Re: Bug in tty cooked mode kernel 3.12.3

[Peter Hurley]

On 12/17/2013 12:30 PM, Greg Kroah-Hartman wrote:
> On Mon, Dec 09, 2013 at 06:06:07PM -0500, Peter Hurley wrote:
> > On 12/07/2013 06:46 PM, Karl Dahlke wrote:
> > > This may have appeared in 3.9.11 with the changes to tty.
> > > Don't know; I just started running 3.12 from kernel.org.
> > > Perhaps nobody saw it before because nobody runs command line programs,
> > > we're all on desktops or x or whatever,
> > > and even those in the command line are still raw.
> > > bash is raw by default, but I run it cooked.
> > > You can supress its readline functions like this.
> > >
> > > set +o emacs
> > > set +o vi
> > > set +o histexpand
> > > set +o history
> > >
> > > That puts its tty back into cooked mode.
> > >
> > > Come up in run level 3, command line mode,
> > > and bring up two consoles with bash in cooked mode as above.
> > > Set a simple prompt like this.
> > >
> > > PS1='$ '
> > >
> > > Switch to console 2 via alt-f2.
> > > Hit return.
> > > The cursor should drop to a new line then give you the $ prompt.
> > > But it puts the $ prompt next too the old one, then drops down
> > > to a blank line.
> > > The $ prompt and the crlf are out of sequence.
> > > Hit return a few more times and it will straighten itself out.
> > > Then switch back to console 1 alt-f1
> > > Hit return and the same bug,
> > > $ $
> > >
> > > hit return a few more times to straighten it out.
> > > Switch back to console 2 and the same problem.
> > > For me it's repeatable.
> > >
> > > It's also very confusing when I'm running other command line programs with cooked tty.
> > > For unknown reasons the crlf can come out at the wrong time,
> > > breaking lines or leaving lines together.
> > > My editor can run either way, so I've switched it over to readline mode
> > > and I haven't noticed any problems this way, yet.
> > > But I would prefer the cooked mode.
> > >
> > > I looked through MAINTAINERS but couldn't find
> > > a clear maintainer for drivers/tty/tty*.c
> > > Please forward this to the appropriate people.
> >
> > Thanks for the report, Karl.
> >
> > Please test the patch below (requires
> > commit 39434abd942c8e4b9c14c06a03b3245beaf8467f,
> > 'n_tty: Fix missing newline echo').
> > This should fix the 'newline output after the new prompt' problem.
> >
> > Note however that the other output order you observe is correct:
> > you press enter, a newline is echoed to terminal which mixes
> > with program output, the program ends, and the cooked mode
> > shell outputs an extra prompt because it reads a newline (which
> > the program did not read).
> >
> > Regards,
> > Peter Hurley
> >
> > --- >% ---
> > From: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
> > Subject: [PATCH] n_tty: Fix apparent order of echoed output
> >
> > With block processing of echoed output, observed output order is still
> > required. Push completed echoes and echo commands prior to output.
> >
> > Introduce echo_mark echo buffer index, which tracks completed echo
> > commands; ie., those submitted via commit_echoes but which may not
> > have been committed. Ensure that completed echoes are output prior
> > to subsequent terminal writes in process_echoes().
> >
> > Fixes newline/prompt output order in cooked mode shell.
> >
> > Cc: <stable@xxxxxxxxxxxxxxx> # 3.12.x : 39434ab n_tty: Fix missing newline echo
> > Reported-by: Karl Dahlke <eklhad@xxxxxxxxxxx>
> > Reported-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
> > Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
> > ---
> >   drivers/tty/n_tty.c | 7 ++++++-
> >   1 file changed, 6 insertions(+), 1 deletion(-)
>
> Do you want me to queue this up for 3.13-final, or have I already?

Yes, please queue this for 3.13.

Regards,
Peter Hurley

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/