HID: asus: use spinlock to protect concurrent accesses

asus driver has a worker that may access data concurrently.
Proct the accesses using a spinlock.

Fixes: af22a610 ("HID: asus: support backlight on USB keyboards")
Signed-off-by: Pietro Borrello <borrello@diag.uniroma1.it>
Link: https://lore.kernel.org/r/20230125-hid-unregister-leds-v4-4-7860c5763c38@diag.uniroma1.itSigned-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

drivers/hid/hid-asus.c

@@ -98,6 +98,7 @@ struct asus_kbd_leds {
 	struct hid_device *hdev;
 	struct work_struct work;
 	unsigned int brightness;
+	spinlock_t lock;
 	bool removed;
 };
 
@@ -495,7 +496,12 @@ static void asus_kbd_backlight_set(struct led_classdev *led_cdev,
 {
 	struct asus_kbd_leds *led = container_of(led_cdev, struct asus_kbd_leds,
 						 cdev);
+	unsigned long flags;
+
+	spin_lock_irqsave(&led->lock, flags);
 	led->brightness = brightness;
+	spin_unlock_irqrestore(&led->lock, flags);
+
 	schedule_work(&led->work);
 }
 
@@ -503,8 +509,14 @@ static enum led_brightness asus_kbd_backlight_get(struct led_classdev *led_cdev)
 {
 	struct asus_kbd_leds *led = container_of(led_cdev, struct asus_kbd_leds,
 						 cdev);
+	enum led_brightness brightness;
+	unsigned long flags;
 
-	return led->brightness;
+	spin_lock_irqsave(&led->lock, flags);
+	brightness = led->brightness;
+	spin_unlock_irqrestore(&led->lock, flags);
+
+	return brightness;
 }
 
 static void asus_kbd_backlight_work(struct work_struct *work)
@@ -512,11 +524,14 @@ static void asus_kbd_backlight_work(struct work_struct *work)
 	struct asus_kbd_leds *led = container_of(work, struct asus_kbd_leds, work);
 	u8 buf[] = { FEATURE_KBD_REPORT_ID, 0xba, 0xc5, 0xc4, 0x00 };
 	int ret;
+	unsigned long flags;
 
 	if (led->removed)
 		return;
 
+	spin_lock_irqsave(&led->lock, flags);
 	buf[4] = led->brightness;
+	spin_unlock_irqrestore(&led->lock, flags);
 
 	ret = asus_kbd_set_report(led->hdev, buf, sizeof(buf));
 	if (ret < 0)
@@ -584,6 +599,7 @@ static int asus_kbd_register_leds(struct hid_device *hdev)
 	drvdata->kbd_backlight->cdev.brightness_set = asus_kbd_backlight_set;
 	drvdata->kbd_backlight->cdev.brightness_get = asus_kbd_backlight_get;
 	INIT_WORK(&drvdata->kbd_backlight->work, asus_kbd_backlight_work);
+	spin_lock_init(&drvdata->kbd_backlight->lock);
 
 	ret = devm_led_classdev_register(&hdev->dev, &drvdata->kbd_backlight->cdev);
 	if (ret < 0) {
@@ -1119,9 +1135,13 @@ static int asus_probe(struct hid_device *hdev, const struct hid_device_id *id)
 static void asus_remove(struct hid_device *hdev)
 {
 	struct asus_drvdata *drvdata = hid_get_drvdata(hdev);
+	unsigned long flags;
 
 	if (drvdata->kbd_backlight) {
+		spin_lock_irqsave(&drvdata->kbd_backlight->lock, flags);
 		drvdata->kbd_backlight->removed = true;
+		spin_unlock_irqrestore(&drvdata->kbd_backlight->lock, flags);
+
 		cancel_work_sync(&drvdata->kbd_backlight->work);
 	}