PCI: Spread interrupt vectors in pci_alloc_irq_vectors()

Set the affinity_mask in the PCI device before allocating vectors so that
the affinity can be propagated through the MSI descriptor structures to the
core IRQ code.  To facilitate this, new __pci_enable_msi_range() and
__pci_enable_msix_range() helpers are factored out of their not prefixed
variants which assigning the new IRQ affinity mask in the PCI device so
that the low-level interrupt code can perform the interrupt affinity
assignment and do node-local allocations.

A new PCI_IRQ_NOAFFINITY flag is added to pci_alloc_irq_vectors() so that
this function can also be used by drivers that don't wish to use the
automatic affinity assignment.

[bhelgaas: omit "else" after "return" consistently]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Alexander Gordeev <agordeev@redhat.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/Documentation/PCI/MSI-HOWTO.txt b/Documentation/PCI/MSI-HOWTO.txt
index 0ac612b8c3fb..c55df2911136 100644
--- a/Documentation/PCI/MSI-HOWTO.txt
+++ b/Documentation/PCI/MSI-HOWTO.txt
@@ -99,6 +99,10 @@ PCI_IRQ_NOMSI and PCI_IRQ_NOMSIX flag in case a device claims to support
 MSI or MSI-X, but the support is broken, or to pass PCI_IRQ_NOLEGACY in
 case the device does not support legacy interrupt lines.
 
+By default this function will spread the interrupts around the available
+CPUs, but this feature can be disabled by passing the PCI_IRQ_NOAFFINITY
+flag.
+
 To get the Linux IRQ numbers passed to request_irq() and free_irq() and the
 vectors, use the following function: