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 EFACA43BB8; Fri, 1 Mar 2024 07:55:36 +0100 (CET) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id D8FAE4029A; Fri, 1 Mar 2024 07:55:36 +0100 (CET) Received: from szxga07-in.huawei.com (szxga07-in.huawei.com [45.249.212.35]) by mails.dpdk.org (Postfix) with ESMTP id BDC7D4025C for ; Fri, 1 Mar 2024 07:55:33 +0100 (CET) Received: from mail.maildlp.com (unknown [172.19.88.214]) by szxga07-in.huawei.com (SkyGuard) with ESMTP id 4TmJhB5m9lz1Q91f; Fri, 1 Mar 2024 14:53:14 +0800 (CST) Received: from dggpeml500011.china.huawei.com (unknown [7.185.36.84]) by mail.maildlp.com (Postfix) with ESMTPS id BE8641A016C; Fri, 1 Mar 2024 14:55:31 +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; Fri, 1 Mar 2024 14:55:31 +0800 Message-ID: Date: Fri, 1 Mar 2024 14:55:31 +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> <760c70e6-ca2d-4d5e-9a05-809b81d32dd3@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: dggems705-chm.china.huawei.com (10.3.19.182) 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 2024/2/29 17:25, Ferruh Yigit wrote: > On 2/29/2024 3:58 AM, huangdengdui wrote: >> >> >> 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. >> > > I think it is clear that pkt_len and data_len should contain crc_len, we > can ask for more comments. This patch doesn't change the logic for hns3 PMD and the implementation of other PMDs supported KEEP_CRC is like hns3 PMD. Can we merge this patch first? > >> 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. >> > > Not for drivers, just a suggestion that if we should update feature > documentation with above information for users. So there is no > dependency to features document update. > > Sorry I'm more confused. What should we do next?