hwmon: (ams) Fix locking issues
Use a separate mutex to serialize input device creation/removal,
otheriwse we deadlock if we try to remove input device while it is
being polled. Also do not take ams_info.lock when it is not needed.
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
diff --git a/drivers/hwmon/ams/ams-input.c b/drivers/hwmon/ams/ams-input.c
index 48dbf7d..8a71239 100644
--- a/drivers/hwmon/ams/ams-input.c
+++ b/drivers/hwmon/ams/ams-input.c
@@ -27,6 +27,8 @@
module_param(invert, bool, S_IWUSR | S_IRUGO);
MODULE_PARM_DESC(invert, "Invert input data on X and Y axis");
+static DEFINE_MUTEX(ams_input_mutex);
+
static void ams_idev_poll(struct input_polled_dev *dev)
{
struct input_dev *idev = dev->input;
@@ -50,13 +52,11 @@
}
/* Call with ams_info.lock held! */
-static void ams_input_enable(void)
+static int ams_input_enable(void)
{
struct input_dev *input;
s8 x, y, z;
-
- if (ams_info.idev)
- return;
+ int error;
ams_sensors(&x, &y, &z);
ams_info.xcalib = x;
@@ -65,7 +65,7 @@
ams_info.idev = input_allocate_polled_device();
if (!ams_info.idev)
- return;
+ return -ENOMEM;
ams_info.idev->poll = ams_idev_poll;
ams_info.idev->poll_interval = 25;
@@ -84,14 +84,18 @@
set_bit(EV_KEY, input->evbit);
set_bit(BTN_TOUCH, input->keybit);
- if (input_register_polled_device(ams_info.idev)) {
+ error = input_register_polled_device(ams_info.idev);
+ if (error) {
input_free_polled_device(ams_info.idev);
ams_info.idev = NULL;
- return;
+ return error;
}
+
+ joystick = 1;
+
+ return 0;
}
-/* Call with ams_info.lock held! */
static void ams_input_disable(void)
{
if (ams_info.idev) {
@@ -99,6 +103,8 @@
input_free_polled_device(ams_info.idev);
ams_info.idev = NULL;
}
+
+ joystick = 0;
}
static ssize_t ams_input_show_joystick(struct device *dev,
@@ -110,39 +116,42 @@
static ssize_t ams_input_store_joystick(struct device *dev,
struct device_attribute *attr, const char *buf, size_t count)
{
- if (sscanf(buf, "%d\n", &joystick) != 1)
+ unsigned long enable;
+ int error = 0;
+
+ if (strict_strtoul(buf, 0, &enable) || enable > 1)
return -EINVAL;
- mutex_lock(&ams_info.lock);
+ mutex_lock(&ams_input_mutex);
- if (joystick)
- ams_input_enable();
- else
- ams_input_disable();
+ if (enable != joystick) {
+ if (enable)
+ error = ams_input_enable();
+ else
+ ams_input_disable();
+ }
- mutex_unlock(&ams_info.lock);
+ mutex_unlock(&ams_input_mutex);
- return count;
+ return error ? error : count;
}
static DEVICE_ATTR(joystick, S_IRUGO | S_IWUSR,
ams_input_show_joystick, ams_input_store_joystick);
-/* Call with ams_info.lock held! */
int ams_input_init(void)
{
- int result;
-
- result = device_create_file(&ams_info.of_dev->dev, &dev_attr_joystick);
-
- if (!result && joystick)
+ if (joystick)
ams_input_enable();
- return result;
+
+ return device_create_file(&ams_info.of_dev->dev, &dev_attr_joystick);
}
-/* Call with ams_info.lock held! */
void ams_input_exit(void)
{
- ams_input_disable();
device_remove_file(&ams_info.of_dev->dev, &dev_attr_joystick);
+
+ mutex_lock(&ams_input_mutex);
+ ams_input_disable();
+ mutex_unlock(&ams_input_mutex);
}