Re: [bug report] hwmon: (core) New hwmon registration API

Guenter Roeck
2017-01-31T12:01:21Z

On 01/31/2017 02:49 AM, Dan Carpenter wrote:
> Hello Guenter Roeck,
>
> This is a semi-automatic email about new static checker warnings.
>
> The patch d560168b5d0f: "hwmon: (core) New hwmon registration API"
> from Aug 26, 2015, leads to the following Smatch complaint:
>
> drivers/hwmon/hwmon.c:624 __hwmon_device_register()
> error: we previously assumed 'dev' could be null (see line 602)
>
> drivers/hwmon/hwmon.c
> 601 hdev->parent = dev;
> 602 hdev->of_node = dev ? dev->of_node : NULL;
> ^^^
> I gotta be honest, I have no idea why my scripts say this is a new
> warning when it's 2 years old. This check feels like it could be
> deleted and perhaps that's why it didn't complain up to now. It tries
> to ignore extra harmless checks.
>

Nevertheless it is a good warning. hwmon_thermal_add_sensor() calls devm_kzalloc()
with dev as argument.

Guenter

> 603 hwdev->chip = chip;
> 604 dev_set_drvdata(hdev, drvdata);
> 605 dev_set_name(hdev, HWMON_ID_FORMAT, id);
> 606 err = device_register(hdev);
> 607 if (err)
> 608 goto free_hwmon;
> 609
> 610 if (chip && chip->ops->read &&
> 611 chip->info[0]->type == hwmon_chip &&
> 612 (chip->info[0]->config[0] & HWMON_C_REGISTER_TZ)) {
> 613 const struct hwmon_channel_info **info = chip->info;
> 614
> 615 for (i = 1; info[i]; i++) {
> 616 if (info[i]->type != hwmon_temp)
> 617 continue;
> 618
> 619 for (j = 0; info[i]->config[j]; j++) {
> 620 if (!chip->ops->is_visible(drvdata, hwmon_temp,
> 621 hwmon_temp_input, j))
> 622 continue;
> 623 if (info[i]->config[j] & HWMON_T_INPUT)
> 624 hwmon_thermal_add_sensor(dev, hwdev, j);
> ^^^
> Dereference.
>
> 625 }
> 626 }
>
> regards,
> dan carpenter
>