Fw: Re: + add-locking-to-evdev.patch added to -mm tree
From: Paul E. McKenney
Date: Mon Apr 09 2007 - 01:47:45 EST
On Fri, Mar 30, 2007 at 02:06:05PM -0700, akpm@xxxxxxxxxxxxxxxxxxxx wrote:
>
> The patch titled
> Add locking to evdev
> has been added to the -mm tree. Its filename is
> add-locking-to-evdev.patch
>
> *** Remember to use Documentation/SubmitChecklist when testing your code ***
>
> See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
> out what to do about this
>
> ------------------------------------------------------
> Subject: Add locking to evdev
> From: Dmitry Torokhov <dtor@xxxxxxxxxxxxx>
>
> Input: evdev - implement proper locking
OK, so I have to ask -- this is protecting multiple clients of a given
mouse or keyboard, right? Doesn't look like it has much to do with
connecting multiple mice/keyboards/joysticks/whatever to a given system,
but thought I should ask.
Excellent start, but some concerns marked with "!!!". If these are
fixed, either by educating me or by appropriate changes, I will ack.
A signal-related question for Oleg marked with "Oleg".
Thanx, Paul
> Signed-off-by: Dmitry Torokhov <dtor@xxxxxxx>
> Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> ---
>
> drivers/input/evdev.c | 351 ++++++++++++++++++++++++++++------------
> 1 files changed, 254 insertions(+), 97 deletions(-)
>
> diff -puN drivers/input/evdev.c~add-locking-to-evdev drivers/input/evdev.c
> --- a/drivers/input/evdev.c~add-locking-to-evdev
> +++ a/drivers/input/evdev.c
> @@ -31,6 +31,8 @@ struct evdev {
> wait_queue_head_t wait;
> struct evdev_client *grab;
> struct list_head client_list;
> + spinlock_t client_lock;
OK, what does this one protect?
o ev_attach_client(): client_list field (permitting RCU readers).
Adds element.
o evdev_detach_client(): ditto, but deletes element.
o evdev_hangup(): scans the list hanging off of the client_list
field, invoking kill_fasync() on each. Looks to be delivering
a POLL_HUP to all parties receiving events.
Apparently the lock is preventing an entry from being
deleted out from under evdev_hangup(). Need to check races
with close(), I guess... (For example, it would be bad
to have the process torn down to the point that it could
not tolerate receiving (or ignoring) a signal before
removing itself from the list.)
o Readers of the evdev->client_list can use RCU.
> + struct mutex mutex;
And what does this one protect?
o evdev_flush(): evdev->exist flag (which handles race with RCU removal?)
Also invokes input_flush_device(), which invokes some flush-handler
function. There may be more issues here, but they would be with
users of evdev rather than with evdev itself, I am guessing.
o evdev_release(): invokes evdev_ungrab(). This NULLs the
evdev->grab field using rcu_assign_pointer().
o evdev_write(): invokes evdev_event_from_user() and
input_inject_event(). The former copies from user space, so
->mutex indeed cannot be a spinlock. Not sure what we are
protecting here -- perhaps event traffic? @@@
o evdev_ioctl_handler(): protecting ioctl. Consistent with
the thought of protecting event traffic.
o evdev_mark_dead(): protect setting evdev->exist to zero, adding
weight to the speculation under evdev_flush() above that
->exist handles the race with RCU removal.
o Readers of evdev->grab can use RCU. RCU readers caring about
concurrent deletion should check for evdev->exist under evdev->mutex.
Lock order:
o evdev->client_lock => fown_struct->lock
o fown_struct->lock => tasklist_lock
o tasklist_lock => sighand_struct->siglock
o evdev_table_mutex => evdev->client_lock.
> struct device dev;
> };
>
> @@ -38,39 +40,48 @@ struct evdev_client {
> struct input_event buffer[EVDEV_BUFFER_SIZE];
> int head;
> int tail;
> + spinlock_t buffer_lock;
And what does this one protect? Presumably a buffer! ;-)
o evdev_pass_event(): adding an event to evdev_client->buffer.
This includes the evdev_client->head field.
!!! Why doesn't this function need to check the
evdev_client->tail field??? How do we know we won't overflow
the buffer???
o evdev_new_client() [was evdev_open()]: evdev_client->client
field (attaching the evdev to its client, apparently).
Invokes evdev_attach_client() to do the list manipulation
(protected in turn by evdev->client_lock).
