From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.18]) (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 C933E217F27; Thu, 18 Sep 2025 22:10:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=198.175.65.18 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758233443; cv=fail; b=PpWmEtZqZqAgWi7QfOnie3aF0hc+ZMnqq8nkUPT/g3jLiQ8Fqc6poA6ld1KEVi4HPD4Jgw6FSQJcYGy4MGoibdHtPybRIVsNV4P7K+i/kYDfIfxz1uuvKLmXeDg08lIpmwi1uzIUZ8eEDsl7cqNeVUu6VVXnHPJ+liPnoK2PM0E= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758233443; c=relaxed/simple; bh=ONGIVNBR4dPfwF8zNK/A9c3nJYKcn+LgPnqD+SXtP1g=; h=Message-ID:Date:Subject:To:CC:References:From:In-Reply-To: Content-Type:MIME-Version; b=fpASNnp9VkGbd78cAPH7LZqq3oDx+ERdhfc5XJBuHNA7ILZNaaQqp5zlO/fzAwGDRItUrkseiaPYcDFWgZaMamGwTebLjWy11LaUxpvYh83qWCmjdfvWeClXASw7vqOJGB/IXdOxMWZCA5MmereclKSqV8ylJBoi5YurizuMqGA= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=JePGPzF8; arc=fail smtp.client-ip=198.175.65.18 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="JePGPzF8" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1758233442; x=1789769442; h=message-id:date:subject:to:cc:references:from: in-reply-to:mime-version; bh=ONGIVNBR4dPfwF8zNK/A9c3nJYKcn+LgPnqD+SXtP1g=; b=JePGPzF8qxWGD9LnK9cfvcBKIJaXfCVXB/iqqcy8TJGDr1DpvG5afbUp COqEbYhJwBuvnK2G9/Ky9nTyeMVVXJILy5UEoSzf+NeUva4lnDbQ5lTC8 9eACzTTZ5MAd2mgNbKnc3vI0qenKFmeaxB08/AN965h+kHa7PoQyL5dft nClkByZTtPUADLSN5f6ye/MQYrb+Y/3Cb4hQ+eetsyyHQ0cW8oB8AdRfG jQVRhrWB+MbBRxFfGMqp1smLbgpWEIkGcFx8XCxlcdl1aT5mSv/IJAvX2 JngZO53Kg+T6w5n813eCUlwhn6lTQKYXfJaBt5C566+HGI9ePVtANgArN Q==; X-CSE-ConnectionGUID: /nkveHgpRvC5j8TQniyt/g== X-CSE-MsgGUID: 4FraKCcIT/iy1FG+3SUWuA== X-IronPort-AV: E=McAfee;i="6800,10657,11531"; a="60635140" X-IronPort-AV: E=Sophos;i="6.17,312,1747724400"; d="asc'?scan'208";a="60635140" Received: from orviesa001.jf.intel.com ([10.64.159.141]) by orvoesa110.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Sep 2025 15:10:41 -0700 X-CSE-ConnectionGUID: vriTkIiVQ/OXySQy0wwytQ== X-CSE-MsgGUID: AoRIPXm1SoyyeSoXE+uGYA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.18,276,1751266800"; d="asc'?scan'208";a="212820297" Received: from orsmsx903.amr.corp.intel.com ([10.22.229.25]) by orviesa001.