Bluetooth: Simplify Link Key Notification event handling logic

When we get a Link Key Notification HCI event we should already have a
hci_conn object. This should have been created either in the Connection
Request event handler, the hci_connect_acl() function or the
hci_cs_create_conn() function (if the request was not sent by the
kernel).

Since the only case that we'd end up not having a hci_conn in the Link
Key Notification event handler would be essentially broken hardware it's
safe to simply bail out from the function if this happens.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/hci_event.c

@@ -3294,12 +3294,14 @@ static void hci_link_key_notify_evt(struct hci_dev *hdev, struct sk_buff *skb)
 	hci_dev_lock(hdev);
 
 	conn = hci_conn_hash_lookup_ba(hdev, ACL_LINK, &ev->bdaddr);
-	if (conn) {
+	if (!conn)
+		goto unlock;
+
 	hci_conn_hold(conn);
 	conn->disc_timeout = HCI_DISCONN_TIMEOUT;
 	hci_conn_drop(conn);
+
 	conn_set_key(conn, ev->key_type, conn->pin_length);
-	}
 
 	if (!test_bit(HCI_MGMT, &hdev->dev_flags))
 		goto unlock;
@@ -3326,12 +3328,13 @@ static void hci_link_key_notify_evt(struct hci_dev *hdev, struct sk_buff *skb)
 	    !test_bit(HCI_KEEP_DEBUG_KEYS, &hdev->dev_flags)) {
 		list_del_rcu(&key->list);
 		kfree_rcu(key, rcu);
-	} else if (conn) {
+		goto unlock;
+	}
+
 	if (persistent)
 		clear_bit(HCI_CONN_FLUSH_KEY, &conn->flags);
 	else
 		set_bit(HCI_CONN_FLUSH_KEY, &conn->flags);
-	}
 
 unlock:
 	hci_dev_unlock(hdev);