[patch 49/73] Input: evdev - implement proper locking

Greg KH
2008-02-07T00:18:46Z

[-- Attachment #1: input-evdev-implement-proper-locking.patch --]
[-- Type: text/plain, Size: 28275 bytes --]

2.6.23-stable review patch. If anyone has any objections, please let us know.
------------------
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>

patch 6addb1d6de1968b84852f54561cc9a999909b5a9 in mainline.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/input/evdev.c | 719 +++++++++++++++++++++++++++++++++-----------------
1 file changed, 476 insertions(+), 243 deletions(-)

--- a/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -30,6 +30,8 @@ struct evdev {
wait_queue_head_t wait;
struct evdev_client *grab;
struct list_head client_list;
+ spinlock_t client_lock; /* protects client_list */
+ struct mutex mutex;
struct device dev;
};

@@ -37,39 +39,53 @@ struct evdev_client {
struct input_event buffer[EVDEV_BUFFER_SIZE];
int head;
int tail;
+ spinlock_t buffer_lock; /* protects access to buffer, head and tail */
struct fasync_struct *fasync;
struct evdev *evdev;
struct list_head node;
};

static struct evdev *evdev_table[EVDEV_MINORS];
+static DEFINE_MUTEX(evdev_table_mutex);

-static void evdev_event(struct input_handle *handle, unsigned int type, unsigned int code, int value)
+static void evdev_pass_event(struct evdev_client *client,
+ struct input_event *event)
+{
+ /*
+ * Interrupts are disabled, just acquire the lock
+ */
+ spin_lock(&client->buffer_lock);
+ client->buffer[client->head++] = *event;
+ client->head &= EVDEV_BUFFER_SIZE - 1;
+ spin_unlock(&client->buffer_lock);
+
+ kill_fasync(&client->fasync, SIGIO, POLL_IN);
+}
+
+/*
+ * Pass incoming event to all connected clients. Note that we are
+ * caleld under a spinlock with interrupts off so we don't need
+ * to use rcu_read_lock() here. Writers will be using syncronize_sched()
+ * instead of synchrnoize_rcu().
+ */
+static void evdev_event(struct input_handle *handle,
+ unsigned int type, unsigned int code, int value)
{
struct evdev *evdev = handle->private;
struct evdev_client *client;
+ struct input_event event;

- if (evdev->grab) {
- client = evdev->grab;
-
- do_gettimeofday(&client->buffer[client->head].time);
- client->buffer[client->head].type = type;
- client->buffer[client->head].code = code;
- client->buffer[client->head].value = value;
- client->head = (client->head + 1) & (EVDEV_BUFFER_SIZE - 1);
-
- kill_fasync(&client->fasync, SIGIO, POLL_IN);
- } else
- list_for_each_entry(client, &evdev->client_list, node) {
-
- do_gettimeofday(&client->buffer[client->head].time);
- client->buffer[client->head].type = type;
- client->buffer[client->head].code = code;
- client->buffer[client->head].value = value;
- client->head = (client->head + 1) & (EVDEV_BUFFER_SIZE - 1);
-
- kill_fasync(&client->fasync, SIGIO, POLL_IN);
- }
+ do_gettimeofday(&event.time);
+ event.type = type;
+ event.code = code;
+ event.value = value;
+
+ client = rcu_dereference(evdev->grab);
+ if (client)
+ evdev_pass_event(client, &event);
+ else
+ list_for_each_entry_rcu(client, &evdev->client_list, node)
+ evdev_pass_event(client, &event);

wake_up_interruptible(&evdev->wait);
}
@@ -88,38 +104,142 @@ static int evdev_flush(struct file *file
{
struct evdev_client *client = file->private_data;
struct evdev *evdev = client->evdev;
+ int retval;
+
+ retval = mutex_lock_interruptible(&evdev->mutex);
+ if (retval)
+ return retval;

if (!evdev->exist)
- return -ENODEV;
+ retval = -ENODEV;
+ else
+ retval = input_flush_device(&evdev->handle, file);

- return input_flush_device(&evdev->handle, file);
+ mutex_unlock(&evdev->mutex);
+ return retval;
}

static void evdev_free(struct device *dev)
{
struct evdev *evdev = container_of(dev, struct evdev, dev);

