From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MSGID_FROM_MTA_HEADER,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 962F4C35280 for ; Sun, 10 May 2020 04:51:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5EE2D20746 for ; Sun, 10 May 2020 04:51:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="Bur5We4t"; dkim=pass (1024-bit key) header.d=fb.onmicrosoft.com header.i=@fb.onmicrosoft.com header.b="Aqng+Pn0" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725846AbgEJEvq (ORCPT ); Sun, 10 May 2020 00:51:46 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:8714 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725839AbgEJEvq (ORCPT ); Sun, 10 May 2020 00:51:46 -0400 Received: from pps.filterd (m0044012.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 04A4oESb011486; Sat, 9 May 2020 21:51:33 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=subject : to : cc : references : from : message-id : date : in-reply-to : content-type : content-transfer-encoding : mime-version; s=facebook; bh=Vs1lD4HSkD+yTAEITliiWEDk40+NoPAzjERTBscxrjA=; b=Bur5We4tFGIATieyosSKQAkASQReY1E1YKfp8CGPAqShC4XEPmaJWqD3jyWc8LRcIDPE /dPIjQKjLnl6dMgP+sr+NcNQeecCmYg8IGPRnT68BHlwBydJUSAcOeHAGpcTKOQElSy1 KfQz30E9j0brbwvmjHyB6T+1PcT903zHg3g= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 30wt78k0qp-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Sat, 09 May 2020 21:51:33 -0700 Received: from NAM12-BN8-obe.outbound.protection.outlook.com (100.104.31.183) by o365-in.thefacebook.com (100.104.35.173) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1847.3; Sat, 9 May 2020 21:51:31 -0700 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=iv9LdGnIfwbRazsNZb2b4epLgap8PEng/76xKccvWSaZGmbxyZ6AfTAmX3n5KAoduqyueCMV7eMGCreYBcRS5KMLDuS8O88RcGHwLycFSPtaxXe3fd9K66NJZs1V9Ebh1Y04N5bc1HzYcI/6SrqYMS+OCsfdB4y8OZmSqg8livZe3/kVLAM79KqnqumI3BwSvfM08GVruTg81YqsHMwrKje6DIeIbeEiCMooxZTitCJZOxINFc8b/9LWSYCXzti+pDCXtCdMCAkT2d75HXULSdkYIiCk41Xcbww51XlPE+oG/Tj9LCYKA4FZDgnjN1q22AuBFpadymrgWfffIG0Njg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=Vs1lD4HSkD+yTAEITliiWEDk40+NoPAzjERTBscxrjA=; b=YxdeD9YVVXgioEfz3iys68tSMAt6iysaCbZiQydJUTRu+GfDeyqq1Gd4DQtofez4XvDI6rdi060M+pWX2BdGhDc7y6GxTr/sQd9j+NhS+Sd/bQ+/mB3sqGSktSN3ojiyrAGE0+yoe2qtB4I/vUBRWguwv9jaZPjeNxvwZGyuKSsUierooKG4LAmnKld9zjXCwKHU2HNG1+2EkE3LC5jerdOD/OG4XzdNhu9yssgDmPXVl4O+XgjaoJQdpb8t2/9Fet6PF6leRYw7H6vRDIVEp+EVUswn0iV2JJMFJPtd60iNjTWMjFbPjyqyL7Qwtq7iu6oQe5N9xx3W+v62IMP/aQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=fb.com; dmarc=pass action=none header.from=fb.com; dkim=pass header.d=fb.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.onmicrosoft.com; s=selector2-fb-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=Vs1lD4HSkD+yTAEITliiWEDk40+NoPAzjERTBscxrjA=; b=Aqng+Pn0E0fDt/TXWlmkRBo0FEmmeo795OG5MsQHj5GYo0ak72LDA/IrLkC4LB57Rn0y6jr6g/FNmiLUqAIDONI8+MwY1qFSD/GsB0HgL/y6Q2Yd33xe+rXe7yZH2K8Oi2ZnzSW+1XAI2TcBY60rG3i8pHcLEGkHC3MpyfUjkbU= Received: from BYAPR15MB4088.namprd15.prod.outlook.com (2603:10b6:a02:c3::18) by BYAPR15MB2822.namprd15.prod.outlook.com (2603:10b6:a03:15b::14) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2979.34; Sun, 10 May 2020 04:51:17 +0000 Received: from BYAPR15MB4088.namprd15.prod.outlook.com ([fe80::8988:aa27:5d70:6923]) by BYAPR15MB4088.namprd15.prod.outlook.com ([fe80::8988:aa27:5d70:6923%5]) with mapi id 15.20.2958.035; Sun, 