From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from NAM04-DM6-obe.outbound.protection.outlook.com (mail-dm6nam04on2078.outbound.protection.outlook.com [40.107.102.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5472282C6B; Mon, 3 Jun 2024 09:51:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.107.102.78 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717408319; cv=fail; b=DU2ElvlA7d20uuwn8w3oxHNB3tHW1+uM73eh4pBTbk1d8hZPhDn3vvH7GNXJZVm5ogJx2Pjru/fq6uTnXCbRMCvGQGMnC4Bg8pyiK2YZ/zx5wRtJoUY06Z3yzDXHcKuGhMO97W5PkgPwxgkTy3Mu0nBqyFUDrthiVGpbyknNAWQ= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717408319; c=relaxed/simple; bh=ZS24zFDqNxXF7yMkBDG4Vp25RL5tkoks6o6x9NYGTyM=; h=References:From:To:CC:Subject:Date:In-Reply-To:Message-ID: MIME-Version:Content-Type; b=cFDyUnWAL7EaSXqMr5ja0TohM4s04lxCCp2r2HVKyNL3EjAtTAD8IUWVUhtuR3ThUXTm8fdaJqxhs9e5G2t6EZZmojpp1HnksqazUuD+mjmMNgCS2pVI44jyvYWW8JFqP2yZUPwDVxWZiTGvMJ/2hsGS2AEhS2vlyYp9T9VhEFg= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com; spf=fail smtp.mailfrom=nvidia.com; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b=W3tlswbm; arc=fail smtp.client-ip=40.107.102.78 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=nvidia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b="W3tlswbm" ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=oeGJZMkeILmu3xDxn9IwTtN32OX5CFj5iWxf+jNtl9YdqlPpdv1YjuabeA66tIrWbuB1c0KKds/MmCrnsL0DbEdWArNENeEeNcQ4p/q5cEwN7ynlmt5+pI57KzjWquMASiZVcsbxc//+KpNbXkDU029X/Kgx+l91N0r/BxCapKVaSpSGXOSTWP3s4pYkuMAnCw8KLbrMW32nh1vW9xTht7sCR9uvyH/mvO0qiqQxr4OUaqVOrdicVTPwSj6+fTYw4aqmo6Xk9f60HPSCC6yO691EnMqG1YFQ23lVP6S2mqyc6ZAuJmpuw2WnkbFK1gnI0FVfVNrA3dH+D9LzdQ1hcA== 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=JEOtnCfSkmOcUi1ppa7J8y4ALl/Y8XkdVGPnQCbTe2Y=; b=kshWeRJskXGeYv5QYbwKQ1rhqe76HfVYLuJAt9aj0yVRSeytY2IkE3czfdkj6LaG11CaF1aQckCNyUW8+HXf4uQlLw4YXEDyXiagrwqZntLp3EfDkYvuTGacVZpALdohORAQO/3zpYYSesHmLLMEGDR67k1SDaIcpe4Bp73Ngh5JS78f0REBVxvtnLkGrUePcSRQZbOPsN6cJl01X8IZiNXixoEuZA1xa2u1UAiK/4SELwWlFFLZp3GgiABNQniPQOE2MgAEVto3GUSbGZyQcYb3npXzy4cnhfTO56rprWp/oQTuxO8vt5w1wHeuAsHoI64H5/1T6UQwDuDX+RRBLA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 216.228.117.160) smtp.rcpttodomain=kernel.org smtp.mailfrom=nvidia.com; dmarc=pass (p=reject sp=reject pct=100) action=none header.from=nvidia.com; dkim=none (message not signed); arc=none (0) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=JEOtnCfSkmOcUi1ppa7J8y4ALl/Y8XkdVGPnQCbTe2Y=; b=W3tlswbmjJwqpNxsMtnQiFzyUXK+lvZTH3ojyTxpz26oaPgX4vue88GQNoAh+dw3aCIX2NWs3dReeNWGJX76BICHZQfcPbnbTjizMvgeXHa+rnIiaXq/IqQkiihqL1XVuoC4LIh8zCup+eZONgYrLPlNG6p6AEcPJ6uif1K1OmQbJ3fCo90cyFKP1accreKfvAD42ekHcvSaAzOYpwdOp4X4euAGnVECHpD/bMNEEjCpfQg0utp7yj51m33FIA1whMDYa8wtvmu9DZFQHguGXEvMOldrx535a0H1uUtIRwiLTKPltY2KnIz0yQ7qt5nFWRtJkV8brO2atxe0Kf5hfA== Received: from MN2PR15CA0024.namprd15.prod.outlook.com (2603:10b6:208:1b4::37) by PH8PR12MB7302.namprd12.prod.outlook.com (2603:10b6:510:221::12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7633.22; Mon, 3 Jun 2024 09:51:54 +0000 Received: from BL02EPF0001A101.namprd05.prod.outlook.com (2603:10b6:208:1b4:cafe::71) by MN2PR15CA0024.outlook.office365.com (2603:10b6:208:1b4::37) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7633.27 via Frontend Transport; Mon, 3 Jun 2024 09:51:54 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 216.228.117.160) smtp.mailfrom=nvidia.