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[83.233.221.133]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c46bd350b52sm513224766b.7.2026.10.27.14.25.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Oct 2026 14:25:09 -0700 (PDT) From: Yongzhao Chen To: Andrew Lunn Cc: netdev-bot+sinfo@kernel.org, netdev@vger.kernel.org, Christian Marangi , Vladimir Oltean , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Russell King , Florian Fainelli , linux-kernel@vger.kernel.org, Ziyang Huang , Stanislaw Pal Subject: Re: [PATCH net v7] net: dsa: qca8k: preserve port state across MTU changes Date: Tue, 27 Oct 2026 22:25:05 +0100 Message-ID: <20261027212505.1848-1-yongzhao.derek@gmail.com> X-Mailer: git-send-email 2.55.0.windows.5 In-Reply-To: <47e9713f-815e-4caf-8928-a7ec12d0087b@lunn.ch> References: <20261022155837.760-1-yongzhao.derek@gmail.com> <179268501671.3290.6623232109527554630@kernel.org> <20261027092718.266370-1-yongzhao.derek@gmail.com> <47e9713f-815e-4caf-8928-a7ec12d0087b@lunn.ch> X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Andrew, On Tue, Oct 27, 2026 at 01:54:16PM +0100, Andrew Lunn wrote: > Is this a real problem which bothers somebody? If it has not been seen > in production, it sounds like it does not bother anybody. So net-next. It has not been seen in production. Following your suggestion, I will move it to net-next. v7 needs another revision anyway. Sashiko's review [1] is right: a concurrent PORT_STATUS reader such as the PCS poll can corrupt the MTU snapshot, because the qca8k regmap is created with disable_locking and shares its work_buf. Clearing the MAC bits unconditionally would not be enough, since the restore uses the same snapshot and the MAX_FRAME_SIZE write also goes through work_buf. Stanislaw's patch [2] enables the regmap lock. With it, the v7 code passes a local KUnit test that forces this interleaving against the real regmap core. I will send v8 for net-next once it reopens and [2] is in net-next, and say in the commit message how the problem was found, as sinfo asked. [1] https://lore.kernel.org/netdev/179303171241.3134.15019965307136674652@kernel.org/ [2] https://lore.kernel.org/netdev/20261022192933.384898-2-kuncy7@gmail.com/ pw-bot: cr