[PATCH 5.5 275/367] virtio-pci: check name when counting MSI-X vectors

[Greg Kroah-Hartman]

From: Daniel Verkamp <dverkamp@xxxxxxxxxxxx>

commit 303090b513fd1ee45aa1536b71a3838dc054bc05 upstream.

VQs without a name specified are not valid; they are skipped in the
later loop that assigns MSI-X vectors to queues, but the per_vq_vectors
loop above that counts the required number of vectors previously still
counted any queue with a non-NULL callback as needing a vector.

Add a check to the per_vq_vectors loop so that vectors with no name are
not counted to make the two loops consistent.  This prevents
over-counting unnecessary vectors (e.g. for features which were not
negotiated with the device).

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
Signed-off-by: Daniel Verkamp <dverkamp@xxxxxxxxxxxx>
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Reviewed-by: Wang, Wei W <wei.w.wang@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/virtio/virtio_pci_common.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -294,7 +294,7 @@ static int vp_find_vqs_msix(struct virti
 		/* Best option: one for change interrupt, one per vq. */
 		nvectors = 1;
 		for (i = 0; i < nvqs; ++i)
-			if (callbacks[i])
+			if (names[i] && callbacks[i])
 				++nvectors;
 	} else {
 		/* Second best: one for change, shared for all vqs. */