[{"id":3688367,"web_url":"http://patchwork.ozlabs.org/comment/3688367/","msgid":"<20260508115309.GA9254@nvidia.com>","list_archive_url":null,"date":"2026-05-08T11:53:09","subject":"Re: [PATCH v10 8/9] platform/chrome: Protect cros_ec_device\n lifecycle with revocable","submitter":{"id":79424,"url":"http://patchwork.ozlabs.org/api/people/79424/","name":"Jason Gunthorpe","email":"jgg@nvidia.com"},"content":"On Fri, May 08, 2026 at 06:54:47PM +0800, Tzung-Bi Shih wrote:\n> struct cros_ec_device *cros_ec_device_alloc(struct device *dev)\n> @@ -47,6 +49,15 @@ struct cros_ec_device *cros_ec_device_alloc(struct device *dev)\n> \tif (!ec_dev)\n> \t\treturn NULL;\n> \n> +\tec_dev->its_rev = revocable_alloc(ec_dev);\n> +\tif (!ec_dev->its_rev)\n> +\t\treturn NULL;\n> +\t/*\n> +\t * Drop the extra reference for the caller as the caller is the\n> +\t * resource provider.\n> +\t */\n> +\trevocable_put(ec_dev->its_rev);\n> +\n> \tec_dev->din_size = sizeof(struct ec_host_response) +\n> \t\t\t sizeof(struct ec_response_get_protocol_info) +\n> \t\t\t EC_MAX_RESPONSE_OVERHEAD;\n\nFWIW I am still very much against seeing any revokable concept used\n*between two drivers*. That will turn the kernel's lifetime model into\nspaghetti code.\n\nYour other series where you only have to change\ndrivers/platform/chrome/cros_ec_chardev.c just confirms how wrong this\napproach is.\n\nGiven you say this is such a bug I think you really should be sending\na series that is patches 5 through 7 from the other series and a\nsimple rwsem instead of misc_deregister_sync() to deal with this bug\nASAP. No need to complicate a simple bug fix in a driver with all\nthese core changes.\n\nOnce the bug is fixed you can continue to try to propose more general\nsolutions.\n\nJason","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-gpio@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=Nvidia.com header.i=@Nvidia.com header.a=rsa-sha256\n header.s=selector2 header.b=IDB4Kc2i;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c04:e001:36c::12fc:5321; helo=tor.lore.kernel.org;\n envelope-from=linux-gpio+bounces-36460-incoming=patchwork.ozlabs.org@vger.kernel.org;\n receiver=patchwork.ozlabs.org)","smtp.subspace.kernel.org;\n\tdkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com\n header.b=\"IDB4Kc2i\"","smtp.subspace.kernel.org;\n arc=fail smtp.client-ip=52.101.48.38","smtp.subspace.kernel.org;\n dmarc=pass (p=reject dis=none) header.from=nvidia.com","smtp.subspace.kernel.org;\n spf=fail smtp.mailfrom=nvidia.com","dkim=none (message not signed)\n header.d=none;dmarc=none action=none header.from=nvidia.com;"],"Received":["from tor.lore.kernel.org (tor.lore.kernel.org\n [IPv6:2600:3c04:e001:36c::12fc:5321])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519 server-signature ECDSA (secp384r1) server-digest SHA384)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4gBnZC2TzMz1yKd\n\tfor ; Fri, 08 May 2026 21:53:23 +1000 (AEST)","from smtp.subspace.kernel.org (conduit.subspace.kernel.org\n [100.90.174.1])\n\tby tor.lore.kernel.org (Postfix) with ESMTP id A9E0D302C369\n\tfor ; Fri, 8 May 2026 11:53:20 +0000 (UTC)","from localhost.localdomain (localhost.localdomain [127.0.0.1])\n\tby smtp.subspace.kernel.org (Postfix) with ESMTP id 9E7A7397E9A;\n\tFri, 8 May 2026 11:53:19 +0000 (UTC)","from MW6PR02CU001.outbound.protection.outlook.com\n (mail-westus2azon11012038.outbound.protection.outlook.com [52.101.48.38])\n\t(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby smtp.subspace.kernel.org (Postfix) with ESMTPS id 2319A2E9757;\n\tFri, 8 May 2026 11:53:17 +0000 (UTC)","from LV8PR12MB9620.namprd12.prod.outlook.com (2603:10b6:408:2a1::19)\n by SA0PR12MB7076.namprd12.prod.outlook.com (2603:10b6:806:2d5::11) with\n Microsoft SMTP Server (version=TLS1_2,\n cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9891.15; Fri, 8 May\n 2026 11:53:11 +0000","from LV8PR12MB9620.namprd12.prod.outlook.com\n ([fe80::299d:f5e0:3550:1528]) by LV8PR12MB9620.namprd12.prod.outlook.com\n ([fe80::299d:f5e0:3550:1528%5]) with mapi id 15.20.9891.017; Fri, 8 May 2026\n 11:53:11 +0000"],"ARC-Seal":["i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116;\n\tt=1778241199; cv=fail;\n b=ArdufyrivGpo7uB3lgXYXWcsT8Bj7F26CHE9iUVtUUBXduSNV9PvN/PJCG19aaJ8z1Ew5W0VShXvkD0DE11mfuVdwIFojROXDfvOaMFftxJB1Pmn+9Z/f5/Nvi6OonaN5PjR1jXIkDUMcxKYGgb8ypY40mvog71kAi3xBcuSq1Q=","i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none;\n b=FmaQuh8tHB+DHtkNRGwrAPbk5wKr46jSzsIazBfb+B8sO1MddihgVBDfiXfaUjQ3NPY17OhbB1tIw+b0VpwRNW+F5yjBnQrC2GL8oDkQ1H5bgWqb0UBty4sgSMUoQzEsHCjXTPr5Fa5WMirN987MPthsROWUVJ+hC77hcvWtY/CPyLZet9CDNk6EDFier5X6QYubdCE7uSEdepxVV6ifzBvd70MYBqiyRCGnv/Cg8yys2iC1MASf9MKmsUBdFYwDp6rw3pwKu0c5arBTYjNUhspj8rY7ulNFGm4kV/9hhjZEPD2T0j0Xzp6Ti20ReY/CIPSBkxH6wubo+oH6Q54PcA=="],"ARC-Message-Signature":["i=2; a=rsa-sha256; d=subspace.kernel.org;\n\ts=arc-20240116; t=1778241199; c=relaxed/simple;\n\tbh=kUruMmg4aOFo9e3NNr9KsKyOO8lo94kuiR9hXz3V4is=;\n\th=Date:From:To:Cc:Subject:Message-ID:References:Content-Type:\n\t Content-Disposition:In-Reply-To:MIME-Version;\n b=VZ7Kk5/p8dsNNvFvPqjAwrkhoNcVlSsr65Agd5GUBkMc2xs1RNnizIyVs07bYnVrCrQRUBWku1nEoADDzInRzlQukvv2YZkEDyjm83OJRqOEeu0pf+9K/md3k2ysOgXKf9d8xiHFuC5uFSZkd44xPU2l+xMiKoTB3h/nYKbsiRQ=","i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com;\n s=arcselector10001;\n 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;\n bh=0rIgBVNnQtKV9bJPq8waCbpORckLkslBlkOWlwr9rHE=;\n b=WYxXQ9f5pu3Il4pg7GO8rfHFwo7UjfxAb/Za98HFQn2h7QTXjnplPPAUCP5aM/Hkyfs0IDelrCY9Cms0UMgVGtZMwo47l6MxnWVb6S3znNPgivHa2X2Bjg6huwxBTQvdmD4yCdzpzm1dKQofqSsqysJiuXUJvBoBvhIjlJKyPAgiNuybTQcOIqAK9b/3YX9IdAmyfDwk7o2yDMo6lBy1z0xO4LuhpEcO+6WeyMGXLCKfmTyxlpNbYNYppuSbgJ6Jfonixo99d3X7sJUbhyVRpFK67tsYqLDCrEvMlG7vuvxIyKVIMMBYX2DMR6g1K1MYuOC//MkeqIKLfiAt1jsdtA=="],"ARC-Authentication-Results":["i=2; smtp.subspace.kernel.org;\n dmarc=pass (p=reject dis=none) header.from=nvidia.com;\n spf=fail smtp.mailfrom=nvidia.com;\n dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com\n header.b=IDB4Kc2i; arc=fail smtp.client-ip=52.101.48.38","i=1; mx.microsoft.com 1; spf=pass\n smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com;\n dkim=pass header.d=nvidia.com; arc=none"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com;\n s=selector2;\n h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck;\n bh=0rIgBVNnQtKV9bJPq8waCbpORckLkslBlkOWlwr9rHE=;\n b=IDB4Kc2iUH80uaISiABF2NexgU3i1veYOOQtAqMndb1VEWWuOG6Y2zSxJa77o4xuyx01kxw9RNlra0ApcWWQqPKH7DN3fRBjYPgb+PDAgB5rLCZb+61f3VUL7fJsLVVkQgGc4NFT+xYsJqnvQ2W2I9qdPHNV+vSCzuHh/3AReEVinx0+PtYlCojH0+tGnfESgyIoxQ/c7X+ZIs4jh+KiY0CniB3KLmZrMK0FCrXsU0C3OGN/CRXFmpg/TqWTZ+AZBPtGkcV6S8Nh2XwF+JbPlgJ8/emyy7moWaXbnKAX+C5PLmScIQ4rmPlNKlw1L53DhQsz61hKMb2Jji1xKQhQnA==","Date":"Fri, 8 May 2026 