- evdev_table[evdev->minor] = NULL;
kfree(evdev);
}

+/*
+ * Grabs an event device (along with underlying input device).
+ * This function is called with evdev->mutex taken.
+ */
+static int evdev_grab(struct evdev *evdev, struct evdev_client *client)
+{
+ int error;
+
+ if (evdev->grab)
+ return -EBUSY;
+
+ error = input_grab_device(&evdev->handle);
+ if (error)
+ return error;
+
+ rcu_assign_pointer(evdev->grab, client);
+ /*
+ * We don't use synchronize_rcu() here because read-side
+ * critical section is protected by a spinlock instead
+ * of rcu_read_lock().
+ */
+ synchronize_sched();
+
+ return 0;
+}
+
+static int evdev_ungrab(struct evdev *evdev, struct evdev_client *client)
+{
+ if (evdev->grab != client)
+ return -EINVAL;
+
+ rcu_assign_pointer(evdev->grab, NULL);
+ synchronize_sched();
+ input_release_device(&evdev->handle);
+
+ return 0;
+}
+
+static void evdev_attach_client(struct evdev *evdev,
+ struct evdev_client *client)
+{
+ spin_lock(&evdev->client_lock);
+ list_add_tail_rcu(&client->node, &evdev->client_list);
+ spin_unlock(&evdev->client_lock);
+ synchronize_sched();
+}
+
+static void evdev_detach_client(struct evdev *evdev,
+ struct evdev_client *client)
+{
+ spin_lock(&evdev->client_lock);
+ list_del_rcu(&client->node);
+ spin_unlock(&evdev->client_lock);
+ synchronize_sched();
+}
+
+static int evdev_open_device(struct evdev *evdev)
+{
+ int retval;
+
+ retval = mutex_lock_interruptible(&evdev->mutex);
+ if (retval)
+ return retval;
+
+ if (!evdev->exist)
+ retval = -ENODEV;
+ else if (!evdev->open++)
+ retval = input_open_device(&evdev->handle);
+
+ mutex_unlock(&evdev->mutex);
+ return retval;
+}
+
+static void evdev_close_device(struct evdev *evdev)
+{
+ mutex_lock(&evdev->mutex);
+
+ if (evdev->exist && !--evdev->open)
+ input_close_device(&evdev->handle);
+
+ mutex_unlock(&evdev->mutex);
+}
+
+/*
+ * Wake up users waiting for IO so they can disconnect from
+ * dead device.
+ */
+static void evdev_hangup(struct evdev *evdev)
+{
+ struct evdev_client *client;
+
+ spin_lock(&evdev->client_lock);
+ list_for_each_entry(client, &evdev->client_list, node)
+ kill_fasync(&client->fasync, SIGIO, POLL_HUP);
+ spin_unlock(&evdev->client_lock);
+
+ wake_up_interruptible(&evdev->wait);
+}
+
static int evdev_release(struct inode *inode, struct file *file)
{
struct evdev_client *client = file->private_data;
struct evdev *evdev = client->evdev;

- if (evdev->grab == client) {
- input_release_device(&evdev->handle);
- evdev->grab = NULL;
- }
+ mutex_lock(&evdev->mutex);
+ if (evdev->grab == client)
+ evdev_ungrab(evdev, client);
+ mutex_unlock(&evdev->mutex);

evdev_fasync(-1, file, 0);
- list_del(&client->node);
+ evdev_detach_client(evdev, client);
kfree(client);

- if (!--evdev->open && evdev->exist)
- input_close_device(&evdev->handle);
-
+ evdev_close_device(evdev);
put_device(&evdev->dev);

return 0;
@@ -127,41 +247,44 @@ static int evdev_release(struct inode *i

static int evdev_open(struct inode *inode, struct file *file)
{
- struct evdev_client *client;
struct evdev *evdev;
+ struct evdev_client *client;
int i = iminor(inode) - EVDEV_MINOR_BASE;
int error;

if (i >= EVDEV_MINORS)
return -ENODEV;

+ error = mutex_lock_interruptible(&evdev_table_mutex);
+ if (error)
+ return error;
evdev = evdev_table[i];
+ if (evdev)
+ get_device(&evdev->dev);
+ mutex_unlock(&evdev_table_mutex);

- if (!evdev || !evdev->exist)
+ if (!evdev)
return -ENODEV;

- get_device(&evdev->dev);
-
client = kzalloc(sizeof(struct evdev_client), GFP_KERNEL);
if (!client) {
error = -ENOMEM;
goto err_put_evdev;
}

