OSCL-LXR linux-6.0.1/​drivers/​input/​evdev.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Event char devices, giving access to raw input device events.
  *
  * Copyright (c) 1999-2002 Vojtech Pavlik
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #define EVDEV_MINOR_BASE    64
 #define EVDEV_MINORS        32
 #define EVDEV_MIN_BUFFER_SIZE   64U
 #define EVDEV_BUF_PACKETS   8
 
 #include <linux/poll.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/input/mt.h>
 #include <linux/major.h>
 #include <linux/device.h>
 #include <linux/cdev.h>
 #include "input-compat.h"
 
 struct evdev {
     int open;
     struct input_handle handle;
     struct evdev_client __rcu *grab;
     struct list_head client_list;
     spinlock_t client_lock; /* protects client_list */
     struct mutex mutex;
     struct device dev;
     struct cdev cdev;
     bool exist;
 };
 
 struct evdev_client {
     unsigned int head;
     unsigned int tail;
     unsigned int packet_head; /* [future] position of the first element of next packet */
     spinlock_t buffer_lock; /* protects access to buffer, head and tail */
     wait_queue_head_t wait;
     struct fasync_struct *fasync;
     struct evdev *evdev;
     struct list_head node;
     enum input_clock_type clk_type;
     bool revoked;
     unsigned long *evmasks[EV_CNT];
     unsigned int bufsize;
     struct input_event buffer[];
 };
 
 static size_t evdev_get_mask_cnt(unsigned int type)
 {
     static const size_t counts[EV_CNT] = {
         /* EV_SYN==0 is EV_CNT, _not_ SYN_CNT, see EVIOCGBIT */
         [EV_SYN]    = EV_CNT,
         [EV_KEY]    = KEY_CNT,
         [EV_REL]    = REL_CNT,
         [EV_ABS]    = ABS_CNT,
         [EV_MSC]    = MSC_CNT,
         [EV_SW]     = SW_CNT,
         [EV_LED]    = LED_CNT,
         [EV_SND]    = SND_CNT,
         [EV_FF]     = FF_CNT,
     };
 
     return (type < EV_CNT) ? counts[type] : 0;
 }
 
 /* requires the buffer lock to be held */
 static bool __evdev_is_filtered(struct evdev_client *client,
                 unsigned int type,
                 unsigned int code)
 {
     unsigned long *mask;
     size_t cnt;
 
     /* EV_SYN and unknown codes are never filtered */
     if (type == EV_SYN || type >= EV_CNT)
         return false;
 
     /* first test whether the type is filtered */
     mask = client->evmasks[0];
     if (mask && !test_bit(type, mask))
         return true;
 
     /* unknown values are never filtered */
     cnt = evdev_get_mask_cnt(type);
     if (!cnt || code >= cnt)
         return false;
 
     mask = client->evmasks[type];
     return mask && !test_bit(code, mask);
 }
 
 /* flush queued events of type @type, caller must hold client->buffer_lock */
 static void __evdev_flush_queue(struct evdev_client *client, unsigned int type)
 {
     unsigned int i, head, num;
     unsigned int mask = client->bufsize - 1;
     bool is_report;
     struct input_event *ev;
 
     BUG_ON(type == EV_SYN);
 
     head = client->tail;
     client->packet_head = client->tail;
 
     /* init to 1 so a leading SYN_REPORT will not be dropped */
     num = 1;
 
     for (i = client->tail; i != client->head; i = (i + 1) & mask) {
         ev = &client->buffer[i];
         is_report = ev->type == EV_SYN && ev->code == SYN_REPORT;
 
         if (ev->type == type) {
             /* drop matched entry */
             continue;
         } else if (is_report && !num) {
             /* drop empty SYN_REPORT groups */
             continue;
         } else if (head != i) {
             /* move entry to fill the gap */
             client->buffer[head] = *ev;
         }
 
         num++;
         head = (head + 1) & mask;
 
         if (is_report) {
             num = 0;
             client->packet_head = head;
         }
     }
 
     client->head = head;
 }
 
 static void __evdev_queue_syn_dropped(struct evdev_client *client)
 {
     ktime_t *ev_time = input_get_timestamp(client->evdev->handle.dev);
     struct timespec64 ts = ktime_to_timespec64(ev_time[client->clk_type]);
     struct input_event ev;
 
