Error should be checked with IS_ERR after calling kthread_run()
instead of comparing the returned pointer to an int.
Found by sparse warning:
incompatible types for operation (<)
    left side has type struct task_struct *tx_task_struct
    right side has type int
Signed-off-by: Joseph Wright <rjosephwright@gmail.com>
Reviewed-by: Marcus Wolf <linux@wolf-entwicklungen.de>
Tested-by: Marcus Wolf <linux@wolf-entwicklungen.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
        device->tx_task_struct = kthread_run(pi433_tx_thread,
                                             device,
                                             "pi433_tx_task");
-       if (device->tx_task_struct < 0)
+       if (IS_ERR(device->tx_task_struct))
        {
                dev_dbg(device->dev, "start of send thread failed");
                goto send_thread_failed;