+ spin_lock_init(&client->buffer_lock);
client->evdev = evdev;
- list_add_tail(&client->node, &evdev->client_list);
+ evdev_attach_client(evdev, client);

- if (!evdev->open++ && evdev->exist) {
- error = input_open_device(&evdev->handle);
- if (error)
- goto err_free_client;
- }
+ error = evdev_open_device(evdev);
+ if (error)
+ goto err_free_client;

file->private_data = client;
return 0;

err_free_client:
- list_del(&client->node);
+ evdev_detach_client(evdev, client);
kfree(client);
err_put_evdev:
put_device(&evdev->dev);
@@ -197,12 +320,14 @@ static inline size_t evdev_event_size(vo
sizeof(struct input_event_compat) : sizeof(struct input_event);
}

-static int evdev_event_from_user(const char __user *buffer, struct input_event *event)
+static int evdev_event_from_user(const char __user *buffer,
+ struct input_event *event)
{
if (COMPAT_TEST) {
struct input_event_compat compat_event;

- if (copy_from_user(&compat_event, buffer, sizeof(struct input_event_compat)))
+ if (copy_from_user(&compat_event, buffer,
+ sizeof(struct input_event_compat)))
return -EFAULT;

event->time.tv_sec = compat_event.time.tv_sec;
@@ -219,7 +344,8 @@ static int evdev_event_from_user(const c
return 0;
}

-static int evdev_event_to_user(char __user *buffer, const struct input_event *event)
+static int evdev_event_to_user(char __user *buffer,
+ const struct input_event *event)
{
if (COMPAT_TEST) {
struct input_event_compat compat_event;
@@ -230,7 +356,8 @@ static int evdev_event_to_user(char __us
compat_event.code = event->code;
compat_event.value = event->value;

- if (copy_to_user(buffer, &compat_event, sizeof(struct input_event_compat)))
+ if (copy_to_user(buffer, &compat_event,
+ sizeof(struct input_event_compat)))
return -EFAULT;

} else {
@@ -248,7 +375,8 @@ static inline size_t evdev_event_size(vo
return sizeof(struct input_event);
}

-static int evdev_event_from_user(const char __user *buffer, struct input_event *event)
+static int evdev_event_from_user(const char __user *buffer,
+ struct input_event *event)
{
if (copy_from_user(event, buffer, sizeof(struct input_event)))
return -EFAULT;
@@ -256,7 +384,8 @@ static int evdev_event_from_user(const c
return 0;
}

-static int evdev_event_to_user(char __user *buffer, const struct input_event *event)
+static int evdev_event_to_user(char __user *buffer,
+ const struct input_event *event)
{
if (copy_to_user(buffer, event, sizeof(struct input_event)))
return -EFAULT;
@@ -266,37 +395,71 @@ static int evdev_event_to_user(char __us

#endif /* CONFIG_COMPAT */

-static ssize_t evdev_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
+static ssize_t evdev_write(struct file *file, const char __user *buffer,
+ size_t count, loff_t *ppos)
{
struct evdev_client *client = file->private_data;
struct evdev *evdev = client->evdev;
struct input_event event;
- int retval = 0;
+ int retval;

- if (!evdev->exist)
- return -ENODEV;
+ retval = mutex_lock_interruptible(&evdev->mutex);
+ if (retval)
+ return retval;
+
+ if (!evdev->exist) {
+ retval = -ENODEV;
+ goto out;
+ }

while (retval < count) {

- if (evdev_event_from_user(buffer + retval, &event))
- return -EFAULT;
- input_inject_event(&evdev->handle, event.type, event.code, event.value);
+ if (evdev_event_from_user(buffer + retval, &event)) {
+ retval = -EFAULT;
+ goto out;
+ }
+
+ input_inject_event(&evdev->handle,
+ event.type, event.code, event.value);
retval += evdev_event_size();
}

+ out:
+ mutex_unlock(&evdev->mutex);
return retval;
}

-static ssize_t evdev_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
+static int evdev_fetch_next_event(struct evdev_client *client,
+ struct input_event *event)
+{
+ int have_event;
+
+ spin_lock_irq(&client->buffer_lock);
+
+ have_event = client->head != client->tail;
+ if (have_event) {
+ *event = client->buffer[client->tail++];
+ client->tail &= EVDEV_BUFFER_SIZE - 1;
+ }
+
+ spin_unlock_irq(&client->buffer_lock);
+
+ return have_event;
+}
+
+static ssize_t evdev_read(struct file *file, char __user *buffer,
+ size_t count, loff_t *ppos)
{
struct evdev_client *client = file->private_data;
struct evdev *evdev = client->evdev;
+ struct input_event event;
int retval;

if (count < evdev_event_size())
return -EINVAL;