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Sep 2025 15:10:41 -0700 Received: from ORSMSX903.amr.corp.intel.com (10.22.229.25) by ORSMSX903.amr.corp.intel.com (10.22.229.25) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.17; Thu, 18 Sep 2025 15:10:40 -0700 Received: from ORSEDG901.ED.cps.intel.com (10.7.248.11) by ORSMSX903.amr.corp.intel.com (10.22.229.25) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.17 via Frontend Transport; Thu, 18 Sep 2025 15:10:40 -0700 Received: from SJ2PR03CU001.outbound.protection.outlook.com (52.101.43.5) by edgegateway.intel.com (134.134.137.111) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.17; Thu, 18 Sep 2025 15:10:40 -0700 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=ZVT0/SWdxMD8zGhUESs+trHgKNiDDrDArI6IC2V8LIgSnFxkLg2DbedbdYkkyb3hnpwO70r+UWaY3RVwX4FJXpHueaaRohkGUXegi1h5wzGZ93rFs6tR1B7SIHP7R/JTF8gFBZiH30kL18V6DFZ7zfq3jV8/M83URze5iSFQian6wQogvoYWjuzTaWIRINuEESXyjz9uDNoj+6xe/zCuqdflrQeNPjuHX8VytyqzCtqbo1R+L6yAN4Xbn12stkyscQyqeZrtfD1vz2aJejccvYyXbqEx6IlUCKnNvztm6rl1/bz+feygXFEv1pSzEFvImc/TklnJu/RbH+YlIXgf0Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; 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=fF8wWGOMek9b+AbMwtlZJRx6vuweXcezTzXgiQpDET8=; b=UvU652OFeM9RfRwdC4i1Z0IGqFfa6rox5ZQaPCeMlCKRh/cY63u0ZrRVTNq7C1MppyQXXrkweEPJ/s8JEhGmM5XVuEyBFISXytlskfKiEwvuu/iCxfeeHUQXgduQYyFqtczIDyegxG0TovHhGALH1+Cp+aH9cbQGqLyBDcSrxJJ+7m1tFLGFzdXE6AWYZPHh6FvtjbY1KJjrBMD7U+uABO1NFdof+qbNrPtmydsZCxnfm0/mW1lIKl43cnxAhFY7ujjUm9KU1cdttrSrd0K4R8/YpGRI6p1zBm3FEqnlu3sChleHGdOpUtzdnOrTkZHTvb77FDcxdDyxzmoBSwTI5w== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=intel.com; dmarc=pass action=none header.from=intel.com; dkim=pass header.d=intel.com; arc=none Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=intel.com; Received: from CO1PR11MB5089.namprd11.prod.outlook.com (2603:10b6:303:9b::16) by MW4PR11MB8292.namprd11.prod.outlook.com (2603:10b6:303:20c::16) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9115.22; Thu, 18 Sep 2025 22:10:38 +0000 Received: from CO1PR11MB5089.namprd11.prod.outlook.com ([fe80::81f7:c6c0:ca43:11c3]) by CO1PR11MB5089.namprd11.prod.outlook.com ([fe80::81f7:c6c0:ca43:11c3%4]) with mapi id 15.20.9137.012; Thu, 18 Sep 2025 22:10:38 +0000 Message-ID: Date: Thu, 18 Sep 2025 15:10:33 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [Intel-wired-lan] [PATCH iwl-net v1] igc: fix race condition in TX timestamp read for register 0 To: Vadim Fedorenko , Chwee-Lin Choong , Tony Nguyen , Przemek Kitszel , Andrew Lunn , "David S . Miller" , "Eric Dumazet" , Jakub Kicinski , Paolo Abeni , Richard Cochran , "Vinicius Costa Gomes" CC: , , , Avi Shalev , "Song Yoong Siang" References: <20250918183811.31270-1-chwee.lin.choong@intel.com> <0fc877a5-4b35-4802-9cda-e4eca561c5d1@linux.dev> Content-Language: en-US From: Jacob Keller Autocrypt: