leds: fix multiple requests and releases of IRQ for GPIO LED Trigger

When setting the same GPIO number, multiple IRQ shared requests will be
done without freing the previous request.  It will also try to free a
failed request or an already freed IRQ if 0 was written to the gpio file.

All these oops and leaks were fixed with the following solution: keep the
previous allocated GPIO (if any) still allocated in case the new request
fails.  The alternative solution would desallocate the previous allocated
GPIO and set gpio as 0.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Signed-off-by: Samuel R. C. Vale <srcvale@holoscopio.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 14 insertions, 7 deletions

diff --git a/drivers/leds/ledtrig-gpio.c b/drivers/leds/ledtrig-gpio.c
index a247ae6..8183b81f 100644
--- a/drivers/leds/ledtrig-gpio.c
+++ b/drivers/leds/ledtrig-gpio.c
@@ -146,20 +146,26 @@ static ssize_t gpio_trig_gpio_store(struct device *dev,
 		return -EINVAL;
 	}
 
+	if (gpio_data->gpio == gpio)
+		return n;
+
 	if (!gpio) {
-		free_irq(gpio_to_irq(gpio_data->gpio), led);
+		if (gpio_data->gpio != 0)
+			free_irq(gpio_to_irq(gpio_data->gpio), led);
+		gpio_data->gpio = 0;
 		return n;
 	}
 
-	if (gpio_data->gpio > 0 && gpio_data->gpio != gpio)
-		free_irq(gpio_to_irq(gpio_data->gpio), led);
-
-	gpio_data->gpio = gpio;
 	ret = request_irq(gpio_to_irq(gpio), gpio_trig_irq,
 			IRQF_SHARED | IRQF_TRIGGER_RISING
 			| IRQF_TRIGGER_FALLING, "ledtrig-gpio", led);
-	if (ret)
+	if (ret) {
 		dev_err(dev, "request_irq failed with error %d\n", ret);
+	} else {
+		if (gpio_data->gpio != 0)
+			free_irq(gpio_to_irq(gpio_data->gpio), led);
+		gpio_data->gpio = gpio;
+	}
 
 	return ret ? ret : n;
 }
@@ -211,7 +217,8 @@ static void gpio_trig_deactivate(struct led_classdev *led)
 		device_remove_file(led->dev, &dev_attr_inverted);
 		device_remove_file(led->dev, &dev_attr_desired_brightness);
 		flush_work(&gpio_data->work);
-		free_irq(gpio_to_irq(gpio_data->gpio),led);
+		if (gpio_data->gpio != 0)
+			free_irq(gpio_to_irq(gpio_data->gpio), led);
 		kfree(gpio_data);
 	}
 }