1 files changed, 39 insertions, 30 deletions

diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 3d0687197d09..4d7b56268c79 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -568,7 +568,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
         if (IS_ERR(new_ldisc))
                 return PTR_ERR(new_ldisc);
 
-        tty_lock();
+        tty_lock(tty);
         /*
          *      We need to look at the tty locking here for pty/tty pairs
          *      when both sides try to change in parallel.
@@ -582,12 +582,12 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
          */
 
         if (tty->ldisc->ops->num == ldisc) {
-                tty_unlock();
+                tty_unlock(tty);
                 tty_ldisc_put(new_ldisc);
                 return 0;
         }
 
-        tty_unlock();
+        tty_unlock(tty);
         /*
          *      Problem: What do we do if this blocks ?
          *      We could deadlock here
@@ -595,7 +595,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 
         tty_wait_until_sent(tty, 0);
 
-        tty_lock();
+        tty_lock(tty);
         mutex_lock(&tty->ldisc_mutex);
 
         /*
@@ -605,10 +605,10 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 
         while (test_bit(TTY_LDISC_CHANGING, &tty->flags)) {
                 mutex_unlock(&tty->ldisc_mutex);
-                tty_unlock();
+                tty_unlock(tty);
                 wait_event(tty_ldisc_wait,
                         test_bit(TTY_LDISC_CHANGING, &tty->flags) == 0);
-                tty_lock();
+                tty_lock(tty);
                 mutex_lock(&tty->ldisc_mutex);
         }
 
@@ -623,7 +623,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 
         o_ldisc = tty->ldisc;
 
-        tty_unlock();
+        tty_unlock(tty);
         /*
          *      Make sure we don't change while someone holds a
          *      reference to the line discipline. The TTY_LDISC bit
@@ -650,7 +650,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 
         retval = tty_ldisc_wait_idle(tty, 5 * HZ);
 
-        tty_lock();
+        tty_lock(tty);
         mutex_lock(&tty->ldisc_mutex);
 
         /* handle wait idle failure locked */
@@ -665,7 +665,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
                 clear_bit(TTY_LDISC_CHANGING, &tty->flags);
                 mutex_unlock(&tty->ldisc_mutex);
                 tty_ldisc_put(new_ldisc);
-                tty_unlock();
+                tty_unlock(tty);
                 return -EIO;
         }
 
@@ -708,7 +708,7 @@ enable:
         if (o_work)
                 schedule_work(&o_tty->buf.work);
         mutex_unlock(&tty->ldisc_mutex);
-        tty_unlock();
+        tty_unlock(tty);
         return retval;
 }
 
@@ -816,11 +816,11 @@ void tty_ldisc_hangup(struct tty_struct *tty)
          * need to wait for another function taking the BTM
          */
         clear_bit(TTY_LDISC, &tty->flags);
-        tty_unlock();
+        tty_unlock(tty);
         cancel_work_sync(&tty->buf.work);
         mutex_unlock(&tty->ldisc_mutex);
 retry:
-        tty_lock();
+        tty_lock(tty);
         mutex_lock(&tty->ldisc_mutex);
 
         /* At this point we have a closed ldisc and we want to
@@ -831,7 +831,7 @@ retry:
                 if (atomic_read(&tty->ldisc->users) != 1) {
                         char cur_n[TASK_COMM_LEN], tty_n[64];
                         long timeout = 3 * HZ;
-                        tty_unlock();
+                        tty_unlock(tty);
 
                         while (tty_ldisc_wait_idle(tty, timeout) == -EBUSY) {
                                 timeout = MAX_SCHEDULE_TIMEOUT;
@@ -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
@@ -912,29 +929,21 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
          * race with the set_ldisc code path.
          */
 
+        tty_lock_pair(tty, o_tty);
         tty_ldisc_halt(tty);
         tty_ldisc_flush_works(tty);
-        tty_lock();
-
-        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_unlock();
+        if (o_tty) {
+                tty_ldisc_halt(o_tty);
+                tty_ldisc_flush_works(o_tty);
+        }
 
         /* 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);
 
+        tty_unlock_pair(tty, o_tty);
         /* And the memory resources remaining (buffers, termios) will be
            disposed of when the kref hits zero */
 }