[PATCH 3.16.y-ckt 53/71] virtio_pci: Clear stale cpumask when setting irq affinity

[Luis Henriques]

3.16.7-ckt14 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jiang Liu <jiang.liu at linux.intel.com>

commit 210d150e1f5da506875e376422ba31ead2d49621 upstream.

The cpumask vp_dev->msix_affinity_masks[info->msix_vector] may contain
staled information when vp_set_vq_affinity() gets called, so clear it
before setting the new cpu bit mask.

Signed-off-by: Jiang Liu <jiang.liu at linux.intel.com>
Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
[ luis: backported to 3.16:
  - file rename: virtio_pci_common.c -> virtio_pci.c ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/virtio/virtio_pci.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 52c4607fec9e..c09527df161c 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -645,6 +645,7 @@ static int vp_set_vq_affinity(struct virtqueue *vq, int cpu)
 		if (cpu == -1)
 			irq_set_affinity_hint(irq, NULL);
 		else {
+			cpumask_clear(mask);
 			cpumask_set_cpu(cpu, mask);
 			irq_set_affinity_hint(irq, mask);
 		}