Input: rmi4 - refactor function allocation and registration

Currently, rmi_create_function() allocates memory for the rmi_function
structure, but rmi_register_function() initializes the device via
device_initialize(). This split of ownership makes error handling in
rmi_create_function() confusing because the caller must be aware that
if rmi_register_function() fails, it has already called put_device() to
clean up the memory.

To make the memory lifecycle explicit and fix potential leaks cleanly
introduce rmi_alloc_function() to handle memory allocation and device
initialization, and make the caller of rmi_register_function()
responsible for cleanup.

Assisted-by: Gemini:gemini-3.1-pro
Link: https://patch.msgid.link/20260505045952.1570713-10-dmitry.torokhov@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

3 files changed, 26 insertions, 17 deletions

diff --git a/drivers/input/rmi4/rmi_bus.c b/drivers/input/rmi4/rmi_bus.c
index ade57e2a7201..c58866df555d 100644
--- a/drivers/input/rmi4/rmi_bus.c
+++ b/drivers/input/rmi4/rmi_bus.c
@@ -237,36 +237,46 @@ static int rmi_function_remove(struct device *dev)
 	return 0;
 }
 
-int rmi_register_function(struct rmi_function *fn)
+struct rmi_function *rmi_alloc_function(struct rmi_device *rmi_dev, u8 id)
 {
-	struct rmi_device *rmi_dev = fn->rmi_dev;
-	int error;
+	struct rmi_driver_data *data = dev_get_drvdata(&rmi_dev->dev);
+	struct rmi_function *fn;
+
+	fn = kzalloc(sizeof(*fn) +
+			BITS_TO_LONGS(data->irq_count) * sizeof(unsigned long),
+		     GFP_KERNEL);
+	if (!fn)
+		return NULL;
 
 	device_initialize(&fn->dev);
 
-	dev_set_name(&fn->dev, "%s.fn%02x",
-		     dev_name(&rmi_dev->dev), fn->fd.function_number);
+	dev_set_name(&fn->dev, "%s.fn%02x", dev_name(&rmi_dev->dev), id);
 
 	fn->dev.parent = &rmi_dev->dev;
 	fn->dev.type = &rmi_function_type;
 	fn->dev.bus = &rmi_bus_type;
+	fn->rmi_dev = rmi_dev;
+
+	return fn;
+}
+
+int rmi_register_function(struct rmi_function *fn)
+{
+	struct rmi_device *rmi_dev = fn->rmi_dev;
+	int error;
 
 	error = device_add(&fn->dev);
 	if (error) {
 		dev_err(&rmi_dev->dev,
-			"Failed device_register function device %s\n",
+			"Failed to register function device %s\n",
 			dev_name(&fn->dev));
-		goto err_put_device;
+		return error;
 	}
 
 	rmi_dbg(RMI_DEBUG_CORE, &rmi_dev->dev, "Registered F%02X.\n",
 			fn->fd.function_number);
 
 	return 0;
-
-err_put_device:
-	put_device(&fn->dev);
-	return error;
 }
 
 void rmi_unregister_function(struct rmi_function *fn)
diff --git a/drivers/input/rmi4/rmi_bus.h b/drivers/input/rmi4/rmi_bus.h
index d4d0d82c69aa..90122df21f74 100644
--- a/drivers/input/rmi4/rmi_bus.h
+++ b/drivers/input/rmi4/rmi_bus.h
@@ -49,6 +49,7 @@ struct rmi_function {
 
 bool rmi_is_function_device(struct device *dev);
 
+struct rmi_function *rmi_alloc_function(struct rmi_device *rmi_dev, u8 id);
 int __must_check rmi_register_function(struct rmi_function *);
 void rmi_unregister_function(struct rmi_function *);
 
diff --git a/drivers/input/rmi4/rmi_driver.c b/drivers/input/rmi4/rmi_driver.c
index 94b49e4dd0fa..2ac82cd3ff6d 100644
--- a/drivers/input/rmi4/rmi_driver.c
+++ b/drivers/input/rmi4/rmi_driver.c
@@ -872,9 +872,7 @@ static int rmi_create_function(struct rmi_device *rmi_dev,
 	rmi_dbg(RMI_DEBUG_CORE, dev, "Initializing F%02X.\n",
 			pdt->function_number);
 
-	fn = kzalloc(sizeof(struct rmi_function) +
-			BITS_TO_LONGS(data->irq_count) * sizeof(unsigned long),
-		     GFP_KERNEL);
+	fn = rmi_alloc_function(rmi_dev, pdt->function_number);
 	if (!fn) {
 		dev_err(dev, "Failed to allocate memory for F%02X\n",
 			pdt->function_number);
@@ -884,8 +882,6 @@ static int rmi_create_function(struct rmi_device *rmi_dev,
 	INIT_LIST_HEAD(&fn->node);
 	rmi_driver_copy_pdt_to_fd(pdt, &fn->fd);
 
-	fn->rmi_dev = rmi_dev;
-
 	fn->num_of_irqs = pdt->interrupt_source_count;
 	fn->irq_pos = *current_irq_count;
 	*current_irq_count += fn->num_of_irqs;
@@ -894,8 +890,10 @@ static int rmi_create_function(struct rmi_device *rmi_dev,
 		set_bit(fn->irq_pos + i, fn->irq_mask);
 
 	error = rmi_register_function(fn);
-	if (error)
+	if (error) {
+		put_device(&fn->dev);
 		return error;
+	}
 
 	if (pdt->function_number == 0x01)
 		data->f01_container = fn;