Re: [PATCH 1/2] workqueue: debug flushing deadlocks with lockdep

[Ingo Molnar]

* Oleg Nesterov <oleg@xxxxxxxxxx> wrote:

> Currently it is allowed that work->func() does flush_workqueue() on 
> its own workqueue. So we have
> 
> 	run_workqueue()
> 		work->func()
> 			flush_workqueue()
> 				run_workqueue()
> 
> All but work->func() take wq->lockdep_map, I guess check_deadlock() 
> won't be happy.

yep.

> OTOH. Perhaps we can can forbid such a behaviour? Andrew, do you know 
> any good example of "keventd trying to flush its own queue" ?

i'd prefer to make the API a little bit stricter: such recursion is 
nasty. Btw., what mechanism prevents the second instance of 
run_workqueue() calling into a work->func() again?

	Ingo
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