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)

[Linus Torvalds <torvalds@linux-foundation.org>]

On Wed, 11 Nov 2009, Rafael J. Wysocki wrote:
> 
> I applied the patch and this is the result of 'dmesg | grep ERR' after 10-or-so
> consecutive suspend-resume and hibernate-resume cycles:
> 
> [  129.008689] ERR!! btusb_waker+0x0/0x27 [btusb]
> [  166.477373] ERR!! btusb_waker+0x0/0x27 [btusb]
> [  203.983665] ERR!! btusb_waker+0x0/0x27 [btusb]
> [  241.636547] ERR!! btusb_waker+0x0/0x27 [btusb]
> 
> which kind of confirms my previous observation that the problem was not
> reproducible without Bluetooth.

.. and that btusb thing matches my observation that only a few BT drivers 
seem to use workqueues, and btusb_disconnect() isn't doing any work 
cancel.

> I'm going to test the appended patch, then.

Hmm. the USB disconnect doesn't call hci_dev_put(), it calls 
hci_free_dev() and doesn't seem to call the ->destruct thing. 

Although again, maybe that gets called indirectly.

So I'd put the cancel work in the actual disconnect routine. But maybe 
thar's just me.

		Linus