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 A6FD343C11; Wed, 28 Feb 2024 03:27:48 +0100 (CET) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 67B1040DF5; Wed, 28 Feb 2024 03:27:48 +0100 (CET) Received: from szxga04-in.huawei.com (szxga04-in.huawei.com [45.249.212.190]) by mails.dpdk.org (Postfix) with ESMTP id 5DA654027D for ; Wed, 28 Feb 2024 03:27:46 +0100 (CET) Received: from mail.maildlp.com (unknown [172.19.88.163]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4Tkyr92YKvz2Bdrd; Wed, 28 Feb 2024 10:25:29 +0800 (CST) Received: from dggpeml500011.china.huawei.com (unknown [7.185.36.84]) by mail.maildlp.com (Postfix) with ESMTPS id 14AB718002F; Wed, 28 Feb 2024 10:27:44 +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; Wed, 28 Feb 2024 10:27:43 +0800 Message-ID: <7e376ab0-67a0-4a3c-a528-7928077e7b56@huawei.com> Date: Wed, 28 Feb 2024 10:27:43 +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> From: huangdengdui In-Reply-To: <1ec105cf-c8d2-4010-867d-30970c25a2a1@amd.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.67.121.193] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) 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 2024/2/27 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?