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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 46B57C433EF for ; Thu, 3 Feb 2022 17:15:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241438AbiBCRPV (ORCPT ); Thu, 3 Feb 2022 12:15:21 -0500 Received: from mx0b-00069f02.pphosted.com ([205.220.177.32]:16294 "EHLO mx0b-00069f02.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352755AbiBCRPH (ORCPT ); Thu, 3 Feb 2022 12:15:07 -0500 Received: from pps.filterd (m0246631.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 213H5CNh028542; Thu, 3 Feb 2022 17:14:00 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : in-reply-to : content-type : content-transfer-encoding : mime-version; s=corp-2021-07-09; bh=J7b6tNhNVTaGE0rpAa49P1gFTW7UhrqGVtE/LqzkbmE=; b=fRozKMbEcqV3GMCwcxeTwt8rumLMXIo7rTbrt06FDUe/asPDlokLuPBwbOmog89yyMTt vP9t8g73jNPyxm2pKXsZEP0NxyfU8YfWiU95RK5XrWlTaXa5RU1wJaY9234QGplOH6D4 oTH/SIHIS5x5SgYnJeFRgD1A87LzOgIW2BlOEGEUa/CzYIUlZR9xT1FbzZjs6fNm86GC NocPQOpvtw0NhlbanCLx4co8Znq/iAQ6dS7wWkDFJgzEzfiLB6DUrIL0O7sxqDKWyb2S p0MQf2WYwziD/27cv7ZDYp77xtKj58c5/OYpAIKjwYkvqpyeXK+/8Tb3Z0AdGhGbyet5 QA== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by mx0b-00069f02.pphosted.com with ESMTP id 3e0het8dae-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 03 Feb 2022 17:14:00 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.1.2/8.16.1.2) with SMTP id 213H5S35124383; Thu, 3 Feb 2022 17:13:59 GMT Received: from nam10-dm6-obe.outbound.protection.outlook.com (mail-dm6nam10lp2103.outbound.protection.outlook.com [104.47.58.103]) by userp3020.oracle.com with ESMTP id 3dvy1ve6bk-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 03 Feb 2022 17:13:59 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=QFUsmbPKfMorLbsuC2QWTM1Z3QRUYlk1gspy4fWFNn8J/6aVYTs/5mQpeAdsSCBb+TaOe4CZIdAWo7YAs0/vEvSkPpH2uhALkWklbGCwa5PXVfSi0k7z1S+m20IcoQn0ZLLdJpGLuopPRoUzzzzMcLpaBH9+Il2OKttU+ZFtbywePs4h6GCodSirTM45N0ANPT4l7atQ5P8FS+rKbZsqMglKxVqoZn0eL6rb63Usx5mmtWJdN3Hxb7nNaX+VZJdXqrrIBM6XzOzqAkaST9XOtjjNdlUtsAPkGDB5JziZpFJiQ/Jm6p8EzHd2wVJg6KAZfFbnCx0UF0BPwdmFjs8zpQ== 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-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=J7b6tNhNVTaGE0rpAa49P1gFTW7UhrqGVtE/LqzkbmE=; b=m76XsmD69Uqp3xThY7bAI/hq/1KIbrjZ7kc5pyzs/8dPuHurrdEghhMe5URqYpjoas8Zn0arHUqKPVQjGSarm/MvdjJGvNmoP32SoEnU6T4l8U280KHI+oJSxLgdKtMbEY1gO34y3Ojyn5ZAwbmVeXc7kaq0gWsjxbFzy1+/HbouKmkWH1BfHfUSHB8NOS5y4Q3Yrk8VjqDf9BV7KUZBWb7rVDkHlHYp8LzyOR5B7GlAK5JlGJNFjQCx5udvTe2NjunX+0CRnIfDHEgKZi3DPMHsBI+u93afrTSKyP2dR3Ot9DjrxQVM/aT/pGjaj24F3md2YMq1Tdp+M9X8w3LY3w== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=none; dmarc=none; dkim=none; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.onmicrosoft.com; s=selector2-oracle-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=J7b6tNhNVTaGE0rpAa49P1gFTW7UhrqGVtE/LqzkbmE=; b=M84RKTZb4XuNb9mTKtcX+XqZs3Clwi8p3WSw6KOGtRrV92a6l/tlXQ+QXehaCm2TTwLdrFtokAgcU0Xl8rBhMSus825WqJg40RGmErFlbbqe895kOEoCl2VsS6gaflvyad9ffoFPVN8btQSIgxGnYI/wWIUEvhGWDfr/AKDzQ2A= Received: from BYAPR10MB2663.namprd10.prod.outlook.com (2603:10b6:a02:a9::20) by DM6PR10MB3132.namprd10.prod.outlook.com (2603:10b6:5:1af::24) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4930.19; Thu, 3 Feb 2022 17:13:56 +0000 Received: from BYAPR10MB2663.namprd10.prod.outlook.com ([fe80::60be:11d2:239:dcef]) by BYAPR10MB2663.namprd10.prod.outlook.com ([fe80::60be:11d2:239:dcef%7]) with mapi id 15.20.4930.021; Thu, 3 Feb 2022 17:13:56 +0000 Subject: Re: [PATCH RFC 1/4] net: skb: use line number to trace dropped skb To: David Ahern Cc: linux-kernel@vger.kernel.org, rostedt@goodmis.org, mingo@redhat.com, davem@davemloft.net, kuba@kernel.org, edumazet@google.com, yoshfuji@linux-ipv6.org, dsahern@kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, imagedong@tencent.com, joao.m.martins@oracle.com, joe.jin@oracle.com, netdev@vger.kernel.org, bpf@vger.kernel.org References: <20220203153731.8992-1-dongli.zhang@oracle.com> <20220203153731.8992-2-dongli.zhang@oracle.com> From: Dongli Zhang Message-ID: <79e4d4d4-b87a-e8ad-af24-b95a02d5ec76@oracle.com> Date: Thu, 3 Feb 2022 09:13:52 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SA0PR11CA0109.namprd11.prod.outlook.com (2603:10b6:806:d1::24) To BYAPR10MB2663.namprd10.prod.outlook.com (2603:10b6:a02:a9::20) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 253142be-d5bb-4285-403c-08d9e7388f60 X-MS-TrafficTypeDiagnostic: DM6PR10MB3132:EE_ X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:913; X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 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:BYAPR10MB2663.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230001)(366004)(2616005)(6916009)(508600001)(38100700002)(7416002)(186003)(2906002)(316002)(31696002)(83380400001)(36756003)(6486002)(5660300002)(66946007)(66476007)(44832011)(4326008)(31686004)(6506007)(8676002)(6512007)(66556008)(53546011)(86362001)(8936002)(6666004)(45980500001)(43740500002);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?R0dLYytMUUpQVnYxanpwSkI1cFVRYzJpNzNtOGRjYm1mdkhCQTlqQ0tsWC80?