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=-14.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 2677BC07E96 for ; Thu, 8 Jul 2021 16:49:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 079D361457 for ; Thu, 8 Jul 2021 16:49:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229872AbhGHQvo (ORCPT ); Thu, 8 Jul 2021 12:51:44 -0400 Received: from mail-ot1-f45.google.com ([209.85.210.45]:39704 "EHLO mail-ot1-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229489AbhGHQvm (ORCPT ); Thu, 8 Jul 2021 12:51:42 -0400 Received: by mail-ot1-f45.google.com with SMTP id w15-20020a056830144fb02904af2a0d96f3so6477428otp.6; Thu, 08 Jul 2021 09:49:00 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=lQK96t76fu/viRfS7rLob+VMQvsI00nK8s2Auj7HOsQ=; b=SGaL5D8KDYE3S3BRd3+WX/pjWCjI8IyQ6lNHMdXt4nkSAKfloueEoYA7hjGomUJbg0 LAjN6tpQkgG45xxlZuIe5yhUgNrb8D7BiMUiYWwlLuhE+cqb4lBFN4wjxsVQ9cSq1Cj0 dhul73F5Wciqqq4BByxWT7MizswKECQ8xHvq12ADfHopftZBnM3H3mBLx2qvOaWHhiwU cKoBMm/yXwu74P13qk9klOGX7BjtTB+iNhyc/uzDZqgYFeXoA+kre4sO3EepyUVdoC6P nCoOkqe3QQKiA3GV3RWyHHmQF2S+ULmlJgZk67lMnZ3H3ceDCnL1iuBuzksJi2tK2k3w +edA== X-Gm-Message-State: AOAM533vS/42WKQU5rl6EZNEcvaj8uvGK99GJ2PdwmeYgrxFBbILtpJH nyWKQVoXK7IKRcvo/Bo1VU0NYdrRLowufN0XdVs= X-Google-Smtp-Source: ABdhPJyIlh9xB+6VLvmszP6WGsbjnMfmlePYhY/UBVQ8Y263rHJ+3utwsYldHN/2ciIg8RVEndHMJg+6Qb5tlA2JvOo= X-Received: by 2002:a9d:22a5:: with SMTP id y34mr13919681ota.321.1625762939894; Thu, 08 Jul 2021 09:48:59 -0700 (PDT) MIME-Version: 1.0 References: <20210707172948.1025-1-adrian.hunter@intel.com> <20210707172948.1025-3-adrian.hunter@intel.com> <66130101-b0c5-a9a3-318a-468c6f3b380f@intel.com> In-Reply-To: From: "Rafael J. Wysocki" Date: Thu, 8 Jul 2021 18:48:48 +0200 Message-ID: Subject: Re: [PATCH RFC 2/2] scsi: ufshcd: Fix device links when BOOT WLUN fails to probe To: Saravana Kannan Cc: Adrian Hunter , "Rafael J. Wysocki" , Greg Kroah-Hartman , "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 Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 8, 2021 at 6:46 PM Saravana Kannan wrote: > > On Thu, Jul 8, 2021 at 7:17 AM 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. > > Is there a reason you can't use DL_FLAG_STATELESS? It doesn't preclude > you from using RPM_ACTIVE as far as I can tell. Perhaps he wants the links to be managed if they are used after all. Anyway, this is a valid use case that is not covered right now.