- if (client->head == client->tail && evdev->exist && (file->f_flags & O_NONBLOCK))
+ if (client->head == client->tail && evdev->exist &&
+ (file->f_flags & O_NONBLOCK))
return -EAGAIN;

retval = wait_event_interruptible(evdev->wait,
@@ -307,14 +470,12 @@ static ssize_t evdev_read(struct file *f
if (!evdev->exist)
return -ENODEV;

- while (client->head != client->tail && retval + evdev_event_size() <= count) {
-
- struct input_event *event = (struct input_event *) client->buffer + client->tail;
+ while (retval + evdev_event_size() <= count &&
+ evdev_fetch_next_event(client, &event)) {

- if (evdev_event_to_user(buffer + retval, event))
+ if (evdev_event_to_user(buffer + retval, &event))
return -EFAULT;

- client->tail = (client->tail + 1) & (EVDEV_BUFFER_SIZE - 1);
retval += evdev_event_size();
}

@@ -409,8 +570,8 @@ static int str_to_user(const char *str,
return copy_to_user(p, str, len) ? -EFAULT : len;
}

-static long evdev_ioctl_handler(struct file *file, unsigned int cmd,
- void __user *p, int compat_mode)
+static long evdev_do_ioctl(struct file *file, unsigned int cmd,
+ void __user *p, int compat_mode)
{
struct evdev_client *client = file->private_data;
struct evdev *evdev = client->evdev;
@@ -421,186 +582,208 @@ static long evdev_ioctl_handler(struct f
int i, t, u, v;
int error;

- if (!evdev->exist)
- return -ENODEV;
-
switch (cmd) {

- case EVIOCGVERSION:
- return put_user(EV_VERSION, ip);
+ case EVIOCGVERSION:
+ return put_user(EV_VERSION, ip);

- case EVIOCGID:
- if (copy_to_user(p, &dev->id, sizeof(struct input_id)))
- return -EFAULT;
- return 0;
+ case EVIOCGID:
+ if (copy_to_user(p, &dev->id, sizeof(struct input_id)))
+ return -EFAULT;
+ return 0;

- case EVIOCGREP:
- if (!test_bit(EV_REP, dev->evbit))
- return -ENOSYS;
- if (put_user(dev->rep[REP_DELAY], ip))
- return -EFAULT;
- if (put_user(dev->rep[REP_PERIOD], ip + 1))
- return -EFAULT;
- return 0;
+ case EVIOCGREP:
+ if (!test_bit(EV_REP, dev->evbit))
+ return -ENOSYS;
+ if (put_user(dev->rep[REP_DELAY], ip))
+ return -EFAULT;
+ if (put_user(dev->rep[REP_PERIOD], ip + 1))
+ return -EFAULT;
+ return 0;

- case EVIOCSREP:
- if (!test_bit(EV_REP, dev->evbit))
- return -ENOSYS;
- if (get_user(u, ip))
- return -EFAULT;
- if (get_user(v, ip + 1))
- return -EFAULT;
+ case EVIOCSREP:
+ if (!test_bit(EV_REP, dev->evbit))
+ return -ENOSYS;
+ if (get_user(u, ip))
+ return -EFAULT;
+ if (get_user(v, ip + 1))
+ return -EFAULT;

- input_inject_event(&evdev->handle, EV_REP, REP_DELAY, u);
- input_inject_event(&evdev->handle, EV_REP, REP_PERIOD, v);
+ input_inject_event(&evdev->handle, EV_REP, REP_DELAY, u);
+ input_inject_event(&evdev->handle, EV_REP, REP_PERIOD, v);

- return 0;
+ return 0;

- case EVIOCGKEYCODE:
- if (get_user(t, ip))
- return -EFAULT;
+ case EVIOCGKEYCODE:
+ if (get_user(t, ip))
+ return -EFAULT;

- error = dev->getkeycode(dev, t, &v);
- if (error)
- return error;
+ error = dev->getkeycode(dev, t, &v);
+ if (error)
+ return error;