     ev.input_event_sec = ts.tv_sec;
     ev.input_event_usec = ts.tv_nsec / NSEC_PER_USEC;
     ev.type = EV_SYN;
     ev.code = SYN_DROPPED;
     ev.value = 0;
 
     client->buffer[client->head++] = ev;
     client->head &= client->bufsize - 1;
 
     if (unlikely(client->head == client->tail)) {
         /* drop queue but keep our SYN_DROPPED event */
         client->tail = (client->head - 1) & (client->bufsize - 1);
         client->packet_head = client->tail;
     }
 }
 
 static void evdev_queue_syn_dropped(struct evdev_client *client)
 {
     unsigned long flags;
 
     spin_lock_irqsave(&client->buffer_lock, flags);
     __evdev_queue_syn_dropped(client);
     spin_unlock_irqrestore(&client->buffer_lock, flags);
 }
 
 static int evdev_set_clk_type(struct evdev_client *client, unsigned int clkid)
 {
     unsigned long flags;
     enum input_clock_type clk_type;
 
     switch (clkid) {
 
     case CLOCK_REALTIME:
         clk_type = INPUT_CLK_REAL;
         break;
     case CLOCK_MONOTONIC:
         clk_type = INPUT_CLK_MONO;
         break;
     case CLOCK_BOOTTIME:
         clk_type = INPUT_CLK_BOOT;
         break;
     default:
         return -EINVAL;
     }
 
     if (client->clk_type != clk_type) {
         client->clk_type = clk_type;
 
         /*
          * Flush pending events and queue SYN_DROPPED event,
          * but only if the queue is not empty.
          */
         spin_lock_irqsave(&client->buffer_lock, flags);
 
         if (client->head != client->tail) {
             client->packet_head = client->head = client->tail;
             __evdev_queue_syn_dropped(client);
         }
 
         spin_unlock_irqrestore(&client->buffer_lock, flags);
     }
 
     return 0;
 }
 
 static void __pass_event(struct evdev_client *client,
              const struct input_event *event)
 {
     client->buffer[client->head++] = *event;
     client->head &= client->bufsize - 1;
 
     if (unlikely(client->head == client->tail)) {
         /*
          * This effectively "drops" all unconsumed events, leaving
          * EV_SYN/SYN_DROPPED plus the newest event in the queue.
          */
         client->tail = (client->head - 2) & (client->bufsize - 1);
 
         client->buffer[client->tail] = (struct input_event) {
             .input_event_sec = event->input_event_sec,
             .input_event_usec = event->input_event_usec,
             .type = EV_SYN,
             .code = SYN_DROPPED,
             .value = 0,
         };
 
         client->packet_head = client->tail;
     }
 
     if (event->type == EV_SYN && event->code == SYN_REPORT) {
         client->packet_head = client->head;
         kill_fasync(&client->fasync, SIGIO, POLL_IN);
     }
 }
 
 static void evdev_pass_values(struct evdev_client *client,
             const struct input_value *vals, unsigned int count,
             ktime_t *ev_time)
 {
     const struct input_value *v;
     struct input_event event;
     struct timespec64 ts;
     bool wakeup = false;
 
     if (client->revoked)
         return;
 
     ts = ktime_to_timespec64(ev_time[client->clk_type]);
     event.input_event_sec = ts.tv_sec;
     event.input_event_usec = ts.tv_nsec / NSEC_PER_USEC;
 
     /* Interrupts are disabled, just acquire the lock. */
     spin_lock(&client->buffer_lock);
 
     for (v = vals; v != vals + count; v++) {
         if (__evdev_is_filtered(client, v->type, v->code))
             continue;
 
         if (v->type == EV_SYN && v->code == SYN_REPORT) {
             /* drop empty SYN_REPORT */
             if (client->packet_head == client->head)
                 continue;
 
             wakeup = true;
         }
 
         event.type = v->type;
         event.code = v->code;
         event.value = v->value;
         __pass_event(client, &event);
     }
 
     spin_unlock(&client->buffer_lock);
 
     if (wakeup)
         wake_up_interruptible_poll(&client->wait,
             EPOLLIN | EPOLLOUT | EPOLLRDNORM | EPOLLWRNORM);
 }
 
