1 files changed, 30 insertions, 20 deletions

diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c
index 3f653f7d849f..500e740ec5e4 100644
--- a/drivers/char/tty_ldisc.c
+++ b/drivers/char/tty_ldisc.c
@@ -706,12 +706,13 @@ static void tty_reset_termios(struct tty_struct *tty)
 /**
  *      tty_ldisc_reinit        -       reinitialise the tty ldisc
  *      @tty: tty to reinit
+ *      @ldisc: line discipline to reinitialize
  *
- *      Switch the tty back to N_TTY line discipline and leave the
- *      ldisc state closed
+ *      Switch the tty to a line discipline and leave the ldisc
+ *      state closed
  */
 
-static void tty_ldisc_reinit(struct tty_struct *tty)
+static void tty_ldisc_reinit(struct tty_struct *tty, int ldisc)
 {
         struct tty_ldisc *ld;
 
@@ -721,10 +722,10 @@ static void tty_ldisc_reinit(struct tty_struct *tty)
         /*
          *      Switch the line discipline back
          */
-        ld = tty_ldisc_get(N_TTY);
+        ld = tty_ldisc_get(ldisc);
         BUG_ON(IS_ERR(ld));
         tty_ldisc_assign(tty, ld);
-        tty_set_termios_ldisc(tty, N_TTY);
+        tty_set_termios_ldisc(tty, ldisc);
 }
 
 /**
@@ -745,6 +746,8 @@ static void tty_ldisc_reinit(struct tty_struct *tty)
 void tty_ldisc_hangup(struct tty_struct *tty)
 {
         struct tty_ldisc *ld;
+        int reset = tty->driver->flags & TTY_DRIVER_RESET_TERMIOS;
+        int err = 0;
 
         /*
          * FIXME! What are the locking issues here? This may me overdoing
@@ -772,25 +775,32 @@ void tty_ldisc_hangup(struct tty_struct *tty)
         wake_up_interruptible_poll(&tty->read_wait, POLLIN);
         /*
          * Shutdown the current line discipline, and reset it to
-         * N_TTY.
+         * N_TTY if need be.
+         *
+         * Avoid racing set_ldisc or tty_ldisc_release
          */
-        if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
-                /* Avoid racing set_ldisc or tty_ldisc_release */
-                mutex_lock(&tty->ldisc_mutex);
-                tty_ldisc_halt(tty);
-                if (tty->ldisc) {       /* Not yet closed */
-                        /* Switch back to N_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 */
+        mutex_lock(&tty->ldisc_mutex);
+        tty_ldisc_halt(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 */
+        if (tty->ldisc) {       /* Not yet closed */
+                if (reset == 0) {
+                        tty_ldisc_reinit(tty, tty->termios->c_line);
+                        err = tty_ldisc_open(tty, tty->ldisc);
+                }
+                /* If the re-open fails or we reset then go to N_TTY. The
+                   N_TTY open cannot fail */
+                if (reset || err) {
+                        tty_ldisc_reinit(tty, N_TTY);
                         WARN_ON(tty_ldisc_open(tty, tty->ldisc));
-                        tty_ldisc_enable(tty);
                 }
-                mutex_unlock(&tty->ldisc_mutex);
-                tty_reset_termios(tty);
+                tty_ldisc_enable(tty);
         }
+        mutex_unlock(&tty->ldisc_mutex);
+        if (reset)
+                tty_reset_termios(tty);
 }
 
 /**