linux-kernel - [PATCH 2/3] Fix multiple requests and releases of IRQ for GPIO LED Trigger.

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Date:	Tue, 14 Jul 2009 14:03:34 -0300
From:	Thadeu Lima de Souza Cascardo <cascardo@...oscopio.com>
To:	me@...ipe.balbi.com
Cc:	linux-kernel@...r.kernel.org, rpurdie@...ux.intel.com,
	rpurdie@...ys.net, srcvale@...oscopio.com,
	Thadeu Lima de Souza Cascardo <cascardo@...oscopio.com>
Subject: [PATCH 2/3] 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@...oscopio.com>
Signed-off-by: Samuel R. C. Vale <srcvale@...oscopio.com>
---
 drivers/leds/ledtrig-gpio.c |   21 ++++++++++++++-------
 1 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/leds/ledtrig-gpio.c b/drivers/leds/ledtrig-gpio.c
index 6b7bb12..7c9aff9 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);
 	}
 }
-- 
1.6.3.3

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