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 A2C77C07E99 for ; Thu, 8 Jul 2021 15:12:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8F183613AA for ; Thu, 8 Jul 2021 15:12:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231944AbhGHPPP (ORCPT ); Thu, 8 Jul 2021 11:15:15 -0400 Received: from mail-ot1-f45.google.com ([209.85.210.45]:34717 "EHLO mail-ot1-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229738AbhGHPPN (ORCPT ); Thu, 8 Jul 2021 11:15:13 -0400 Received: by mail-ot1-f45.google.com with SMTP id w8-20020a0568304108b02904b3da3d49e5so2132025ott.1; Thu, 08 Jul 2021 08:12:31 -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=lHkFWAI46E+RSb2XZ10M/xDZvWjRWEurjhsODZuJHjc=; b=U1VHhIvISmOuh5EEB0gIXeSpSvYR6qzVCJv02hWVpQyzu+81QC4zebDOhqjHzLXd+d nn/4WJSNCtX7i8mGXzFOu86lSi3gQmrJ8CNObSDbdUd/54UpnWgpkeGmVHng0L6BS+W6 JHy2M0ChATV3gFsMzSmZ8i56TXttOE8NPvmVAY/F0mq5+pi25Eivrq3WXy7YvE3I9NkE BRsJGbs5hGPUu6X98NL3HyUNKdOn3XekGVQzJ0dz70w0qE4dkdkio4Sdg60ImHzhkqXk zC0RbIGMrbcTVZ12uyZkC0Mg9RgVqunKoU6Y29J5LKzKTBvuC9RxoSaJJpSJKx/kLkFF nGlw== X-Gm-Message-State: AOAM5307XKKRmnuVJP1d7MDCS2QREyPvquN3zi192E2HtgGXUGSUbhcX VwhNizFpv7KigI/geybtKzwKs43xJT1VHobP9dk= X-Google-Smtp-Source: ABdhPJwWtvD1dy8XmFCerRnLCI+5IhOQi32NO6ZlcK5C3WdV7WQt22Qnox4uBIYWWPdHccyyCbJOQlUIxRgHttRoUuo= X-Received: by 2002:a9d:604e:: with SMTP id v14mr24087786otj.260.1625757151210; Thu, 08 Jul 2021 08:12:31 -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 17:12:20 +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 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"); }