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

From: Tushar Nimkar
Date: Mon Nov 21 2022 - 01:08:54 EST


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