- if (put_user(v, ip + 1))
- return -EFAULT;
+ if (put_user(v, ip + 1))
+ return -EFAULT;

- return 0;
+ return 0;

- case EVIOCSKEYCODE:
- if (get_user(t, ip) || get_user(v, ip + 1))
- return -EFAULT;
+ case EVIOCSKEYCODE:
+ if (get_user(t, ip) || get_user(v, ip + 1))
+ return -EFAULT;

- return dev->setkeycode(dev, t, v);
+ return dev->setkeycode(dev, t, v);

- case EVIOCSFF:
- if (copy_from_user(&effect, p, sizeof(effect)))
- return -EFAULT;
+ case EVIOCSFF:
+ if (copy_from_user(&effect, p, sizeof(effect)))
+ return -EFAULT;

- error = input_ff_upload(dev, &effect, file);
+ error = input_ff_upload(dev, &effect, file);

- if (put_user(effect.id, &(((struct ff_effect __user *)p)->id)))
- return -EFAULT;
+ if (put_user(effect.id, &(((struct ff_effect __user *)p)->id)))
+ return -EFAULT;

- return error;
+ return error;

- case EVIOCRMFF:
- return input_ff_erase(dev, (int)(unsigned long) p, file);
+ case EVIOCRMFF:
+ return input_ff_erase(dev, (int)(unsigned long) p, file);

- case EVIOCGEFFECTS:
- i = test_bit(EV_FF, dev->evbit) ? dev->ff->max_effects : 0;
- if (put_user(i, ip))
- return -EFAULT;
- return 0;
+ case EVIOCGEFFECTS:
+ i = test_bit(EV_FF, dev->evbit) ?
+ dev->ff->max_effects : 0;
+ if (put_user(i, ip))
+ return -EFAULT;
+ return 0;

- case EVIOCGRAB:
- if (p) {
- if (evdev->grab)
- return -EBUSY;
- if (input_grab_device(&evdev->handle))
- return -EBUSY;
- evdev->grab = client;
- return 0;
- } else {
- if (evdev->grab != client)
- return -EINVAL;
- input_release_device(&evdev->handle);
- evdev->grab = NULL;
- return 0;
+ case EVIOCGRAB:
+ if (p)
+ return evdev_grab(evdev, client);
+ else
+ return evdev_ungrab(evdev, client);
+
+ default:
+
+ if (_IOC_TYPE(cmd) != 'E')
+ return -EINVAL;
+
+ if (_IOC_DIR(cmd) == _IOC_READ) {
+
+ if ((_IOC_NR(cmd) & ~EV_MAX) == _IOC_NR(EVIOCGBIT(0, 0))) {
+
+ unsigned long *bits;
+ int len;
+
+ switch (_IOC_NR(cmd) & EV_MAX) {
+
+ case 0: bits = dev->evbit; len = EV_MAX; break;
+ case EV_KEY: bits = dev->keybit; len = KEY_MAX; break;
+ case EV_REL: bits = dev->relbit; len = REL_MAX; break;
+ case EV_ABS: bits = dev->absbit; len = ABS_MAX; break;
+ case EV_MSC: bits = dev->mscbit; len = MSC_MAX; break;
+ case EV_LED: bits = dev->ledbit; len = LED_MAX; break;
+ case EV_SND: bits = dev->sndbit; len = SND_MAX; break;
+ case EV_FF: bits = dev->ffbit; len = FF_MAX; break;
+ case EV_SW: bits = dev->swbit; len = SW_MAX; break;
+ default: return -EINVAL;
+ }
+ return bits_to_user(bits, len, _IOC_SIZE(cmd), p, compat_mode);
}

- default:
+ if (_IOC_NR(cmd) == _IOC_NR(EVIOCGKEY(0)))
+ return bits_to_user(dev->key, KEY_MAX, _IOC_SIZE(cmd),
+ p, compat_mode);

- if (_IOC_TYPE(cmd) != 'E')
- return -EINVAL;
+ if (_IOC_NR(cmd) == _IOC_NR(EVIOCGLED(0)))
+ return bits_to_user(dev->led, LED_MAX, _IOC_SIZE(cmd),
+ p, compat_mode);

- if (_IOC_DIR(cmd) == _IOC_READ) {
+ if (_IOC_NR(cmd) == _IOC_NR(EVIOCGSND(0)))
+ return bits_to_user(dev->snd, SND_MAX, _IOC_SIZE(cmd),
+ p, compat_mode);

