Re: [PATCH net v2 1/1] net: stmmac: Prevent DSA tags from breaking COE on stmmac

From: Romain Gantois <romain.gantois@bootlin.com>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Romain Gantois <romain.gantois@bootlin.com>,
	 Alexandre Torgue <alexandre.torgue@foss.st.com>,
	 Jose Abreu <joabreu@synopsys.com>,
	"David S. Miller" <davem@davemloft.net>,
	 Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>,
	 Paolo Abeni <pabeni@redhat.com>,
	 Maxime Coquelin <mcoquelin.stm32@gmail.com>,
	 Miquel Raynal <miquel.raynal@bootlin.com>,
	 Maxime Chevallier <maxime.chevallier@bootlin.com>,
	 Sylvain Girard <sylvain.girard@se.com>,
	 Vladimir Oltean <olteanv@gmail.com>,
	Andrew Lunn <andrew@lunn.ch>,
	 Pascal EBERHARD <pascal.eberhard@se.com>,
	 Richard Tresidder <rtresidd@electromag.com.au>,
	netdev@vger.kernel.org,
	 linux-stm32@st-md-mailman.stormreply.com,
	 linux-arm-kernel@lists.infradead.org, stable@vger.kernel.org
Subject: Re: [PATCH net v2 1/1] net: stmmac: Prevent DSA tags from breaking COE on stmmac
Date: Wed, 3 Jan 2024 10:11:54 +0100 (CET)	[thread overview]
Message-ID: <d3d73e26-10a9-bd2b-ff44-cbdc72e1f6ee@bootlin.com> (raw)
In-Reply-To: <CACRpkdZjOBpD6HoobgMBA27dS+uz5pqb8otL+fGtMvsywYBTPA@mail.gmail.com>

Hi Linus,

On Tue, 2 Jan 2024, Linus Walleij wrote:
...
> > +static inline bool stmmac_has_ip_ethertype(struct sk_buff *skb)
> > +{
> > +       __be16 proto = eth_header_parse_protocol(skb);
> 
> I made a new function for this in my patch
> https://lore.kernel.org/netdev/20231222-new-gemini-ethernet-regression-v4-2-a36e71b0f32b@linaro.org/
> 
> I was careful to add if (!pskb_may_pull(skb, ETH_HLEN)) because Eric
> was very specific about this, I suppose you could get fragment frames that
> are smaller than an ethernet header.

Okay nice, then I'll rewrite this series to use the new function once your 
changes make it in.

> Should we add an if (!pskb_may_pull(skb, ETH_HLEN)) to
> eth_header_parse_protocol()?
That does sound logical to me but I couldn't tell you what the impact on current 
callers would be. The net maintainers will probably have a better idea of this.

Best Regards,

-- 
Romain Gantois, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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