Hello Johan Hovold, The patch 20777bc57c34: "NFC: fix broken device allocation" from Mar 30, 2017, leads to the following static checker warning: drivers/nfc/pn533/pn533.c:2653 pn533_register_device() error: 'priv->nfc_dev' dereferencing possible ERR_PTR() drivers/nfc/pn533/pn533.c 2639 skb_queue_head_init(&priv->resp_q); 2640 skb_queue_head_init(&priv->fragment_skb); 2641 2642 INIT_LIST_HEAD(&priv->cmd_queue); 2643 2644 priv->nfc_dev = nfc_allocate_device(&pn533_nfc_ops, protocols, 2645 priv->ops->tx_header_len + 2646 PN533_CMD_DATAEXCH_HEAD_LEN, 2647 priv->ops->tx_tail_len); We changed this to return error pointers as well as NULL. When functions return a NULL as well as error pointers, then NULL is supposed to be a special case of success but here it's just a failure. That's messy and bug prone. 2648 if (!priv->nfc_dev) { 2649 rc = -ENOMEM; 2650 goto destroy_wq; 2651 } 2652 2653 nfc_set_parent_dev(priv->nfc_dev, parent); ^^^^^^^^^^^^^ Oops. 2654 nfc_set_drvdata(priv->nfc_dev, priv); 2655 2656 rc = nfc_register_device(priv->nfc_dev); 2657 if (rc) 2658 goto free_nfc_dev; regards, dan carpenter