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,URIBL_BLOCKED, 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 CC868C07E9C for ; Thu, 8 Jul 2021 16:02:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A792561878 for ; Thu, 8 Jul 2021 16:02:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232080AbhGHQF1 (ORCPT ); Thu, 8 Jul 2021 12:05:27 -0400 Received: from mga02.intel.com ([134.134.136.20]:39679 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229592AbhGHQF0 (ORCPT ); Thu, 8 Jul 2021 12:05:26 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10039"; a="196707792" X-IronPort-AV: E=Sophos;i="5.84,224,1620716400"; d="scan'208";a="196707792" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jul 2021 09:02:34 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.84,224,1620716400"; d="scan'208";a="628562316" Received: from ahunter-desktop.fi.intel.com (HELO [10.237.72.79]) ([10.237.72.79]) by orsmga005.jf.intel.com with ESMTP; 08 Jul 2021 09:02:29 -0700 Subject: Re: [PATCH RFC 2/2] scsi: ufshcd: Fix device links when BOOT WLUN fails to probe 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: <20210707172948.1025-1-adrian.hunter@intel.com> <20210707172948.1025-3-adrian.hunter@intel.com> <66130101-b0c5-a9a3-318a-468c6f3b380f@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: <4bb516f8-d987-dc4a-5e32-8db827ac486b@intel.com> Date: Thu, 8 Jul 2021 19:02:42 +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 8/07/21 6:12 pm, Rafael J. Wysocki wrote: > On Thu, Jul 8, 2021 at 5:03 PM Rafael J. Wysocki wrote: >> >> On Thu, Jul 8, 2021 at 4:17 PM Adrian Hunter wrote: >>> >>> On 8/07/21 3:31 pm, Rafael J. Wysocki wrote: >>>> On Wed, Jul 7, 2021 at 7:49 PM Adrian Hunter wrote: >>>>> >>>>> On 7/07/21 8:39 pm, Greg Kroah-Hartman wrote: >>>>>> On Wed, Jul 07, 2021 at 08:29:48PM +0300, Adrian Hunter wrote: >>>>>>> If a LUN fails to probe (e.g. absent BOOT WLUN), the device will not have >>>>>>> been registered but can still have a device link holding a reference to the >>>>>>> device. The unwanted device link will prevent runtime suspend indefinitely, >>>>>>> and cause some warnings if the supplier is ever deleted (e.g. by unbinding >>>>>>> the UFS host controller). Fix by explicitly deleting the device link when >>>>>>> SCSI destroys the SCSI device. >>>>>>> >>>>>>> Signed-off-by: Adrian Hunter >>>>>>> --- >>>>>>> drivers/scsi/ufs/ufshcd.c | 7 +++++++ >>>>>>> 1 file changed, 7 insertions(+) >>>>>>> >>>>>>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c >>>>>>> index 708b3b62fc4d..483aa74fe2c8 100644 >>>>>>> --- a/drivers/scsi/ufs/ufshcd.c >>>>>>> +++ b/drivers/scsi/ufs/ufshcd.c >>>>>>> @@ -5029,6 +5029,13 @@ static void ufshcd_slave_destroy(struct scsi_device *sdev) >>>>>>> spin_lock_irqsave(hba->host->host_lock, flags); >>>>>>> hba->sdev_ufs_device = NULL; >>>>>>> spin_unlock_irqrestore(hba->host->host_lock, flags); >>>>>>> + } else { >>>>>>> + /* >>>>>>> + * If a LUN fails to probe (e.g. absent BOOT WLUN), the device >>>>>>> + * will not have been registered but can still have a device >>>>>>> + * link holding a reference to the device. >>>>>>> + */ >>>>>>> + device_links_scrap(&sdev->sdev_gendev); >>>>>> >>>>>> What created that link? And why did it do that before probe happened >>>>>> successfully? >>>>> >>>>> The same driver created the link. >>>>> >>>>> The documentation seems to say it is allowed to, if it is the consumer. >>>>> From Documentation/driver-api/device_link.rst >>>>> >>>>> Usage >>>>> ===== >>>>> >>>>> The earliest point in time when device links can be added is after >>>>> :c:func:`device_add()` has been called for the supplier and >>>>> :c:func:`device_initialize()` has been called for the consumer. >>>> >>>> Yes, this is allowed, but if you've added device links to a device >>>> object that is not going to be registered after all, you are >>>> responsible for doing the cleanup. >>>> >>>> Why can't you call device_link_del() directly on those links? >>>> >>>> Or device_link_remove() if you don't want to deal with link pointers? >>>> >>> >>> Those only work for DL_FLAG_STATELESS device links, but we use only >>> DL_FLAG_PM_RUNTIME | DL_FLAG_RPM_ACTIVE flags. >> >> So I'd probably modify device_link_remove() to check if the consumer >> device has been registered and run __device_link_del() directly >> instead of device_link_put_kref() if it hasn't. >> >> Or add an argument to it to force the removal. > > Or even modify device_link_put_kref() like this: > > 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); > else > WARN(1, "Unable to drop a managed device link reference\n"); > } > Thanks! :-) I will do that.