tty: Remove TTY_HUPPING

Now that tty_ldisc_hangup() does not drop the tty lock, it is no
longer possible to observe TTY_HUPPING while holding the tty lock
on another cpu.

Remove TTY_HUPPING bit definition.

Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 9d1e247..873793c 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -690,9 +690,6 @@
 		return;
 	}
 
-	/* some functions below drop BTM, so we need this bit */
-	set_bit(TTY_HUPPING, &tty->flags);
-
 	/* inuse_filps is protected by the single tty lock,
 	   this really needs to change if we want to flush the
 	   workqueue with the lock held */
@@ -717,10 +714,6 @@
 	while (refs--)
 		tty_kref_put(tty);
 
-	/*
-	 * it drops BTM and thus races with reopen
-	 * we protect the race by TTY_HUPPING
-	 */
 	tty_ldisc_hangup(tty);
 
 	spin_lock_irq(&tty->ctrl_lock);
@@ -752,8 +745,6 @@
 	 * can't yet guarantee all that.
 	 */
 	set_bit(TTY_HUPPED, &tty->flags);
-	clear_bit(TTY_HUPPING, &tty->flags);
-
 	tty_unlock(tty);
 
 	if (f)
@@ -1461,8 +1452,7 @@
 {
 	struct tty_driver *driver = tty->driver;
 
-	if (test_bit(TTY_CLOSING, &tty->flags) ||
-			test_bit(TTY_HUPPING, &tty->flags))
+	if (test_bit(TTY_CLOSING, &tty->flags))
 		return -EIO;
 
 	if (driver->type == TTY_DRIVER_TYPE_PTY &&