linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Adrian Hunter <adrian.hunter@intel.com>
To: "Rafael J . Wysocki" <rafael@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Saravana Kannan <saravanak@google.com>,
	"Martin K . Petersen" <martin.petersen@oracle.com>,
	"James E . J . Bottomley" <jejb@linux.ibm.com>,
	linux-scsi@vger.kernel.org, Avri Altman <avri.altman@wdc.com>,
	Bean Huo <huobean@gmail.com>, Can Guo <cang@codeaurora.org>,
	Asutosh Das <asutoshd@codeaurora.org>,
	Bart Van Assche <bvanassche@acm.org>,
	linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH V4 2/2] scsi: ufshcd: Fix device links when BOOT WLUN fails to probe
Date: Fri, 16 Jul 2021 14:44:08 +0300	[thread overview]
Message-ID: <20210716114408.17320-3-adrian.hunter@intel.com> (raw)
In-Reply-To: <20210716114408.17320-1-adrian.hunter@intel.com>

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 discovering
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 (unless the supplier is deleted).

For UFSHCD, 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.

Amend device link removal to accept removal of a link with an unregistered
consumer device (suggested by Rafael), and fix UFSHCD by explicitly
deleting the device link when SCSI destroys the SCSI device.

Fixes: b294ff3e34490 ("scsi: ufs: core: Enable power management for wlun")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Rafael J. Wysocki <rafael@kernel.org>
---
 drivers/base/core.c       |  2 ++
 drivers/scsi/ufs/ufshcd.c | 23 +++++++++++++++++++++--
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 2de8f7d8cf54..983e895d4ced 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -887,6 +887,8 @@ 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");
 }
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 708b3b62fc4d..9864a8ee0263 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -5020,15 +5020,34 @@ static int ufshcd_slave_configure(struct scsi_device *sdev)
 static void ufshcd_slave_destroy(struct scsi_device *sdev)
 {
 	struct ufs_hba *hba;
+	unsigned long flags;
 
 	hba = shost_priv(sdev->host);
 	/* Drop the reference as it won't be needed anymore */
 	if (ufshcd_scsi_to_upiu_lun(sdev->lun) == UFS_UPIU_UFS_DEVICE_WLUN) {
-		unsigned long flags;
-
 		spin_lock_irqsave(hba->host->host_lock, flags);
 		hba->sdev_ufs_device = NULL;
 		spin_unlock_irqrestore(hba->host->host_lock, flags);
+	} else if (hba->sdev_ufs_device) {
+		struct device *supplier = NULL;
+
+		/* Ensure UFS Device WLUN exists and does not disappear */
+		spin_lock_irqsave(hba->host->host_lock, flags);
+		if (hba->sdev_ufs_device) {
+			supplier = &hba->sdev_ufs_device->sdev_gendev;
+			get_device(supplier);
+		}
+		spin_unlock_irqrestore(hba->host->host_lock, flags);
+
+		if (supplier) {
+			/*
+			 * 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_link_remove(&sdev->sdev_gendev, supplier);
+			put_device(supplier);
+		}
 	}
 }
 
-- 
2.17.1


  parent reply	other threads:[~2021-07-16 11:44 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-16 11:44 [PATCH V4 0/2] driver core: Add ability to delete device links of unregistered devices Adrian Hunter
2021-07-16 11:44 ` [PATCH V4 1/2] driver core: Prevent warning when removing a device link from unregistered consumer Adrian Hunter
2021-07-21 15:29   ` Greg Kroah-Hartman
2021-07-16 11:44 ` Adrian Hunter [this message]
2021-07-17 18:02   ` [PATCH V4 2/2] scsi: ufshcd: Fix device links when BOOT WLUN fails to probe Avri Altman
2021-08-02  5:45     ` Adrian Hunter
2021-08-02  7:03       ` Avri Altman
2021-08-04 15:33   ` Adrian Hunter
2021-08-05 21:49     ` Bart Van Assche
2021-08-06  2:50       ` Martin K. Petersen
2021-08-06 12:59         ` Adrian Hunter
2021-08-06 13:04           ` [PATCH V5] " Adrian Hunter
2021-08-10  3:21             ` Martin K. Petersen
2021-08-17  3:17             ` Martin K. Petersen

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210716114408.17320-3-adrian.hunter@intel.com \
    --to=adrian.hunter@intel.com \
    --cc=asutoshd@codeaurora.org \
    --cc=avri.altman@wdc.com \
    --cc=bvanassche@acm.org \
    --cc=cang@codeaurora.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=huobean@gmail.com \
    --cc=jejb@linux.ibm.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=linux-scsi@vger.kernel.org \
    --cc=martin.petersen@oracle.com \
    --cc=rafael@kernel.org \
    --cc=saravanak@google.com \
    --subject='Re: [PATCH V4 2/2] scsi: ufshcd: Fix device links when BOOT WLUN fails to probe' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
on how to clone and mirror all data and code used for this inbox