PCI/MSI: Check that we have a legacy interrupt line before using it

It seems like there are some devices (e.g. the PCIe root port driver) that
may not always have a INTx interrupt.  Check for dev->irq before returning
a legacy interrupt in pci_irq_alloc_vectors to properly handle this case.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index b44ad7c..52ac675 100644 (file)
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -1198,9 +1198,11 @@ int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs,
        }
 
        /* use legacy irq if allowed */
-       if ((flags & PCI_IRQ_LEGACY) && min_vecs == 1) {
-               pci_intx(dev, 1);
-               return 1;
+       if (flags & PCI_IRQ_LEGACY) {
+               if (min_vecs == 1 && dev->irq) {
+                       pci_intx(dev, 1);
+                       return 1;
+               }
        }
 
        return vecs;