pci/xen: When free-ing MSI-X/MSI irq->desc also use generic code.

This code path is only run when an MSI/MSI-X PCI device is passed
in to PV DomU.

In 2.6.37 time-frame we over-wrote the default cleanup handler for
MSI/MSI-X irq->desc to be "xen_teardown_msi_irqs". That function
calls the the xen-pcifront driver which can tell the backend to
cleanup/take back the MSI/MSI-X device.

However, we forgot to continue the process of free-ing the MSI/MSI-X
device resources (irq->desc) in the PV domU side. Which is what
the default cleanup handler: default_teardown_msi_irqs did.

Hence we would leak IRQ descriptors.

Without this patch, doing "rmmod igbvf;modprobe igbvf" multiple
times ends with abandoned IRQ descriptors:

 28:          5  xen-pirq-pcifront-msi-x
 29:          8  xen-pirq-pcifront-msi-x
...
130:         10  xen-pirq-pcifront-msi-x

with the end result of running out of IRQ descriptors.

Reviewed-by: Ian Campbell <Ian.Campbell@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
index 30fdd09dea05..57afd1da491d 100644
--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -193,6 +193,9 @@ static void xen_teardown_msi_irqs(struct pci_dev *dev)
                 xen_pci_frontend_disable_msix(dev);
         else
                 xen_pci_frontend_disable_msi(dev);
+
+        /* Free the IRQ's and the msidesc using the generic code. */
+        default_teardown_msi_irqs(dev);
 }
 
 static void xen_teardown_msi_irq(unsigned int irq)