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Input: fix regression when re-registering input handlers

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Commit d469647baf ("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: "Ned T. Crigler" <crigler@gmail.com>
Reported-by: Christian Heusel <christian@heusel.eu>
Tested-by: "Ned T. Crigler" <crigler@gmail.com>
Tested-by: Peter Seiderer <ps.report@gmx.net>
Fixes: d469647baf ("Input: simplify event handling logic")
Link: https://lore.kernel.org/r/Zx2iQp6csn42PJA7@xavtug
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
This commit is contained in:
Dmitry Torokhov 2024-10-27 22:31:15 -07:00
parent 2860586c58
commit 071b24b54d
2 changed files with 82 additions and 62 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

134
drivers/input/input.c
View File

@ -119,12 +119,12 @@ 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);
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().

10
include/linux/input.h
View File

@ -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;
};