linux/drivers/input/input-polldev.c
Samu Onkalo d9c4f84699 Input: polldev can cause crash in case when polling disabled
When polled input device is opened and closed and there are no other
users of polled device, the workqueue is created and destroyed in
every open / close operation. It is probable that at some point
dynamic allocation of internal parts of the workqueue cause changes to the
workqueue.

When a work is queued to the workqueue the work struct contains pointers
to the workqueue data. If the workqueue has been changed and the work
has never been queued to the new workqueue, work-struct contains pointers
to the non-existing workqueue. This will cause crash at the work
cancellation during device close since cancellation of a work assumes
that the workqueue exists.

To prevent that, work struct is cleaned up at device close. This keeps
work struct clean for the next use.

Signed-off-by: Samu Onkalo <samu.p.onkalo@nokia.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
2010-02-20 01:23:55 -08:00

297 lines
7.1 KiB
C

/*
* Generic implementation of a polled input device
* Copyright (c) 2007 Dmitry Torokhov
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
*/
#include <linux/jiffies.h>
#include <linux/mutex.h>
#include <linux/input-polldev.h>
MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
MODULE_DESCRIPTION("Generic implementation of a polled input device");
MODULE_LICENSE("GPL v2");
MODULE_VERSION("0.1");
static DEFINE_MUTEX(polldev_mutex);
static int polldev_users;
static struct workqueue_struct *polldev_wq;
static int input_polldev_start_workqueue(void)
{
int retval;
retval = mutex_lock_interruptible(&polldev_mutex);
if (retval)
return retval;
if (!polldev_users) {
polldev_wq = create_singlethread_workqueue("ipolldevd");
if (!polldev_wq) {
printk(KERN_ERR "input-polldev: failed to create "
"ipolldevd workqueue\n");
retval = -ENOMEM;
goto out;
}
}
polldev_users++;
out:
mutex_unlock(&polldev_mutex);
return retval;
}
static void input_polldev_stop_workqueue(void)
{
mutex_lock(&polldev_mutex);
if (!--polldev_users)
destroy_workqueue(polldev_wq);
mutex_unlock(&polldev_mutex);
}
static void input_polldev_queue_work(struct input_polled_dev *dev)
{
unsigned long delay;
delay = msecs_to_jiffies(dev->poll_interval);
if (delay >= HZ)
delay = round_jiffies_relative(delay);
queue_delayed_work(polldev_wq, &dev->work, delay);
}
static void input_polled_device_work(struct work_struct *work)
{
struct input_polled_dev *dev =
container_of(work, struct input_polled_dev, work.work);
dev->poll(dev);
input_polldev_queue_work(dev);
}
static int input_open_polled_device(struct input_dev *input)
{
struct input_polled_dev *dev = input_get_drvdata(input);
int error;
error = input_polldev_start_workqueue();
if (error)
return error;
if (dev->open)
dev->open(dev);
/* Only start polling if polling is enabled */
if (dev->poll_interval > 0)
queue_delayed_work(polldev_wq, &dev->work, 0);
return 0;
}
static void input_close_polled_device(struct input_dev *input)
{
struct input_polled_dev *dev = input_get_drvdata(input);
cancel_delayed_work_sync(&dev->work);
/*
* Clean up work struct to remove references to the workqueue.
* It may be destroyed by the next call. This causes problems
* at next device open-close in case of poll_interval == 0.
*/
INIT_DELAYED_WORK(&dev->work, dev->work.work.func);
input_polldev_stop_workqueue();
if (dev->close)
dev->close(dev);
}
/* SYSFS interface */
static ssize_t input_polldev_get_poll(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct input_polled_dev *polldev = dev_get_drvdata(dev);
return sprintf(buf, "%d\n", polldev->poll_interval);
}
static ssize_t input_polldev_set_poll(struct device *dev,
struct device_attribute *attr, const char *buf,
size_t count)
{
struct input_polled_dev *polldev = dev_get_drvdata(dev);
struct input_dev *input = polldev->input;
unsigned long interval;
if (strict_strtoul(buf, 0, &interval))