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=nvidia.com; Received-SPF: Pass (protection.outlook.com: domain of nvidia.com designates 216.228.117.160 as permitted sender) receiver=protection.outlook.com; client-ip=216.228.117.160; helo=mail.nvidia.com; pr=C Received: from mail.nvidia.com (216.228.117.160) by BL02EPF0001A101.mail.protection.outlook.com (10.167.241.132) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7633.15 via Frontend Transport; Mon, 3 Jun 2024 09:51:53 +0000 Received: from rnnvmail201.nvidia.com (10.129.68.8) by mail.nvidia.com (10.129.200.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.4; Mon, 3 Jun 2024 02:51:42 -0700 Received: from yaviefel (10.126.231.35) by rnnvmail201.nvidia.com (10.129.68.8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.4; Mon, 3 Jun 2024 02:51:37 -0700 References: <20240529111844.13330-1-petrm@nvidia.com> <20240529111844.13330-3-petrm@nvidia.com> User-agent: mu4e 1.8.11; emacs 29.3 From: Petr Machata To: Eric Dumazet CC: Petr Machata , "David S. Miller" , Jakub Kicinski , Paolo Abeni , , Ido Schimmel , David Ahern , Jonathan Corbet , , Simon Horman Subject: Re: [PATCH net-next 2/4] net: ipv4: Add a sysctl to set multipath hash seed Date: Mon, 3 Jun 2024 11:50:50 +0200 In-Reply-To: Message-ID: <87wmn68icf.fsf@nvidia.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: rnnvmail201.nvidia.com (10.129.68.8) To rnnvmail201.nvidia.com (10.129.68.8) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL02EPF0001A101:EE_|PH8PR12MB7302:EE_ X-MS-Office365-Filtering-Correlation-Id: da52f9c7-4f8a-4444-a518-08dc83b2ccac X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230031|82310400017|1800799015|376005|36860700004; X-Microsoft-Antispam-Message-Info: =?utf-8?B?a1ZZTVFoT1gyUC9lWUFtYVkyTFcxTWcrbG9iVkhOcWhqOHFpL3Mrc3JHcEFR?= =?utf-8?B?M2lIQnZqN3JOaW82UFdva05MdGh3OXRWd0xzL0V6ZGp6aWp4bWU5ZzNXK0NV?= =?utf-8?B?QzBpN1FWTis0RW5qcS9DRmc4bFBWM1ZmdlJqOVpjQmRXaFFONmhHYXlHMDVr?= =?utf-8?B?enZObXNsSmNuckw3SmtrOVdqOC9xVVpZU1dubmMwVUpOMGRlZ0oybWVxTVA3?= =?utf-8?B?ZXdRNGprVGlpNlV5K2svR1BlczRlOWxQb1Jxb1VSRk8rNkhRdGI2YVd4eGlw?= =?utf-8?B?K0Jua25jTXp2QUxlczdTdTFLNmNKcU1ZQzZjYWp2eVI2YytYZnUwUWwrZmhq?= =?utf-8?B?UVYzbjR6aUkxK3NsTjY2ejZiYkJCTHJ0LzVYVElMek9sTGdQZFhUa0U1cElz?= =?utf-8?B?RDdKR1JQa3lOZTNsK0ZHYk1aNiszNmRoT1Q5UFhaMmN2UG14dmpCSjlxNThy?= =?utf-8?B?SWp0Rkh5SXRuUmw1alkrbldQbzJWbWtnZW5nbEY4ZjkrS1JjcVBkZzBEdVFM?= =?utf-8?B?eEJHemh6a0ZIVngxZlgxMWpNVmV6dGlleDBIMkJyV1ZlZ3Ywd1A3bXJMRU4v?= =?utf-8?B?THdYd255cDd3ZllMMDc4SkhDb0pBNDA1UzVzVXN5VTVNblQ2YUR3WkpGNGlH?= =?utf-8?B?VHlCRVc4T2NMa1lJMFRiVVJHSHRFMzBkOWRaQllyTHNCbjY5NTZ6MitsUHlr?= =?utf-8?B?cUh6ZUh4b0VTNEtSOWVDa2ljWEsrd1lrUEpIeDNaQUxacENqUjMrL3hvS2tx?= =?utf-8?B?ZDhkaWp3WnZtaHp1R0dKeEMwMXBtOWJxTVdRUVNGaHN6QXpmdnExMCtWTEtH?