linux-kernel - Re: GPF in run_workqueue()/list_del_init(cwq->worklist.next) on resume (was: Re: Help needed: Resume problems in 2.6.32-rc, perhaps related to preempt

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Date:	Wed, 11 Nov 2009 22:13:30 +0100
From:	Oliver Neukum <oliver@...kum.org>
To:	Marcel Holtmann <marcel@...tmann.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Thomas Gleixner <tglx@...utronix.de>,
	Mike Galbraith <efault@....de>, Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>,
	Greg KH <gregkh@...e.de>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Tejun Heo <tj@...nel.org>, Oleg Nesterov <oleg@...hat.com>,
	linux-bluetooth@...r.kernel.org
Subject: Re: GPF in run_workqueue()/list_del_init(cwq->worklist.next) on resume (was: Re: Help needed: Resume problems in 2.6.32-rc, perhaps related to preempt_count leakage in keventd)

Am Mittwoch, 11. November 2009 21:18:39 schrieb Marcel Holtmann:
> > I'm looking at btusb_disconnect(), for example. It's one of the few BT 
> > drivers that seem to use workqueues, and I'm not seeing a 
> > cancel_work_sync() in the disconnect routine - but maybe the
> > btusb_close()  routine is called indirectly some way that I just don't
> > see.
> 
> so the btusb_close() should be called before btusb_destruct() and the
> destruct() callback is only when the last reference count gets dropped
> and we do have to free the memory. So it seems we are doing something
> wrong in btusb_close(). The close() callback is triggered via
> hci_unregister_dev() from btusb_disconnect().
> 
> As it seems the btusb_close() only cancels the work workqueue and not
> the waker workqueue. Could that be the problem.

Yes, btusb_close() needs to cancel the waker workqueue, too.
In addition, in order to avoid a memory leak it must call
usb_scuttle_anchored_urbs(&data->deferred)
to make sure any deferred data is destroyed.

	Regards
		Oliver
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