From: Adrian Hunter adrian.hunter@intel.com
[ Upstream commit bf25967ac54129ffb676ee0dbe3b8b34af6c6232 ]
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 Signed-off-by: Sasha Levin sashal@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 6c0ef9d55a34..8c77e14987d4 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -886,6 +886,8 @@ 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 8275127749d2..15ac5fa14805 100644 --- a/drivers/scsi/ufs/ufshcd.c +++ b/drivers/scsi/ufs/ufshcd.c @@ -5006,15 +5006,34 @@ 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); + } } }