 /*
  * Pass incoming events to all connected clients.
  */
 static void evdev_events(struct input_handle *handle,
              const struct input_value *vals, unsigned int count)
 {
     struct evdev *evdev = handle->private;
     struct evdev_client *client;
     ktime_t *ev_time = input_get_timestamp(handle->dev);
 
     rcu_read_lock();
 
     client = rcu_dereference(evdev->grab);
 
     if (client)
         evdev_pass_values(client, vals, count, ev_time);
     else
         list_for_each_entry_rcu(client, &evdev->client_list, node)
             evdev_pass_values(client, vals, count, ev_time);
 
     rcu_read_unlock();
 }
 
 /*
  * Pass incoming event to all connected clients.
  */
 static void evdev_event(struct input_handle *handle,
             unsigned int type, unsigned int code, int value)
 {
     struct input_value vals[] = { { type, code, value } };
 
     evdev_events(handle, vals, 1);
 }
 
 static int evdev_fasync(int fd, struct file *file, int on)
 {
     struct evdev_client *client = file->private_data;
 
     return fasync_helper(fd, file, on, &client->fasync);
 }
 
 static void evdev_free(struct device *dev)
 {
     struct evdev *evdev = container_of(dev, struct evdev, dev);
 
     input_put_device(evdev->handle.dev);
     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);
 
     return 0;
 }
 
 static int evdev_ungrab(struct evdev *evdev, struct evdev_client *client)
 {
     struct evdev_client *grab = rcu_dereference_protected(evdev->grab,
                     lockdep_is_held(&evdev->mutex));
 
     if (grab != client)
         return  -EINVAL;
 
     rcu_assign_pointer(evdev->grab, NULL);
     synchronize_rcu();
     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);
 }
 
 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_rcu();
 }
 
 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);
         if (retval)
             evdev->open--;
     }
 
     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);
         wake_up_interruptible_poll(&client->wait, EPOLLHUP | EPOLLERR);
     }
     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;
     unsigned int i;
 
     mutex_lock(&evdev->mutex);
 
     if (evdev->exist && !client->revoked)
         input_flush_device(&evdev->handle, file);
 
     evdev_ungrab(evdev, client);
     mutex_unlock(&evdev->mutex);
 
     evdev_detach_client(evdev, client);
 
     for (i = 0; i < EV_CNT; ++i)
         bitmap_free(client->evmasks[i]);
 
     kvfree(client);
 
     evdev_close_device(evdev);
 
     return 0;
 }
 
 static unsigned int evdev_compute_buffer_size(struct input_dev *dev)
 {
     unsigned int n_events =
         max(dev->hint_events_per_packet * EVDEV_BUF_PACKETS,
             EVDEV_MIN_BUFFER_SIZE);
 
     return roundup_pow_of_two(n_events);
 }
 
 static int evdev_open(struct inode *inode, struct file *file)
 {
     struct evdev *evdev = container_of(inode->i_cdev, struct evdev, cdev);
     unsigned int bufsize = evdev_compute_buffer_size(evdev->handle.dev);
     struct evdev_client *client;
     int error;
 
     client = kvzalloc(struct_size(client, buffer, bufsize), GFP_KERNEL);
     if (!client)
         return -ENOMEM;
 
     init_waitqueue_head(&client->wait);
     client->bufsize = bufsize;
     spin_lock_init(&client->buffer_lock);
     client->evdev = evdev;
     evdev_attach_client(evdev, client);
 
     error = evdev_open_device(evdev);
     if (error)
         goto err_free_client;
 
     file->private_data = client;
     stream_open(inode, file);
 
     return 0;
 
  err_free_client:
     evdev_detach_client(evdev, client);
     kvfree(client);
     return error;
 }
 
 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;
 
     if (count != 0 && count < input_event_size())
         return -EINVAL;
 
     retval = mutex_lock_interruptible(&evdev->mutex);
     if (retval)
         return retval;
 
     if (!evdev->exist || client->revoked) {
         retval = -ENODEV;
         goto out;
     }
 
     while (retval + input_event_size() <= count) {
 
         if (input_event_from_user(buffer + retval, &event)) {
             retval = -EFAULT;
             goto out;
         }
         retval += input_event_size();
 
         input_inject_event(&evdev->handle,
                    event.type, event.code, event.value);
         cond_resched();
     }
 
  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->packet_head != client->tail;
     if (have_event) {
         *event = client->buffer[client->tail++];
         client->tail &= client->bufsize - 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;
     size_t read = 0;
     int error;
 
     if (count != 0 && count < input_event_size())
         return -EINVAL;
 
     for (;;) {
         if (!evdev->exist || client->revoked)
             return -ENODEV;
 
         if (client->packet_head == client->tail &&
             (file->f_flags & O_NONBLOCK))
             return -EAGAIN;
 
