netdev - Re: [PATCH net v3 2/3] net: stmmac: Consider Tx VLAN offload tag length for maxSDU

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Message-ID: <aPI6MEVp9WBR3nRo@shell.armlinux.org.uk>
Date: Fri, 17 Oct 2025 13:44:32 +0100
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: rohan.g.thomas@...era.com
Cc: Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Jose Abreu <Jose.Abreu@...opsys.com>,
	Rohan G Thomas <rohan.g.thomas@...el.com>,
	Boon Khai Ng <boon.khai.ng@...era.com>, netdev@...r.kernel.org,
	linux-stm32@...md-mailman.stormreply.com,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Matthew Gerlach <matthew.gerlach@...era.com>
Subject: Re: [PATCH net v3 2/3] net: stmmac: Consider Tx VLAN offload tag
 length for maxSDU

On Fri, Oct 17, 2025 at 02:11:20PM +0800, Rohan G Thomas via B4 Relay wrote:
> From: Rohan G Thomas <rohan.g.thomas@...era.com>
> 
> On hardware with Tx VLAN offload enabled, add the VLAN tag length to
> the skb length before checking the Qbv maxSDU if Tx VLAN offload is
> requested for the packet. Add 4 bytes for 802.1Q tag.

This needs to say _why_. Please describe the problem that the current
code suffers from. (e.g. the packet becomes too long for the queue to
handle, which causes it to be dropped - which is my guess.)

We shouldn't be guessing the reasons behind changes.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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