RE: [PATCH v2 2/2] virtio-pci: check name when counting MSI-X vectors

Subject: [PATCH v2 2/2] 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 <redacted>
---

v1:
https://lists.linuxfoundation.org/pipermail/virtualization/2019-December/0448
28.html

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

diff --git a/drivers/virtio/virtio_pci_common.c

b/drivers/virtio/virtio_pci_common.c
index f2862f66c2ac..222d630c41fc 100644

--- 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. */
--
2.24.1.735.g03f4e72817-goog