From 917d1deb6c756bdeafdb7f746bbff3669703e0f2 Mon Sep 17 00:00:00 2001
From: Alan Cox <alan@linux.intel.com>
Date: Tue, 29 May 2012 13:45:16 +0100
Subject: [PATCH] --- yaml --- r: 308533 b: refs/heads/master c:
 8f6576ad476b2a22d05ddafd2ddaee102577a4ed h: refs/heads/master i:   308531:
 1815b08a31d73f09f8ea58579837a368bb3e8006 v: v3

---
 [refs]                        |  2 +-
 trunk/drivers/tty/tty_ldisc.c | 41 +++++++++++++++++++++--------------
 2 files changed, 26 insertions(+), 17 deletions(-)

diff --git a/[refs] b/[refs]
index 919e879c31e7..667cdb9d0a27 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: d3ca8b64b97ef4dc54d7bb0b88bbc01a1fca8cb9
+refs/heads/master: 8f6576ad476b2a22d05ddafd2ddaee102577a4ed
diff --git a/trunk/drivers/tty/tty_ldisc.c b/trunk/drivers/tty/tty_ldisc.c
index 173a9000a6cb..ba8be396a621 100644
--- a/trunk/drivers/tty/tty_ldisc.c
+++ b/trunk/drivers/tty/tty_ldisc.c
@@ -894,6 +894,23 @@ int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty)
 	tty_ldisc_enable(tty);
 	return 0;
 }
+
+static void tty_ldisc_kill(struct tty_struct *tty)
+{
+	mutex_lock(&tty->ldisc_mutex);
+	/*
+	 * Now kill off the ldisc
+	 */
+	tty_ldisc_close(tty, tty->ldisc);
+	tty_ldisc_put(tty->ldisc);
+	/* Force an oops if we mess this up */
+	tty->ldisc = NULL;
+
+	/* Ensure the next open requests the N_TTY ldisc */
+	tty_set_termios_ldisc(tty, N_TTY);
+	mutex_unlock(&tty->ldisc_mutex);
+}
+
 /**
  *	tty_ldisc_release		-	release line discipline
  *	@tty: tty being shut down
@@ -912,27 +929,19 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
 	 * race with the set_ldisc code path.
 	 */
 
-	tty_unlock(tty);
+	tty_unlock_pair(tty, o_tty);
 	tty_ldisc_halt(tty);
 	tty_ldisc_flush_works(tty);
-	tty_lock(tty);
-
-	mutex_lock(&tty->ldisc_mutex);
-	/*
-	 * Now kill off the ldisc
-	 */
-	tty_ldisc_close(tty, tty->ldisc);
-	tty_ldisc_put(tty->ldisc);
-	/* Force an oops if we mess this up */
-	tty->ldisc = NULL;
+	if (o_tty) {
+		tty_ldisc_halt(o_tty);
+		tty_ldisc_flush_works(o_tty);
+	}
+	tty_lock_pair(tty, o_tty);
 
-	/* Ensure the next open requests the N_TTY ldisc */
-	tty_set_termios_ldisc(tty, N_TTY);
-	mutex_unlock(&tty->ldisc_mutex);
 
-	/* This will need doing differently if we need to lock */
+	tty_ldisc_kill(tty);
 	if (o_tty)
-		tty_ldisc_release(o_tty, NULL);
+		tty_ldisc_kill(o_tty);
 
 	/* And the memory resources remaining (buffers, termios) will be
 	   disposed of when the kref hits zero */