From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 66DFE43C30; Thu, 29 Feb 2024 04:58:11 +0100 (CET) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id E7198402AC; Thu, 29 Feb 2024 04:58:10 +0100 (CET) Received: from szxga04-in.huawei.com (szxga04-in.huawei.com [45.249.212.190]) by mails.dpdk.org (Postfix) with ESMTP id 3C1CB402A3 for ; Thu, 29 Feb 2024 04:58:08 +0100 (CET) Received: from mail.maildlp.com (unknown [172.19.162.112]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4Tlcpk0hPkz1xppV; Thu, 29 Feb 2024 11:56:30 +0800 (CST) Received: from dggpeml500011.china.huawei.com (unknown [7.185.36.84]) by mail.maildlp.com (Postfix) with ESMTPS id 08D8614011F; Thu, 29 Feb 2024 11:58:01 +0800 (CST) Received: from [10.67.121.193] (10.67.121.193) by dggpeml500011.china.huawei.com (7.185.36.84) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.35; Thu, 29 Feb 2024 11:58:00 +0800 Message-ID: <760c70e6-ca2d-4d5e-9a05-809b81d32dd3@huawei.com> Date: Thu, 29 Feb 2024 11:58:00 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] net/hns3: fix Rx packet truncation when KEEP CRC enabled Content-Language: en-US To: Ferruh Yigit , Jie Hai , CC: , , References: <20240206011030.2007689-1-haijie1@huawei.com> <11b8feac-4a9e-4d2c-8995-ed492d684750@amd.com> <7438563e-c7b4-6e13-68bf-74ff423546af@huawei.com> <6246e1f8-dcd4-468d-a05d-2e292f6e1714@amd.com> <6c831a66-f916-48d4-68d9-4c3bcfcb4979@huawei.com> <1ec105cf-c8d2-4010-867d-30970c25a2a1@amd.com> <7e376ab0-67a0-4a3c-a528-7928077e7b56@huawei.com> From: huangdengdui In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.67.121.193] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggpeml500011.china.huawei.com (7.185.36.84) X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org On 2024/2/28 21:07, Ferruh Yigit wrote: > On 2/28/2024 2:27 AM, huangdengdui wrote: >> >> >> On 2024/2/27 0:43, Ferruh Yigit wrote: >>> On 2/26/2024 3:16 AM, Jie Hai wrote: >>>> On 2024/2/23 21:53, Ferruh Yigit wrote: >>>>> On 2/20/2024 3:58 AM, Jie Hai wrote: >>>>>> Hi, Ferruh, >>>>>> >>>>>> Thanks for your review. >>>>>> >>>>>> On 2024/2/7 22:15, Ferruh Yigit wrote: >>>>>>> On 2/6/2024 1:10 AM, Jie Hai wrote: >>>>>>>> From: Dengdui Huang >>>>>>>> >>>>>>>> When KEEP_CRC offload is enabled, some packets will be truncated and >>>>>>>> the CRC is still be stripped in following cases: >>>>>>>> 1. For HIP08 hardware, the packet type is TCP and the length >>>>>>>>      is less than or equal to 60B. >>>>>>>> 2. For other hardwares, the packet type is IP and the length >>>>>>>>      is less than or equal to 60B. >>>>>>>> >>>>>>> >>>>>>> If a device doesn't support the offload by some packets, it can be >>>>>>> option to disable offload for that device, instead of calculating it in >>>>>>> software and append it. >>>>>> >>>>>> The KEEP CRC feature of hns3 is faulty only in the specific packet >>>>>> type and small packet(<60B) case. >>>>>> What's more, the small ethernet packet is not common. >>>>>> >>>>>>> Unless you have a specific usecase, or requirement to support the >>>>>>> offload. >>>>>> >>>>>> Yes, some users of hns3 are already using this feature. >>>>>> So we cannot drop this offload >>>>>> >>>>>>> <...