return -EINVAL;
if (interval < polldev->poll_interval_min)
return -EINVAL;
if (interval > polldev->poll_interval_max)
return -EINVAL;
mutex_lock(&input->mutex);
polldev->poll_interval = interval;
if (input->users) {
cancel_delayed_work_sync(&polldev->work);
if (polldev->poll_interval > 0)
input_polldev_queue_work(polldev);
}
mutex_unlock(&input->mutex);
return count;
}
static DEVICE_ATTR(poll, S_IRUGO | S_IWUSR, input_polldev_get_poll,
input_polldev_set_poll);
static ssize_t input_polldev_get_max(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct input_polled_dev *polldev = dev_get_drvdata(dev);
return sprintf(buf, "%d\n", polldev->poll_interval_max);
}
static DEVICE_ATTR(max, S_IRUGO, input_polldev_get_max, NULL);
static ssize_t input_polldev_get_min(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct input_polled_dev *polldev = dev_get_drvdata(dev);
return sprintf(buf, "%d\n", polldev->poll_interval_min);
}
static DEVICE_ATTR(min, S_IRUGO, input_polldev_get_min, NULL);
static struct attribute *sysfs_attrs[] = {
&dev_attr_poll.attr,
&dev_attr_max.attr,
&dev_attr_min.attr,
NULL
};
static struct attribute_group input_polldev_attribute_group = {
.attrs = sysfs_attrs
};
/**
* input_allocate_polled_device - allocated memory polled device
*
* The function allocates memory for a polled device and also
* for an input device associated with this polled device.
*/
struct input_polled_dev *input_allocate_polled_device(void)
{
struct input_polled_dev *dev;
dev = kzalloc(sizeof(struct input_polled_dev), GFP_KERNEL);
if (!dev)
return NULL;
dev->input = input_allocate_device();
if (!dev->input) {
kfree(dev);
return NULL;
}
return dev;
}
EXPORT_SYMBOL(input_allocate_polled_device);
/**
* input_free_polled_device - free memory allocated for polled device
* @dev: device to free
*
* The function frees memory allocated for polling device and drops
* reference to the associated input device.
*/
void input_free_polled_device(struct input_polled_dev *dev)
{
if (dev) {
input_free_device(dev->input);
kfree(dev);
}
}
EXPORT_SYMBOL(input_free_polled_device);
/**
* input_register_polled_device - register polled device
* @dev: device to register
*
* The function registers previously initialized polled input device
* with input layer. The device should be allocated with call to
* input_allocate_polled_device(). Callers should also set up poll()
* method and set up capabilities (id, name, phys, bits) of the
* corresponing input_dev structure.
*/
int input_register_polled_device(struct input_polled_dev *dev)
{
struct input_dev *input = dev->input;
int error;
input_set_drvdata(input, dev);
INIT_DELAYED_WORK(&dev->work, input_polled_device_work);
if (!dev->poll_interval)
dev->poll_interval = 500;
if (!dev->poll_interval_max)
dev->poll_interval_max = dev->poll_interval;
input->open = input_open_polled_device;
input->close = input_close_polled_device;
error = input_register_device(input);
if (error)
return error;
error = sysfs_create_group(&input->dev.kobj,
&input_polldev_attribute_group);
if (error) {
input_unregister_device(input);
return error;
}
/*
* Take extra reference to the underlying input device so
* that it survives call to input_unregister_polled_device()
* and is deleted only after input_free_polled_device()
* has been invoked. This is needed to ease task of freeing
* sparse keymaps.
*/
input_get_device(input);
return 0;
}
EXPORT_SYMBOL(input_register_polled_device);
/**
* input_unregister_polled_device - unregister polled device
* @dev: device to unregister
*
* The function unregisters previously registered polled input
* device from input layer. Polling is stopped and device is
* ready to be freed with call to input_free_polled_device().
*/
void input_unregister_polled_device(struct input_polled_dev *dev)
{
sysfs_remove_group(&dev->input->dev.kobj,
&input_polldev_attribute_group);
input_unregister_device(dev->input);
}
EXPORT_SYMBOL(input_unregister_polled_device);