linux-kernel - Re: [net-next v3 2/3] net: dsa: tag_yt921x: add support for Motorcomm YT921x tags

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Message-ID: <095df250-2ef9-4589-893d-f28193076f16@lunn.ch>
Date: Sat, 16 Aug 2025 17:24:52 +0200
From: Andrew Lunn <andrew@...n.ch>
To: David Yang <mmyangfl@...il.com>
Cc: netdev@...r.kernel.org, Vladimir Oltean <olteanv@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Simon Horman <horms@...nel.org>,
	Russell King <linux@...linux.org.uk>, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [net-next v3 2/3] net: dsa: tag_yt921x: add support for
 Motorcomm YT921x tags

> +static struct sk_buff *
> +yt921x_tag_rcv(struct sk_buff *skb, struct net_device *netdev)
> +{
> +	unsigned int port;
> +	__be16 *tag;
> +	u16 rx;
> +
> +	if (unlikely(!pskb_may_pull(skb, YT921X_TAG_LEN)))
> +		return NULL;
> +
> +	tag = (__be16 *)skb->data;
> +
> +	/* Locate which port this is coming from */
> +	rx = ntohs(tag[1]);
> +	if (unlikely((rx & YT921X_TAG_PORT_EN) == 0)) {
> +		netdev_err(netdev, "Unexpected rx tag 0x%04x\n", rx);
> +		return NULL;
> +	}
> +
> +	port = FIELD_GET(YT921X_TAG_RX_PORT_M, rx);
> +	skb->dev = dsa_conduit_find_user(netdev, 0, port);
> +	if (unlikely(!skb->dev)) {
> +		dev_warn_ratelimited(&netdev->dev,
> +				     "Cannot locate rx port %u\n", port);
> +		return NULL;
> +	}

Why do you rate limit the second, but not the first?

	Andrew