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Date: Tue, 3 Oct 2023 06:34:01 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Vladimir Oltean <olteanv@gmail.com>
Cc: Lukasz Majewski <lukma@denx.de>, Tristram.Ha@microchip.com, Eric Dumazet
 <edumazet@google.com>, Andrew Lunn <andrew@lunn.ch>, davem@davemloft.net,
 Woojung Huh <woojung.huh@microchip.com>, Oleksij Rempel
 <o.rempel@pengutronix.de>, Florian Fainelli <f.fainelli@gmail.com>, Paolo
 Abeni <pabeni@redhat.com>, UNGLinuxDriver@microchip.com, Oleksij Rempel
 <linux@rempel-privat.de>, netdev@vger.kernel.org,
 linux-kernel@vger.kernel.org
Subject: Re: [[RFC PATCH v4 net-next] 0/2] net: dsa: hsr: Enable HSR HW
 offloading for KSZ9477
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On Mon, 11 Sep 2023 20:02:22 +0300 Vladimir Oltean wrote:
> Hi @Jakub, I remember you fixed some issues with the dev->dev_addr writes,
> after dev_addr_lists.c was changed to a rbtree. Is it easy for you to
> tell if the change below is safe from an API perspective?
> 
> Is the answer "yes, because dev_uc_add() uses an addr_type of NETDEV_HW_ADDR_T_UNICAST,
> and dev->dev_addr uses NETDEV_HW_ADDR_T_LAN, so they never share a struct netdev_hw_addr
> for the same MAC address, and thus, they never collide"?
> 
> The DSA and 8021q drivers currently have this pattern, from around 2008.
> But 8021q also tracks NETDEV_CHANGEADDR events on the real_dev, which is
> absent in DSA. If the change below is safe, it would be a simpler solution.

FWIW I think it should be fine from the rbtree perspective, but IDK how
the user space would react to having a duplicate lladdr.