Re: [Bug #15127] Bluetooth: sleeping function called from invalid context

Marcel Holtmann
2010-02-02T05:41:24Z

Hi David,

> >>>> This message has been generated automatically as a part of a report
> >>>> of regressions introduced between 2.6.31 and 2.6.32.
> >>>>
> >>>> The following bug entry is on the current list of known regressions
> >>>> introduced between 2.6.31 and 2.6.32. Please verify if it still should
> >>>> be listed and let me know (either way).
> >>>>
> >>>>
> >>>> Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=15127
> >>>> Subject : Bluetooth: sleeping function called from invalid context
> >>>> Submitter : David John <davidjon-XRr60H37pjdAfugRpC6u6w@public.gmane.org>
> >>>> Date : 2010-01-12 9:19 (20 days old)
> >>>> First-Bad-Commit: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=9e726b17422bade75fba94e625cd35fd1353e682
> >>>> References : http://marc.info/?l=linux-kernel&m=126328727021949&w=4
> >>>
> >>> you have an outdated email from Luiz and I change it to the right one
> >>> now.
> >>>
> >>> I looked with him at the patch and I think this will fix it:
> >>>
> >>> diff --git a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c
> >>> index fc5ee32..2b50637 100644
> >>> --- a/net/bluetooth/rfcomm/core.c
> >>> +++ b/net/bluetooth/rfcomm/core.c
> >>> @@ -252,7 +252,6 @@ static void rfcomm_session_timeout(unsigned long
> >>> arg)
> >>> BT_DBG("session %p state %ld", s, s->state);
> >>>
> >>> set_bit(RFCOMM_TIMED_OUT, &s->flags);
> >>> - rfcomm_session_put(s);
> >>> rfcomm_schedule(RFCOMM_SCHED_TIMEO);
> >>> }
> >>>
> >>> @@ -1920,6 +1919,7 @@ static inline void rfcomm_process_sessions(void)
> >>> if (test_and_clear_bit(RFCOMM_TIMED_OUT, &s->flags)) {
> >>> s->state = BT_DISCONN;
> >>> rfcomm_send_disc(s, 0);
> >>> + rfcomm_session_put(s);
> >>> continue;
> >>> }
> >>>
> >>> We need some extra testing on this with the actual hardware we did the
> >>> patch for. So this will take at least a few days before we get our hands
> >>> on it.
> >>
> >> FWIW, your patch fixes the issue.
> >
> > nice. So I can add a tested-by line to the final patch?
>
> Sure,
>
> Tested-by: David John <davidjon-XRr60H37pjdAfugRpC6u6w@public.gmane.org>
>
> >
> > Just our of curiosity, which hardware did you test this with.
>
> I have an inbuilt (laptop) USB Dell Wireless 365 Bluetooth Module
> (413c:8160). I can send more info about the device if you want.

I meant which device you are connection to. Is it a headset or another
computer.

> > We only know about one headset that should cause this issue.
>
> That's weird. I assumed it would happen for any device, since
> rfcomm_session_add is called from multiple places and it adds
> rfcomm_session_timeout on a timer which will cause the trace
> if the timer fires.

The timer will only fire for non-behaving remote stacks. With a proper
stack following the RFCOMM specification it should never fire.

Regards

Marcel