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([2a0d:3344:2706:e010:b099:aac6:4e70:6198]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-441b2ad7ab1sm212836775e9.4.2025.05.06.04.23.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 06 May 2025 04:23:23 -0700 (PDT) Message-ID: <3e91e070-24a2-4dab-bca5-157fea921bf0@redhat.com> Date: Tue, 6 May 2025 13:23:21 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [net-next v11 4/7] net: mtip: The L2 switch driver for imx287 To: Lukasz Majewski Cc: Andrew Lunn , davem@davemloft.net, Eric Dumazet , Jakub Kicinski , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Richard Cochran , netdev@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, Stefan Wahren , Simon Horman , Andrew Lunn References: <20250504145538.3881294-1-lukma@denx.de> <20250504145538.3881294-5-lukma@denx.de> <61ebe754-d895-47cb-a4b2-bb2650b9ff7b@redhat.com> <20250506130438.149c137e@wsk> From: Paolo Abeni In-Reply-To: <20250506130438.149c137e@wsk> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: Bkon7cb9kR4upCjKIoZQcR118B8xxklyt3kj2aZXuwA_1746530605 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250506_042327_934931_2183E6DB X-CRM114-Status: GOOD ( 16.08 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 5/6/25 1:04 PM, Lukasz Majewski wrote: >> On 5/4/25 4:55 PM, Lukasz Majewski wrote: >>> + /* This does 16 byte alignment, exactly what we >>> need. >>> + * The packet length includes FCS, but we don't >>> want to >>> + * include that when passing upstream as it messes >>> up >>> + * bridging applications. >>> + */ >>> + skb = netdev_alloc_skb(pndev, pkt_len + >>> NET_IP_ALIGN); >>> + if (unlikely(!skb)) { >>> + dev_dbg(&fep->pdev->dev, >>> + "%s: Memory squeeze, dropping >>> packet.\n", >>> + pndev->name); >>> + pndev->stats.rx_dropped++; >>> + goto err_mem; >>> + } else { >>> + skb_reserve(skb, NET_IP_ALIGN); >>> + skb_put(skb, pkt_len); /* Make room */ >>> + skb_copy_to_linear_data(skb, data, >>> pkt_len); >>> + skb->protocol = eth_type_trans(skb, pndev); >>> + napi_gro_receive(&fep->napi, skb); >>> + } >>> + >>> + bdp->cbd_bufaddr = dma_map_single(&fep->pdev->dev, >>> data, >>> + bdp->cbd_datlen, >>> + DMA_FROM_DEVICE); >>> + if (unlikely(dma_mapping_error(&fep->pdev->dev, >>> + bdp->cbd_bufaddr))) >>> { >>> + dev_err(&fep->pdev->dev, >>> + "Failed to map descriptor rx >>> buffer\n"); >>> + pndev->stats.rx_errors++; >>> + pndev->stats.rx_dropped++; >>> + dev_kfree_skb_any(skb); >>> + goto err_mem; >>> + } >> >> This is doing the mapping and ev. dropping the skb _after_ pushing the >> skb up the stack, you must attempt the mapping first. >> >>> +static void mtip_free_buffers(struct net_device *dev) >>> +{ >>> + struct mtip_ndev_priv *priv = netdev_priv(dev); >>> + struct switch_enet_private *fep = priv->fep; >>> + struct sk_buff *skb; >>> + struct cbd_t *bdp; >>> + int i; >>> + >>> + bdp = fep->rx_bd_base; >>> + for (i = 0; i < RX_RING_SIZE; i++) { >>> + skb = fep->rx_skbuff[i]; >>> + >>> + if (bdp->cbd_bufaddr) >>> + dma_unmap_single(&fep->pdev->dev, >>> bdp->cbd_bufaddr, >>> + MTIP_SWITCH_RX_FRSIZE, >>> + DMA_FROM_DEVICE); >>> + if (skb) >>> + dev_kfree_skb(skb); >> >> I suspect that on error paths mtip_free_buffers() can be invoked >> multiple consecutive times with any successful allocation in between: >> skb will be freed twice. Likely you need to clear fep->rx_skbuff[i] >> here. > > I don't know what I shall say now.... really... I suspect my email was not clear. AFAICS the current code contains at least 2 serious issues, possibly more not yet discovered due to the patch size. You need to submit (at least) a new revision coping with the provided feedback. Thanks, Paolo