From: Randy Dunlap <randy.dunlap@oracle.com>

Fix sparse warning in tty_io:
drivers/char/tty_io.c:1536:34: warning: Using plain integer as NULL pointer

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/char/tty_io.c |    2 +-
 1 files changed, 1 insertion(+), 1 deletion(-)

diff -puN drivers/char/tty_io.c~tty-use-null-for-ptrs drivers/char/tty_io.c
--- a/drivers/char/tty_io.c~tty-use-null-for-ptrs
+++ a/drivers/char/tty_io.c
@@ -1533,7 +1533,7 @@ void disassociate_ctty(int on_exit)
 
 	spin_lock_irq(&current->sighand->siglock);
 	tty_pgrp = current->signal->tty_old_pgrp;
-	current->signal->tty_old_pgrp = 0;
+	current->signal->tty_old_pgrp = NULL;
 	spin_unlock_irq(&current->sighand->siglock);
 	put_pid(tty_pgrp);
 
_