On Wed, 2014-06-18 at 19:05 +0300, Janne Kanniainen wrote:
> This driver adds support for USB controlled led panels that exists in
> MSI GT683R laptop
>
> +static int gt683r_led_probe(struct hid_device *hdev,
> + const struct hid_device_id *id)
> +{
> + int i;
> + int ret;
> + int name_sz;
> + char *name;
> + struct gt683r_led *led;
> +
> + led = devm_kzalloc(&hdev->dev, sizeof(*led), GFP_KERNEL);
> + if (!led)
> + return -ENOMEM;
> +
> + led->mode = GT683R_LED_NORMAL;
> + led->hdev = hdev;
> + hid_set_drvdata(hdev, led);
> +
> + ret = hid_parse(hdev);
> + if (ret) {
> + hid_err(hdev, "hid parsing failed\n");
> + return ret;
> + }
> +
> + ret = hid_hw_start(hdev, HID_CONNECT_HIDRAW);
> + if (ret) {
> + hid_err(hdev, "hw start failed\n");
> + return ret;
> + }
> +
> + for (i = 0; i < GT683R_LED_COUNT; i++) {
> + name_sz = strlen(dev_name(&hdev->dev)) +
> + strlen(gt683r_panel_names[i]) + 3;
> +
> + name = devm_kzalloc(&hdev->dev, name_sz, GFP_KERNEL);
> + if (!name) {
> + ret = -ENOMEM;
> + goto fail;
> + }
> +
> + snprintf(name, name_sz, "%s::%s",
> + dev_name(&hdev->dev), gt683r_panel_names[i]);
> + led->led_devs[i].name = name;
> + led->led_devs[i].max_brightness = 1;
> + led->led_devs[i].brightness_set = gt683r_brightness_set;
> + ret = led_classdev_register(&hdev->dev, &led->led_devs[i]);
> + if (ret) {
> + hid_err(hdev, "could not register led device\n");
> + goto fail;
> + }
> + }
> +
> + ret = device_create_file(&led->hdev->dev, &dev_attr_leds_mode);
> + if (ret) {
> + hid_err(hdev, "could not make mode attribute file\n");
> + goto fail;
> + }
> +
This is the window.
> + mutex_init(&led->lock);
> + INIT_WORK(&led->work, gt683r_led_work);
> +
And here we have a problem. This is a race condition.
At this time you've already created the sysfs files. So
their methods can be called. They will lock a mutex and/or
schedule work that hasn't been initialized.
The initialization must be done before anything in sysfs
is created.
> + return 0;
> +
> +fail:
> + for (i = i - 1; i >= 0; i--)
> + led_classdev_unregister(&led->led_devs[i]);
> + hid_hw_stop(hdev);
> + return ret;
> +}
> +
Sorry for noticing this thread late.
Regards
Oliver
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