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From: Vladimir Oltean <vladimir.oltean@nxp.com>
To: Florian Fainelli <f.fainelli@gmail.com>
Cc: Maxime Chevallier <maxime.chevallier@bootlin.com>,
	"davem@davemloft.net" <davem@davemloft.net>,
	Rob Herring <robh+dt@kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"thomas.petazzoni@bootlin.com" <thomas.petazzoni@bootlin.com>,
	Andrew Lunn <andrew@lunn.ch>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	Russell King <linux@armlinux.org.uk>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	Luka Perkov <luka.perkov@sartura.hr>,
	Robert Marko <robert.marko@sartura.hr>
Subject: Re: [PATCH net-next v2 2/5] net: dsa: add out-of-band tagging protocol
Date: Thu, 19 May 2022 17:34:37 +0000	[thread overview]
Message-ID: <20220519173436.z7g2sshz5ivqlpe7@skbuf> (raw)
In-Reply-To: <c16384a3-d868-11e7-ceed-bc8e7029962a@gmail.com>

On Thu, May 19, 2022 at 10:11:13AM -0700, Florian Fainelli wrote:
> unless we somehow manage to put it in the linear portion of
> the SKB to avoid using any control buffer or extension.

But how? Essentially the DSA master has to look at a packet and
determine whether it came from DSA based on something which non-DSA
code could not have done. In fact, I'm looking at the calls to
skb_reset_mac_{header,len} from net/core/skbuff.c, specifically at VLAN
and MPLS, and I believe (but haven't tested) that pushing such headers
would also alter skb->mac_len to some value != ETH_HLEN. So simply
having the DSA master check whether DSA was there by checking whether
skb->mac_len is ETH_HLEN + DSA tag len could easily confuse DSA with
some other protocol of same header size.

  reply	other threads:[~2022-05-19 17:34 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-14 15:06 [PATCH net-next v2 0/5] net: ipqess: introduce Qualcomm IPQESS driver Maxime Chevallier
2022-05-14 15:06 ` [PATCH net-next v2 1/5] net: ipqess: introduce the " Maxime Chevallier
2022-05-14 17:18   ` Russell King (Oracle)
2022-05-17  7:09     ` Maxime Chevallier
2022-05-14 20:44   ` Vladimir Oltean
2022-05-17  7:11     ` Maxime Chevallier
2022-05-16  2:51   ` Andrew Lunn
2022-05-17  7:13     ` Maxime Chevallier
2022-05-17 21:03   ` Christophe JAILLET
2022-05-14 15:06 ` [PATCH net-next v2 2/5] net: dsa: add out-of-band tagging protocol Maxime Chevallier
2022-05-14 16:33   ` Florian Fainelli
2022-05-17  7:06     ` Maxime Chevallier
2022-05-14 22:40   ` Vladimir Oltean
2022-05-17  7:01     ` Maxime Chevallier
2022-05-19 14:52       ` Vladimir Oltean
2022-05-19 17:11         ` Florian Fainelli
2022-05-19 17:34           ` Vladimir Oltean [this message]
2022-05-16 19:20   ` Jakub Kicinski
2022-05-17  6:53     ` Maxime Chevallier
2022-05-17 20:58       ` Jakub Kicinski
2022-05-14 15:06 ` [PATCH net-next v2 3/5] net: ipqess: Add out-of-band DSA tagging support Maxime Chevallier
2022-05-14 15:06 ` [PATCH net-next v2 4/5] net: dt-bindings: Introduce the Qualcomm IPQESS Ethernet controller Maxime Chevallier
2022-05-18  0:52   ` Rob Herring
2022-05-14 15:06 ` [PATCH net-next v2 5/5] ARM: dts: qcom: ipq4019: Add description for the " Maxime Chevallier

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