scsi: ufshcd: Fix device links when BOOT WLUN fails to probe

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.

Link: https://lore.kernel.org/r/a1c9bac8-b560-b662-f0aa-58c7e000cbbd@intel.com
Fixes: b294ff3e3449 ("scsi: ufs: core: Enable power management for wlun")
Reviewed-by: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/base/core.c b/drivers/base/core.c
index cadcade658253c3ca050c2906537f0ad714ab0ea..9badd7f7fe62192136a6f4fccfad8d6c864f66a7 100644 (file)
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -884,6 +884,8 @@ 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 38cf516b0c6d14058c927c770996cd971c5e70c4..b408be3c5cb7fca53743d4d2ceb48d0ed01a5020 100644 (file)
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -5028,6 +5028,7 @@ 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);
 
@@ -5035,11 +5036,29 @@ static void ufshcd_slave_destroy(struct scsi_device *sdev)
 
        /* 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);
+               }
        }
 }