Re: [PATCH v2 1/4] virtio_net: Add a virtqueue for outbound control commands

Rusty Russell
2009-01-30T05:08:14Z

On Friday 30 January 2009 09:35:07 Alex Williamson wrote:
> +static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
> + void *data, unsigned int len)
> +{
> + struct scatterlist sg[3];
> + struct virtio_net_ctrl_hdr ctrl;
> + virtio_net_ctrl_ack status;
> + unsigned int tmp;
> + int i = 0;
> +
> + if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ))
> + return false;
> +
> + sg_init_table(sg, len ? 3 : 2);

I'd test data rather than len here.

> + sg_set_buf(&sg[i++], &ctrl, sizeof(ctrl));
> + if (len)
> + sg_set_buf(&sg[i++], data, len);
> + sg_set_buf(&sg[i], &status, sizeof(status));
> +
> + ctrl.class = class;
> + ctrl.cmd = cmd;
> +
> + status = ~0;
> +
> + if (vi->cvq->vq_ops->add_buf(vi->cvq, sg, i, 1, vi) != 0)
> + BUG();

Hmm, I prefer initialize buffer, then set sg to refer to it. Seems to make
more sense to me.

> + while (!vi->cvq->vq_ops->get_buf(vi->cvq, &tmp))
> + cpu_relax();

This probably deserves a comment about why it's OK to spin here.

> + return status == VIRTIO_NET_OK ? true : false;

Or "return status == VIRTIO_NET_OK;" ?

See what I mean about nit-picking?
Rusty.