Re: 2.6.22-rc2-mm1

[Oleg Nesterov]

On 05/23, Alan Stern wrote:
>
> Okay, it's clear that the two threads are in deadlock.  It's not clear 
> how the deadlock arose to begin with -- apparently there was a remote 
> wakeup request for a root hub at the same time as a device below that 
> root hub was disconnected, which doesn't make much sense.

Please note that this flush_workqueue() was not safe anyway. We are freezing
tasks, and ksuspend_usb_wq is freezeable. So, it could be frozen before
"khubd" task, and we have another deadlock.

> Anyway, this looks like a good place to use cancel_work_sync().  The

Could you use cancel_rearming_delayed_work() ? (It should be renamed to
cancel_delayed_work_sync()).

Oleg.

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