7b9 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1342,7 +1342,7 @@ pci_alloc_irq_vectors_affinity(struct pci_dev *dev, 
unsigned int min_vecs,
                               unsigned int max_vecs, unsigned int flags,
                               const struct irq_affinity *aff_desc)
 {
-       if (min_vecs > 1)
+       if (min_vecs > 1 || !(flags & PCI_IRQ_LEGACY))
                return -EINVAL;
        return 1;
 }