Martin, perhaps you could consider picking up this patch if no one objects?
On 16/07/21 2:44 pm, Adrian Hunter wrote:
> 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@xxxxxxxxx>
> Reviewed-by: Rafael J. Wysocki <rafael@xxxxxxxxxx>
> ---
> 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);
> + }
> }
> }
>
>