08:53:09 -0300","From":"Jason Gunthorpe ","To":"Tzung-Bi Shih ","Cc":"Arnd Bergmann ,\n\tGreg Kroah-Hartman ,\n\tBartosz Golaszewski ,\n\tLinus Walleij ,\n\tBenson Leung , linux-kernel@vger.kernel.org,\n\tchrome-platform@lists.linux.dev, driver-core@lists.linux.dev,\n\tlinux-doc@vger.kernel.org, linux-gpio@vger.kernel.org,\n\t\"Rafael J. Wysocki\" ,\n\tDanilo Krummrich ,\n\tJonathan Corbet , Shuah Khan ,\n\tLaurent Pinchart ,\n\tWolfram Sang ,\n\tJohan Hovold ,\n\t\"Paul E . McKenney\" ","Subject":"Re: [PATCH v10 8/9] platform/chrome: Protect cros_ec_device\n lifecycle with revocable","Message-ID":"<20260508115309.GA9254@nvidia.com>","References":"<20260508105448.31799-1-tzungbi@kernel.org>\n <20260508105448.31799-9-tzungbi@kernel.org>","Content-Type":"text/plain; charset=us-ascii","Content-Disposition":"inline","In-Reply-To":"<20260508105448.31799-9-tzungbi@kernel.org>","X-ClientProxiedBy":"SN7P222CA0024.NAMP222.PROD.OUTLOOK.COM\n (2603:10b6:806:124::20) To LV8PR12MB9620.namprd12.prod.outlook.com\n (2603:10b6:408:2a1::19)","Precedence":"bulk","X-Mailing-List":"linux-gpio@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","MIME-Version":"1.0","X-MS-PublicTrafficType":"Email","X-MS-TrafficTypeDiagnostic":"LV8PR12MB9620:EE_|SA0PR12MB7076:EE_","X-MS-Office365-Filtering-Correlation-Id":"d07708bd-fb1d-45e8-5c9d-08deacf860eb","X-MS-Exchange-SenderADCheck":"1","X-MS-Exchange-AntiSpam-Relay":"0","X-Microsoft-Antispam":"\n\tBCL:0;ARA:13230040|1800799024|366016|376014|7416014|18002099003|56012099003|22082099003|3023799003;","X-Microsoft-Antispam-Message-Info":"\n\t4zi5IIremP9VsW1EXLtNtdICHLO+NvApW5I5OTFUjbi5R0V6KnzBeMfIlesuDEJvBP/YplokrmtHyzoOVwh7a+sm9KfHOFPbJqreqenwTx3KazD6fJ6tECxN3aZ4xuF91yGPA4JkbwqXK5GJgc5LJgb9fqPKOhHgpQiPhdpU2x33gbkWoVF2glkmu1F4fmcY+RkyEInG0IkjqtpiiUA8uCYk3QPwykeaezCiPf0oPOpJGvePBz0oG2/yi0uGVwg6jvq2GCFXNQ99sUgscVNONB0z5NAN5DIrNZA48KZCKUIBMyZQXw/ooABBrtEAXk8erVGXICyTdrAdUO9DlbjS7jKQM2C/FpDlLkjQ25Q0MfXeUCIxzWrodSQi+ZSIDIC7tV0sWK55nAGmxojZ8o7rNA/uKXiojk1dClodd7lWwE0q//1T8WlcurTdy6rzI7YeQ7JFmM26bFz95XgptRdn7aRk4KACrBw/tYiozKJCKZGKBnUT+qGdGF2iRQAeRpYOYUxxPK5uOtUZHorKkgvK3qsAZt5Wz/HeXjUgobvci3eAR6L9KWImwwOqQLQE6Cv4ls7zp6jCaoBRhbx4rudAS39looJb/oVlaK3BpnxAWvpLezMqnRgbuM3rO4rfrCG5EpHyUWdVyd+IuUFmZODQqZ9BoDXGmnwULDpehEV/q3PkT/HKC2JK/JKq48XKl6ed","X-Forefront-Antispam-Report":"\n\tCIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:LV8PR12MB9620.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(366016)(376014)(7416014)(18002099003)(56012099003)(22082099003)(3023799003);DIR:OUT;SFP:1101;","X-MS-Exchange-AntiSpam-MessageData-ChunkCount":"1","X-MS-Exchange-AntiSpam-MessageData-0":"\n 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","X-OriginatorOrg":"Nvidia.com","X-MS-Exchange-CrossTenant-Network-Message-Id":"\n d07708bd-fb1d-45e8-5c9d-08deacf860eb","X-MS-Exchange-CrossTenant-AuthSource":"LV8PR12MB9620.namprd12.prod.outlook.com","X-MS-Exchange-CrossTenant-AuthAs":"Internal","X-MS-Exchange-CrossTenant-OriginalArrivalTime":"08 May 2026 11:53:11.2786\n (UTC)","X-MS-Exchange-CrossTenant-FromEntityHeader":"Hosted","X-MS-Exchange-CrossTenant-Id":"43083d15-7273-40c1-b7db-39efd9ccc17a","X-MS-Exchange-CrossTenant-MailboxType":"HOSTED","X-MS-Exchange-CrossTenant-UserPrincipalName":"\n v5XO68bUrStqZpJOVcv9Ac/RkMTV02P2ZFJM4o4j+64z5XeV9/MgWCY5VciUrMpR","X-MS-Exchange-Transport-CrossTenantHeadersStamped":"SA0PR12MB7076"}}]