virtio-pci: check name when counting MSI-X vectors

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@vger.kernel.org
Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Wang, Wei W <wei.w.wang@intel.com>

diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index f2862f6..222d630 100644 (file)
--- 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 virtio_device *vdev, unsigned nvqs,
                /* 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. */