Re: Problems with CF bluetooth (fwd) (fwd)

[Marcel Holtmann <marcel@holtmann.org>]

Hi Pavel,

> > > Thanks, Russell. Marcel, this is probably solution to that oops.
> > 
> > cool that you worked something out. Do you have a patch for me?
> 
> Well, I have that ugly workaround that helps me, but is wrong (as rmk
> confirmed). His comment was:
> 
> |> Sep 29 15:42:34 amd kernel: Call Trace:
> |> Sep 29 15:42:34 amd kernel:  [<c03f9df6>] hci_uart_flush+0x66/0x80
> |> Sep 29 15:42:34 amd kernel:  [<c03f9e27>] hci_uart_close+0x17/0x20
> |> Sep 29 15:42:34 amd kernel:  [<c03f9f86>]
> |> hci_uart_tty_close+0x26/0x60
> |> Sep 29 15:42:34 amd kernel:  [<c02a5ed7>] release_dev+0x587/0x670
> |
> |Looking at release_dev(), it does things in the following order:
> |
> |1. various sanity checks
> |2. close the driver
> |3. more sanity checks and other housekeeping
> |4. close the ldisc
> |5. reset the ldisc for the tty to N_TTY
> |
> |This means that bluetooth is calling into a TTY driver with a tty
> |for which the driver has already shut down.  No surprise it oopses.
> |Bluetooth should not call the driver during it's closedown.
> |
> |(There also appears to be an interesting race condition between the
> |driver shutting down and the ldisc write functions getting to know
> |about it... Alan?)
> 
> But no, I do not have patch for that.

I won't have time to look at it for the next two weeks. So if someone
comes up with a patch I am happy to create another -mh patch to make it
available for testing.

Regards

Marcel