diff options
Diffstat (limited to 'drivers/input')
| -rw-r--r-- | drivers/input/input.c | 666 |
1 files changed, 491 insertions, 175 deletions
diff --git a/drivers/input/input.c b/drivers/input/input.c index 5fe755586623..c59544f7e232 100644 --- a/drivers/input/input.c +++ b/drivers/input/input.c @@ -17,10 +17,10 @@ #include <linux/major.h> #include <linux/proc_fs.h> #include <linux/seq_file.h> -#include <linux/interrupt.h> #include <linux/poll.h> #include <linux/device.h> #include <linux/mutex.h> +#include <linux/rcupdate.h> MODULE_AUTHOR("Vojtech Pavlik <vojtech@suse.cz>"); MODULE_DESCRIPTION("Input core"); @@ -31,167 +31,244 @@ MODULE_LICENSE("GPL"); static LIST_HEAD(input_dev_list); static LIST_HEAD(input_handler_list); +/* + * input_mutex protects access to both input_dev_list and input_handler_list. + * This also causes input_[un]register_device and input_[un]register_handler + * be mutually exclusive which simplifies locking in drivers implementing + * input handlers. + */ +static DEFINE_MUTEX(input_mutex); + static struct input_handler *input_table[8]; -/** - * input_event() - report new input event - * @dev: device that generated the event - * @type: type of the event - * @code: event code - * @value: value of the event - * - * This function should be used by drivers implementing various input devices - * See also input_inject_event() - */ -void input_event(struct input_dev *dev, unsigned int type, unsigned int code, int value) +static inline int is_event_supported(unsigned int code, + unsigned long *bm, unsigned int max) { - struct input_handle *handle; + return code <= max && test_bit(code, bm); +} - if (type > EV_MAX || !test_bit(type, dev->evbit)) - return; +static int input_defuzz_abs_event(int value, int old_val, int fuzz) +{ + if (fuzz) { + if (value > old_val - fuzz / 2 && value < old_val + fuzz / 2) + return old_val; - add_input_randomness(type, code, value); + if (value > old_val - fuzz && value < old_val + fuzz) + return (old_val * 3 + value) / 4; - switch (type) { + if (value > old_val - fuzz * 2 && value < old_val + fuzz * 2) + return (old_val + value) / 2; + } - case EV_SYN: - switch (code) { - case SYN_CONFIG: - if (dev->event) - dev->event(dev, type, code, value); - break; - - case SYN_REPORT: - if (dev->sync) - return; - dev->sync = 1; - break; - } - break; + return value; +} - case EV_KEY: +/* + * Pass event through all open handles. This function is called with + * dev->event_lock held and interrupts disabled. Because of that we + * do not need to use rcu_read_lock() here although we are using RCU + * to access handle list. Note that because of that write-side uses + * synchronize_sched() instead of synchronize_ru(). + */ +static void input_pass_event(struct input_dev *dev, + unsigned int type, unsigned int code, int value) +{ + struct input_handle *handle = rcu_dereference(dev->grab); - if (code > KEY_MAX || !test_bit(code, dev->keybit) || !!test_bit(code, dev->key) == value) - return; + if (handle) + handle->handler->event(handle, type, code, value); + else + list_for_each_entry_rcu(handle, &dev->h_list, d_node) + if (handle->open) + handle->handler->event(handle, + type, code, value); +} - if (value == 2) - break; +/* + * Generate software autorepeat event. Note that we take + * dev->event_lock here to avoid racing with input_event + * which may cause keys get "stuck". + */ +static void input_repeat_key(unsigned long data) +{ + struct input_dev *dev = (void *) data; + unsigned long flags; - change_bit(code, dev->key); + spin_lock_irqsave(&dev->event_lock, flags); - if (test_bit(EV_REP, dev->evbit) && dev->rep[REP_PERIOD] && dev->rep[REP_DELAY] && dev->timer.data && value) { - dev->repeat_key = code; - mod_timer(&dev->timer, jiffies + msecs_to_jiffies(dev->rep[REP_DELAY])); - } + if (test_bit(dev->repeat_key, dev->key) && + is_event_supported(dev->repeat_key, dev->keybit, KEY_MAX)) { - break; + input_pass_event(dev, EV_KEY, dev->repeat_key, 2); - case EV_SW: + if (dev->sync) { + /* + * Only send SYN_REPORT if we are not in a middle + * of driver parsing a new hardware packet. + * Otherwise assume that the driver will send + * SYN_REPORT once it's done. + */ + input_pass_event(dev, EV_SYN, SYN_REPORT, 1); + } - if (code > SW_MAX || !test_bit(code, dev->swbit) || !!test_bit(code, dev->sw) == value) - return; + if (dev->rep[REP_PERIOD]) + mod_timer(&dev->timer, jiffies + + msecs_to_jiffies(dev->rep[REP_PERIOD])); + } - change_bit(code, dev->sw); + spin_unlock_irqrestore(&dev->event_lock, flags); +} - break; +static void input_start_autorepeat(struct input_dev *dev, int code) +{ + if (test_bit(EV_REP, dev->evbit) && + dev->rep[REP_PERIOD] && dev->rep[REP_DELAY] && + dev->timer.data) { + dev->repeat_key = code; + mod_timer(&dev->timer, + jiffies + msecs_to_jiffies(dev->rep[REP_DELAY])); + } +} - case EV_ABS: +#define INPUT_IGNORE_EVENT 0 +#define INPUT_PASS_TO_HANDLERS 1 +#define INPUT_PASS_TO_DEVICE 2 +#define INPUT_PASS_TO_ALL (INPUT_PASS_TO_HANDLERS | INPUT_PASS_TO_DEVICE) - if (code > ABS_MAX || !test_bit(code, dev->absbit)) - return; +static void input_handle_event(struct input_dev *dev, + unsigned int type, unsigned int code, int value) +{ + int disposition = INPUT_IGNORE_EVENT; - if (dev->absfuzz[code]) { - if ((value > dev->abs[code] - (dev->absfuzz[code] >> 1)) && - (value < dev->abs[code] + (dev->absfuzz[code] >> 1))) - return; + switch (type) { - if ((value > dev->abs[code] - dev->absfuzz[code]) && - (value < dev->abs[code] + dev->absfuzz[code])) - value = (dev->abs[code] * 3 + value) >> 2; + case EV_SYN: + switch (code) { + case SYN_CONFIG: + disposition = INPUT_PASS_TO_ALL; + break; - if ((value > dev->abs[code] - (dev->absfuzz[code] << 1)) && - (value < dev->abs[code] + (dev->absfuzz[code] << 1))) - value = (dev->abs[code] + value) >> 1; + case SYN_REPORT: + if (!dev->sync) { + dev->sync = 1; + disposition = INPUT_PASS_TO_HANDLERS; } - - if (dev->abs[code] == value) - return; - - dev->abs[code] = value; break; + } + break; - case EV_REL: + case EV_KEY: + if (is_event_supported(code, dev->keybit, KEY_MAX) && + !!test_bit(code, dev->key) != value) { - if (code > REL_MAX || !test_bit(code, dev->relbit) || (value == 0)) - return; + if (value != 2) { + __change_bit(code, dev->key); + if (value) + input_start_autorepeat(dev, code); + } - break; + disposition = INPUT_PASS_TO_HANDLERS; + } + break; - case EV_MSC: + case EV_SW: + if (is_event_supported(code, dev->swbit, SW_MAX) && + !!test_bit(code, dev->sw) != value) { - if (code > MSC_MAX || !test_bit(code, dev->mscbit)) - return; + __change_bit(code, dev->sw); + disposition = INPUT_PASS_TO_HANDLERS; + } + break; - if (dev->event) - dev->event(dev, type, code, value); + case EV_ABS: + if (is_event_supported(code, dev->absbit, ABS_MAX)) { - break; + value = input_defuzz_abs_event(value, + dev->abs[code], dev->absfuzz[code]); - case EV_LED: + if (dev->abs[code] != value) { + dev->abs[code] = value; + disposition = INPUT_PASS_TO_HANDLERS; + } + } + break; - if (code > LED_MAX || !test_bit(code, dev->ledbit) || !!test_bit(code, dev->led) == value) - return; + case EV_REL: + if (is_event_supported(code, dev->relbit, REL_MAX) && value) + disposition = INPUT_PASS_TO_HANDLERS; - change_bit(code, dev->led); + break; - if (dev->event) - dev->event(dev, type, code, value); + case EV_MSC: + if (is_event_supported(code, dev->mscbit, MSC_MAX)) + disposition = INPUT_PASS_TO_ALL; - break; + break; + + case EV_LED: + if (is_event_supported(code, dev->ledbit, LED_MAX) && + !!test_bit(code, dev->led) != value) { - case EV_SND: + __change_bit(code, dev->led); + disposition = INPUT_PASS_TO_ALL; + } + break; - if (code > SND_MAX || !test_bit(code, dev->sndbit)) - return; + case EV_SND: + if (is_event_supported(code, dev->sndbit, SND_MAX)) { if (!!test_bit(code, dev->snd) != !!value) - change_bit(code, dev->snd); + __change_bit(code, dev->snd); + disposition = INPUT_PASS_TO_ALL; + } + break; - if (dev->event) - dev->event(dev, type, code, value); + case EV_REP: + if (code <= REP_MAX && value >= 0 && dev->rep[code] != value) { + dev->rep[code] = value; + disposition = INPUT_PASS_TO_ALL; + } + break; - break; + case EV_FF: + if (value >= 0) + disposition = INPUT_PASS_TO_ALL; + break; + } - case EV_REP: + if (type != EV_SYN) + dev->sync = 0; - if (code > REP_MAX || value < 0 || dev->rep[code] == value) - return; + if ((disposition & INPUT_PASS_TO_DEVICE) && dev->event) + dev->event(dev, type, code, value); - dev->rep[code] = value; - if (dev->event) - dev->event(dev, type, code, value); + if (disposition & INPUT_PASS_TO_HANDLERS) + input_pass_event(dev, type, code, value); +} - break; +/** + * input_event() - report new input event + * @dev: device that generated the event + * @type: type of the event + * @code: event code + * @value: value of the event + * + * This function should be used by drivers implementing various input + * devices. See also input_inject_event(). + */ - case EV_FF: +void input_event(struct input_dev *dev, + unsigned int type, unsigned int code, int value) +{ + unsigned long flags; - if (value < 0) - return; + if (is_event_supported(type, dev->evbit, EV_MAX)) { - if (dev->event) - dev->event(dev, type, code, value); - break; + spin_lock_irqsave(&dev->event_lock, flags); + add_input_randomness(type, code, value); + input_handle_event(dev, type, code, value); + spin_unlock_irqrestore(&dev->event_lock, flags); } - - if (type != EV_SYN) - dev->sync = 0; - - if (dev->grab) - dev->grab->handler->event(dev->grab, type, code, value); - else - list_for_each_entry(handle, &dev->h_list, d_node) - if (handle->open) - handle->handler->event(handle, type, code, value); } EXPORT_SYMBOL(input_event); @@ -202,102 +279,230 @@ EXPORT_SYMBOL(input_event); * @code: event code * @value: value of the event * - * Similar to input_event() but will ignore event if device is "grabbed" and handle - * injecting event is not the one that owns the device. + * Similar to input_event() but will ignore event if device is + * "grabbed" and handle injecting event is not the one that owns + * the device. */ -void input_inject_event(struct input_handle *handle, unsigned int type, unsigned int code, int value) +void input_inject_event(struct input_handle *handle, + unsigned int type, unsigned int code, int value) { - if (!handle->dev->grab || handle->dev->grab == handle) - input_event(handle->dev, type, code, value); -} -EXPORT_SYMBOL(input_inject_event); - -static void input_repeat_key(unsigned long data) -{ - struct input_dev *dev = (void *) data; + struct input_dev *dev = handle->dev; + struct input_handle *grab; + unsigned long flags; - if (!test_bit(dev->repeat_key, dev->key)) - return; + if (is_event_supported(type, dev->evbit, EV_MAX)) { + spin_lock_irqsave(&dev->event_lock, flags); - input_event(dev, EV_KEY, dev->repeat_key, 