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Sun, 15 Nov 2026 05:49:23 -0800 (PST) Received: from kordpc.lan ([2a13:e746:396c:c600::8fa]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c5095b7eb14sm314858866b.75.2026.11.15.05.49.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 15 Nov 2026 05:49:23 -0800 (PST) From: Kordian Chmielewski To: netdev@vger.kernel.org Cc: Florian Fainelli , Florian Fainelli , =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= , bcm-kernel-feedback-list@broadcom.com, Andrew Lunn , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-kernel@vger.kernel.org Subject: Re: [PATCH net v3 1/7] net: bcm4908_enet: fix the TX ring wrap Date: Sun, 15 Nov 2026 14:49:20 +0100 Message-ID: <20261115134920.55329-1-kudzo51@gmail.com> X-Mailer: git-send-email 2.56.1 In-Reply-To: <20261113235847.517308-2-kudzo51@gmail.com> References: <20261113235847.517308-2-kudzo51@gmail.com> X-Mailing-List: linux-kernel@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 Sashiko's review of this patch [1] attributes one Medium point to it: start_xmit() still stops the queue with netif_stop_queue() when the descriptor at write_idx has OWN set, and poll_tx() no longer wakes the queue unconditionally, so a stale OWN descriptor after ifdown/ifup could stop the queue for good. In the case the review describes, the ring is empty: start_xmit() returns before anything has kicked the DMA, so no TX interrupt comes and poll_tx() never runs. That stop could not be undone before this patch either; patch 3's changelog describes it. With stale OWN descriptors further in the ring and frames in flight, the old unconditional wake could undo such a stop and the new wake does not, until patch 3 removes the check and clears the TX descriptors when the ring is initialised. I left that change in patch 3 so that this one stays the ring wrap fix. The other points in that review are older than this series. Patches 3, 6 and 7 fix three of them, and the missing TX interrupt is the question I asked under v2. [1] https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20261113235847.517308-1-kudzo51%40gmail.com