[PATCH] do_SAK: don't depend on session ID 0

I'm not really certain what the thinking was but the code obviously wanted to
walk processes other than just those in it's session, for purposes of do_SAK.
Just walking those tasks that don't have a session assigned sounds at the very
least incomplete.

So modify the code to kill everything in the session and anything else that
might have the tty open.  Hopefully this helps if the do_SAK functionality is
ever finished.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/char/tty_io.c

@@ -2672,7 +2672,7 @@ static void __do_SAK(void *arg)
 	tty_hangup(tty);
 #else
 	struct tty_struct *tty = arg;
-	struct task_struct *p;
+	struct task_struct *g, *p;
 	int session;
 	int		i;
 	struct file	*filp;
@@ -2693,8 +2693,18 @@ static void __do_SAK(void *arg)
 		tty->driver->flush_buffer(tty);
 
 	read_lock(&tasklist_lock);
+	/* Kill the entire session */
 	do_each_task_pid(session, PIDTYPE_SID, p) {
-		if (p->signal->tty == tty || session > 0) {
+		printk(KERN_NOTICE "SAK: killed process %d"
+			" (%s): p->signal->session==tty->session\n",
+			p->pid, p->comm);
+		send_sig(SIGKILL, p, 1);
+	} while_each_task_pid(session, PIDTYPE_SID, p);
+	/* Now kill any processes that happen to have the
+	 * tty open.
+	 */
+	do_each_thread(g, p) {
+		if (p->signal->tty == tty) {
 			printk(KERN_NOTICE "SAK: killed process %d"
 			    " (%s): p->signal->session==tty->session\n",
 			    p->pid, p->comm);
@@ -2721,7 +2731,7 @@ static void __do_SAK(void *arg)
 			rcu_read_unlock();
 		}
 		task_unlock(p);
-	} while_each_task_pid(session, PIDTYPE_SID, p);
+	} while_each_thread(g, p);
 	read_unlock(&tasklist_lock);
 #endif
 }