addr=jacob.e.keller@intel.com; keydata= xjMEaFx9ShYJKwYBBAHaRw8BAQdAE+TQsi9s60VNWijGeBIKU6hsXLwMt/JY9ni1wnsVd7nN J0phY29iIEtlbGxlciA8amFjb2IuZS5rZWxsZXJAaW50ZWwuY29tPsKTBBMWCgA7FiEEIEBU qdczkFYq7EMeapZdPm8PKOgFAmhcfUoCGwMFCwkIBwICIgIGFQoJCAsCBBYCAwECHgcCF4AA CgkQapZdPm8PKOiZAAEA4UV0uM2PhFAw+tlK81gP+fgRqBVYlhmMyroXadv0lH4BAIf4jLxI UPEL4+zzp4ekaw8IyFz+mRMUBaS2l+cpoBUBzjgEaFx9ShIKKwYBBAGXVQEFAQEHQF386lYe MPZBiQHGXwjbBWS5OMBems5rgajcBMKc4W4aAwEIB8J4BBgWCgAgFiEEIEBUqdczkFYq7EMe apZdPm8PKOgFAmhcfUoCGwwACgkQapZdPm8PKOjbUQD+MsPBANqBUiNt+7w0dC73R6UcQzbg cFx4Yvms6cJjeD4BAKf193xbq7W3T7r9BdfTw6HRFYDiHXgkyoc/2Q4/T+8H In-Reply-To: <0fc877a5-4b35-4802-9cda-e4eca561c5d1@linux.dev> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="------------WItSTxHYuETg844T6vGRedFX" X-ClientProxiedBy: SJ0PR13CA0180.namprd13.prod.outlook.com (2603:10b6:a03:2c7::35) To CO1PR11MB5089.namprd11.prod.outlook.com (2603:10b6:303:9b::16) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CO1PR11MB5089:EE_|MW4PR11MB8292:EE_ X-MS-Office365-Filtering-Correlation-Id: c1ddc160-fc9d-4ca0-227f-08ddf700317e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|376014|7416014|366016|921020; X-Microsoft-Antispam-Message-Info: =?utf-8?B?S3F4NmtFYjVneFJWWFA0bWdaT2EyaWJkYWkyWWhvZFY2ODBrL2U1TnRLWUZa?= =?utf-8?B?S2JpSXVGcllqa1hSZ083TE4rZXJwdGp0MGk5aDl0UC9sNTZiSHFlZTJTQzJC?= =?utf-8?B?UGhXQWFObHRaTEVYdmIzM0o5OHdWeXpxVVU4TXBaelloaDJhMHJiOXEvZnZO?= =?utf-8?B?UFA1U2pCNzVCY0ExRGZQcVdmeU5MV215R2QxeENjNzBZU1dvQTNvRlJXc2pB?= =?utf-8?B?ekRDY0dramxWRktpT2Z5TzdNWldkaUEwNVVHdldpR215SzA3cmFDaTBPVHRD?= =?utf-8?B?dzVvWVBSTmNtNXhnWDNjMkRhOWhzckFINC9CMEIzSW5ibEM1Snc2ZUFueVE2?= =?utf-8?B?UURxbnZRYzJacGVMaVJscWNyYVRBQ3IzZnlFdFdaU09mSFFKTGpNMk1qbjVG?= =?utf-8?B?V2VUOUhqWDZjbWlTaHk4Z1A1STYvcWVmY2tkZm44dktVUUowYkhoOEJTZitL?= =?utf-8?B?ZC9wWGZVUHJFS3JSQ3BKT2IzQjA5YWhodjVlVmh1ZTNSdEVBUUliQzJJNFF2?= =?utf-8?B?cUZaa1NPeVNDeUszVy9xNGZmMm54SWZMKy9DNWJRUzIxSGJNa0cvZUxmRG1N?= =?utf-8?B?ajgzc0libmNlTUFCWEswVnZNeWU1VVRMelFoSjFDNEtPaytHcExyY0piRDc5?= =?utf-8?B?a1IxRnZzdzlBbVlYMEhUQ2luam5yNlhkM01XbE9tdVZTOEZ1ZnQ4ZFZpejlL?= =?utf-8?B?VFUrUDF2b3NJRUUvVzNSYUhhQmVlL2hDSnRjcU5WM25vU3BrbzFTa0ZpMDBn?= =?utf-8?B?ZXhiNFlyVWVscW5RbVRvYXQzZ3l4RE5rOGhTcXk5c014bnkySHlGZXZtakFV?= =?utf-8?B?MXdCTVpZV0xnYjZqTDNrdGxST0tmSnBKWDlWVUlJY1BmYm8rdCtlWVR5c0dC?= =?utf-8?B?b1NEZ01HanY3eGNVd0oyZkFOSnR1bEtmTnAxZXBUeDJ0bE5Zbmd6SUZFZFJt?= =?utf-8?B?azExYmx2WmFIU0E0c3pVcXZjVnhiOVB6MHp5NGJoWWNzWnFDQkZ3eDhHTytu?= =?utf-8?B?YWlNNW9MOWlweDRBTXRieUJmQ3QrL3lNWXZjWE4vREtRUm94Tm92emJTam9B?= =?utf-8?B?NDlCRmg4UnJZalJ6TDhkRTVWQ1RzWGVxKzI5a3VZdXpHRS9tSW5NLzRiTHRy?