Re: [PATCH net v2 1/2] virtio_net: Do not set rss_indir if RSS is not supported

[Heng Qi]

在 2024/3/28 下午10:37, Breno Leitao 写道:
> > > On Wed, Mar 27, 2024 at 09:37:43AM +0800, Xuan Zhuo wrote:
> > > > On Tue, 26 Mar 2024 08:19:08 -0700, Breno Leitao <leitao@xxxxxxxxxx> wrote:
> > > > > Do not set virtnet_info->rss_indir_table_size if RSS is not available
> > > > > for the device.
> > > > >
> > > > > Currently, rss_indir_table_size is set if either has_rss or
> > > > > has_rss_hash_report is available, but, it should only be set if has_rss
> > > > > is set.
> > > > >
> > > > > On the virtnet_set_rxfh(), return an invalid command if the request has
> > > > > indirection table set, but virtnet does not support RSS.
> > > > >
> > > > > Suggested-by: Heng Qi <hengqi@xxxxxxxxxxxxxxxxx>
> > > > > Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx>
> > > > > ---
> > > > >   drivers/net/virtio_net.c | 9 +++++++--
> > > > >   1 file changed, 7 insertions(+), 2 deletions(-)
> > > > >
> > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > > > > index c22d1118a133..c640fdf28fc5 100644
> > > > > --- a/drivers/net/virtio_net.c
> > > > > +++ b/drivers/net/virtio_net.c
> > > > > @@ -3813,6 +3813,9 @@ static int virtnet_set_rxfh(struct net_device *dev,
> > > > >   	    rxfh->hfunc != ETH_RSS_HASH_TOP)
> > > > >   		return -EOPNOTSUPP;
> > > > >
> > > > > +	if (rxfh->indir && !vi->has_rss)
> > > > > +		return -EINVAL;
> > > > > +
> > > > >   	if (rxfh->indir) {
> > > > Put !vi->has_rss here?
> > > I am not sure I understand the suggestion. Where do you suggest we have
> > > !vi->has_rss?
> > >
> > > If we got this far, we either have:
> > >
> > > a) rxfh->indir set and vi->has_rss is also set
> > > b) rxfh->indir not set. (vi->has_rss could be set or not).
> >
> > This function does two tasks.
> > 1. update indir table
> > 2. update rss key
> >
> > #1 only for has_rss
> > #2 for has_rss or has_rss_hash_report
> >
> >
> > So I would code:
> >
> > 	bool update = false
> >
> > 	if (rxfh->indir) {
> > 		if (!vi->has_rss)
> > 			return -EINVAL;
> >
> > 		for (i = 0; i < vi->rss_indir_table_size; ++i)
> > 			vi->ctrl->rss.indirection_table[i] = rxfh->indir[i];
> >
> > 		update = true
> > 	}
> >
> > 	if (rxfh->key) {
> > 		if (!vi->has_rss && !vi->has_rss_hash_report)
> > 			return -EINVAL;
> >
> > 		memcpy(vi->ctrl->rss.key, rxfh->key, vi->rss_key_size);
> > 		update = true
> > 	}
> >
> >
> > 	if (update)
> > 		virtnet_commit_rss_command(vi);
> >
> > Thanks.
> This is a bit different from the previous proposal, but, I like this one
> approach better. It makes the code easier to read.
>
> How does the full patch looks like?
>
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index c22d1118a133..180f342f1898 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -3807,20 +3807,35 @@ static int virtnet_set_rxfh(struct net_device *dev,
>   			    struct netlink_ext_ack *extack)
>   {
>   	struct virtnet_info *vi = netdev_priv(dev);
> +	bool update = false;
>   	int i;
>   
> +	if (!vi->has_rss && !vi->has_rss_hash_report)
> +		return -EOPNOTSUPP;
> +

I think this two modifications are no longer needed as they have been 
embedded below.

>   	if (rxfh->hfunc != ETH_RSS_HASH_NO_CHANGE &&
>   	    rxfh->hfunc != ETH_RSS_HASH_TOP)
>   		return -EOPNOTSUPP;
>   
>   	if (rxfh->indir) {
> +		if (!vi->has_rss)
> +			return -EINVAL;

-EOPNOTSUPP seems better.

> +
>   		for (i = 0; i < vi->rss_indir_table_size; ++i)
>   			vi->ctrl->rss.indirection_table[i] = rxfh->indir[i];
> +		update = true;
>   	}
> -	if (rxfh->key)
> +
> +	if (rxfh->key) {
> +		if (!vi->has_rss && !vi->has_rss_hash_report)
> +			return -EINVAL;

Same as above. return -EOPNOTSUPP.

Others look good.

Thanks.

> +
>   		memcpy(vi->ctrl->rss.key, rxfh->key, vi->rss_key_size);
> +		update = true;
> +	}
>   
> -	virtnet_commit_rss_command(vi);
> +	if (update)
> +		virtnet_commit_rss_command(vi);
>   
>   	return 0;
>   }
> @@ -4729,13 +4744,15 @@ static int virtnet_probe(struct virtio_device *vdev)
>   	if (virtio_has_feature(vdev, VIRTIO_NET_F_HASH_REPORT))
>   		vi->has_rss_hash_report = true;
>   
> -	if (virtio_has_feature(vdev, VIRTIO_NET_F_RSS))
> +	if (virtio_has_feature(vdev, VIRTIO_NET_F_RSS)) {
>   		vi->has_rss = true;
>   
> -	if (vi->has_rss || vi->has_rss_hash_report) {
>   		vi->rss_indir_table_size =
>   			virtio_cread16(vdev, offsetof(struct virtio_net_config,
>   				rss_max_indirection_table_length));
> +	}
> +
> +	if (vi->has_rss || vi->has_rss_hash_report) {
>   		vi->rss_key_size =
>   			virtio_cread8(vdev, offsetof(struct virtio_net_config, rss_max_key_size));
>