Commit 30ff3e8c authored by Piotr Stankiewicz's avatar Piotr Stankiewicz Committed by Bjorn Helgaas
Browse files

PCI/MSI: Forward MSI-X error code in pci_alloc_irq_vectors_affinity() 

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.

Link: https://lore.kernel.org/r/20200616073318.20229-1-piotr.stankiewicz@intel.com


Signed-off-by: default avatarPiotr Stankiewicz <piotr.stankiewicz@intel.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@intel.com>
Reviewed-by: default avatarLogan Gunthorpe <logang@deltatee.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent b3a9e3b9

drivers/pci/msi.c

+9 −13
Original line number Diff line number Diff line
@@ -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);