2); - input_sync(dev); + grab = rcu_dereference(dev->grab); + if (!grab || grab == handle) + input_handle_event(dev, type, code, value); - if (dev->rep[REP_PERIOD]) - mod_timer(&dev->timer, jiffies + msecs_to_jiffies(dev->rep[REP_PERIOD])); + spin_unlock_irqrestore(&dev->event_lock, flags); + } } +EXPORT_SYMBOL(input_inject_event); +/** + * input_grab_device - grabs device for exclusive use + * @handle: input handle that wants to own the device + * + * When a device is grabbed by an input handle all events generated by + * the device are delivered only to this handle. Also events injected + * by other input handles are ignored while device is grabbed. + */ int input_grab_device(struct input_handle *handle) { - if (handle->dev->grab) - return -EBUSY; + struct input_dev *dev = handle->dev; + int retval; - handle->dev->grab = handle; - return 0; + retval = mutex_lock_interruptible(&dev->mutex); + if (retval) + return retval; + + if (dev->grab) { + retval = -EBUSY; + goto out; + } + + rcu_assign_pointer(dev->grab, handle); + /* + * Not using synchronize_rcu() because read-side is protected + * by a spinlock with interrupts off instead of rcu_read_lock(). + */ + synchronize_sched(); + + out: + mutex_unlock(&dev->mutex); + return retval; } EXPORT_SYMBOL(input_grab_device); -void input_release_device(struct input_handle *handle) +static void __input_release_device(struct input_handle *handle) { struct input_dev *dev = handle->dev; if (dev->grab == handle) { - dev->grab = NULL; + rcu_assign_pointer(dev->grab, NULL); + /* Make sure input_pass_event() notices that grab is gone */ + synchronize_sched(); list_for_each_entry(handle, &dev->h_list, d_node) - if (handle->handler->start) + if (handle->open && handle->handler->start) handle->handler->start(handle); } } + +/** + * input_release_device - release previously grabbed device + * @handle: input handle that owns the device + * + * Releases previously grabbed device so that other input handles can + * start receiving input events. Upon release all handlers attached + * to the device have their start() method called so they have a change + * to synchronize device state with the rest of the system. + */ +void input_release_device(struct input_handle *handle) +{ + struct input_dev *dev = handle->dev; + + mutex_lock(&dev->mutex); + __input_release_device(handle); + mutex_unlock(&dev->mutex); +} EXPORT_SYMBOL(input_release_device); +/** + * input_open_device - open input device + * @handle: handle through which device is being accessed + * + * This function should be called by input handlers when they + * want to start receive events from given input device. + */ int input_open_device(struct input_handle *handle) { struct input_dev *dev = handle->dev; - int err; + int retval; - err = mutex_lock_interruptible(&dev->mutex); - if (err) - return err; + retval = mutex_lock_interruptible(&dev->mutex); + if (retval) + return retval; + + if (dev->going_away) { + retval = -ENODEV; + goto out; + } handle->open++; if (!dev->users++ && dev->open) - err = dev->open(dev); - - if (err) - handle->open--; + retval = dev->open(dev); + + if (retval) { + dev->users--; + if (!