         /*
          * count == 0 is special - no IO is done but we check
          * for error conditions (see above).
          */
         if (count == 0)
             break;
 
         while (read + input_event_size() <= count &&
                evdev_fetch_next_event(client, &event)) {
 
             if (input_event_to_user(buffer + read, &event))
                 return -EFAULT;
 
             read += input_event_size();
         }
 
         if (read)
             break;
 
         if (!(file->f_flags & O_NONBLOCK)) {
             error = wait_event_interruptible(client->wait,
                     client->packet_head != client->tail ||
                     !evdev->exist || client->revoked);
             if (error)
                 return error;
         }
     }
 
     return read;
 }
 
 /* No kernel lock - fine */
 static __poll_t evdev_poll(struct file *file, poll_table *wait)
 {
     struct evdev_client *client = file->private_data;
     struct evdev *evdev = client->evdev;
     __poll_t mask;
 
     poll_wait(file, &client->wait, wait);
 
     if (evdev->exist && !client->revoked)
         mask = EPOLLOUT | EPOLLWRNORM;
     else
         mask = EPOLLHUP | EPOLLERR;
 
     if (client->packet_head != client->tail)
         mask |= EPOLLIN | EPOLLRDNORM;
 
     return mask;
 }
 
 #ifdef CONFIG_COMPAT
 
 #define BITS_PER_LONG_COMPAT (sizeof(compat_long_t) * 8)
 #define BITS_TO_LONGS_COMPAT(x) ((((x) - 1) / BITS_PER_LONG_COMPAT) + 1)
 
 #ifdef __BIG_ENDIAN
 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
             unsigned int maxlen, void __user *p, int compat)
 {
     int len, i;
 
     if (compat) {
         len = BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t);
         if (len > maxlen)
             len = maxlen;
 
         for (i = 0; i < len / sizeof(compat_long_t); i++)
             if (copy_to_user((compat_long_t __user *) p + i,
                      (compat_long_t *) bits +
                         i + 1 - ((i % 2) << 1),
                      sizeof(compat_long_t)))
                 return -EFAULT;
     } else {
         len = BITS_TO_LONGS(maxbit) * sizeof(long);
         if (len > maxlen)
             len = maxlen;
 
         if (copy_to_user(p, bits, len))
             return -EFAULT;
     }
 
     return len;
 }
 
 static int bits_from_user(unsigned long *bits, unsigned int maxbit,
               unsigned int maxlen, const void __user *p, int compat)
 {
     int len, i;
 
     if (compat) {
         if (maxlen % sizeof(compat_long_t))
             return -EINVAL;
 
         len = BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t);
         if (len > maxlen)
             len = maxlen;
 
         for (i = 0; i < len / sizeof(compat_long_t); i++)
             if (copy_from_user((compat_long_t *) bits +
                         i + 1 - ((i % 2) << 1),
                        (compat_long_t __user *) p + i,
                        sizeof(compat_long_t)))
                 return -EFAULT;
         if (i % 2)
             *((compat_long_t *) bits + i - 1) = 0;
 
     } else {
         if (maxlen % sizeof(long))
             return -EINVAL;
 
         len = BITS_TO_LONGS(maxbit) * sizeof(long);
         if (len > maxlen)
             len = maxlen;
 
         if (copy_from_user(bits, p, len))
             return -EFAULT;
     }
 
     return len;
 }
 
 #else
 
 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
             unsigned int maxlen, void __user *p, int compat)
 {
     int len = compat ?
             BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t) :
             BITS_TO_LONGS(maxbit) * sizeof(long);
 
     if (len > maxlen)
         len = maxlen;
 
     return copy_to_user(p, bits, len) ? -EFAULT : len;
 }
 
 static int bits_from_user(unsigned long *bits, unsigned int maxbit,
               unsigned int maxlen, const void __user *p, int compat)
 {
     size_t chunk_size = compat ? sizeof(compat_long_t) : sizeof(long);
     int len;
 
     if (maxlen % chunk_size)
         return -EINVAL;
 
     len = compat ? BITS_TO_LONGS_COMPAT(maxbit) : BITS_TO_LONGS(maxbit);
     len *= chunk_size;
     if (len > maxlen)
         len = maxlen;
 
