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

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Hi Adrian,

On 11/21/2022 11:38 AM, Tushar Nimkar wrote:
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.

EBUSY is returned from below code for consumer dev 0:0:0:0.
scsi_runtime_idle is called from scsi_autopm_put_device which inturn is called from ufshcd_async_scan (Process 1 as per above call stack)
static int scsi_runtime_idle(struct device *dev)
{
	:

	if (scsi_is_sdev_device(dev)) {
		pm_runtime_mark_last_busy(dev);
		pm_runtime_autosuspend(dev);
		return -EBUSY; ---> EBUSY returned from here.
	}

	
}


[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

Thanks,
Nitin



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