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

[Linus Torvalds]

On Fri, May 19, 2017 at 5:46 AM, Christoph Hellwig <hch@xxxxxx> wrote:
>
> 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;
>  }

Side note: why is it doing that " > 1" check, when any value _other_
than 1 is wrong?

Also, to match the non-MSI implementation, wouldn't it be nicer to
just write it that same way (and also verify "dev->irq"):

        if (flags & PCI_IRQ_LEGACY) {
                if (min_vecs == 1 && dev->irq)
                        return 1;
        }
        return -ENOSPC;

(the exact error value probably doesn't matter in practice, but the
CONFIG_MSI case returns ENOSPC by default and that's what
Documentation/PCI/MSI-HOWTO.txt says too).

Hmm?

             Linus