     return copy_from_user(bits, p, len) ? -EFAULT : len;
 }
 
 #endif /* __BIG_ENDIAN */
 
 #else
 
 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
             unsigned int maxlen, void __user *p, int compat)
 {
     int len = BITS_TO_LONGS(maxbit) * sizeof(long);
 
     if (len > maxlen)
         len = maxlen;
 
     return copy_to_user(p, bits, len) ? -EFAULT : len;
 }
 
 static int bits_from_user(unsigned long *bits, unsigned int maxbit,
               unsigned int maxlen, const void __user *p, int compat)
 {
     int len;
 
     if (maxlen % sizeof(long))
         return -EINVAL;
 
     len = BITS_TO_LONGS(maxbit) * sizeof(long);
     if (len > maxlen)
         len = maxlen;
 
     return copy_from_user(bits, p, len) ? -EFAULT : len;
 }
 
 #endif /* CONFIG_COMPAT */
 
 static int str_to_user(const char *str, unsigned int maxlen, void __user *p)
 {
     int len;
 
     if (!str)
         return -ENOENT;
 
     len = strlen(str) + 1;
     if (len > maxlen)
         len = maxlen;
 
     return copy_to_user(p, str, len) ? -EFAULT : len;
 }
 
 static int handle_eviocgbit(struct input_dev *dev,
                 unsigned int type, unsigned int size,
                 void __user *p, int compat_mode)
 {
     unsigned long *bits;
     int len;
 
     switch (type) {
 
     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, size, p, compat_mode);
 }
 
 static int evdev_handle_get_keycode(struct input_dev *dev, void __user *p)
 {
     struct input_keymap_entry ke = {
         .len    = sizeof(unsigned int),
         .flags  = 0,
     };
     int __user *ip = (int __user *)p;
     int error;
 
     /* legacy case */
     if (copy_from_user(ke.scancode, p, sizeof(unsigned int)))
         return -EFAULT;
 
     error = input_get_keycode(dev, &ke);
     if (error)
         return error;
 
     if (put_user(ke.keycode, ip + 1))
         return -EFAULT;
 
     return 0;
 }
 
 static int evdev_handle_get_keycode_v2(struct input_dev *dev, void __user *p)
 {
     struct input_keymap_entry ke;
     int error;
 
     if (copy_from_user(&ke, p, sizeof(ke)))
         return -EFAULT;
 
     error = input_get_keycode(dev, &ke);
     if (error)
         return error;
 
     if (copy_to_user(p, &ke, sizeof(ke)))
         return -EFAULT;
 
     return 0;
 }
 
 static int evdev_handle_set_keycode(struct input_dev *dev, void __user *p)
 {
     struct input_keymap_entry ke = {
         .len    = sizeof(unsigned int),
         .flags  = 0,
     };
     int __user *ip = (int __user *)p;
 
     if (copy_from_user(ke.scancode, p, sizeof(unsigned int)))
         return -EFAULT;
 
     if (get_user(ke.keycode, ip + 1))
         return -EFAULT;
 
     return input_set_keycode(dev, &ke);
 }
 
 static int evdev_handle_set_keycode_v2(struct input_dev *dev, void __user *p)
 {
     struct input_keymap_entry ke;
 
     if (copy_from_user(&ke, p, sizeof(ke)))
         return -EFAULT;
 
     if (ke.len > sizeof(ke.scancode))
         return -EINVAL;
 
     return input_set_keycode(dev, &ke);
 }
 
 /*
  * If we transfer state to the user, we should flush all pending events
  * of the same type from the client's queue. Otherwise, they might end up
  * with duplicate events, which can screw up client's state tracking.
  * If bits_to_user fails after flushing the queue, we queue a SYN_DROPPED
  * event so user-space will notice missing events.
  *
  * LOCKING:
  * We need to take event_lock before buffer_lock to avoid dead-locks. But we
  * need the even_lock only to guarantee consistent state. We can safely release
  * it while flushing the queue. This allows input-core to handle filters while
  * we flush the queue.
  */
 static int evdev_handle_get_val(struct evdev_client *client,
                 struct input_dev *dev, unsigned int type,
                 unsigned long *bits, unsigned int maxbit,
                 unsigned int maxlen, void __user *p,
                 int compat)
 {
     int ret;
     unsigned long *mem;
 
     mem = bitmap_alloc(maxbit, GFP_KERNEL);
     if (!mem)
         return -ENOMEM;
 
     spin_lock_irq(&dev->event_lock);
     spin_lock(&client->buffer_lock);
 
     bitmap_copy(mem, bits, maxbit);
 
     spin_unlock(&dev->event_lock);
 
