[questions] dmesg: Non-NULL drvdata on register

[Alexey Klimov <klimov.linux@gmail.com>]

Hello, 

Not so many time ago i noticed such line in dmesg:

radio-mr800 2-1:1.0: Non-NULL drvdata on register

Quick review showed that it appears in usb_amradio_probe fucntions. Then
i found such code in v4l2_device_register() function (v4l2-device.c
file):

/* Set name to driver name + device name if it is empty. */
        if (!v4l2_dev->name[0])
                snprintf(v4l2_dev->name, sizeof(v4l2_dev->name), "%s %
s",
                        dev->driver->name, dev_name(dev));
        if (dev_get_drvdata(dev))
                v4l2_warn(v4l2_dev, "Non-NULL drvdata on register\n");
        dev_set_drvdata(dev, v4l2_dev);
        return 0;

The questions is - should i deal with this warning in dmesg? Probably
the order of callbacks in radio-mr800 probe function is incorrect.

The second questions - should i make atomic_t users counter instead of
int users counter? Then i can use atomic_inc(), atomic_dec(),
atomic_set(). It helps me to remove lock/unlock_kernel() functions. 

-- 
Best regards, Klimov Alexey