[RFC] [PATCH] virtio: Dont add "config" to list for !per_vq_vector

[Krishna Kumar <krkumar2@in.ibm.com>]

For the MSI but non-per_vq_vector case, the config/change vq
also gets added to the list of vqs that need to process the
MSI interrupt. This is not needed as config has it's own
handler (vp_config_changed). In any case, vring_interrupt()
finds nothing needs to be done on this vq.

I tested this patch by testing the "Fallback:" and "Finally
fall back" cases in vp_find_vqs(). Please review.

Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
---
 drivers/virtio/virtio_pci.c |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff -ruNp org/drivers/virtio/virtio_pci.c new/drivers/virtio/virtio_pci.c
--- org/drivers/virtio/virtio_pci.c	2011-10-03 09:10:11.000000000 +0530
+++ new/drivers/virtio/virtio_pci.c	2011-10-04 19:16:34.000000000 +0530
@@ -415,9 +415,13 @@ static struct virtqueue *setup_vq(struct
 		}
 	}
 
-	spin_lock_irqsave(&vp_dev->lock, flags);
-	list_add(&info->node, &vp_dev->virtqueues);
-	spin_unlock_irqrestore(&vp_dev->lock, flags);
+	if (callback) {
+		spin_lock_irqsave(&vp_dev->lock, flags);
+		list_add(&info->node, &vp_dev->virtqueues);
+		spin_unlock_irqrestore(&vp_dev->lock, flags);
+	} else {
+		INIT_LIST_HEAD(&info->node);
+	}
 
 	return vq;