10 May 2020 04:51:17 +0000 Subject: Re: [PATCH bpf-next v4 05/21] bpf: implement bpf_seq_read() for bpf iterator To: Alexei Starovoitov CC: Andrii Nakryiko , , Martin KaFai Lau , , Alexei Starovoitov , Daniel Borkmann , References: <20200509175859.2474608-1-yhs@fb.com> <20200509175904.2475468-1-yhs@fb.com> <20200510003036.3xzunae5nd75ckc2@ast-mbp> From: Yonghong Song Message-ID: <6cca36ce-2f8e-e5a4-4e80-f838f7f543fd@fb.com> Date: Sat, 9 May 2020 21:51:14 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 In-Reply-To: <20200510003036.3xzunae5nd75ckc2@ast-mbp> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BYAPR02CA0010.namprd02.prod.outlook.com (2603:10b6:a02:ee::23) To BYAPR15MB4088.namprd15.prod.outlook.com (2603:10b6:a02:c3::18) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from macbook-pro-52.local.dhcp.thefacebook.com (2620:10d:c090:400::5:e956) by BYAPR02CA0010.namprd02.prod.outlook.com (2603:10b6:a02:ee::23) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2979.26 via Frontend Transport; Sun, 10 May 2020 04:51:16 +0000 X-Originating-IP: [2620:10d:c090:400::5:e956] X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 0a2c72c3-cbfc-494b-3d12-08d7f49dc621 X-MS-TrafficTypeDiagnostic: BYAPR15MB2822: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-FB-Source: Internal X-MS-Oob-TLC-OOBClassifiers: OLM:5797; X-Forefront-PRVS: 039975700A X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BYAPR15MB4088.namprd15.prod.outlook.com;PTR:;CAT:NONE;SFTY:;SFS:(346002)(39860400002)(376002)(396003)(136003)(366004)(33430700001)(6506007)(31696002)(186003)(53546011)(2616005)(31686004)(16526019)(52116002)(478600001)(4744005)(36756003)(2906002)(5660300002)(4326008)(8936002)(316002)(6486002)(6512007)(33440700001)(8676002)(6916009)(54906003)(66946007)(66476007)(86362001)(66556008)(43740500002);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData: 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 X-MS-Exchange-CrossTenant-Network-Message-Id: 0a2c72c3-cbfc-494b-3d12-08d7f49dc621 X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 May 2020 04:51:17.0042 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 0tQI8snaLqpUlCbxJWq7q5WXXZ4o7LGaNStT7vOYx3oZxn/rhYZpkcEvAU1M+oAQ X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB2822 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216,18.0.676 definitions=2020-05-10_01:2020-05-08,2020-05-10 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 mlxscore=0 mlxlogscore=862 priorityscore=1501 spamscore=0 lowpriorityscore=0 impostorscore=0 adultscore=0 suspectscore=0 bulkscore=0 phishscore=0 malwarescore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2005100044 X-FB-Internal: deliver Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 5/9/20 5:30 PM, Alexei Starovoitov wrote: > On Sat, May 09, 2020 at 10:59:04AM -0700, Yonghong Song wrote: >> + >> + err = seq->op->show(seq, p); >> + if (err > 0) { >> + seq->count = offs; > > as far as I can see this condition can never happen. > I understand that seq_read() has this logic, but four iterators > implemented don't exercise this path. > I guess it's ok to keep it, but may be add warn_once so we notice > when things change? Yes, it won't happen with our current bpf return values. I keep it to be compatible with seq_read() and for potential future use in case we want to enable this. we will add a warn_once here.