[Bluetooth] Fix reference count when connection lookup fails

When the connection lookup for the device structure fails, the reference
count for the HCI device needs to be decremented.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/bnep/core.c

@@ -528,12 +528,10 @@ static struct device *bnep_get_device(struct bnep_session *session)
 		return NULL;
 
 	conn = hci_conn_hash_lookup_ba(hdev, ACL_LINK, dst);
-	if (!conn)
-		return NULL;
 
 	hci_dev_put(hdev);
 
-	return &conn->dev;
+	return conn ? &conn->dev : NULL;
 }
 
 int bnep_add_connection(struct bnep_connadd_req *req, struct socket *sock)

net/bluetooth/hidp/core.c

@@ -541,12 +541,10 @@ static struct device *hidp_get_device(struct hidp_session *session)
 		return NULL;
 
 	conn = hci_conn_hash_lookup_ba(hdev, ACL_LINK, dst);
-	if (!conn)
-		return NULL;
 
 	hci_dev_put(hdev);
 
-	return &conn->dev;
+	return conn ? &conn->dev : NULL;
 }
 
 static inline void hidp_setup_input(struct hidp_session *session, struct hidp_connadd_req *req)

net/bluetooth/rfcomm/tty.c

@@ -172,12 +172,10 @@ static struct device *rfcomm_get_device(struct rfcomm_dev *dev)
 		return NULL;
 
 	conn = hci_conn_hash_lookup_ba(hdev, ACL_LINK, &dev->dst);
-	if (!conn)
-		return NULL;
 
 	hci_dev_put(hdev);
 
-	return &conn->dev;
+	return conn ? &conn->dev : NULL;
 }
 
 static int rfcomm_dev_add(struct rfcomm_dev_req *req, struct rfcomm_dlc *dlc)