The API of pci_alloc_irq_vectors_affinity() requires to return -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.
Users of pci_alloc_irq_vectors_affinity() may try to reduce irq vectors
and allocate vectors again in case that -ENOSPC is returned, such as NVMe,
so we need to respect the current interface and give preference to -ENOSPC.
Especially the min/max vecs doesn't work correctly when using the
irq_affinity nr_sets because rebalancing the set counts is driver specific.
To get around that, drivers using nr_sets have to set min and max to the same
value and handle the "reduce and try again".
Cc: Jens Axboe <axboe@xxxxxx>
Cc: Keith Busch <keith.busch@xxxxxxxxx>
Cc: linux-nvme@xxxxxxxxxxxxxxxxxxx
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
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 7a1c8a09efa5..4c0b47867258 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -1168,7 +1168,8 @@ 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)
@@ -1179,16 +1180,17 @@ 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 */
@@ -1199,7 +1201,9 @@ 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);
--
2.9.5
