On Tue, Feb 03, 2026 at 12:55:07PM +0100, Harald Mommer wrote:
>
>
> On 1/9/26 18:23, Francesco Valla wrote:
> >> +static u8 virtio_can_send_ctrl_msg(struct net_device *ndev, u16 msg_type)
> >> +{
> >> + struct scatterlist sg_out, sg_in, *sgs[2] = { &sg_out, &sg_in };
> >> + struct virtio_can_priv *priv = netdev_priv(ndev);
> >> + struct device *dev = &priv->vdev->dev;
> >> + struct virtqueue *vq;
> >> + unsigned int len;
> >> + int err;
> >> +
> >> + vq = priv->vqs[VIRTIO_CAN_QUEUE_CONTROL];
> > Nit: consider initializing this above, while declaring it.
>
> All those "Nit" regarding initialization cause problems. There is a reason
> why it was done the way it is.
>
> The network people require that the declaration lines are ordered by line
> length. longest line first. This is called "Reverse Christmas tree". Don't
> ask me why, this formatting style is what the network people require. Their
> subsystem, their rules.
>
> To initialize the vq you need now already the priv initialized. If now the vq
> line becomes longer than the priv line you will violate the special
> formatting requirements of the network subsystem.
>
> Solution was: What you see above.
>
> Regards
> Harald
So you reorder it then:
struct scatterlist sg_out, sg_in, *sgs[2] = { &sg_out, &sg_in };
struct virtqueue *vq = priv->vqs[VIRTIO_CAN_QUEUE_CONTROL];
struct virtio_can_priv *priv = netdev_priv(ndev);
struct device *dev = &priv->vdev->dev;
unsigned int len;
int err;
and where is the problem?
On the flip size, this guarantees we will not forget to initialize.
--
MST
