Re: WARNING: at drivers/tty/tty_buffer.c:476 (tty is NULL)

From: Michael Ellerman
Date: Mon Feb 11 2013 - 21:00:55 EST


On Mon, Feb 11, 2013 at 09:42:30AM -0500, Peter Hurley wrote:
> Hi Michael,
>
> On Mon, 2013-02-11 at 13:44 +1100, Michael Ellerman wrote:
> > On Wed, Jan 30, 2013 at 01:33:57PM -0500, Peter Hurley wrote:
> > > On Sat, 2013-01-19 at 22:00 +0100, Jiri Slaby wrote:
> > > > On 01/18/2013 10:07 PM, Greg Kroah-Hartman wrote:
> > > > > Jiri, was there anything on the mailing list that I missed that should
> > > > > have resolved this issue? I thought it was being worked on, but I can't
> > > > > seem to find any resolution at the moment.
> > > >
> > > > Somebody had a patchset and promised to repost IIRC. I forgot his name
> > > > though.
> > > >
> > > > /me back from digging in the mail history.
> > > >
> > > > Peter Hurley is the name.
> > > >
> > > > Peter, what happened with your patches in the end, please?
> > >
> > > The tty subsystem is very resilient to fixing :)
> > >
> > > The thing I'm working on right now -- which hopefully is the last issue
> > > with the line discipline logic -- occurs with parallel __tty_hangup()
> > > and tty_release().
> > >
> > > At the moment, I'm trying to narrow the conditions when this happens.
> >
> > If it helps I seem to be able to reproduce this in just a few seconds by
> ^^^^^^^^^^^^^^
> you get this WARNING from a parallel __tty_hangup?
>
> Or do you mean simply that you get this WARNING?

Sorry I just mean I'm seeing the warning, I have no idea how.

> > running trinity and hitting Ctrl-C to quit the watchdog.
>
> Can you reproduce after using the following patch series?
> [PATCH v3 00/23] ldisc fixes

What are they against? I tried Linus' tree and linux-next but they
didn't apply cleanly against either.

cheers
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