Re: [PATCH net-next v5 05/15] net: airoha: Move DSA tag in DMA descriptor

[Jakub Kicinski <kuba@kernel.org>]

On Mon, 17 Feb 2025 14:01:09 +0100 Lorenzo Bianconi wrote:
> +static u32 airoha_get_dsa_tag(struct sk_buff *skb, struct net_device *dev)
> +{
> +#if IS_ENABLED(CONFIG_NET_DSA)
> +	struct ethhdr *ehdr;
> +	struct dsa_port *dp;
> +	u8 xmit_tpid;
> +	u16 tag;
> +
> +	if (!netdev_uses_dsa(dev))
> +		return 0;
> +
> +	dp = dev->dsa_ptr;
> +	if (IS_ERR(dp))
> +		return 0;
> +
> +	if (dp->tag_ops->proto != DSA_TAG_PROTO_MTK)
> +		return 0;
> +
> +	if (skb_ensure_writable(skb, ETH_HLEN))
> +		return 0;

skb_cow_head() is a lot cheaper (for TCP)

> +	ehdr = (struct ethhdr *)skb->data;
> +	tag = be16_to_cpu(ehdr->h_proto);
> +	xmit_tpid = tag >> 8;

> @@ -2390,8 +2498,10 @@ static int airoha_probe(struct platform_device *pdev)
>  	for (i = 0; i < ARRAY_SIZE(eth->ports); i++) {
>  		struct airoha_gdm_port *port = eth->ports[i];
>  
> -		if (port && port->dev->reg_state == NETREG_REGISTERED)
> +		if (port && port->dev->reg_state == NETREG_REGISTERED) {
> +			airoha_metadata_dst_free(port);
>  			unregister_netdev(port->dev);

Looks a tiny bit reversed, isn't it?
First unregister the netdev, then free its metadata.

> +		}
>  	}
>  	free_netdev(eth->napi_dev);
>  	platform_set_drvdata(pdev, NULL);
> @@ -2416,6 +2526,7 @@ static void airoha_remove(struct platform_device *pdev)
>  			continue;
>  
>  		airoha_dev_stop(port->dev);
> +		airoha_metadata_dst_free(port);
>  		unregister_netdev(port->dev);

same here

>  	}
>  	free_netdev(eth->napi_dev);