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

["Wang, Wei W" <wei.w.wang@intel.com>]

On Saturday, January 4, 2020 2:41 AM, Daniel Verkamp wrote:
> 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 <dverkamp@chromium.org>
> ---
> 
> 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

Reviewed-by: Wang, Wei W <wei.w.wang@intel.com>

Best,
Wei