- if ((_IOC_NR(cmd) & ~EV_MAX) == _IOC_NR(EVIOCGBIT(0,0))) {
+ if (_IOC_NR(cmd) == _IOC_NR(EVIOCGSW(0)))
+ return bits_to_user(dev->sw, SW_MAX, _IOC_SIZE(cmd),
+ p, compat_mode);

- unsigned long *bits;
- int len;
+ if (_IOC_NR(cmd) == _IOC_NR(EVIOCGNAME(0)))
+ return str_to_user(dev->name, _IOC_SIZE(cmd), p);

- switch (_IOC_NR(cmd) & EV_MAX) {
- case 0: bits = dev->evbit; len = EV_MAX; break;
- case EV_KEY: bits = dev->keybit; len = KEY_MAX; break;
- case EV_REL: bits = dev->relbit; len = REL_MAX; break;
- case EV_ABS: bits = dev->absbit; len = ABS_MAX; break;
- case EV_MSC: bits = dev->mscbit; len = MSC_MAX; break;
- case EV_LED: bits = dev->ledbit; len = LED_MAX; break;
- case EV_SND: bits = dev->sndbit; len = SND_MAX; break;
- case EV_FF: bits = dev->ffbit; len = FF_MAX; break;
- case EV_SW: bits = dev->swbit; len = SW_MAX; break;
- default: return -EINVAL;
- }
- return bits_to_user(bits, len, _IOC_SIZE(cmd), p, compat_mode);
- }
+ if (_IOC_NR(cmd) == _IOC_NR(EVIOCGPHYS(0)))
+ return str_to_user(dev->phys, _IOC_SIZE(cmd), p);

- if (_IOC_NR(cmd) == _IOC_NR(EVIOCGKEY(0)))
- return bits_to_user(dev->key, KEY_MAX, _IOC_SIZE(cmd),
- p, compat_mode);
+ if (_IOC_NR(cmd) == _IOC_NR(EVIOCGUNIQ(0)))
+ return str_to_user(dev->uniq, _IOC_SIZE(cmd), p);

- if (_IOC_NR(cmd) == _IOC_NR(EVIOCGLED(0)))
- return bits_to_user(dev->led, LED_MAX, _IOC_SIZE(cmd),
- p, compat_mode);
+ if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCGABS(0))) {

- if (_IOC_NR(cmd) == _IOC_NR(EVIOCGSND(0)))
- return bits_to_user(dev->snd, SND_MAX, _IOC_SIZE(cmd),
- p, compat_mode);
+ t = _IOC_NR(cmd) & ABS_MAX;

- if (_IOC_NR(cmd) == _IOC_NR(EVIOCGSW(0)))
- return bits_to_user(dev->sw, SW_MAX, _IOC_SIZE(cmd),
- p, compat_mode);
+ abs.value = dev->abs[t];
+ abs.minimum = dev->absmin[t];
+ abs.maximum = dev->absmax[t];
+ abs.fuzz = dev->absfuzz[t];
+ abs.flat = dev->absflat[t];

- if (_IOC_NR(cmd) == _IOC_NR(EVIOCGNAME(0)))
- return str_to_user(dev->name, _IOC_SIZE(cmd), p);
+ if (copy_to_user(p, &abs, sizeof(struct input_absinfo)))
+ return -EFAULT;

- if (_IOC_NR(cmd) == _IOC_NR(EVIOCGPHYS(0)))
- return str_to_user(dev->phys, _IOC_SIZE(cmd), p);
+ return 0;
+ }

- if (_IOC_NR(cmd) == _IOC_NR(EVIOCGUNIQ(0)))
- return str_to_user(dev->uniq, _IOC_SIZE(cmd), p);
+ }

- if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCGABS(0))) {
+ if (_IOC_DIR(cmd) == _IOC_WRITE) {

- t = _IOC_NR(cmd) & ABS_MAX;
+ if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCSABS(0))) {

- abs.value = dev->abs[t];
- abs.minimum = dev->absmin[t];
- abs.maximum = dev->absmax[t];
- abs.fuzz = dev->absfuzz[t];
- abs.flat = dev->absflat[t];
+ t = _IOC_NR(cmd) & ABS_MAX;