--handle->open) { + /* + * Make sure we are not delivering any more events + * through this handle + */ + synchronize_sched(); + } + } + out: mutex_unlock(&dev->mutex); - - return err; + return retval; } EXPORT_SYMBOL(input_open_device); -int input_flush_device(struct input_handle* handle, struct file* file) +int input_flush_device(struct input_handle *handle, struct file *file) { - if (handle->dev->flush) - return handle->dev->flush(handle->dev, file); + struct input_dev *dev = handle->dev; + int retval; - return 0; + retval = mutex_lock_interruptible(&dev->mutex); + if (retval) + return retval; + + if (dev->flush) + retval = dev->flush(dev, file); + + mutex_unlock(&dev->mutex); + return retval; } EXPORT_SYMBOL(input_flush_device); +/** + * input_close_device - close input device + * @handle: handle through which device is being accessed + * + * This function should be called by input handlers when they + * want to stop receive events from given input device. + */ void input_close_device(struct input_handle *handle) { struct input_dev *dev = handle->dev; - input_release_device(handle); - mutex_lock(&dev->mutex); + __input_release_device(handle); + if (!--dev->users && dev->close) dev->close(dev); - handle->open--; + + if (!--handle->open) { + /* + * synchronize_sched() makes sure that input_pass_event() + * completed and that no more input events are delivered + * through this handle + */ + synchronize_sched(); + } mutex_unlock(&dev->mutex); } EXPORT_SYMBOL(input_close_device); +/* + * Prepare device for unregistering + */ +static void input_disconnect_device(struct input_dev *dev) +{ + struct input_handle *handle; + int code; + + /* + * Mark device as going away. Note that we take dev->mutex here + * not to protect access to dev->going_away but rather to ensure + * that there are no threads in the middle of input_open_device() + */ + mutex_lock(&dev->mutex); + dev->going_away = 1; + mutex_unlock(&dev->mutex); + + spin_lock_irq(&dev->event_lock); + + /* + * Simulate keyup events for all pressed keys so that handlers + * are not left with "stuck" keys. The driver may continue + * generate events even after we done here but they will not + * reach any handlers. + */ + if (is_event_supported(EV_KEY, dev->evbit, EV_MAX)) { + for (code = 0; code <= KEY_MAX; code++) { + if (is_event_supported(code, dev->keybit, KEY_MAX) && + test_bit(code, dev->key)) { + input_pass_event(dev, EV_KEY, code, 0); + } + } + input_pass_event(dev, EV_SYN, SYN_REPORT, 1); + } + + list_for_each_entry(handle, &dev->h_list, d_node) + handle->open = 0; + + spin_unlock_irq(&dev->event_lock); +} + static int input_fetch_keycode(struct input_dev *dev, int scancode) { switch (dev->keycodesize) { @@ -473,7 +678,8 @@ static unsigned int input_proc_devices_poll(struct file *file, poll_table *wait) static void *input_devices_seq_start(struct seq_file *seq, loff_t *pos) { - /* acquire lock here ... Yes, we do need locking, I knowi, I know... */ + if (mutex_lock_interruptible(&input_mutex)) + return NULL; return seq_list_start(&input_dev_list, *pos); } @@ -485,7 +691,7 @@ static void *input_devices_seq_next(struct seq_file *seq, void *v, loff_t *pos) static void input_devices_seq_stop(struct seq_file *seq, void *v) { - /* release lock here */ + mutex_unlock(&input_mutex); } static void input_seq_print_bitmap(struct seq_file *seq, const char *name, @@ -569,7 +775,9 @@ static const struct file_operations input_devices_fileops = { static void *input_handlers_seq_start(struct seq_file *seq, loff_t *pos) { - /* acquire lock here ... Yes, we do need locking, I knowi, I know... */ + if (mutex_lock_interruptible(&input_mutex)) + return NULL; + seq->private = (void *)(unsigned long)*pos; return seq_list_start(&input_handler_list, *pos); } @@ -582,7 +790,7 @@ static void *input_handlers_seq_next(struct seq_file *seq, void *v, loff_t *pos) static void input_handlers_seq_stop(struct seq_file *seq, void *v) { - /* release lock here */ + mutex_unlock(&input_mutex); } static int input_handlers_seq_show(struct seq_file *seq, void *v) @@ -1005,6 +1213,7 @@ struct input_dev *input_allocate_device(void) dev->dev.class = &input_class; device_initialize(&dev->dev); mutex_init(&dev->mutex); + spin_lock_init(&dev->event_lock); INIT_LIST_HEAD(&dev->h_list); INIT_LIST_HEAD(&dev->node); @@ -1022,7 +1231,7 @@ EXPORT_SYMBOL(input_allocate_device); * This function should only be used if input_register_device() * was not called yet or if it failed. Once device was registered * use input_unregister_device() and memory will be freed once last - * refrence to the device is dropped. + * reference to the device is dropped. * * Device should be allocated by input_allocate_device(). * @@ -1092,6 +1301,18 @@ void input_set_capability(struct input_dev *dev, unsigned int type, unsigned int } EXPORT_SYMBOL(input_set_capability); +/** + * input_register_device - register device with input core + * @dev: device to be registered + * + * This function registers device with input core. The device must be + * allocated with input_allocate_device() and all it's capabilities + * set up before registering. + * If function fails the device must be freed with input_free_device(). + * Once device has been successfully registered it can be unregistered + * with input_unregister_device(); input_free_device() should not be + * called in this case. + */ int input_register_device(struct input_dev *dev) { static atomic_t input_no = ATOMIC_INIT(0); @@ -1099,7 +1320,7 @@ int input_register_device(struct input_dev *dev) const char *path; int error; - set_bit(EV_SYN, dev->evbit); + __set_bit(EV_SYN, dev->evbit); /* * If delay and period are pre-set by the driver, then autorepeating @@ -1120,8 +1341,6 @@ int input_register_device(struct input_dev *dev) if (!dev->setkeycode) dev->setkeycode = input_default_setkeycode; - list_add_tail(&dev->node, &input_dev_list); - snprintf(dev->dev.bus_id, sizeof(dev->dev.bus_id), "input%ld", (unsigned long) atomic_inc_return(&input_no) - 1); @@ -1137,49 +1356,79 @@ int input_register_device(struct input_dev *dev) dev->name ? dev->name : "Unspecified device", path ? path : "N/A"); kfree(path); + error = mutex_lock_interruptible(&input_mutex); + if (error) { + device_del(&dev->dev); + return error; + } + + list_add_tail(&dev->node, &input_dev_list); + list_for_each_entry(handler, &input_handler_list, node) input_attach_handler(dev, handler); input_wakeup_procfs_readers(); + mutex_unlock(&input_mutex); + return 0; } EXPORT_SYMBOL(input_register_device); +/** + * input_unregister_device - unregister previously registered device + * @dev: device to be unregistered + * + * This function unregisters an input device. Once device is unregistered + * the caller should not try to access it as it may get freed at any moment. + */ void input_unregister_device(struct input_dev *dev) { struct input_handle *handle, *next; - int code; - for (code = 0; code <= KEY_MAX; code++) - if (test_bit(code, dev->key)) - input_report_key(dev, code, 0); - input_sync(dev); + input_disconnect_device(dev); - del_timer_sync(&dev->timer); + mutex_lock(&input_mutex); list_for_each_entry_safe(handle, next, &dev->h_list, d_node) handle->handler->disconnect(handle); WARN_ON(!list_empty(&dev->h_list)); + del_timer_sync(&dev->timer); list_del_init(&dev->node); - device_unregister(&dev->dev); - input_wakeup_procfs_readers(); + + mutex_unlock(&input_mutex); + + device_unregister(&dev->dev); } EXPORT_SYMBOL(input_unregister_device); +/** + * input_register_handler - register a new input handler + * @handler: handler to be registered + * + * This function registers a new input handler (interface) for