TTY: Fix tty miss restart after we turn off flow-control
authorWang YanQing <udknight@gmail.com>
Thu, 9 May 2013 06:16:47 +0000 (14:16 +0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 7 Jun 2013 19:49:11 +0000 (12:49 -0700)
commit893f9ef045f5b8eee088489be7177859e74b690d
tree7be2ea1d96e1c770fdbdbd9c5f2e8929662501e4
parentfcaa80f4f20519ee7d432d727b375e7a181e6a50
TTY: Fix tty miss restart after we turn off flow-control

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@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/tty/n_tty.c