From: Hugh Dickins <hugh@veritas.com>

I get a hang at startup or shutdown: tiocsctty() holds tty_mutex, and
now with Eric's tty-in-tiocsctty-when-we-steal-a-tty-hang-it-up.patch
it can end up calling con_close(), which tries to take tty_mutex.
So best revert that in hot-fixes, until Eric provides a better.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/char/tty_io.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff -puN drivers/char/tty_io.c~tty-in-tiocsctty-when-we-steal-a-tty-hang-it-up-fix drivers/char/tty_io.c
--- a/drivers/char/tty_io.c~tty-in-tiocsctty-when-we-steal-a-tty-hang-it-up-fix
+++ a/drivers/char/tty_io.c
@@ -2980,7 +2980,9 @@ static int tiocsctty(struct tty_struct *
 			/*
 			 * Steal it away
 			 */
-			tty_vhangup(tty);
+			read_lock(&tasklist_lock);
+			session_clear_tty(tty->session);
+			read_unlock(&tasklist_lock);
 		} else {
 			ret = -EPERM;
 			goto unlock;
_