Messages in this thread | | | Subject | Re: [PATCH] device probe: add self triggered delayed work request | From | Qing Huang <> | Date | Tue, 9 Aug 2016 13:57:47 -0700 |
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On 08/09/2016 03:11 AM, Shamir Rabinovitch wrote: > On Mon, Aug 08, 2016 at 05:10:05PM -0700, Qing Huang wrote: >> Not sure if I understood your scenario. Why there is a deadlock here? >> > CPU0 | CPU1 > --------------------------------------------------------------------------------------------- > driver_deferred_probe_add | driver_deferred_probe_trigger_wrapper > mutex_lock(&deferred_probe_mutex) | driver_deferred_probe_trigger > cancel_delayed_work(&deferred_probe_trigger_work) | mutex_lock(&deferred_probe_mutex) > wait for "driver_deferred_probe_trigger_wrapper" | wait for "deferred_probe_mutex" > > is this possible scenario with this patch? > > if yes then CPU0 will wait for CPU1 to finish the delayed work whith > mutex deferred_probe_mutex held while CPU1 will try to finish the > delayed work and will wait for the same mutex forever.
CPU0 will not wait for "driver_deferred_probe_trigger_wrapper" to finish, it simply puts the work request onto the queue and returns.
Qing
> > it seems like dead lock scenario to me. > > please say if this scenario is possible. > > BR, Shamir Rabinovitch
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