tty: Move the leader test in disassociate

There are two call points, both want to check that tty->signal->leader is
set. Move the test into disassociate_ctty() as that will make locking
changes easier in a bit
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/char/tty_io.c

@@ -707,6 +707,8 @@ void disassociate_ctty(int on_exit)
 	struct tty_struct *tty;
 	struct pid *tty_pgrp = NULL;
 
+	if (!current->signal->leader)
+		return;
 
 	tty = get_current_tty();
 	if (tty) {
@@ -772,7 +774,6 @@ void no_tty(void)
 {
 	struct task_struct *tsk = current;
 	lock_kernel();
-	if (tsk->signal->leader)
 	disassociate_ctty(0);
 	unlock_kernel();
 	proc_clear_tty(tsk);

kernel/exit.c

@@ -971,7 +971,7 @@ NORET_TYPE void do_exit(long code)
 	exit_thread();
 	cgroup_exit(tsk, 1);
 
-	if (group_dead && tsk->signal->leader)
+	if (group_dead)
 		disassociate_ctty(1);
 
 	module_put(task_thread_info(tsk)->exec_domain->module);