Argh... Strike that -- spin_lock_init() rather than spin_lock().
o evdev_fetch_next_event(): removing an event from
evdev_client->buffer. This includes evdev_client->head and
evdev_client->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);
One would guess that this one protects evdev_table[], but why guess?
o evdev_open(): adding a new client to the evdev_table[].
o evdev_install_chrdev() [was evdev_connect()]: Adding a
character device to the list. Invokes evdev_attach_client(),
which acquires evdev->client_lock.
o evdev_remove_chrdev(): remove a client from the evdev_table[].
Summary of RCU protection:
o Readers of the evdev->client_list can use RCU.
o Readers of evdev->grab can use RCU. RCU readers caring about
concurrent deletion should check for evdev->exist under evdev->mutex.
> +
> +static void evdev_pass_event(struct evdev_client *client, struct input_event *event)
> +{
> + unsigned long flags;
> +
> + spin_lock_irqsave(&client->buffer_lock, flags);
> + client->buffer[client->head++] = *event;
> + client->head &= EVDEV_BUFFER_SIZE - 1;
!!! Why don't we need to check for overflow here???
> + spin_unlock_irqrestore(&client->buffer_lock, flags);
> +
> + kill_fasync(&client->fasync, SIGIO, POLL_IN);
> +}
>
> 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;
> +
> + rcu_read_lock();
> +
> + client = rcu_dereference(evdev->grab);
OK: protecting evdev->grab. Not clear why we don't need to check
evdev->exist!!!
> + if (client)
> + evdev_pass_event(client, &event);
> + else
> + list_for_each_entry_rcu(client, &evdev->client_list, node)
evdev->client_list is under rcu_read_lock(), so OK.
> + evdev_pass_event(client, &event);
>
> - kill_fasync(&client->fasync, SIGIO, POLL_IN);
> - }
> + rcu_read_unlock();
>
> wake_up_interruptible(&evdev->wait);
> }
> @@ -89,33 +100,98 @@ 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)
OK, holding ->mutex, so ->exist is stable.
> - 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);
> }
>
> +static int evdev_grab(struct evdev *evdev, struct evdev_client *client)
> +{
> + int error;
> +
> + if (evdev->grab)
Need either rcu_read_lock() or to be holding evdev->mutex. All callers
do in fact hold evdev_mutex, see below.
> + return -EBUSY;
> +
> + error = input_grab_device(&evdev->handle);
> + if (error)
> + return error;
> +
> + rcu_assign_pointer(evdev->grab, client);
OK, but does every caller hold evdev->mutex? Yes, as follows:
o evdev_do_ioctl(): yes, via the only caller, evdev_ioctl_handler().
o evdev_ioctl_handler(): yes.
> + synchronize_rcu();
> +
> + return 0;
> +}
> +
> +static int evdev_ungrab(struct evdev *evdev, struct evdev_client *client)
> +{
> + if (evdev->grab != client)
Need either rcu_read_lock() or to be holding evdev->mutex. All callers
do in fact hold evdev_mutex, see below.
> + return -EINVAL;
> +
> + rcu_assign_pointer(evdev->grab, NULL);
Do all our callers hold evdev->mutex?
o evdev_release(): yes.
o evdev_do_ioctl(): yes, via the only caller, evdev_ioctl_handler().
o evdev_ioctl_handler(): yes.
> + synchronize_rcu();
> + input_release_device(&evdev->handle);
OK -- we apparently tolerate manipulation of evdev->grab for up to a grace
period after NULLing the pointer. People picking up evdev->grab therefore
should not be picking it up twice -- at least not without holding the
->mutex or without tolerating the second grab coming up NULL.
> +
> + 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);
OK, ->client_list modified while holding ->client_lock.
> + spin_unlock(&evdev->client_lock);
> + synchronize_rcu();
> +}
> +
> +static void evdev_detach_client(struct evdev *evdev, struct evdev_client *client)
> +{
> + spin_lock(&evdev->client_lock);
> + list_del_rcu(&client->node);
OK, assuming that clients->node is only ever added to the evdev->client_list.
Which does appear to be the case.
> + spin_unlock(&evdev->client_lock);
> + synchronize_rcu();
> +}
> +
> +static void evdev_hangup(struct evdev *evdev)
> +{
> + struct evdev_client *client;
> +
> + wake_up_interruptible(&evdev->wait);
> +
> + spin_lock(&evdev->client_lock);
> + list_for_each_entry(client, &evdev->client_list, node)
OK, traversing ->client_list while holding ->client_lock.
> + kill_fasync(&client->fasync, SIGIO, POLL_HUP);
The kill_fasync() function in turn calls __kill_fasync(), but while
read-holding fasync_lock. But bails if the file pointer is already NULL.
