Re: [PATCH] device probe: add self triggered delayed work request

[Qing Huang]

On 08/08/2016 03:42 AM, Shamir Rabinovitch wrote:

Hi Qing,

I suspect there is potential dead-lock with this patch:

cpu0                                                    cpu1

driver_deferred_probe_add                               deferred_probe_work_func
  ...                                                     
mutex_unlock(&deferred_probe_mutex)
  mutex_lock(&deferred_probe_mutex)                        bus_probe_device(dev)
   ...                                                      device return 
-EPROBE_DEFER
   ...                                                       
driver_deferred_probe_add
   ...                                                        
mutex_lock(&deferred_probe_mutex)
   ...                                                         <deadlock!>
   cancel_delayed_work(&deferred_probe_trigger_work)
    <work will never end - deadlock!>

Not sure if I understood your scenario. Why there is a deadlock here?

Please confirm if this scenario is possible.

BR, Shamir Rabinovitch