Commit 071b24b5 authored by Dmitry Torokhov's avatar Dmitry Torokhov
Browse files

Input: fix regression when re-registering input handlers 



Commit d469647b ("Input: simplify event handling logic") introduced
code that would set handler->events() method to either
input_handler_events_filter() or input_handler_events_default() or
input_handler_events_null(), depending on the kind of input handler
(a filter or a regular one) we are dealing with. Unfortunately this
breaks cases when we try to re-register the same filter (as is the case
with sysrq handler): after initial registration the handler will have 2
event handling methods defined, and will run afoul of the check in
input_handler_check_methods():

	input: input_handler_check_methods: only one event processing method can be defined (sysrq)
	sysrq: Failed to register input handler, error -22

Fix this by adding handle_events() method to input_handle structure and
setting it up when registering a new input handle according to event
handling methods defined in associated input_handler structure, thus
avoiding modifying the input_handler structure.

Reported-by: default avatar"Ned T. Crigler" <crigler@gmail.com>
Reported-by: default avatarChristian Heusel <christian@heusel.eu>
Tested-by: default avatar"Ned T. Crigler" <crigler@gmail.com>
Tested-by: default avatarPeter Seiderer <ps.report@gmx.net>
Fixes: d469647b ("Input: simplify event handling logic")
Link: https://lore.kernel.org/r/Zx2iQp6csn42PJA7@xavtug


Cc: stable@vger.kernel.org
Signed-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
parent 2860586c

drivers/input/input.c

+73 −61
Original line number Diff line number Diff line
@@ -119,11 +119,11 @@ static void input_pass_values(struct input_dev *dev, 


	handle = rcu_dereference(dev->grab);

	if (handle) {

		count = handle->handler->events(handle, vals, count);

		count = handle->handle_events(handle, vals, count);

	} else {

		list_for_each_entry_rcu(handle, &dev->h_list, d_node)

			if (handle->open) {

				count = handle->handler->events(handle, vals,

				count = handle->handle_events(handle, vals,

							      count);

				if (!count)

					break;
@@ -2537,57 +2537,6 @@ static int input_handler_check_methods(const struct input_handler *handler) 
	return 0;

}



/*

 * An implementation of input_handler's events() method that simply

 * invokes handler->event() method for each event one by one.

 */

static unsigned int input_handler_events_default(struct input_handle *handle,

						 struct input_value *vals,

						 unsigned int count)

{

	struct input_handler *handler = handle->handler;

	struct input_value *v;



	for (v = vals; v != vals + count; v++)

		handler->event(handle, v->type, v->code, v->value);



	return count;

}



/*

 * An implementation of input_handler's events() method that invokes

 * handler->filter() method for each event one by one and removes events

 * that were filtered out from the "vals" array.

 */

static unsigned int input_handler_events_filter(struct input_handle *handle,

						struct input_value *vals,

						unsigned int count)

{

	struct input_handler *handler = handle->handler;

	struct input_value *end = vals;

	struct input_value *v;



	for (v = vals; v != vals + count; v++) {

		if (handler->filter(handle, v->type, v->code, v->value))

			continue;

		if (end != v)

			*end = *v;

		end++;

	}



	return end - vals;

}



/*

 * An implementation of input_handler's events() method that does nothing.

 */

static unsigned int input_handler_events_null(struct input_handle *handle,

					      struct input_value *vals,

					      unsigned int count)

{

	return count;

}



/**

 * input_register_handler - register a new input handler

 * @handler: handler to be registered
@@ -2607,13 +2556,6 @@ int input_register_handler(struct input_handler *handler) 


	INIT_LIST_HEAD(&handler->h_list);



	if (handler->filter)

		handler->events = input_handler_events_filter;

	else if (handler->event)

		handler->events = input_handler_events_default;

	else if (!handler->events)

		handler->events = input_handler_events_null;



	error = mutex_lock_interruptible(&input_mutex);

	if (error)

		return error;
@@ -2687,6 +2629,75 @@ int input_handler_for_each_handle(struct input_handler *handler, void *data, 
}

EXPORT_SYMBOL(input_handler_for_each_handle);



/*

 * An implementation of input_handle's handle_events() method that simply

 * invokes handler->event() method for each event one by one.

 */

static unsigned int input_handle_events_default(struct input_handle *handle,

						struct input_value *vals,

						unsigned int count)

{

	struct input_handler *handler = handle->handler;

	struct input_value *v;



	for (v = vals; v != vals + count; v++)

		handler->event(handle, v->type, v->code, v->value);



	return count;

}



/*

 * An implementation of input_handle's handle_events() method that invokes

 * handler->filter() method for each event one by one and removes events

 * that were filtered out from the "vals" array.

 */

static unsigned int input_handle_events_filter(struct input_handle *handle,

					       struct input_value *vals,

					       unsigned int count)

{

	struct input_handler *handler = handle->handler;

	struct input_value *end = vals;

	struct input_value *v;



	for (v = vals; v != vals + count; v++) {

		if (handler->filter(handle, v->type, v->code, v->value))

			continue;

		if (end != v)

			*end = *v;

		end++;

	}



	return end - vals;

}



/*

 * An implementation of input_handle's handle_events() method that does nothing.

 */

static unsigned int input_handle_events_null(struct input_handle *handle,

					     struct input_value *vals,

					     unsigned int count)

{

	return count;

}



/*

 * Sets up appropriate handle->event_handler based on the input_handler

 * associated with the handle.

 */

static void input_handle_setup_event_handler(struct input_handle *handle)

{

	struct input_handler *handler = handle->handler;



	if (handler->filter)

		handle->handle_events = input_handle_events_filter;

	else if (handler->event)

		handle->handle_events = input_handle_events_default;

	else if (handler->events)

		handle->handle_events = handler->events;

	else

		handle->handle_events = input_handle_events_null;

}



/**

 * input_register_handle - register a new input handle

 * @handle: handle to register
@@ -2704,6 +2715,7 @@ int input_register_handle(struct input_handle *handle) 
	struct input_dev *dev = handle->dev;

	int error;



	input_handle_setup_event_handler(handle);

	/*

	 * We take dev->mutex here to prevent race with

	 * input_release_device().

include/linux/input.h

+9 −1
Original line number Diff line number Diff line
@@ -339,12 +339,16 @@ struct input_handler { 
 * @name: name given to the handle by handler that created it

 * @dev: input device the handle is attached to

 * @handler: handler that works with the device through this handle

 * @handle_events: event sequence handler. It is set up by the input core

 *	according to event handling method specified in the @handler. See

 *	input_handle_setup_event_handler().

 *	This method is being called by the input core with interrupts disabled

 *	and dev->event_lock spinlock held and so it may not sleep.

 * @d_node: used to put the handle on device's list of attached handles

 * @h_node: used to put the handle on handler's list of handles from which

 *	it gets events

 */

struct input_handle {



	void *private;



	int open;
@@ -353,6 +357,10 @@ struct input_handle { 
	struct input_dev *dev;

	struct input_handler *handler;



	unsigned int (*handle_events)(struct input_handle *handle,

				      struct input_value *vals,

				      unsigned int count);



	struct list_head	d_node;

	struct list_head	h_node;

};