= =?utf-8?B?WngwZ3FJZFhjV1I4cDdCZU5JeDZvRlBTZmRxYXlWOWRDczRlNG83SVIvTmhp?= =?utf-8?B?aDZOK3pFa3FLaWxaUmdDdnF3K0R6cGVkSGZ5REJuV29WT1NtR0p5dkV6QXp6?= =?utf-8?B?eG8vb2dhVHQ0RlFYQlFJUGdlYUhQM1FHMEFNbXlDMlRvOTFZQ01CQUNJc3Jn?= =?utf-8?B?ay9NNnhmQVR2QjdydUZwTTJrTHlDWUZrdTRPbm5aYVFKWWUvWkk5N2VVbmNz?= =?utf-8?B?ZGxLeEpHRm9ZM0M1MUFTZTJPVUNBbm5ta1RGbXMxcXhOTFQwbU0xRUVEMTEx?= =?utf-8?B?cnJnelg5SHhPR3BvU29QWU51dGpkQVRNd2NTdFBlU1l4V2ROdlQxbzk0aEJo?= =?utf-8?B?S25YZ3k2cExvS0g4UU5SbTV3Ulc1WWt6SUdaY09ENjhkREE2Wm1vVy9xNDJ2?= =?utf-8?B?RUtzcUg4TnZZWFpHL0FRTVN3dEJJTTQ1OWQ2bjdmYUhzS1RvT0lmTDhROTZH?= =?utf-8?B?amprU3JDc0JvM2kwZDl6c1hwRTFBeVBjMzc0b1B6T0pSZlVyUHA4UVg5N2p5?= =?utf-8?B?UTJCWXJBRXRickVhMjlzbFlZN1BPMzE3SmxrZGFITjRaTkxVVHVaRHBNZ3Iy?= =?utf-8?B?dnNmMTBXU2ZMcTNTVEhuRW5rVXlORUpVdWJzdGRrU0tZUXpnUVVkNzBYRkZ3?= =?utf-8?B?UElLSWxaUm02VkJDMTRNcXFxSG9zZ0VUSmpYeWNwV21GVit2UktrdDlkNU41?= =?utf-8?B?bDVnR0tXS3NLNDJ2RE1tQVFtVmNZdXZWMUtIZHZCSWg3V25JYXVCQWpiTkxX?= =?utf-8?B?anVZKzdUZWJFdUx3Tk5FZFZwMlpxcytCcXRPM0t3dWM5bkVoZ3hZamNtV080?= =?utf-8?B?ZWNUd0hpekF3PT0=?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CO1PR11MB5089.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(376014)(7416014)(366016)(921020);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?UXRFOXhEclJmRkdqbFNyNEVnK2ZLRFJXeVR2SU5mYTluSlp4cklXNWUxVUh6?= =?utf-8?B?WmFMTUxaWUlKMW9kNnlUSkxYOXdjdzJwZmxEN081ckJlbUlKWW9rZGdTMjFi?= =?utf-8?B?b1REQXFCeEF6VzIrK3F0dk93SFkzUnFiUEJaWkxGZWZ2SVgzbi9yR0dJQXE1?= =?utf-8?B?L1dPUUlMNG5DeERZU0VFdkdISTVqTVFPTUlLRTJVNi9LSHdCVllBVTJYa1RF?= =?utf-8?B?SkNBdndVcVUvWkRURG9qdVI0SXV1UFgwcVZVOE9CMGVZdWZHblQxN1B4cXRL?= =?utf-8?B?Q1VBNC9TMEV3TXdocEdWNUxValFabFZ5M201SHQrdXJNbnJMVlEzZ2lFV0xq?= =?utf-8?B?MVBqVEIvakprdWxDV3dja2JwSFBCcWhaNmFPcldzbWg2K1RDWmZ0TmVzWnM2?= =?utf-8?B?SlJvT1ZQdm5KZzcyeTVJbjhwdVF2Y1lvUE96OVozRlNRTklQdVArNDV6WFNN?= =?utf-8?B?MmFuQ1ZwV1BFV0owVTFiMjd1elJ4QzVmRG9PdUR1ME9pQ1lkWmt5enYyQVl3?= =?utf-8?B?S1dRN2Z4WllHMjlBd2t1dnFnSHBNQ3hKVDdWUEEyVTNWeU9tYUNsekVGelRB?= =?utf-8?B?d3Rad2VlVG92YjhCYnVaU1pCRUtPUzVXTTdDMDQ4WWFtUldWaHZBTFhGYzhP?= =?utf-8?B?UWI2dGxmTmg2Y3VqNUwrZ0VkVTJPQ3lkK3dvMnBQa3RpelFXbkw1U2lFOWZM?= =?utf-8?B?UEhRaEtBQ0RBd1NiZjgrVGlKaTJ2SFdxaXR1YzdtMkZPNEJVbFh4ZTBxVUE4?= =?utf-8?B?dUlzdzNNNXNOc3FrYUt5ZWRJYVhBTUVZcHhsQlc0aE1SMytmZjVEa1htQ2Vj?= =?utf-8?B?ZDZySUVxOFBPckZvY1kyS24wR202bXlQcmRzYzZGcGUxYXBiRmlrRGR1eXRN?= =?utf-8?B?eE5TVUZDbHVzMGFPdll3QXhmblpiNzcwQ2MwelBwMG4vOEp4bTNWSGtLQ2wx?= =?utf-8?B?c0hObldodXVBdXc2eUJOaEJ1b1FNMzhqV01RSnNxRWlSTmhzUHdiZVBmZFNp?= =?utf-8?B?T1M5Qi95RDgrbHRQTHRwV0VFUGlEWFBVaXpmc3l0VDdyK1pVbnE1UGFNK01U?