     __evdev_flush_queue(client, type);
 
     spin_unlock_irq(&client->buffer_lock);
 
     ret = bits_to_user(mem, maxbit, maxlen, p, compat);
     if (ret < 0)
         evdev_queue_syn_dropped(client);
 
     bitmap_free(mem);
 
     return ret;
 }
 
 static int evdev_handle_mt_request(struct input_dev *dev,
                    unsigned int size,
                    int __user *ip)
 {
     const struct input_mt *mt = dev->mt;
     unsigned int code;
     int max_slots;
     int i;
 
     if (get_user(code, &ip[0]))
         return -EFAULT;
     if (!mt || !input_is_mt_value(code))
         return -EINVAL;
 
     max_slots = (size - sizeof(__u32)) / sizeof(__s32);
     for (i = 0; i < mt->num_slots && i < max_slots; i++) {
         int value = input_mt_get_value(&mt->slots[i], code);
         if (put_user(value, &ip[1 + i]))
             return -EFAULT;
     }
 
     return 0;
 }
 
 static int evdev_revoke(struct evdev *evdev, struct evdev_client *client,
             struct file *file)
 {
     client->revoked = true;
     evdev_ungrab(evdev, client);
     input_flush_device(&evdev->handle, file);
     wake_up_interruptible_poll(&client->wait, EPOLLHUP | EPOLLERR);
 
     return 0;
 }
 
 /* must be called with evdev-mutex held */
 static int evdev_set_mask(struct evdev_client *client,
               unsigned int type,
               const void __user *codes,
               u32 codes_size,
               int compat)
 {
     unsigned long flags, *mask, *oldmask;
     size_t cnt;
     int error;
 
     /* we allow unknown types and 'codes_size > size' for forward-compat */
     cnt = evdev_get_mask_cnt(type);
     if (!cnt)
         return 0;
 
     mask = bitmap_zalloc(cnt, GFP_KERNEL);
     if (!mask)
         return -ENOMEM;
 
     error = bits_from_user(mask, cnt - 1, codes_size, codes, compat);
     if (error < 0) {
         bitmap_free(mask);
         return error;
     }
 
     spin_lock_irqsave(&client->buffer_lock, flags);
     oldmask = client->evmasks[type];
     client->evmasks[type] = mask;
     spin_unlock_irqrestore(&client->buffer_lock, flags);
 
     bitmap_free(oldmask);
 
     return 0;
 }
 
 /* must be called with evdev-mutex held */
 static int evdev_get_mask(struct evdev_client *client,
               unsigned int type,
               void __user *codes,
               u32 codes_size,
               int compat)
 {
     unsigned long *mask;
     size_t cnt, size, xfer_size;
     int i;
     int error;
 
     /* we allow unknown types and 'codes_size > size' for forward-compat */
     cnt = evdev_get_mask_cnt(type);
     size = sizeof(unsigned long) * BITS_TO_LONGS(cnt);
     xfer_size = min_t(size_t, codes_size, size);
 
     if (cnt > 0) {
         mask = client->evmasks[type];
         if (mask) {
             error = bits_to_user(mask, cnt - 1,
                          xfer_size, codes, compat);
             if (error < 0)
                 return error;
         } else {
             /* fake mask with all bits set */
             for (i = 0; i < xfer_size; i++)
                 if (put_user(0xffU, (u8 __user *)codes + i))
                     return -EFAULT;
         }
     }
 
     if (xfer_size < codes_size)
         if (clear_user(codes + xfer_size, codes_size - xfer_size))
             return -EFAULT;
 
     return 0;
 }
 
 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;
     struct input_dev *dev = evdev->handle.dev;
     struct input_absinfo abs;
     struct input_mask mask;
     struct ff_effect effect;
     int __user *ip = (int __user *)p;
     unsigned int i, t, u, v;
     unsigned int size;
     int error;
 
     /* First we check for fixed-length commands */
     switch (cmd) {
 
     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 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;
 
         input_inject_event(&evdev->handle, EV_REP, REP_DELAY, u);
         input_inject_event(&evdev->handle, EV_REP, REP_PERIOD, v);
 
         return 0;
 
