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 33E61C07E99 for ; Thu, 8 Jul 2021 15:03:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1ED3F613C1 for ; Thu, 8 Jul 2021 15:03:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232060AbhGHPGB (ORCPT ); Thu, 8 Jul 2021 11:06:01 -0400 Received: from mail-oo1-f48.google.com ([209.85.161.48]:40878 "EHLO mail-oo1-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229738AbhGHPGA (ORCPT ); Thu, 8 Jul 2021 11:06:00 -0400 Received: by mail-oo1-f48.google.com with SMTP id j4-20020a4ac5440000b029025992521cf0so1439097ooq.7; Thu, 08 Jul 2021 08:03:19 -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=9fRsjb6ixRhrvN3TM5YwQx/rG19O2SMWtEg9Q+v6fqM=; b=RZcVw6UVkCfkoNzRdLXsQ/xzOsilWpKp2jKa90VknW060g9lqzmf8yO2BfQs3q0e3W HwYXdqWs3B8hIMzXraZO8KF3i4gwCw4km6+gHcd64+2+GOGzpK5HD+Ybcp29EjziZUqB uAEGsVGwcD5Z8rxnXq9u2KJ+QuEetxsgOSLXkGg2k8TOULZXRNU0iCw3RabazC08T0P0 wR5nQtodsic9DUeyN4yZtAv1sAwtLacEOA5B3357fQ0b1e4Xgg620IybKRCkE3JfFjgj 9JHwCUmBtdGLafSFSwqEIOteIon48Ve9QEgpP9XI9NDSJi7EJBCG3yI/47qXebCa3QOi kvWA== X-Gm-Message-State: AOAM532rVi4e+PharUK+s3zBulFGDdE8xMrKEo5HgP/L5FDb+0/qeBqR ln9Ih1y4217z+PKQvwgFvWDE8hv0isd4rztHLNM= X-Google-Smtp-Source: ABdhPJw6rRUj1eTPCAv1/80AGJMjw6lgLatnsz92iWe8QDTP7Wr4l6gE3Ui3oQXimZNb02HlGgqmJ+koMz7JDPGIVuE= X-Received: by 2002:a4a:5dc6:: with SMTP id w189mr22866611ooa.1.1625756598703; Thu, 08 Jul 2021 08:03:18 -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 17:03:07 +0200 Message-ID: Subject: Re: [PATCH RFC 2/2] scsi: ufshcd: Fix device links when BOOT WLUN fails to probe To: Adrian Hunter Cc: "Rafael J. Wysocki" , 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 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 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.