= =?utf-8?B?RUtIajNVTlFRZGFEQThFWnpvSTRBeU5DaWFGTVNwUUFSSWlJWndPeG9GNmc5?= =?utf-8?B?WFI4c0syVDVYcUR1RVdybWl6bWJiWEswTHpNWVplZ1lRTTcrVVN6RzhoM042?= =?utf-8?B?MnkvU3BQRlk0TFFqV0JKVllKb3oxWVdEL1lETnVvMUVmYUtCRVYwN1g0cTdx?= =?utf-8?B?T3piWEwzSVA2UUw3OUdhYzBFWkZQbjUyeVN4QUtJMllnWUkxWThmcTJndXZW?= =?utf-8?B?RHFxN0JjbVNSUzJwck9XS1VZRFN4ZGJSNFFLRzU3Q2VWbTh4cklSVVZwVDBF?= =?utf-8?B?amU1alJVZ0tjZXNTSjZHQU5jbWNxSkpvN2tXalQxWUc2MGhGQlNQRU1kZUV2?= =?utf-8?B?VWVCYmkvMm5TbitLN2tueDFKRkZUVG9vL3NOaXFjTTRHcVExbGNhMnNIVEQ3?= =?utf-8?B?UGlqQkt1V1Rad1pmNVRDNWdWSTU3ZGdVNXg4RkpmaXpqWC9CQWRCVlMybG5j?= =?utf-8?B?STcwUzlzQjRxK0ROTTB0UmxObU9lSlhoSXJGSldoNmVQWlZ1NGxGSGFqaVRh?= =?utf-8?B?aDVRNTJhL3dCaWZ4cVA3RDBSYkxraG1XMFFoQko5TEFGd3RPdFkrbHBsUWtp?= =?utf-8?B?cU11MkdqQlFjZndNRllTWGhLVTBObEFTS2RiUUt5VXZjUERjMk52Q0FSN3l5?= =?utf-8?B?b05RNGFBaHZFQklXN0hMK3FoeGR1NzZMc2VjWTQ2bUZ1SVJiZk5GNTRXNXVI?= =?utf-8?B?L3ltQlZlMGtoV1RONklwcjFNSXVCTzlhTXV0d203czMvSVg0OENubGlaQjhR?= =?utf-8?B?OXVvM0pWTkwzc01yZjQ3Q3dsZkZTdWhRMkw1NC80VFlZbzBwZ2xXeWxJSWRi?= =?utf-8?B?SytBN2pGS3FKYjlRd1pjTHd0SU1mQmJzeC85TXhhZk0wYndMS0pQZERZZmRE?= =?utf-8?B?YzNoMGF2S0JYRHB1NTI5VlRvazZZVkRFWDFld3hvVUp2bGVQdGdZQ3h4aE5v?= =?utf-8?B?NFY3Y2hNOTNQV3dTb3F2WHFtNy8vb0xYSEVtWDNUaVkrU2ZZNG81NWtZYkRo?= =?utf-8?B?VmNURnN4dDZLakVtMEVWM29iVTJFNGlqSmNBYzNLbmZ0YUk5R0Q5bjVpV2V6?= =?utf-8?B?TGp2SnRzT1VZSzdhU3BkM1BsQ1Q4OHJ4R2xzcEIrbmpteDQ3RHBXOW1CL2Jz?= =?utf-8?B?azRQSldhTGtaeTZoSnRuR0FJRHJxMklSTnVzNkZCalRyaG5ndVIwUHk3SHlJ?= =?utf-8?B?M2o2T21IWWFBLytJZVlHQXFrSENsbktmQVVzak1aZGJ0Z2ErLzM3MFdsZVc0?= =?utf-8?B?WnZtWFJTMzQ1V3BKN2llcUlseUVCSkZOQkpzclYrRkR5bkNoMHUwMUtMS2cw?= =?utf-8?B?YnhDSVgvT0M2TlVyaEh1VWtFd3lrUVlQWWIyeVhIcGdLbEllc2QwZ1BGV3FF?= =?utf-8?B?NWllMmQwSjlLcnRiVTB6VCtqazFYejRPRDZqUkhlTDlsYktBd2Jqb0psUXRH?= =?utf-8?B?ZEg3V0lsSDB6RFh3TDNCVndtMHpPVFJTSmhhdy8zVEtldE4vZy90OGZBcENI?= =?utf-8?B?b3R2WjgvN25ENmNYeDdnL2dXN1hMbmFqMTU4NElrMlprL05vMm4rM09Vb1JE?= =?utf-8?B?MHhOd0FydlpZM0ZkcWtROTZkUG1WTU9jNEdCMUpEOFc3M3NRa3U3RDhzeXdY?= =?utf-8?B?YzR0VmM5K3hyNGdDUzBvU2s4TS8yVXdUNzFsVnB5UjlZZmJSUm0yb2xnRFBv?= =?utf-8?B?MFZTQklHdDBuR1Jxa2diMDRxaG1rZ0tQWU4rSjVWUHhwUXR4cUdxZzhHbThz?= =?utf-8?B?Y1VpNUNwdk5yMStTaGpFM2E0UHAyRUJ1SDBya2VnRkNIN21COGZpRlN0bkxT?= =?utf-8?B?emJ4UHExZlcwcktMRkNHbDBzYjZKS3BwWE9rYTdYeE5QbWRIODAzaUFCVy9E?= =?utf-8?B?Nk9FYndzYUYxRUw5NGovS2lHTk5DZjlOLzZxSVYyK0NLRGs0MmZsL25tQWpq?= =?utf-8?B?L2p6Zk1WOTVvQytGSGs1QW4vempBTEI5T3FHbU5rNWI5MGVVamluSXM0bUNT?= =?utf-8?B?Mys0aVRrVXVseHNZck9ibUNCeWJTaDNSRWhiV1EzTVVoSk5DVkI4a3RYT0xw?= =?utf-8?B?bE53MTF1QVpJNjZvdlVDTkdHNTRBb1NzN1VVa2NOTnA3eFFScUFaUzYvYmI1?