     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)
             return evdev_grab(evdev, client);
         else
             return evdev_ungrab(evdev, client);
 
     case EVIOCREVOKE:
         if (p)
             return -EINVAL;
         else
             return evdev_revoke(evdev, client, file);
 
     case EVIOCGMASK: {
         void __user *codes_ptr;
 
         if (copy_from_user(&mask, p, sizeof(mask)))
             return -EFAULT;
 
         codes_ptr = (void __user *)(unsigned long)mask.codes_ptr;
         return evdev_get_mask(client,
                       mask.type, codes_ptr, mask.codes_size,
                       compat_mode);
     }
 
     case EVIOCSMASK: {
         const void __user *codes_ptr;
 
         if (copy_from_user(&mask, p, sizeof(mask)))
             return -EFAULT;
 
         codes_ptr = (const void __user *)(unsigned long)mask.codes_ptr;
         return evdev_set_mask(client,
                       mask.type, codes_ptr, mask.codes_size,
                       compat_mode);
     }
 
     case EVIOCSCLOCKID:
         if (copy_from_user(&i, p, sizeof(unsigned int)))
             return -EFAULT;
 
         return evdev_set_clk_type(client, i);
 
     case EVIOCGKEYCODE:
         return evdev_handle_get_keycode(dev, p);
 
     case EVIOCSKEYCODE:
         return evdev_handle_set_keycode(dev, p);
 
     case EVIOCGKEYCODE_V2:
         return evdev_handle_get_keycode_v2(dev, p);
 
     case EVIOCSKEYCODE_V2:
         return evdev_handle_set_keycode_v2(dev, p);
     }
 
     size = _IOC_SIZE(cmd);
 
     /* Now check variable-length commands */
 #define EVIOC_MASK_SIZE(nr) ((nr) & ~(_IOC_SIZEMASK << _IOC_SIZESHIFT))
     switch (EVIOC_MASK_SIZE(cmd)) {
 
     case EVIOCGPROP(0):
         return bits_to_user(dev->propbit, INPUT_PROP_MAX,
                     size, p, compat_mode);
 
     case EVIOCGMTSLOTS(0):
         return evdev_handle_mt_request(dev, size, ip);
 
     case EVIOCGKEY(0):
         return evdev_handle_get_val(client, dev, EV_KEY, dev->key,
                         KEY_MAX, size, p, compat_mode);
 
     case EVIOCGLED(0):
         return evdev_handle_get_val(client, dev, EV_LED, dev->led,
                         LED_MAX, size, p, compat_mode);
 
     case EVIOCGSND(0):
         return evdev_handle_get_val(client, dev, EV_SND, dev->snd,
                         SND_MAX, size, p, compat_mode);
 
     case EVIOCGSW(0):
         return evdev_handle_get_val(client, dev, EV_SW, dev->sw,
                         SW_MAX, size, p, compat_mode);
 
     case EVIOCGNAME(0):
         return str_to_user(dev->name, size, p);
 
     case EVIOCGPHYS(0):
         return str_to_user(dev->phys, size, p);
 
     case EVIOCGUNIQ(0):
         return str_to_user(dev->uniq, size, p);
 
     case EVIOC_MASK_SIZE(EVIOCSFF):
         if (input_ff_effect_from_user(p, size, &effect))
             return -EFAULT;
 
         error = input_ff_upload(dev, &effect, file);
         if (error)
             return error;
 
         if (put_user(effect.id, &(((struct ff_effect __user *)p)->id)))
             return -EFAULT;
 
         return 0;
     }
 
     /* Multi-number variable-length handlers */
     if (_IOC_TYPE(cmd) != 'E')
         return -EINVAL;
 
     if (_IOC_DIR(cmd) == _IOC_READ) {
 
         if ((_IOC_NR(cmd) & ~EV_MAX) == _IOC_NR(EVIOCGBIT(0, 0)))
             return handle_eviocgbit(dev,
                         _IOC_NR(cmd) & EV_MAX, size,
                         p, compat_mode);
 
         if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCGABS(0))) {
 
             if (!dev->absinfo)
                 return -EINVAL;
 
             t = _IOC_NR(cmd) & ABS_MAX;
             abs = dev->absinfo[t];
 
             if (copy_to_user(p, &abs, min_t(size_t,
                     size, sizeof(struct input_absinfo))))
                 return -EFAULT;
 
             return 0;
         }
     }
 
     if (_IOC_DIR(cmd) == _IOC_WRITE) {
 
         if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCSABS(0))) {
 
             if (!dev->absinfo)
                 return -EINVAL;
 
             t = _IOC_NR(cmd) & ABS_MAX;
 
             if (copy_from_user(&abs, p, min_t(size_t,
                     size, sizeof(struct input_absinfo))))
                 return -EFAULT;
 
             if (size < sizeof(struct input_absinfo))
                 abs.resolution = 0;
 
