This is a note to let you know that I've just added the patch titled
TTY: Fix tty miss restart after we turn off flow-control
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tty-fix-tty-miss-restart-after-we-turn-off-flow-control.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From dab73b4eb9ef924a2b90dab84e539076d82b256f Mon Sep 17 00:00:00 2001
From: Wang YanQing <udknight@xxxxxxxxx>
Date: Thu, 9 May 2013 14:16:47 +0800
Subject: TTY: Fix tty miss restart after we turn off flow-control
From: Wang YanQing <udknight@xxxxxxxxx>
commit dab73b4eb9ef924a2b90dab84e539076d82b256f upstream.
I meet emacs hang in start if I do the operation below:
1: echo 3 > /proc/sys/vm/drop_caches
2: emacs BigFile
3: Press CTRL-S follow 2 immediately
Then emacs hang on, CTRL-Q can't resume, the terminal
hang on, you can do nothing with this terminal except
close it.
The reason is before emacs takeover control the tty,
we use CTRL-S to XOFF it. Then when emacs takeover the
control, it may don't use the flow-control, so emacs hang.
This patch fix it.
This patch will fix a kind of strange tty relation hang problem,
I believe I meet it with vim in ssh, and also see below bug report:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=465823
Signed-off-by: Wang YanQing <udknight@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/n_tty.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -1529,6 +1529,14 @@ static void n_tty_set_termios(struct tty
tty->real_raw = 0;
}
n_tty_set_room(tty);
+ /*
+ * Fix tty hang when I_IXON(tty) is cleared, but the tty
+ * been stopped by STOP_CHAR(tty) before it.
+ */
+ if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) {
+ start_tty(tty);
+ }
+
/* The termios change make the tty ready for I/O */
wake_up_interruptible(&tty->write_wait);
wake_up_interruptible(&tty->read_wait);
Patches currently in stable-queue which might be from udknight@xxxxxxxxx are
queue-3.4/tty-fix-tty-miss-restart-after-we-turn-off-flow-control.patch
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