- if (copy_to_user(p, &abs, sizeof(struct input_absinfo)))
- return -EFAULT;
+ if (copy_from_user(&abs, p,
+ sizeof(struct input_absinfo)))
+ return -EFAULT;
+
+ /*
+ * Take event lock to ensure that we are not
+ * changing device parameters in the middle
+ * of event.
+ */
+ spin_lock_irq(&dev->event_lock);
+
+ dev->abs[t] = abs.value;
+ dev->absmin[t] = abs.minimum;
+ dev->absmax[t] = abs.maximum;
+ dev->absfuzz[t] = abs.fuzz;
+ dev->absflat[t] = abs.flat;

- return 0;
- }
+ spin_unlock_irq(&dev->event_lock);

+ return 0;
}
+ }
+ }
+ return -EINVAL;
+}

- if (_IOC_DIR(cmd) == _IOC_WRITE) {
-
- if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCSABS(0))) {
+static long evdev_ioctl_handler(struct file *file, unsigned int cmd,
+ void __user *p, int compat_mode)
+{
+ struct evdev_client *client = file->private_data;
+ struct evdev *evdev = client->evdev;
+ int retval;

- t = _IOC_NR(cmd) & ABS_MAX;
+ retval = mutex_lock_interruptible(&evdev->mutex);
+ if (retval)
+ return retval;

- if (copy_from_user(&abs, p, sizeof(struct input_absinfo)))
- return -EFAULT;
+ if (!evdev->exist) {
+ retval = -ENODEV;
+ goto out;
+ }

- dev->abs[t] = abs.value;
- dev->absmin[t] = abs.minimum;
- dev->absmax[t] = abs.maximum;
- dev->absfuzz[t] = abs.fuzz;
- dev->absflat[t] = abs.flat;
+ retval = evdev_do_ioctl(file, cmd, p, compat_mode);

- return 0;
- }
- }
- }
- return -EINVAL;
+ out:
+ mutex_unlock(&evdev->mutex);
+ return retval;
}

static long evdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
@@ -609,27 +792,79 @@ static long evdev_ioctl(struct file *fil
}

#ifdef CONFIG_COMPAT
-static long evdev_ioctl_compat(struct file *file, unsigned int cmd, unsigned long arg)
+static long evdev_ioctl_compat(struct file *file,
+ unsigned int cmd, unsigned long arg)
{
return evdev_ioctl_handler(file, cmd, compat_ptr(arg), 1);
}
#endif

static const struct file_operations evdev_fops = {
- .owner = THIS_MODULE,
- .read = evdev_read,
- .write = evdev_write,
- .poll = evdev_poll,
- .open = evdev_open,
- .release = evdev_release,
- .unlocked_ioctl = evdev_ioctl,
+ .owner = THIS_MODULE,
+ .read = evdev_read,
+ .write = evdev_write,
+ .poll = evdev_poll,
+ .open = evdev_open,
+ .release = evdev_release,
+ .unlocked_ioctl = evdev_ioctl,
#ifdef CONFIG_COMPAT
- .compat_ioctl = evdev_ioctl_compat,
+ .compat_ioctl = evdev_ioctl_compat,
#endif
- .fasync = evdev_fasync,
- .flush = evdev_flush
+ .fasync = evdev_fasync,
+ .flush = evdev_flush
};

+static int evdev_install_chrdev(struct evdev *evdev)
+{
+ /*
+ * No need to do any locking here as calls to connect and
+ * disconnect are serialized by the input core
+ */
+ evdev_table[evdev->minor] = evdev;
+ return 0;
+}
+
+static void evdev_remove_chrdev(struct evdev *evdev)
+{
+ /*
+ * Lock evdev table to prevent race with evdev_open()
+ */
+ mutex_lock(&evdev_table_mutex);
+ evdev_table[evdev->minor] = NULL;
+ mutex_unlock(&evdev_table_mutex);
+}
+
+/*
+ * Mark device non-existent. This disables writes, ioctls and
+ * prevents new users from opening the device. Already posted
+ * blocking reads will stay, however new ones will fail.
+ */
+static void evdev_mark_dead(struct evdev *evdev)
+{
+ mutex_lock(&evdev->mutex);
+ evdev->exist = 0;
+ mutex_unlock(&evdev->mutex);
+}
+
+static void evdev_cleanup(struct evdev *evdev)
+{
+ struct input_handle *handle = &evdev->handle;
+
+ evdev_mark_dead(evdev);
+ evdev_hangup(evdev);
+ evdev_remove_chrdev(evdev);
+
+ /* evdev is marked dead so no one else accesses evdev->open */
+ if (evdev->open) {
+ input_flush_device(handle, NULL);
+ input_close_device(handle);
+ }
+}
+
+/*
+ * Create new evdev device. Note that input core serializes calls
+ * to connect and disconnect so we don't need to lock evdev_table here.
+ */
static int evdev_connect(struct input_handler *handler, struct input_dev *dev,
const struct input_device_id *id)
{
@@ -637,7 +872,10 @@ static int evdev_connect(struct input_ha
int minor;
int error;

