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=-15.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 3A0DFC11F66 for ; Fri, 9 Jul 2021 13:18:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 272EC61357 for ; Fri, 9 Jul 2021 13:18:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231950AbhGINVd (ORCPT ); Fri, 9 Jul 2021 09:21:33 -0400 Received: from mga18.intel.com ([134.134.136.126]:25063 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231925AbhGINVc (ORCPT ); Fri, 9 Jul 2021 09:21:32 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10039"; a="196974898" X-IronPort-AV: E=Sophos;i="5.84,226,1620716400"; d="scan'208";a="196974898" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Jul 2021 06:18:48 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.84,226,1620716400"; d="scan'208";a="628856893" Received: from ahunter-desktop.fi.intel.com (HELO [10.237.72.79]) ([10.237.72.79]) by orsmga005.jf.intel.com with ESMTP; 09 Jul 2021 06:18:44 -0700 Subject: Re: [PATCH V2 1/2] driver core: Add ability to delete device links of unregistered devices To: "Rafael J. Wysocki" Cc: Greg Kroah-Hartman , Saravana Kannan , "Martin K . Petersen" , "James E . J . Bottomley" , "open list:TARGET SUBSYSTEM" , Avri Altman , Bean Huo , Can Guo , Asutosh Das , Bart Van Assche , Linux PM , Linux Kernel Mailing List References: <20210709064341.6206-1-adrian.hunter@intel.com> <20210709064341.6206-2-adrian.hunter@intel.com> From: Adrian Hunter Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki Message-ID: Date: Fri, 9 Jul 2021 16:18:57 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/07/21 2:28 pm, Rafael J. Wysocki wrote: > On Fri, Jul 9, 2021 at 8:43 AM Adrian Hunter wrote: >> >> Managed device links are deleted by device_del(). However it is possible to >> add a device link to a consumer before device_add(), and then discover an >> error prevents the device from being used. In that case normally references >> to the device would be dropped and the device would be deleted. However the >> device link holds a reference to the device, so the device link and device >> remain indefinitely. >> >> Amend device link removal to accept removal of a link with an >> unregistered consumer device. >> >> To make that work nicely, the devlink_remove_symlinks() function must be >> amended to cope with the absence of the consumer's sysfs presence, >> otherwise sysfs_remove_link() will generate a warning. >> >> Suggested-by: Rafael J. Wysocki >> Fixes: b294ff3e34490 ("scsi: ufs: core: Enable power management for wlun") >> Signed-off-by: Adrian Hunter >> --- >> drivers/base/core.c | 11 ++++++++--- >> 1 file changed, 8 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/base/core.c b/drivers/base/core.c >> index ea5b85354526..24bacdb315c6 100644 >> --- a/drivers/base/core.c >> +++ b/drivers/base/core.c >> @@ -562,7 +562,8 @@ static void devlink_remove_symlinks(struct device *dev, >> struct device *con = link->consumer; >> char *buf; >> >> - sysfs_remove_link(&link->link_dev.kobj, "consumer"); >> + if (device_is_registered(con)) >> + sysfs_remove_link(&link->link_dev.kobj, "consumer"); > > I think that this is needed regardless of the changes in > device_link_put_kref(), because if somebody decides to delete a > stateless device link before registering the consumer device, > sysfs_remove_link() will still complain, won't it? I would think so. > >> sysfs_remove_link(&link->link_dev.kobj, "supplier"); >> >> len = max(strlen(dev_bus_name(sup)) + strlen(dev_name(sup)), >> @@ -575,8 +576,10 @@ static void devlink_remove_symlinks(struct device *dev, >> return; >> } >> >> - snprintf(buf, len, "supplier:%s:%s", dev_bus_name(sup), dev_name(sup)); >> - sysfs_remove_link(&con->kobj, buf); >> + if (device_is_registered(con)) { >> + snprintf(buf, len, "supplier:%s:%s", dev_bus_name(sup), dev_name(sup)); >> + sysfs_remove_link(&con->kobj, buf); >> + } > > And here too, if I'm not mistaken. > > So in that case it would be better to put the above changes into a > separate patch and add a Fixes tag to it. Yes, that makes sense. I'll send a V3 > >> snprintf(buf, len, "consumer:%s:%s", dev_bus_name(con), dev_name(con)); >> sysfs_remove_link(&sup->kobj, buf); >> kfree(buf); >> @@ -885,6 +888,8 @@ static void device_link_put_kref(struct device_link *link) >> { >> if (link->flags & DL_FLAG_STATELESS) >> kref_put(&link->kref, __device_link_del); >> + else if (!device_is_registered(link->consumer)) >> + __device_link_del(&link->kref); >> else >> WARN(1, "Unable to drop a managed device link reference\n"); >> } >> -- >> 2.17.1 >>