             /* We can't change number of reserved MT slots */
             if (t == ABS_MT_SLOT)
                 return -EINVAL;
 
             /*
              * Take event lock to ensure that we are not
              * changing device parameters in the middle
              * of event.
              */
             spin_lock_irq(&dev->event_lock);
             dev->absinfo[t] = abs;
             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 || client->revoked) {
         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)
 {
     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,
 #ifdef CONFIG_COMPAT
     .compat_ioctl   = evdev_ioctl_compat,
 #endif
     .fasync     = evdev_fasync,
     .llseek     = no_llseek,
 };
 
 /*
  * 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 = false;
     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 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.
  */
 static int evdev_connect(struct input_handler *handler, struct input_dev *dev,
              const struct input_device_id *id)
 {
     struct evdev *evdev;
     int minor;
     int dev_no;
     int error;
 
     minor = input_get_new_minor(EVDEV_MINOR_BASE, EVDEV_MINORS, true);
     if (minor < 0) {
         error = minor;
         pr_err("failed to reserve new minor: %d\n", error);
         return error;
     }
 
     evdev = kzalloc(sizeof(struct evdev), GFP_KERNEL);
     if (!evdev) {
         error = -ENOMEM;
         goto err_free_minor;
     }
 
     INIT_LIST_HEAD(&evdev->client_list);
     spin_lock_init(&evdev->client_lock);
     mutex_init(&evdev->mutex);
     evdev->exist = true;
 
     dev_no = minor;
     /* Normalize device number if it falls into legacy range */
     if (dev_no < EVDEV_MINOR_BASE + EVDEV_MINORS)
         dev_no -= EVDEV_MINOR_BASE;
     dev_set_name(&evdev->dev, "event%d", dev_no);
 
     evdev->handle.dev = input_get_device(dev);
     evdev->handle.name = dev_name(&evdev->dev);
     evdev->handle.handler = handler;
     evdev->handle.private = evdev;
 
     evdev->dev.devt = MKDEV(INPUT_MAJOR, minor);
     evdev->dev.class = &input_class;
     evdev->dev.parent = &dev->dev;
     evdev->dev.release = evdev_free;
     device_initialize(&evdev->dev);
 
     error = input_register_handle(&evdev->handle);
     if (error)
         goto err_free_evdev;
 
     cdev_init(&evdev->cdev, &evdev_fops);
 
     error = cdev_device_add(&evdev->cdev, &evdev->dev);
     if (error)
         goto err_cleanup_evdev;
 
     return 0;
 
  err_cleanup_evdev:
     evdev_cleanup(evdev);
     input_unregister_handle(&evdev->handle);
  err_free_evdev:
     put_device(&evdev->dev);
  err_free_minor:
     input_free_minor(minor);
     return error;
 }
 
 static void evdev_disconnect(struct input_handle *handle)
 {
     struct evdev *evdev = handle->private;
 
     cdev_device_del(&evdev->cdev, &evdev->dev);
     evdev_cleanup(evdev);
     input_free_minor(MINOR(evdev->dev.devt));
     input_unregister_handle(handle);
     put_device(&evdev->dev);
 }
 
 static const struct input_device_id evdev_ids[] = {
     { .driver_info = 1 },   /* Matches all devices */
     { },            /* Terminating zero entry */
 };
 
 MODULE_DEVICE_TABLE(input, evdev_ids);
 
 static struct input_handler evdev_handler = {
     .event      = evdev_event,
     .events     = evdev_events,
     .connect    = evdev_connect,
     .disconnect = evdev_disconnect,
     .legacy_minors  = true,
     .minor      = EVDEV_MINOR_BASE,
     .name       = "evdev",
     .id_table   = evdev_ids,
 };
 
 static int __init evdev_init(void)
 {
     return input_register_handler(&evdev_handler);
 }
 
 static void __exit evdev_exit(void)
 {
     input_unregister_handler(&evdev_handler);
 }
 
 module_init(evdev_init);
 module_exit(evdev_exit);
 
 MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
 MODULE_DESCRIPTION("Input driver event char devices");
 MODULE_LICENSE("GPL");

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