Bluetooth: Simplify the error handling of Start Discovery command

The Start Discovery command has some complicated code when it comes
to error handling. With the future introduction of Start Service
Discovery simplifying this makes it easier to read.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

net/bluetooth/mgmt.c

@@ -3771,14 +3771,8 @@ static int start_discovery(struct sock *sk, struct hci_dev *hdev,
 		goto failed;
 	}
 
-	if (test_bit(HCI_PERIODIC_INQ, &hdev->dev_flags)) {
-		err = cmd_complete(sk, hdev->id, MGMT_OP_START_DISCOVERY,
-				   MGMT_STATUS_BUSY, &cp->type,
-				   sizeof(cp->type));
-		goto failed;
-	}
-
-	if (hdev->discovery.state != DISCOVERY_STOPPED) {
+	if (hdev->discovery.state != DISCOVERY_STOPPED ||
+	    test_bit(HCI_PERIODIC_INQ, &hdev->dev_flags)) {
 		err = cmd_complete(sk, hdev->id, MGMT_OP_START_DISCOVERY,
 				   MGMT_STATUS_BUSY, &cp->type,
 				   sizeof(cp->type));
@@ -3909,10 +3903,12 @@ static int start_discovery(struct sock *sk, struct hci_dev *hdev,
 	}
 
 	err = hci_req_run(&req, start_discovery_complete);
-	if (err < 0)
+	if (err < 0) {
 		mgmt_pending_remove(cmd);
-	else
-		hci_discovery_set_state(hdev, DISCOVERY_STARTING);
+		goto failed;
+	}
+
+	hci_discovery_set_state(hdev, DISCOVERY_STARTING);
 
 failed:
 	hci_dev_unlock(hdev);