linux-kernel - [PATCH 3/4] Input: simplify event handling logic

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Message-ID: <20240701060553.869989-4-dmitry.torokhov@gmail.com>
Date: Sun, 30 Jun 2024 23:05:51 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: linux-input@...r.kernel.org
Cc: Benjamin Tissoires <bentiss@...nel.org>,
	Jeff LaBundy <jeff@...undy.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 3/4] Input: simplify event handling logic

Streamline event handling code by providing batch implementations for
filtering and event processing and using them in place of the main
event handler, as needed, instead of having complex branching logic
in the middle of the event processing code.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
---
 drivers/input/input.c | 90 ++++++++++++++++++++++++-------------------
 1 file changed, 51 insertions(+), 39 deletions(-)

diff --git a/drivers/input/input.c b/drivers/input/input.c
index 8434348faeac..eeb755cb12e7 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -99,41 +99,6 @@ static void input_stop_autorepeat(struct input_dev *dev)
 	del_timer(&dev->timer);
 }
 
-/*
- * Pass event first through all filters and then, if event has not been
- * filtered out, through all open handles. This function is called with
- * dev->event_lock held and interrupts disabled.
- */
-static unsigned int input_to_handler(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;
-
-	if (handler->filter) {
-		for (v = vals; v != vals + count; v++) {
-			if (handler->filter(handle, v->type, v->code, v->value))
-				continue;
-			if (end != v)
-				*end = *v;
-			end++;
-		}
-		count = end - vals;
-	}
-
-	if (!count)
-		return 0;
-
-	if (handler->events)
-		handler->events(handle, vals, count);
-	else if (handler->event)
-		for (v = vals; v != vals + count; v++)
-			handler->event(handle, v->type, v->code, v->value);
-
-	return count;
-}
-
 /*
  * Pass values first through all filters and then, if event has not been
  * filtered out, through all open handles. This function is called with
@@ -154,11 +119,12 @@ static void input_pass_values(struct input_dev *dev,
 
 	handle = rcu_dereference(dev->grab);
 	if (handle) {
-		count = input_to_handler(handle, vals, count);
+		count = handle->handler->events(handle, vals, count);
 	} else {
 		list_for_each_entry_rcu(handle, &dev->h_list, d_node)
 			if (handle->open) {
-				count = input_to_handler(handle, vals, count);
+				count = handle->handler->events(handle, vals,
+								count);
 				if (!count)
 					break;
 			}
@@ -2537,6 +2503,47 @@ 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;
+}
+
 /**
  * input_register_handler - register a new input handler
  * @handler: handler to be registered
@@ -2554,12 +2561,17 @@ int input_register_handler(struct input_handler *handler)
 	if (error)
 		return error;
 
+	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;
+
 	error = mutex_lock_interruptible(&input_mutex);
 	if (error)
 		return error;
 
-	INIT_LIST_HEAD(&handler->h_list);
-
 	list_add_tail(&handler->node, &input_handler_list);
 
 	list_for_each_entry(dev, &input_dev_list, node)
-- 
2.45.2.803.g4e1b14247a-goog