= =?utf-8?B?elFYY3dDWFZiMlZrK3VveFV4VTVLQTNKVEMwMEJML2x1TXFDaUVlZzl2UzlV?= =?utf-8?B?L0VKUUxLL1hTS1JjeUYxcjdGb2s5cFRvWFFFbXExejVsYU1sOGIwUytZb0lD?= =?utf-8?B?MXN1NjYyMGJkTVU1S0QraUxtWlNWZHdSR1NmRlJqZ1RSb1Q2OFhmY29qTHQ2?= =?utf-8?B?aHpIaThwWU55aEo2T1RhUXVSU1FDMy9DZUpHU2RGTTNXZFFoYUZpKzNMeFZV?= =?utf-8?B?ZkkwOENzQnNJZFJodU83MTFhSS92QllHRnFBMER5SWQrMEE1amkrYUF0TU5S?= =?utf-8?B?dno4YWJTcHMvZGJDay8ySFluQnNrS1ZhaWE3WmNuZENCdXA3WnhKTDdPdTJG?= =?utf-8?B?cXpKcWhKSjVGWGVYdzBQblcwZG5sSDBQVzBlSjBsaHZiNCtUM3o5QnpJUEFs?= =?utf-8?B?VmJJdk16NXRvMVVrWFdGeWhKTGQ4c1R3NTVjSXpyOXFrZVIrZTdsSkZpY3Yw?= =?utf-8?B?U1ptbW02MzFmTC9WaFRlNzNsMWdDSkRTVUVSQU55b2VSV3MrcFk1dDQ5R1dS?= =?utf-8?B?SUtaQW1lYkVFdVY4RmZ5ZTc0M0pwckxucmdSek1iSFVkUDZ4NkpiQXBqMmRu?= =?utf-8?B?NG9ZdlhKQmpBZ2dHVUZBSkhvYlNib3F6Q3ZYKzJJYjJkalVQbzJ6bEQvTG9y?= =?utf-8?B?V3VtR0UzaWh0MXFwd3lmOThGTlU5bVI4eWZHVFNtcE42YTJMaHl4UzdHUmIy?= =?utf-8?B?YXhqd2NEd1RhUXJLelc5RXRaUm1CMTlLdHRDQnlEQ1BTRjJ5bThZVzU3UHZt?= =?utf-8?B?VHZRYnZYbW50OFVLdDdwU2hHcjdmMi9JWmNtaEVKbCtON1pIZkJyaGZPWndw?= =?utf-8?B?VDdBZ1VXc1VFWjBJVS9nVVNYQWlKeERETlo5d0VJZHRnRkpYdzRuT2FONStU?= =?utf-8?B?MnBMclR3NWhZeU9YTEtrL2FMVXd1ZHZCNmVpeGMreTlEbks0ekJHaFRTOVVv?= =?utf-8?Q?vahnScXktbtcFtL73RHOL8c0PEPKocbNpXl0Y=3D?= X-Forefront-Antispam-Report: CIP:216.228.117.160;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge1.nvidia.com;CAT:NONE;SFS:(13230031)(82310400017)(1800799015)(376005)(36860700004);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Jun 2024 09:51:53.9020 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: da52f9c7-4f8a-4444-a518-08dc83b2ccac X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BL02EPF0001A101.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH8PR12MB7302 Eric Dumazet writes: > On Wed, May 29, 2024 at 1:21=E2=80=AFPM Petr Machata w= rote: >> >> When calculating hashes for the purpose of multipath forwarding, both IP= v4 >> and IPv6 code currently fall back on flow_hash_from_keys(). That uses a >> randomly-generated seed. That's a fine choice by default, but unfortunat= ely >> some deployments may need a tighter control over the seed used. >> >> In this patch, make the seed configurable by adding a new sysctl key, >> net.ipv4.fib_multipath_hash_seed to control the seed. This seed is used >> specifically for multipath forwarding and not for the other concerns that >> flow_hash_from_keys() is used for, such as queue selection. Expose the k= nob >> as sysctl because other such settings, such as headers to hash, are also >> handled that way. Like those, the multipath hash seed is a per-netns >> variable. >> >> Despite being placed in the net.ipv4 namespace, the multipath seed sysctl >> is used for both IPv4 and IPv6, similarly to e.g. a number of TCP >> variables. >> > ... > >> + rtnl_lock(); >> + old =3D rcu_replace_pointer_rtnl(net->ipv4.sysctl_fib_multipath_= hash_seed, >> + mphs); >> + rtnl_unlock(); >> + > > In case you keep RCU for the next version, please do not use rtnl_lock() = here. Thanks. It looks like it's going to be inline and key constructed at the point of use, so no RCU.