= =?utf-8?B?aS8xbjYreDlLejVuaHJpeE95dmU2MEwyTllkK0lXZlpsTVFzam1GWXdxb0ZO?= =?utf-8?B?b0tDVStWdUFJRnk2NDlYajliWUN1R3ExYzgvd3BLOFlEcFQ5UUJxNVRJdGFm?= =?utf-8?B?S01tcnNIRk1HSE83YXlyRXVpTWlDVW9uRHc1TWZOU1FhNXZ2TGNmZGhPVEZP?= =?utf-8?B?ckFoSGNEQzkvemhDYUVDOFBrRkNrUlpOVHlDck82SkZabzZkd1J2eHM5VlMr?= =?utf-8?B?Y21UNWIwQ2NDMW01cG1qWncyeHJEOWNKOE9teGJFeWYxd2JKNXF6MURmT1Ny?= =?utf-8?B?STJjYUxNMWpvOGxPbU5PTmlHSXVJNlNqem43SVU2U0VKejFsTFo2SXRvNmpm?= =?utf-8?B?NktDY1NMM0pnUjZvRHFXaDBRUDVyeHE0MmRHMldZVXZNOTlmSmxBeFJ1Si9h?= =?utf-8?B?RGhYcDF5Yzc3ZCticTVPUGNqTzFwOE01RXNnNnBiQzdocHo2VjBXNWtQMmND?= =?utf-8?B?UisvMHZCeU9ucExiRjdFRjJYKzEvdGZpbThWaTY3Q0oza2ZoZjA5UGUrL3lK?= =?utf-8?B?ZGprT2o1NUUyN0RSb1NLT2p2M0ptMW16MVFORi9yK2VGcWtVOXlsZFZsU2t6?= =?utf-8?B?MzdhQU9sK2ppRmVuYVlaa2NXNFFCdkJLbk9heDJ5VEs3c1l1Y0JWakxBTUNX?= =?utf-8?B?YjJtbGI0Nm9KcW1UYms5dlNkand5b2xiTmIwREpSRzBaajIzS1NqT1R3NW1o?= =?utf-8?B?NU9oM25wNFdmOTRkaC9ZSk5wSW1IdWFvRXZnOVNuMGhYYlhvWTdVd3BTMHl3?= =?utf-8?B?eFN1SENVcWJWQUJvVjVVTlJWSzR2RENESm53SHUrZDV0aTdxVjA2VCtOcGFS?= =?utf-8?B?RjdscXFYVGh2cVNtZk9DOUtaUUpNR2gzQXNEdUdTQUxhVUxKV3IzTnhhajBN?= =?utf-8?B?RGNuRVBmSDJEQ0FDL09FeHdqMUNHd25PUzFFd3hXNVE0MC9saUNCRVA0QXhD?= =?utf-8?B?TFVNeVEzUm4vVXlrVzliT2dNVjF4ZGg1NFlkNmdUTk5ueGxpY09DazYrQlp4?= =?utf-8?B?dmFuVUVzL3Axemtia0xFZC9QNWh0MG9WbVJKWEZUOWQ2UnRRcGFzNEI0cldG?= =?utf-8?B?akE9PQ==?= X-MS-Exchange-CrossTenant-Network-Message-Id: c1ddc160-fc9d-4ca0-227f-08ddf700317e X-MS-Exchange-CrossTenant-AuthSource: CO1PR11MB5089.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Sep 2025 22:10:38.2281 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: bik0kIqx+uQOIWZYP7FprFn2FreVXFu8uDr/Cs96YqLPLgRmTIvdnJGnmy/VwN0CYj0ZeOitXNUpUwkvL0NXqIpCIMwbmIASnhT3FwgYH+E= X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW4PR11MB8292 X-OriginatorOrg: intel.com --------------WItSTxHYuETg844T6vGRedFX Content-Type: multipart/mixed; boundary="------------MDKVYXwNmKKdKiCl5nwrwzb4"; protected-headers="v1" From: Jacob Keller To: Vadim Fedorenko , Chwee-Lin Choong , Tony Nguyen , Przemek Kitszel , Andrew Lunn , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Richard Cochran , Vinicius Costa Gomes Cc: intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Avi Shalev , Song Yoong Siang Message-ID: Subject: Re: [Intel-wired-lan] [PATCH iwl-net v1] igc: fix race condition in TX timestamp read for register 0 References: <20250918183811.31270-1-chwee.lin.choong@intel.com> <0fc877a5-4b35-4802-9cda-e4eca561c5d1@linux.dev> In-Reply-To: <0fc877a5-4b35-4802-9cda-e4eca561c5d1@linux.dev> --------------MDKVYXwNmKKdKiCl5nwrwzb4 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 