Re: 2.6.31-rc5 regression: Oops when USB Serial disconnected while in use

Bruno Prémont
2009-08-21T09:34:17Z

On Thu, 20 Aug 2009 17:20:35 Alan Stern <stern@rowland.harvard.edu> wrote:
> On Thu, 20 Aug 2009, Bruno [UTF-8] Prémont wrote:
>
> > No, that one does not really help (well it avoids dereferencing a
> > bad pointer (NULL for pl2302 or invalid for ftdi) with
> > serial_do_free() after destroy_serial() but is does underflow
> > module refcount (refcount ends up at 2^32-1) and lets the kernel
> > stall/panic a short time later without any useful information at
> > that moment (only very first line of trace ever appears) [ftdi for
> > the panic/freeze].
>
> More information, please. Does the problem occur with the pl2303 or
> only with the ftdi? Which module's refcount underflows? What else
> can you provide?

The module refcount was for both. It's the pl2302/ftdi-sio module's
refcount.

I don't remember for sure about the panic if it also affects
pl2302 or not.
At least one of the panics was when running dmesg after exiting minicom.

I will redo the tests this evening when I get home and report back with
more details.

> I don't see the same sort of thing with my pl2303 device, but maybe
> I'm using a different version of minicom.
>
> Alan Stern

Bruno