input + * devices in the system and attaches it to all input devices that + * are compatible with the handler. + */ int input_register_handler(struct input_handler *handler) { struct input_dev *dev; + int retval; + + retval = mutex_lock_interruptible(&input_mutex); + if (retval) + return retval; INIT_LIST_HEAD(&handler->h_list); if (handler->fops != NULL) { - if (input_table[handler->minor >> 5]) - return -EBUSY; - + if (input_table[handler->minor >> 5]) { + retval = -EBUSY; + goto out; + } input_table[handler->minor >> 5] = handler; } @@ -1189,14 +1438,26 @@ int input_register_handler(struct input_handler *handler) input_attach_handler(dev, handler); input_wakeup_procfs_readers(); - return 0; + + out: + mutex_unlock(&input_mutex); + return retval; } EXPORT_SYMBOL(input_register_handler); +/** + * input_unregister_handler - unregisters an input handler + * @handler: handler to be unregistered + * + * This function disconnects a handler from its input devices and + * removes it from lists of known handlers. + */ void input_unregister_handler(struct input_handler *handler) { struct input_handle *handle, *next; + mutex_lock(&input_mutex); + list_for_each_entry_safe(handle, next, &handler->h_list, h_node) handler->disconnect(handle); WARN_ON(!list_empty(&handler->h_list)); @@ -1207,14 +1468,50 @@ void input_unregister_handler(struct input_handler *handler) input_table[handler->minor >> 5] = NULL; input_wakeup_procfs_readers(); + + mutex_unlock(&input_mutex); } EXPORT_SYMBOL(input_unregister_handler); +/** + * input_register_handle - register a new input handle + * @handle: handle to register + * + * This function puts a new input handle onto device's + * and handler's lists so that events can flow through + * it once it is opened using input_open_device(). + * + * This function is supposed to be called from handler's + * connect() method. + */ int input_register_handle(struct input_handle *handle) { struct input_handler *handler = handle->handler; + struct input_dev *dev = handle->dev; + int error; + + /* + * We take dev->mutex here to prevent race with + * input_release_device(). + */ + error = mutex_lock_interruptible(&dev->mutex); + if (error) + return error; + list_add_tail_rcu(&handle->d_node, &dev->h_list); + mutex_unlock(&dev->mutex); + /* + * We don't use synchronize_rcu() here because we rely + * on dev->event_lock to protect read-side critical + * section in input_pass_event(). + */ + synchronize_sched(); - list_add_tail(&handle->d_node, &handle->dev->h_list); + /* + * Since we are supposed to be called from ->connect() + * which is mutually exclusive with ->disconnect() + * we can't be racing with input_unregister_handle() + * and so separate lock is not needed here. + */ list_add_tail(&handle->h_node, &handler->h_list); if (handler->start) @@ -1224,10 +1521,29 @@ int input_register_handle(struct input_handle *handle) } EXPORT_SYMBOL(input_register_handle); +/** + * input_unregister_handle - unregister an input handle + * @handle: handle to unregister + * + * This function removes input handle from device's + * and handler's lists. + * + * This function is supposed to be called from handler's + * disconnect() method. + */ void input_unregister_handle(struct input_handle *handle) { + struct input_dev *dev = handle->dev; + list_del_init(&handle->h_node); - list_del_init(&handle->d_node); + + /* + * Take dev->mutex to prevent race with input_release_device(). + */ + mutex_lock(&dev->mutex); + list_del_rcu(&handle->d_node); + mutex_unlock(&dev->mutex); + synchronize_sched(); } EXPORT_SYMBOL(input_unregister_handle); |