> >>>>>>> >>>>>>>> @@ -2492,10 +2544,16 @@ hns3_recv_pkts_simple(void *rx_queue, >>>>>>>>                goto pkt_err; >>>>>>>>              rxm->packet_type = hns3_rx_calc_ptype(rxq, l234_info, >>>>>>>> ol_info); >>>>>>>> - >>>>>>>>            if (rxm->packet_type == RTE_PTYPE_L2_ETHER_TIMESYNC) >>>>>>>>                rxm->ol_flags |= RTE_MBUF_F_RX_IEEE1588_PTP; >>>>>>>>    +        if (unlikely(rxq->crc_len > 0)) { >>>>>>>> +            if (hns3_need_recalculate_crc(rxq, rxm)) >>>>>>>> +                hns3_recalculate_crc(rxq, rxm); >>>>>>>> +            rxm->pkt_len -= rxq->crc_len; >>>>>>>> +            rxm->data_len -= rxq->crc_len; >>>>>>>> >>>>>>> >>>>>>> Removing 'crc_len' from 'mbuf->pkt_len' & 'mbuf->data_len' is >>>>>>> practically same as stripping CRC. >>>>>>> >>>>>>> We don't count CRC length in the statistics, but it should be >>>>>>> accessible >>>>>>> in the payload by the user. >>>>>> Our drivers are behaving exactly as you say. >>>>>> >>>>> >>>>> If so I missed why mbuf 'pkt_len' and 'data_len' reduced by >>>>> 'rxq->crc_len', can you please explain what above lines does? >>>>> >>>>> >>>> @@ -2470,8 +2523,7 @@ hns3_recv_pkts_simple(void *rx_queue, >>>>          rxdp->rx.bd_base_info = 0; >>>> >>>>          rxm->data_off = RTE_PKTMBUF_HEADROOM; >>>> -        rxm->pkt_len = (uint16_t)(rte_le_to_cpu_16(rxd.rx.pkt_len)) - >>>> -                rxq->crc_len; >>>> +        rxm->pkt_len = rte_le_to_cpu_16(rxd.rx.pkt_len); >>>> >>>> In the previous code above, the 'pkt_len' is set to the length obtained >>>> from the BD. the length obtained from the BD already contains CRC length. >>>> But as you said above, the DPDK requires that the length of the mbuf >>>> does not contain CRC length . So we subtract 'rxq->crc_len' from >>>> mbuf'pkt_len' and 'data_len'. This patch doesn't change the logic, it >>>> just moves the code around. >>>> >>> >>> Nope, I am not saying mbuf length shouldn't contain CRC length, indeed >>> it is other way around and this is our confusion. >>> >>> CRC length shouldn't be in the statistics, I mean in received bytes stats. >>> Assume that received packet is 128 bytes and we know it has the CRC, >>> Rx received bytes stat should be 124 (rx_bytes = 128 - CRC = 124) >>> >>> But mbuf->data_len & mbuf->pkt_len should have full frame length, >>> including CRC. >>> >>> As application explicitly requested to KEEP CRC, it will know last 4 >>> bytes are CRC. >>> Anything after 'mbuf->data_len' in the mbuf buffer is not valid, so if >>> you reduce 'mbuf->data_len' by CRC size, application can't know if 4 >>> bytes after 'mbuf->data_len' is valid CRC or not. >>> >> I agree with you. >> >> But the implementation of other PMDs supported KEEP_CRC is like this. >> In addition, there are probably many users that are already using it. >> If we modify it, it may cause applications incompatible. >> >> what do you think? >> > This is documented in the ethdev [1], better to follow the documentation > for all PMDs, can you please highlight the relevant driver code, we can > discuss it with their maintainers. > > Alternatively we can document this additionally in the KEEP_CRC feature > document if it helps for the applications. > > > [1] > https://git.dpdk.org/dpdk/tree/lib/ethdev/rte_ethdev.h?h=v23.11#n257 Currently，this documentation does not describe whether pkt_len and data_len should contain crc_len. Do you mean that we add this description in the KEEP_CRC feature document and notify all drivers that support KEEP_CRC to follow this documentation? If so, can you merge this patch first? Then we send a RFC to disscuss it with all PMDs maintainer.