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>
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