Oddly enough, __kill_fasync() has a debug check on a magic-number field
-- not sure why this isn't conditioned on a debug build or some such.
Maybe someone is chasing problems with this function? And maybe that
is why we have a patch to add locking? ;-)
The __kill_fasync() function in turn calls send_sigio(), which
read-acquires both the fown_struct lock and tasklist_lock, then does
send_sigio_to_task() for each thread in the task.
The send_sigio_to_task() function invokes group_send_sig_info(), which
calls lock_task_sighand(), which expects one of its callers to have
done an rcu_read_lock(). But I believe that read-holding tasklist_lock
also suffices. Oleg, could you please either confirm or educate? @@@
(I think this is OK, just been awhile since I dug through the signal
code.)
> + spin_unlock(&evdev->client_lock);
> +}
> +
> 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)
OK, ->grab stable because we hold ->mutex.
> + 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)
!!! We don't hold ->mutex, so ->exist can change without notice.
Is this really safe??? Do we need to capture the value of ->exist
in a local variable while we hold the lock above?
> @@ -126,47 +202,53 @@ static int evdev_release(struct inode *i
> return 0;
> }
>
> -static int evdev_open(struct inode *inode, struct file *file)
> +static int evdev_new_client(struct evdev *evdev, struct file *file)
> {
> struct evdev_client *client;
> - struct evdev *evdev;
> - int i = iminor(inode) - EVDEV_MINOR_BASE;
> int error;
>
> - if (i >= EVDEV_MINORS)
> - return -ENODEV;
> -
> - evdev = evdev_table[i];
> -
> if (!evdev || !evdev->exist)
!!! We don't hold ->mutex, so this is racy. The value of ->exist might
well go to zero immediately after we check it. We don't appear to
be in an RCU read-side critical section. Why is this safe?
> return -ENODEV;
>
> - get_device(&evdev->dev);
> -
> client = kzalloc(sizeof(struct evdev_client), GFP_KERNEL);
> - if (!client) {
> - error = -ENOMEM;
> - goto err_put_evdev;
> - }
> + if (!client)
> + return -ENOMEM;
>
> + 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) {
!!! We don't hold ->mutex, so this is racy. The value of ->exist might
well go to zero immediately after we check it. We don't appear to
be in an RCU read-side critical section. Why is this safe?
> error = input_open_device(&evdev->handle);
> - if (error)
> - goto err_free_client;
> + if (error) {
> + evdev_detach_client(evdev, client);
> + kfree(client);
> + return error;
> + }
> }
>
> + get_device(&evdev->dev);
> file->private_data = client;
> return 0;
> +}
>
> - err_free_client:
> - list_del(&client->node);
> - kfree(client);
> - err_put_evdev:
> - put_device(&evdev->dev);
> - return error;
> +static int evdev_open(struct inode *inode, struct file *file)
> +{
> + int i = iminor(inode) - EVDEV_MINOR_BASE;
> + int retval;
> +
> + if (i >= EVDEV_MINORS)
> + return -ENODEV;
> +
> + retval = mutex_lock_interruptible(&evdev_table_mutex);
> + if (retval)
> + return retval;
> +
> + retval = evdev_new_client(evdev_table[i], file);
> +
> + mutex_unlock(&evdev_table_mutex);
> +
> + return retval;
> }
>
> #ifdef CONFIG_COMPAT
> @@ -272,26 +354,56 @@ static ssize_t evdev_write(struct file *
> 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) {
We hold ->mutex, so this check is stable. OK!
> + retval = -ENODEV;
> + goto out;
> + }
>
> while (retval < count) {
>
> - if (evdev_event_from_user(buffer + retval, &event))
> - return -EFAULT;
> + 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 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())
> @@ -308,14 +420,12 @@ static ssize_t evdev_read(struct file *f
> if (!evdev->exist)
!!! We don't hold ->mutex, so this is racy. The value of ->exist might
well go to zero immediately after we check it. We don't appear to
be in an RCU read-side critical section. Why is this safe?
> 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();
> }
>
> @@ -410,8 +520,8 @@ 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;
> @@ -422,9 +532,6 @@ static long evdev_ioctl_handler(struct f
> int i, t, u, v;
> int error;
>
> - if (!evdev->exist)
> - return -ENODEV;
> -
> switch (cmd) {
>
> case EVIOCGVERSION:
> @@ -497,20 +604,10 @@ static long evdev_ioctl_handler(struct f
> 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;
> - }
> + if (p)
> + return evdev_grab(evdev, client);
> + else
> + return evdev_ungrab(evdev, client);
>
> default:
>
> @@ -604,6 +701,29 @@ static long evdev_ioctl_handler(struct f
> 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) {
We hold ->mutex, so this check is stable. OK!
