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Date: Mon, 8 Aug 2016 13:42:51 +0300
From: Shamir Rabinovitch <shamir.rabinovitch@oracle.com>
To: Qing Huang <qing.huang@oracle.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Grant Likely <grant.likely@linaro.org>,
        Santosh Shilimkar <santosh.shilimkar@oracle.com>,
        linux-kernel@vger.kernel.org, shamir.rabinovitch@oracle.com
Subject: Re: [PATCH] device probe: add self triggered delayed work request
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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!>

Please confirm if this scenario is possible.

BR, Shamir Rabinovitch