9/18/2025 1:47 PM, Vadim Fedorenko wrote: > On 18/09/2025 19:38, Chwee-Lin Choong wrote: >> The current HW bug workaround checks the TXTT_0 ready bit first, >> then reads LOW -> HIGH -> LOW from register 0 to detect if a >> timestamp was captured. >> >> This sequence has a race: if a new timestamp is latched after >> reading the TXTT mask but before the first LOW read, both old >> and new timestamp match, causing the driver to drop a valid >> timestamp. >> >> Fix by reading the LOW register first, then the TXTT mask, >> so a newly latched timestamp will always be detected. >> >> This fix also prevents TX unit hangs observed under heavy >> timestamping load. >> >> Fixes: c789ad7cbebc ("igc: Work around HW bug causing missing timestam= ps") >> Suggested-by: Avi Shalev >> Signed-off-by: Song Yoong Siang >> Signed-off-by: Chwee-Lin Choong >> --- >> drivers/net/ethernet/intel/igc/igc_ptp.c | 10 ++++++++-- >> 1 file changed, 8 insertions(+), 2 deletions(-) >> >=20 > [...] >=20 >> * timestamp was captured, we can read the "high" >> * register again. >> */ >=20 > This comment begins with 'read the "high" register (to latch a new=20 > timestamp)' ... >=20 >> - u32 txstmpl_old, txstmpl_new; >> + u32 txstmpl_new; >> =20 >> - txstmpl_old =3D rd32(IGC_TXSTMPL); >> rd32(IGC_TXSTMPH); >> txstmpl_new =3D rd32(IGC_TXSTMPL); >=20 > and a couple of lines later in this function you have >=20 > regval =3D txstmpl_new; > regval |=3D (u64)rd32(IGC_TXSTMPH) << 32; >=20 > According to the comment above, the value in the register will be > latched after reading IGC_TXSTMPH. As there will be no read of "low" > part of the register, it will stay latched with old value until the > next call to the same function. Could it be the reason of unit hangs? >=20 > It looks like the value of previous read of IGC_TXSTMPH should be store= d > and used to construct new timestamp, right? >=20 I wouldn't trust the comment, but instead double check the data sheets. Unfortunately, I don't seem to have a copy of the igc hardware data sheet handy :( Thanks, Jake --------------MDKVYXwNmKKdKiCl5nwrwzb4-- --------------WItSTxHYuETg844T6vGRedFX Content-Type: application/pgp-signature; name="OpenPGP_signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="OpenPGP_signature.asc" -----BEGIN PGP SIGNATURE----- wnsEABYIACMWIQQgQFSp1zOQVirsQx5qll0+bw8o6AUCaMyDWgUDAAAAAAAKCRBqll0+bw8o6LCR AQCGQIaf4m7h+Adrf3NDLSAQGnaf/mobq8nTBqWbV1e86QEAsDV3/P2brqdSs7sUKFJ7/y6CpzzR y/+5K0DZBt6sFws= =LX3Q -----END PGP SIGNATURE----- --------------WItSTxHYuETg844T6vGRedFX--