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Fri, 19 Dec 2025 02:04:27 -0800 (PST) Received: from DC5-EXCH05.marvell.com (10.69.176.209) by DC5-EXCH05.marvell.com (10.69.176.209) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.25; Fri, 19 Dec 2025 02:04:40 -0800 Received: from maili.marvell.com (10.69.176.80) by DC5-EXCH05.marvell.com (10.69.176.209) with Microsoft SMTP Server id 15.2.1544.25 via Frontend Transport; Fri, 19 Dec 2025 02:04:40 -0800 Received: from test-OptiPlex-Tower-Plus-7010 (unknown [10.29.37.157]) by maili.marvell.com (Postfix) with SMTP id 56EA15B695F; Fri, 19 Dec 2025 02:04:21 -0800 (PST) Date: Fri, 19 Dec 2025 15:34:20 +0530 From: Hariprasad Kelam To: Wei Fang CC: "andrew+netdev@lunn.ch" , "davem@davemloft.net" , "edumazet@google.com" , "kuba@kernel.org" , "pabeni@redhat.com" , "mcoquelin.stm32@gmail.com" , "alexandre.torgue@foss.st.com" , "ast@kernel.org" , "daniel@iogearbox.net" , "hawk@kernel.org" , "john.fastabend@gmail.com" , "sdf@fomichev.me" , "rmk+kernel@armlinux.org.uk" , "0x1207@gmail.com" <0x1207@gmail.com>, "hayashi.kunihiko@socionext.com" , Vladimir Oltean , "boon.leong.ong@intel.com" , "imx@lists.linux.dev" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-stm32@st-md-mailman.stormreply.com" , "linux-arm-kernel@lists.infradead.org" , "bpf@vger.kernel.org" Subject: Re: [PATCH net] net: stmmac: fix the crash issue for zero copy XDP_TX action Message-ID: References: <20251204071332.1907111-1-wei.fang@nxp.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMjE5MDA4MiBTYWx0ZWRfX9GQmj9XB3SQL oH49VqzVFggN9rADC22341hevpvUlzCz5zG1MrgQuOsIMCNzc3+yjg5UdZhOVtkK4q6l8G3zdXY 0YrrsVUl2BmGnuRzGZujnJcMgtei4YwiBarLbJV7IJV9b3uwcAAOyOVhouAm9Inr25xZLPjTA+a JaPOlv+y1Gydv5xSuOc6A4/xsj4bYcDmU9v7F0q9bL8PwuMdzTX2C3QcpqTaNESo6ESjdLGnSQC UDOuFH5DTivmNSZA2j3S1tkFyrkRoKC4HpGf2brlqlFV0CzjrhplEEo1houxaNc50opKnfnSY0P UOGOX5Hnn5YvpB6OVT8DIQY93acypB0IZys4mklgv0j2nCVseYUkFi2ga82EOKJE72itirstiHr rEg3oD15Mm+229wHkEpCPXIGfjXRkwFgOKUVvMEJpIfH3pl71JKD/3c/WDzv6H5popQK4puDPER +Dd2qK9AGNJtDewE/Tg== X-Proofpoint-ORIG-GUID: lly9dLQ9twDymCjIyijl416JTD7HhVSR X-Authority-Analysis: v=2.4 cv=T4uBjvKQ c=1 sm=1 tr=0 ts=6945232b cx=c_pps a=rEv8fa4AjpPjGxpoe8rlIQ==:117 a=rEv8fa4AjpPjGxpoe8rlIQ==:17 a=w373o-ZMvzc93a0z:21 a=kj9zAlcOel0A:10 a=wP3pNCr1ah4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=8AirrxEcAAAA:8 a=M5GUcnROAAAA:8 a=DZSnwkNSkk__NUsnbCUA:9 a=CjuIK1q_8ugA:10 a=ST-jHhOKWsTCqRlWije3:22 a=OBjm3rFKGHvpk9ecZwUJ:22 X-Proofpoint-GUID: lly9dLQ9twDymCjIyijl416JTD7HhVSR X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2025-12-19_03,2025-12-17_02,2025-10-01_01 On 2025-12-18 at 12:06:47, Wei Fang (wei.fang@nxp.com) wrote: > > On 2025-12-17 at 18:19:19, Wei Fang (wei.fang@nxp.com) wrote: > > > > > - res = stmmac_xdp_xmit_xdpf(priv, queue, xdpf, false); > > > > > - if (res == STMMAC_XDP_TX) > > > > > + /* For zero copy XDP_TX action, dma_map is true */ > > > > > + res = stmmac_xdp_xmit_xdpf(priv, queue, xdpf, zc); > > > > Seems stmmac_xdp_xmit_xdpf is using dma_map_single if we pass zc is > > > > true. > > > > Ideally in case of zc, driver can use > > > > page_pool_get_dma_addr, may be you > > > > need pass zc param as false. Please check > > > > > > > > > > No, the memory type of xdpf->data is MEM_TYPE_PAGE_ORDER0 rather than > > > MEM_TYPE_PAGE_POOL, so we should use dma_map_single(). > > > Otherwise, it will lead to invalid mappings and cause the crash. > > > > > > > > ACK, found below code bit confusing > > case STMMAC_XDP_CONSUMED: > > xsk_buff_free(buf->xdp); > > + fallthrough; > > + case STMMAC_XSK_CONSUMED: > > rx_dropped++; > > > > Ideally in case of STMMAC_XSK_CONSUMED, driver needs to call > > xsk_buff_free. > > And in case of STMMAC_XDP_CONSUMED, driver needs to call > > xdp_return_frame. > > May be you can move all buffer free logic to stmmac_rx_zc with above > > suggested > > changes. > > For zero copy, the xdp_buff is freed by xdp_convert_buff_to_frame() > when converting the xdp_xdp to xdp_frame. So STMMAC_XSK_CONSUMED > means the xdp_buff has been freed, it tells stmmac_rx_zc() no to free a > xdp_buff that has been freed. > > I have added a comment for STMMAC_XSK_CONSUMED, see > > + } else if (res == STMMAC_XDP_CONSUMED && zc) { > + /* xdp has been freed by xdp_convert_buff_to_frame(), > + * no need to call xsk_buff_free() again, so return > + * STMMAC_XSK_CONSUMED. > + */ > + res = STMMAC_XSK_CONSUMED; > + xdp_return_frame(xdpf); > + } > > ACK. Reviewed-by: Hariprasad Kelam