Re: PM-runtime: supplier looses track of consumer during probe

[Tushar Nimkar]

Hi Adrian,

On 11/18/2022 8:25 PM, Adrian Hunter wrote:
> On 4/11/22 11:19, Tushar Nimkar wrote:
> > Hi linux-pm/linux-scsi,

> > > Process -1
> > > ufshcd_async_scan context (process 1)
> > > scsi_autopm_put_device() //0:0:0:0
>
> I am having trouble following your description.  What function is calling
> scsi_autopm_put_device() here?
Below is flow which calls scsi_autopm_put_device()
Process -1
ufshcd_async_scan()
	scsi_probe_and_add_lun()
		scsi_add_lun()
			slave_configure()
				scsi_sysfs_add_sdev()
					scsi_autopm_get_device()
						device_add()     <- invoked [Process 2] sd_probe()
							scsi_autopm_put_device()

> > > pm_runtime_put_sync()
> > > __pm_runtime_idle()
> > > rpm_idle() -- RPM_GET_PUT(4)
> > >       __rpm_callback
> > >           scsi_runtime_idle()
> > >               pm_runtime_mark_last_busy()
> > >               pm_runtime_autosuspend()  --[A]
> > >                   rpm_suspend() -- RPM_AUTO(8)
> > >                       pm_runtime_autosuspend_expiration() use_autosuspend    is false return 0   --- [B]
> > >                           __update_runtime_status to RPM_SUSPENDING
> > >                       __rpm_callback()
> > >                           __rpm_put_suppliers(dev, false)
> > >                       __update_runtime_status to RPM_SUSPENDED
> > >                   rpm_suspend_suppliers()
> > >                       rpm_idle() for supplier -- RPM_ASYNC(1) return (-EAGAIN) [ Other consumer active for supplier]
> > >                   rpm_suspend() – END with return=0
> > >           scsi_runtime_idle() END return (-EBUSY) always.
>
> Not following here either.  Which device is EBUSY and why?

scsi_runtime_idle() return -EBUSY always [3]
Storage/scsi team can better explain -EBUSY implementation.

[3] 
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/scsi/scsi_pm.c?h=next-20221118#n210


> > > [1]: https://lore.kernel.org/lkml/4748074.GXAFRqVoOG@kreacher/T/
> > > [2]: https://lkml.org/lkml/2022/10/12/259
> > >
> > > Thanks,
> > > Tushar Nimkar
Thanks,
Tushar Nimkar