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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 5576BC433E3 for ; Tue, 23 Mar 2021 19:15:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 27B97619D8 for ; Tue, 23 Mar 2021 19:15:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233227AbhCWTO6 (ORCPT ); Tue, 23 Mar 2021 15:14:58 -0400 Received: from mga02.intel.com ([134.134.136.20]:48530 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233258AbhCWTOX (ORCPT ); Tue, 23 Mar 2021 15:14:23 -0400 IronPort-SDR: cQjUnhOMCCXuXx12BL1Uy8CehyLQBdlIVEfChUJfbUMSraHRwGCM3X6xmXYqSBZKJ5oNISFhv8 mRoUtSHGw/6w== X-IronPort-AV: E=McAfee;i="6000,8403,9932"; a="177671199" X-IronPort-AV: E=Sophos;i="5.81,272,1610438400"; d="scan'208";a="177671199" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Mar 2021 12:14:21 -0700 IronPort-SDR: LrlxJMmlWHeXpmw4l3JwHxWZYy2E6m+cwtx6PxY3N63PBQoecCG22sZ8zTZW0otLKrYbc7VVWu YtY0ZYP+JNAg== X-IronPort-AV: E=Sophos;i="5.81,272,1610438400"; d="scan'208";a="452277659" Received: from laguitie-mobl.amr.corp.intel.com (HELO [10.252.129.185]) ([10.252.129.185]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Mar 2021 12:14:20 -0700 Subject: Re: [PATCH] soundwire: intel: move to auxiliary bus To: Greg KH Cc: alsa-devel@alsa-project.org, vinod.koul@linaro.org, linux-kernel@vger.kernel.org, hui.wang@canonical.com, vkoul@kernel.org, srinivas.kandagatla@linaro.org, sanyog.r.kale@intel.com, Bard Liao , rander.wang@linux.intel.com, bard.liao@intel.com References: <20210323004325.19727-1-yung-chuan.liao@linux.intel.com> <777b4ca6-0d51-285d-549f-6ef768f2a523@linux.intel.com> From: Pierre-Louis Bossart Message-ID: <35cc8d35-a778-d8b2-bee3-bb53f8a6c51e@linux.intel.com> Date: Tue, 23 Mar 2021 14:14:18 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/23/21 1:32 PM, Greg KH wrote: > On Tue, Mar 23, 2021 at 01:04:49PM -0500, Pierre-Louis Bossart wrote: >> >>>> Note that the auxiliary bus API has separate init and add steps, which >>>> requires more attention in the error unwinding paths. The main loop >>>> needs to deal with kfree() and auxiliary_device_uninit() for the >>>> current iteration before jumping to the common label which releases >>>> everything allocated in prior iterations. >>> >>> The init/add steps can be moved together in the aux bus code if that >>> makes this usage simpler. Please do that instead. >> >> IIRC the two steps were separated during the auxbus reviews to allow the >> parent to call kfree() on an init failure, and auxiliary_device_uninit() >> afterwards. >> >> https://www.kernel.org/doc/html/latest/driver-api/auxiliary_bus.html#auxiliary-device >> >> With a single auxbus_register(), the parent wouldn't know whether to use >> kfree() or auxiliary_device_uinit() when an error is returned, would it? >> > > It should, you know the difference when you call device_register() vs. > device_initialize()/device_add(), for what to do, right? > > Should be no difference here either :) sorry, not following. with the regular devices, the errors can only happen on the second "add" stage. int device_register(struct device *dev) { device_initialize(dev); return device_add(dev); } that's not what is currently implemented for the auxiliary bus the current flow is ldev = kzalloc(..) some inits ret = auxiliary_device_init(&ldev->auxdev) if (ret < 0) { kfree(ldev); goto err1; } ret = auxiliary_device_add(&ldev->auxdev) if (ret < 0) auxiliary_device_uninit(&ldev->auxdev) goto err2; } ... err2: err1: How would I convert this to ldev = kzalloc(..) some inits ret = auxiliary_device_register() if (ret) { kfree(ldev) or not? unit or not? } IIRC during reviews there was an ask that the parent and name be checked, and that's why the code added the two checks below: int auxiliary_device_init(struct auxiliary_device *auxdev) { struct device *dev = &auxdev->dev; if (!dev->parent) { pr_err("auxiliary_device has a NULL dev->parent\n"); return -EINVAL; } if (!auxdev->name) { pr_err("auxiliary_device has a NULL name\n"); return -EINVAL; } dev->bus = &auxiliary_bus_type; device_initialize(&auxdev->dev); return 0; } does this clarify the sequence?