> + 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);
> @@ -631,47 +751,81 @@ static const struct file_operations evde
> .flush = evdev_flush
> };
>
> -static int evdev_connect(struct input_handler *handler, struct input_dev *dev,
> - const struct input_device_id *id)
> +static int evdev_install_chrdev(struct evdev *evdev)
> {
> - struct evdev *evdev;
> int minor;
> - int error;
> + int retval;
> +
> + retval = mutex_lock_interruptible(&evdev_table_mutex);
> + if (retval)
> + return retval;
>
> for (minor = 0; minor < EVDEV_MINORS && evdev_table[minor]; minor++);
> if (minor == EVDEV_MINORS) {
> printk(KERN_ERR "evdev: no more free evdev devices\n");
> - return -ENFILE;
> + retval = -ENFILE;
> + goto out;
> }
>
> + snprintf(evdev->name, sizeof(evdev->name), "event%d", minor);
> + evdev->minor = minor;
> + strlcpy(evdev->dev.bus_id, evdev->name, sizeof(evdev->dev.bus_id));
> + evdev->dev.devt = MKDEV(INPUT_MAJOR, EVDEV_MINOR_BASE + minor);
> +
> + evdev_table[minor] = evdev;
> +
> + out:
> + mutex_unlock(&evdev_table_mutex);
> + return retval;
> +}
> +
> +static void evdev_remove_chrdev(struct evdev *evdev)
> +{
> + mutex_lock(&evdev_table_mutex);
> + evdev_table[evdev->minor] = NULL;
> + mutex_unlock(&evdev_table_mutex);
> +}
> +
> +static void evdev_mark_dead(struct evdev *evdev)
> +{
> + mutex_lock(&evdev->mutex);
> + evdev->exist = 0;
We hold ->mutex, so this assignment is safe.
> + mutex_unlock(&evdev->mutex);
> +}
> +
> +static int evdev_connect(struct input_handler *handler, struct input_dev *dev,
> + const struct input_device_id *id)
> +{
> + struct evdev *evdev;
> + int error;
> +
> evdev = kzalloc(sizeof(struct evdev), GFP_KERNEL);
> if (!evdev)
> return -ENOMEM;
Initialization -- presumably no one can see the structure yet, so no
worries about concurrency.
>
> INIT_LIST_HEAD(&evdev->client_list);
> + spin_lock_init(&evdev->client_lock);
> + mutex_init(&evdev->mutex);
> init_waitqueue_head(&evdev->wait);
>
> 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);
> 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 = evdev_install_chrdev(evdev);
>From here on, we are globally accessible!!!
!!! Is it going to be OK if a user accesses the character device before
the following initialization completes?
> + if (error)
> + goto err_free_evdev;
>
> error = device_add(&evdev->dev);
> if (error)
> - goto err_free_evdev;
> + goto err_remove_chrdev;
>
> error = input_register_handle(&evdev->handle);
> if (error)
> @@ -681,6 +835,10 @@ static int evdev_connect(struct input_ha
>
> err_delete_evdev:
> device_del(&evdev->dev);
> + err_remove_chrdev:
> + evdev_remove_chrdev(evdev);
> + evdev_mark_dead(evdev);
> + evdev_hangup(evdev);
> err_free_evdev:
> put_device(&evdev->dev);
> return error;
> @@ -689,19 +847,18 @@ static int evdev_connect(struct input_ha
> static void evdev_disconnect(struct input_handle *handle)
> {
> struct evdev *evdev = handle->private;
> - struct evdev_client *client;
> +
> + evdev_remove_chrdev(evdev);
>
> input_unregister_handle(handle);
> device_del(&evdev->dev);
>
> - evdev->exist = 0;
> + evdev_mark_dead(evdev);
> + evdev_hangup(evdev);
>
> if (evdev->open) {
> input_flush_device(handle, NULL);
> input_close_device(handle);
> - wake_up_interruptible(&evdev->wait);
> - list_for_each_entry(client, &evdev->client_list, node)
> - kill_fasync(&client->fasync, SIGIO, POLL_HUP);
> }
>
> put_device(&evdev->dev);
> _
>
> Patches currently in -mm which might be from dtor@xxxxxxxxxxxxx are
>
> git-input.patch
> convert-input-core-to-struct-device.patch
> add-locking-to-evdev.patch
>
----- End forwarded message -----
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