On Wed, Jul 7, 2021 at 7:49 PM Adrian Hunter <adrian.hunter@xxxxxxxxx> 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 <adrian.hunter@xxxxxxxxx>
> >> ---
> >> 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?
