tty: Update code comment in __proc_set_tty()

The session and foreground process group pid references will be
non-NULL if tiocsctty() is stealing the controlling tty from another
session (ie., arg == 1 in tiocsctty()).

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 07275d0e30a2..9d1e247ee330 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -516,8 +516,11 @@ static void __proc_set_tty(struct tty_struct *tty)
 {
         unsigned long flags;
 
-        /* We should not have a session or pgrp to put here but.... */
         spin_lock_irqsave(&tty->ctrl_lock, flags);
+        /*
+         * The session and fg pgrp references will be non-NULL if
+         * tiocsctty() is stealing the controlling tty
+         */
         put_pid(tty->session);
         put_pid(tty->pgrp);
         tty->pgrp = get_pid(task_pgrp(current));