= =?utf-8?Q?5Rfq//BwxEYwQM8SiIdX6iY8GhzWbMi+zMY18GuKKHAH?= X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-Network-Message-Id: 253142be-d5bb-4285-403c-08d9e7388f60 X-MS-Exchange-CrossTenant-AuthSource: BYAPR10MB2663.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Feb 2022 17:13:56.0832 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: X7cDzgEsanzAEyp1FM9xBIx1JrjC8mPvJ20e6s/Sr0Fhn/COwV7secsFAcDSvVoCNFCq/iWt45o6CV4/KIYs5A== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR10MB3132 X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10247 signatures=673430 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 mlxscore=0 spamscore=0 bulkscore=0 adultscore=0 mlxlogscore=999 phishscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2201110000 definitions=main-2202030104 X-Proofpoint-ORIG-GUID: MPQtt-uhDoJoqXC0_Eh42Gh2eUbA-b6P X-Proofpoint-GUID: MPQtt-uhDoJoqXC0_Eh42Gh2eUbA-b6P Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi David, On 2/3/22 7:48 AM, David Ahern wrote: > On 2/3/22 8:37 AM, Dongli Zhang wrote: >> Sometimes the kernel may not directly call kfree_skb() to drop the sk_buff. >> Instead, it "goto drop" and call kfree_skb() at 'drop'. This make it >> difficult to track the reason that the sk_buff is dropped. >> >> The commit c504e5c2f964 ("net: skb: introduce kfree_skb_reason()") has >> introduced the kfree_skb_reason() to help track the reason. However, we may >> need to define many reasons for each driver/subsystem. >> >> To avoid introducing so many new reasons, this is to use line number >> ("__LINE__") to trace where the sk_buff is dropped. As a result, the reason >> will be generated automatically. >> > > I don't agree with this approach. It is only marginally better than the > old kfree_skb that only gave the instruction pointer. That tells you the > function that dropped the packet, but not why the packet is dropped. > Adding the line number only makes users have to consult the source code. > > When I watch drop monitor for kfree_skb I want to know *why* the packet > was dropped, not the line number in the source code. e.g., dropmon > showing OTHERHOST means too many packets are sent to this host (e.g., > hypervisor) that do not belong to the host or the VMs running on it, or > packets have invalid checksum (IP, TCP, UDP). Usable information by > everyone, not just someone with access to the source code for that > specific kernel. > Thank you very much for the suggestion! I will not follow this approach. I will introduce new reasons to TUN and TAP drivers. Dongli Zhang