- for (minor = 0; minor < EVDEV_MINORS && evdev_table[minor]; minor++);
+ for (minor = 0; minor < EVDEV_MINORS; minor++)
+ if (!evdev_table[minor])
+ break;
+
if (minor == EVDEV_MINORS) {
printk(KERN_ERR "evdev: no more free evdev devices\n");
return -ENFILE;
@@ -648,38 +886,44 @@ static int evdev_connect(struct input_ha
return -ENOMEM;

INIT_LIST_HEAD(&evdev->client_list);
+ spin_lock_init(&evdev->client_lock);
+ mutex_init(&evdev->mutex);
init_waitqueue_head(&evdev->wait);

+ snprintf(evdev->name, sizeof(evdev->name), "event%d", minor);
evdev->exist = 1;
evdev->minor = minor;
+
evdev->handle.dev = dev;
evdev->handle.name = evdev->name;
evdev->handle.handler = handler;
evdev->handle.private = evdev;
- snprintf(evdev->name, sizeof(evdev->name), "event%d", minor);

- snprintf(evdev->dev.bus_id, sizeof(evdev->dev.bus_id),
- "event%d", minor);
+ strlcpy(evdev->dev.bus_id, evdev->name, sizeof(evdev->dev.bus_id));
+ evdev->dev.devt = MKDEV(INPUT_MAJOR, EVDEV_MINOR_BASE + minor);
evdev->dev.class = &input_class;
evdev->dev.parent = &dev->dev;
- evdev->dev.devt = MKDEV(INPUT_MAJOR, EVDEV_MINOR_BASE + minor);
evdev->dev.release = evdev_free;
device_initialize(&evdev->dev);

- evdev_table[minor] = evdev;
-
- error = device_add(&evdev->dev);
+ error = input_register_handle(&evdev->handle);
if (error)
goto err_free_evdev;

- error = input_register_handle(&evdev->handle);
+ error = evdev_install_chrdev(evdev);
+ if (error)
+ goto err_unregister_handle;
+
+ error = device_add(&evdev->dev);
if (error)
- goto err_delete_evdev;
+ goto err_cleanup_evdev;

return 0;

- err_delete_evdev:
- device_del(&evdev->dev);
+ err_cleanup_evdev:
+ evdev_cleanup(evdev);
+ err_unregister_handle:
+ input_unregister_handle(&evdev->handle);
err_free_evdev:
put_device(&evdev->dev);
return error;
@@ -688,21 +932,10 @@ static int evdev_connect(struct input_ha
static void evdev_disconnect(struct input_handle *handle)
{
struct evdev *evdev = handle->private;
- struct evdev_client *client;

- input_unregister_handle(handle);
device_del(&evdev->dev);
-
- evdev->exist = 0;
-
- if (evdev->open) {
- input_flush_device(handle, NULL);
- input_close_device(handle);
- list_for_each_entry(client, &evdev->client_list, node)
- kill_fasync(&client->fasync, SIGIO, POLL_HUP);
- wake_up_interruptible(&evdev->wait);
- }
-
+ evdev_cleanup(evdev);
+ input_unregister_handle(handle);
put_device(&evdev->dev);
}

@@ -714,13 +947,13 @@ static const struct input_device_id evde
MODULE_DEVICE_TABLE(input, evdev_ids);

static struct input_handler evdev_handler = {
- .event = evdev_event,
- .connect = evdev_connect,
- .disconnect = evdev_disconnect,
- .fops = &evdev_fops,
- .minor = EVDEV_MINOR_BASE,
- .name = "evdev",
- .id_table = evdev_ids,
+ .event = evdev_event,
+ .connect = evdev_connect,
+ .disconnect = evdev_disconnect,
+ .fops = &evdev_fops,
+ .minor = EVDEV_MINOR_BASE,
+ .name = "evdev",
+ .id_table = evdev_ids,
};

static int __init evdev_init(void)

--