Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=6addb1d6de1968b84852f54561cc9a999909b5a9
Commit:     6addb1d6de1968b84852f54561cc9a999909b5a9
Parent:     8006479c9b75fb6594a7b746af3d7f1fbb68f18f
Author:     Dmitry Torokhov <[EMAIL PROTECTED]>
AuthorDate: Thu Aug 30 00:22:18 2007 -0400
Committer:  Dmitry Torokhov <[EMAIL PROTECTED]>
CommitDate: Thu Aug 30 00:22:18 2007 -0400

    Input: evdev - implement proper locking
    
    Signed-off-by: Dmitry Torokhov <[EMAIL PROTECTED]>
---
 drivers/input/evdev.c |  713 ++++++++++++++++++++++++++++++++-----------------
 1 files changed, 473 insertions(+), 240 deletions(-)

diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index ab4b2d9..bfee4f9 100644
--- 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);
+       do_gettimeofday(&event.time);
+       event.type = type;
+       event.code = code;
+       event.value = value;
 
-                       kill_fasync(&client->fasync, SIGIO, POLL_IN);
-               }
+       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, fl_owner_t id)
 {
        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 *inode, struct file 
*file)
 
 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(void)
                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 char __user *buffer, 
struct input_event *
        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 __user *buffer, const 
struct input_event *ev
                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(void)
        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 char __user *buffer, 
struct input_event *
        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 __user *buffer, const 
struct input_event *ev
 
 #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 *file, char __user 
*buffer, size_t count,
        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, unsigned int 
maxlen, void __user *p)
        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;
@@ -421,215 +582,289 @@ static long evdev_ioctl_handler(struct file *file, 
unsigned int cmd,
        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 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 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)
+                       return evdev_grab(evdev, client);
+               else
+                       return evdev_ungrab(evdev, client);
 
-               default:
+       default:
 
-                       if (_IOC_TYPE(cmd) != 'E')
-                               return -EINVAL;
+               if (_IOC_TYPE(cmd) != 'E')
+                       return -EINVAL;
 
-                       if (_IOC_DIR(cmd) == _IOC_READ) {
+               if (_IOC_DIR(cmd) == _IOC_READ) {
 
-                               if ((_IOC_NR(cmd) & ~EV_MAX) == 
_IOC_NR(EVIOCGBIT(0,0))) {
+                       if ((_IOC_NR(cmd) & ~EV_MAX) == _IOC_NR(EVIOCGBIT(0, 
0))) {
 
-                                       unsigned long *bits;
-                                       int len;
+                               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);
-                               }
+                               switch (_IOC_NR(cmd) & EV_MAX) {
 
-                               if (_IOC_NR(cmd) == _IOC_NR(EVIOCGKEY(0)))
-                                       return bits_to_user(dev->key, KEY_MAX, 
_IOC_SIZE(cmd),
-                                                           p, compat_mode);
+                               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(EVIOCGLED(0)))
-                                       return bits_to_user(dev->led, LED_MAX, 
_IOC_SIZE(cmd),
-                                                           p, compat_mode);
+                       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(EVIOCGSND(0)))
-                                       return bits_to_user(dev->snd, SND_MAX, 
_IOC_SIZE(cmd),
-                                                           p, compat_mode);
+                       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) == _IOC_NR(EVIOCGSW(0)))
-                                       return bits_to_user(dev->sw, SW_MAX, 
_IOC_SIZE(cmd),
-                                                           p, compat_mode);
+                       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) == _IOC_NR(EVIOCGNAME(0)))
-                                       return str_to_user(dev->name, 
_IOC_SIZE(cmd), p);
+                       if (_IOC_NR(cmd) == _IOC_NR(EVIOCGSW(0)))
+                               return bits_to_user(dev->sw, SW_MAX, 
_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(EVIOCGNAME(0)))
+                               return str_to_user(dev->name, _IOC_SIZE(cmd), 
p);
 
-                               if (_IOC_NR(cmd) == _IOC_NR(EVIOCGUNIQ(0)))
-                                       return str_to_user(dev->uniq, 
_IOC_SIZE(cmd), p);
+                       if (_IOC_NR(cmd) == _IOC_NR(EVIOCGPHYS(0)))
+                               return str_to_user(dev->phys, _IOC_SIZE(cmd), 
p);
 
-                               if ((_IOC_NR(cmd) & ~ABS_MAX) == 
_IOC_NR(EVIOCGABS(0))) {
+                       if (_IOC_NR(cmd) == _IOC_NR(EVIOCGUNIQ(0)))
+                               return str_to_user(dev->uniq, _IOC_SIZE(cmd), 
p);
 
-                                       t = _IOC_NR(cmd) & ABS_MAX;
+                       if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCGABS(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;
+                               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];
 
-                                       return 0;
-                               }
+                               if (copy_to_user(p, &abs, sizeof(struct 
input_absinfo)))
+                                       return -EFAULT;
 
+                               return 0;
                        }
 
-                       if (_IOC_DIR(cmd) == _IOC_WRITE) {
+               }
+
+               if (_IOC_DIR(cmd) == _IOC_WRITE) {
 
-                               if ((_IOC_NR(cmd) & ~ABS_MAX) == 
_IOC_NR(EVIOCSABS(0))) {
+                       if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCSABS(0))) 
{
 
-                                       t = _IOC_NR(cmd) & ABS_MAX;
+                               t = _IOC_NR(cmd) & ABS_MAX;
 
-                                       if (copy_from_user(&abs, p, 
sizeof(struct input_absinfo)))
-                                               return -EFAULT;
+                               if (copy_from_user(&abs, p,
+                                               sizeof(struct input_absinfo)))
+                                       return -EFAULT;
 
-                                       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;
+                               /*
+                                * Take event lock to ensure that we are not
+                                * changing device parameters in the middle
+                                * of event.
+                                */
+                               spin_lock_irq(&dev->event_lock);
 
-                                       return 0;
-                               }
+                               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;
+
+                               spin_unlock_irq(&dev->event_lock);
+
+                               return 0;
                        }
+               }
        }
        return -EINVAL;
 }
 
+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;
+
+       retval = mutex_lock_interruptible(&evdev->mutex);
+       if (retval)
+               return retval;
+
+       if (!evdev->exist) {
+               retval = -ENODEV;
+               goto out;
+       }
+
+       retval = evdev_do_ioctl(file, cmd, p, compat_mode);
+
+ out:
+       mutex_unlock(&evdev->mutex);
+       return retval;
+}
+
 static long evdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
        return evdev_ioctl_handler(file, cmd, (void __user *)arg, 0);
 }
 
 #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_handler *handler, 
struct input_dev *dev,
        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_handler *handler, 
struct input_dev *dev,
                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_handler *handler, 
struct input_dev *dev,
 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 evdev_ids[] = {
 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)
-
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