1 files changed, 26 insertions, 15 deletions

diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c
index a19e935847b..acd76b767d4 100644
--- a/drivers/char/tty_ldisc.c
+++ b/drivers/char/tty_ldisc.c
@@ -21,7 +21,6 @@
 #include <linux/proc_fs.h>
 #include <linux/init.h>
 #include <linux/module.h>
-#include <linux/smp_lock.h>
 #include <linux/device.h>
 #include <linux/wait.h>
 #include <linux/bitops.h>
@@ -791,17 +790,20 @@ void tty_ldisc_hangup(struct tty_struct *tty)
 	 * N_TTY.
 	 */
 	if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
-		/* Avoid racing set_ldisc */
+		/* Avoid racing set_ldisc or tty_ldisc_release */
 		mutex_lock(&tty->ldisc_mutex);
-		/* Switch back to N_TTY */
-		tty_ldisc_halt(tty);
-		tty_ldisc_wait_idle(tty);
-		tty_ldisc_reinit(tty);
-		/* At this point we have a closed ldisc and we want to
-		   reopen it. We could defer this to the next open but
-		   it means auditing a lot of other paths so this is a FIXME */
-		WARN_ON(tty_ldisc_open(tty, tty->ldisc));
-		tty_ldisc_enable(tty);
+		if (tty->ldisc) {	/* Not yet closed */
+			/* Switch back to N_TTY */
+			tty_ldisc_halt(tty);
+			tty_ldisc_wait_idle(tty);
+			tty_ldisc_reinit(tty);
+			/* At this point we have a closed ldisc and we want to
+			   reopen it. We could defer this to the next open but
+			   it means auditing a lot of other paths so this is
+			   a FIXME */
+			WARN_ON(tty_ldisc_open(tty, tty->ldisc));
+			tty_ldisc_enable(tty);
+		}
 		mutex_unlock(&tty->ldisc_mutex);
 		tty_reset_termios(tty);
 	}
@@ -866,16 +868,25 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
 
 	tty_ldisc_wait_idle(tty);
 
+	mutex_lock(&tty->ldisc_mutex);
 	/*
-	 * Shutdown the current line discipline, and reset it to N_TTY.
-	 *
-	 * FIXME: this MUST get fixed for the new reflocking
+	 * 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_reinit(tty);
 	/* This will need doing differently if we need to lock */
 	if (o_tty)
 		tty_ldisc_release(o_tty, NULL);
+
+	/* And the memory resources remaining (buffers, termios) will be
+	   disposed of when the kref hits zero */
 }
 
 /**