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    SubjectRe: Bug in tty cooked mode kernel 3.12.3
    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@hurleysoftware.com>
    >> 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@vger.kernel.org> # 3.12.x : 39434ab n_tty: Fix missing newline echo
    >> Reported-by: Karl Dahlke <eklhad@comcast.net>
    >> Reported-by: Mikulas Patocka <mpatocka@redhat.com>
    >> Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
    >> ---
    >> 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



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