tty: Add a kref count

Introduce a kref to the tty structure and use it to protect the tty->signal
tty references. For now we don't introduce it for anything else.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 3 deletions

diff --git a/kernel/sys.c b/kernel/sys.c
index 038a7bc0901d..234d9454294e 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1060,9 +1060,7 @@ asmlinkage long sys_setsid(void)
         group_leader->signal->leader = 1;
         __set_special_pids(sid);
 
-        spin_lock(&group_leader->sighand->siglock);
-        group_leader->signal->tty = NULL;
-        spin_unlock(&group_leader->sighand->siglock);
+        proc_clear_tty(group_leader);
 
         err = session;
 out: