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    SubjectRe: [PATCH v4] PCI/MSI: Forward MSI-X vector enable error code in pci_alloc_irq_vectors_affinity()
    On Tue, Jun 16, 2020 at 09:33:16AM +0200, Piotr Stankiewicz wrote:
    > When debugging an issue where I was asking the PCI machinery to enable a
    > set of MSI-X vectors, without falling back on MSI, I ran across a
    > behaviour which seems odd. The pci_alloc_irq_vectors_affinity() will
    > always return -ENOSPC on failure, when allocating MSI-X vectors only,
    > whereas with MSI fallback it will forward any error returned by
    > __pci_enable_msi_range(). This is a confusing behaviour, so have the
    > pci_alloc_irq_vectors_affinity() forward the error code from
    > __pci_enable_msix_range() when appropriate.
    >
    > Signed-off-by: Piotr Stankiewicz <piotr.stankiewicz@intel.com>
    > Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
    > Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
    > Reviewed-by: Christoph Hellwig <hch@lst.de>

    Applied to pci/msi for v5.8, thanks!

    > ---
    > drivers/pci/msi.c | 22 +++++++++-------------
    > 1 file changed, 9 insertions(+), 13 deletions(-)
    >
    > diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
    > index 6b43a5455c7a..cade9be68b09 100644
    > --- a/drivers/pci/msi.c
    > +++ b/drivers/pci/msi.c
    > @@ -1191,8 +1191,7 @@ int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs,
    > struct irq_affinity *affd)
    > {
    > struct irq_affinity msi_default_affd = {0};
    > - int msix_vecs = -ENOSPC;
    > - int msi_vecs = -ENOSPC;
    > + int nvecs = -ENOSPC;
    >
    > if (flags & PCI_IRQ_AFFINITY) {
    > if (!affd)
    > @@ -1203,17 +1202,16 @@ int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs,
    > }
    >
    > if (flags & PCI_IRQ_MSIX) {
    > - msix_vecs = __pci_enable_msix_range(dev, NULL, min_vecs,
    > - max_vecs, affd, flags);
    > - if (msix_vecs > 0)
    > - return msix_vecs;
    > + nvecs = __pci_enable_msix_range(dev, NULL, min_vecs, max_vecs,
    > + affd, flags);
    > + if (nvecs > 0)
    > + return nvecs;
    > }
    >
    > if (flags & PCI_IRQ_MSI) {
    > - msi_vecs = __pci_enable_msi_range(dev, min_vecs, max_vecs,
    > - affd);
    > - if (msi_vecs > 0)
    > - return msi_vecs;
    > + nvecs = __pci_enable_msi_range(dev, min_vecs, max_vecs, affd);
    > + if (nvecs > 0)
    > + return nvecs;
    > }
    >
    > /* use legacy IRQ if allowed */
    > @@ -1231,9 +1229,7 @@ int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs,
    > }
    > }
    >
    > - if (msix_vecs == -ENOSPC)
    > - return -ENOSPC;
    > - return msi_vecs;
    > + return nvecs;
    > }
    > EXPORT_SYMBOL(pci_alloc_irq_vectors_affinity);
    >
    > --
    > 2.17.2
    >

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