From: Ming Lei ming.lei@redhat.com
[ Upstream commit 77f88abd4a6f73a1a68dbdc0e3f21575fd508fc3 ]
The API of pci_alloc_irq_vectors_affinity() says it returns -ENOSPC if fewer than @min_vecs interrupt vectors are available for @dev.
However, if a device supports MSI-X but not MSI and a caller requests @min_vecs that can't be satisfied by MSI-X, we previously returned -EINVAL (from the failed attempt to enable MSI), not -ENOSPC.
When -ENOSPC is returned, callers may reduce the number IRQs they request and try again. Most callers can use the @min_vecs and @max_vecs parameters to avoid this retry loop, but that doesn't work when using IRQ affinity "nr_sets" because rebalancing the sets is driver-specific.
This return value bug has been present since pci_alloc_irq_vectors() was added in v4.10 by aff171641d18 ("PCI: Provide sensible IRQ vector alloc/free routines"), but it wasn't an issue because @min_vecs/@max_vecs removed the need for callers to iteratively reduce the number of IRQs requested and retry the allocation, so they didn't need to distinguish -ENOSPC from -EINVAL.
In v5.0, 6da4b3ab9a6e ("genirq/affinity: Add support for allocating interrupt sets") added IRQ sets to the interface, which reintroduced the need to check for -ENOSPC and possibly reduce the number of IRQs requested and retry the allocation.
Signed-off-by: Ming Lei ming.lei@redhat.com [bhelgaas: changelog] Signed-off-by: Bjorn Helgaas bhelgaas@google.com Cc: Jens Axboe axboe@fb.com Cc: Keith Busch keith.busch@intel.com Cc: Christoph Hellwig hch@lst.de Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pci/msi.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-)
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c index af24ed50a2452..971dddf62374f 100644 --- a/drivers/pci/msi.c +++ b/drivers/pci/msi.c @@ -1155,7 +1155,8 @@ int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs, const struct irq_affinity *affd) { static const struct irq_affinity msi_default_affd; - int vecs = -ENOSPC; + int msix_vecs = -ENOSPC; + int msi_vecs = -ENOSPC;
if (flags & PCI_IRQ_AFFINITY) { if (!affd) @@ -1166,16 +1167,17 @@ int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs, }
if (flags & PCI_IRQ_MSIX) { - vecs = __pci_enable_msix_range(dev, NULL, min_vecs, max_vecs, - affd); - if (vecs > 0) - return vecs; + msix_vecs = __pci_enable_msix_range(dev, NULL, min_vecs, + max_vecs, affd); + if (msix_vecs > 0) + return msix_vecs; }
if (flags & PCI_IRQ_MSI) { - vecs = __pci_enable_msi_range(dev, min_vecs, max_vecs, affd); - if (vecs > 0) - return vecs; + msi_vecs = __pci_enable_msi_range(dev, min_vecs, max_vecs, + affd); + if (msi_vecs > 0) + return msi_vecs; }
/* use legacy irq if allowed */ @@ -1186,7 +1188,9 @@ int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs, } }
- return vecs; + if (msix_vecs == -ENOSPC) + return -ENOSPC; + return msi_vecs; } EXPORT_SYMBOL(pci_alloc_irq_vectors_affinity);