Bluetooth: hidp: safely acquire hci connection

index e02c6a2..f6db935 100644
@@ -97,8 +97,6 @@ static void __hidp_link_session(struct hidp_session *session)
 {
 	__module_get(THIS_MODULE);
 	list_add(&session->list, &hidp_session_list);
-
-	hci_conn_hold_device(session->conn);
 }
 
 static void __hidp_unlink_session(struct hidp_session *session)

@@ -763,24 +761,26 @@ static int hidp_session(void *arg)
 	return 0;
 }
 
-static struct device *hidp_get_device(struct hidp_session *session)
+static struct hci_conn *hidp_find_connection(struct hidp_session *session)
 {
 	bdaddr_t *src = &bt_sk(session->ctrl_sock->sk)->src;
 	bdaddr_t *dst = &bt_sk(session->ctrl_sock->sk)->dst;
-	struct device *device = NULL;
+	struct hci_conn *conn;
 	struct hci_dev *hdev;
 
 	hdev = hci_get_route(dst, src);
 	if (!hdev)
 		return NULL;
 
-	session->conn = hci_conn_hash_lookup_ba(hdev, ACL_LINK, dst);
-	if (session->conn)
-		device = &session->conn->dev;
+	hci_dev_lock_bh(hdev);
+	conn = hci_conn_hash_lookup_ba(hdev, ACL_LINK, dst);
+	if (conn)
+		hci_conn_hold_device(conn);
+	hci_dev_unlock_bh(hdev);
 
 	hci_dev_put(hdev);
 
-	return device;
+	return conn;
 }
 
 static int hidp_setup_input(struct hidp_session *session,

@@ -830,7 +830,7 @@ static int hidp_setup_input(struct hidp_session *session,
 		input->relbit[0] |= BIT_MASK(REL_WHEEL);
 	}
 
-	input->dev.parent = hidp_get_device(session);
+	input->dev.parent = &session->conn->dev;
 
 	input->event = hidp_input_event;
 

@@ -934,7 +934,7 @@ static int hidp_setup_hid(struct hidp_session *session,
 	strncpy(hid->phys, batostr(&bt_sk(session->ctrl_sock->sk)->src), 64);
 	strncpy(hid->uniq, batostr(&bt_sk(session->ctrl_sock->sk)->dst), 64);
 
-	hid->dev.parent = hidp_get_device(session);
+	hid->dev.parent = &session->conn->dev;
 	hid->ll_driver = &hidp_hid_driver;
 
 	hid->hid_get_raw_report = hidp_get_raw_report;

@@ -975,6 +975,10 @@ int hidp_add_connection(struct hidp_connadd_req *req, struct socket *ctrl_sock,
 		goto failed;
 	}
 
+	session->conn = hidp_find_connection(session);
+	if (!session->conn)
+		goto failed;
+
 	bacpy(&session->bdaddr, &bt_sk(ctrl_sock->sk)->dst);
 
 	session->ctrl_mtu = min_t(uint, l2cap_pi(ctrl_sock->sk)->chan->omtu,

@@ -1000,6 +1004,8 @@ int hidp_add_connection(struct hidp_connadd_req *req, struct socket *ctrl_sock,
 	session->flags   = req->flags & (1 << HIDP_BLUETOOTH_VENDOR_ID);
 	session->idle_to = req->idle_to;
 
+	__hidp_link_session(session);
+
 	if (req->rd_size > 0) {
 		err = hidp_setup_hid(session, req);
 		if (err && err != -ENODEV)

@@ -1012,8 +1018,6 @@ int hidp_add_connection(struct hidp_connadd_req *req, struct socket *ctrl_sock,
 			goto purge;
 	}
 
-	__hidp_link_session(session);
-
 	hidp_set_timer(session);
 
 	if (session->hid) {

@@ -1062,8 +1066,6 @@ int hidp_add_connection(struct hidp_connadd_req *req, struct socket *ctrl_sock,
 unlink:
 	hidp_del_timer(session);
 
-	__hidp_unlink_session(session);
-
 	if (session->input) {
 		input_unregister_device(session->input);
 		session->input = NULL;

@@ -1076,6 +1078,8 @@ unlink:
 	session->rd_data = NULL;
 
 purge:
+	__hidp_unlink_session(session);
+
 	skb_queue_purge(&session->ctrl_transmit);
 	skb_queue_purge(&session->intr_transmit);