[SRU][J][PATCH 06/12] gpio: aggregator: add gpio_aggregator_{alloc, free}()

[Koichiro Den]

BugLink: https://bugs.launchpad.net/bugs/2103496

Prepare for the upcoming configfs interface. These functions will be
used by both the existing sysfs interface and the new configfs
interface, reducing code duplication.

No functional change.

Signed-off-by: Koichiro Den <koichiro.den at canonical.com>
Link: https://lore.kernel.org/r/20250407043019.4105613-4-koichiro.den@canonical.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski at linaro.org>
(backported from commit 88fe1d1a646b3b01dcc335c44e7b33ea510f620e linux-next)
[koichiroden:
* adjusted patch to avoid using __free/guard/scoped_guard, which are
  unavailable due to the missing commit:
  54da6a092431 ("locking: Introduce __cleanup() based infrastructure").
* adjusted patch to avoid using list_count_nodes, which is unavailable
  due to the missing commit:
  4d70c74659d9 ("i915: Move list_count() to list.h as list_count_nodes() for broader use")]
Signed-off-by: Koichiro Den <koichiro.den at canonical.com>
---
 drivers/gpio/gpio-aggregator.c | 60 +++++++++++++++++++++-------------
 1 file changed, 38 insertions(+), 22 deletions(-)

diff --git a/drivers/gpio/gpio-aggregator.c b/drivers/gpio/gpio-aggregator.c
index 8d3ba67fa85f..a81dfb401afa 100644
--- a/drivers/gpio/gpio-aggregator.c
+++ b/drivers/gpio/gpio-aggregator.c
@@ -33,12 +33,43 @@
 struct gpio_aggregator {
 	struct gpiod_lookup_table *lookups;
 	struct platform_device *pdev;
+	int id;
 	char args[];
 };
 
 static DEFINE_MUTEX(gpio_aggregator_lock);	/* protects idr */
 static DEFINE_IDR(gpio_aggregator_idr);
 
+static int gpio_aggregator_alloc(struct gpio_aggregator **aggr, size_t arg_size)
+{
+	struct gpio_aggregator *new = NULL;
+	int ret;
+
+	new = kzalloc(sizeof(*new) + arg_size, GFP_KERNEL);
+	if (!new)
+		return -ENOMEM;
+
+	mutex_lock(&gpio_aggregator_lock);
+	ret = idr_alloc(&gpio_aggregator_idr, new, 0, 0, GFP_KERNEL);
+	mutex_unlock(&gpio_aggregator_lock);
+	if (ret < 0) {
+		kfree(new);
+		return ret;
+	}
+
+	new->id = ret;
+	*aggr = new;
+	return 0;
+}
+
+static void gpio_aggregator_free(struct gpio_aggregator *aggr)
+{
+	mutex_lock(&gpio_aggregator_lock);
+	idr_remove(&gpio_aggregator_idr, aggr->id);
+	mutex_unlock(&gpio_aggregator_lock);
+	kfree(aggr);
+}
+
 static int gpio_aggregator_add_gpio(struct gpio_aggregator *aggr,
 				    const char *key, int hwnum, unsigned int *n)
 {
@@ -346,17 +377,15 @@ static ssize_t gpio_aggregator_new_device_store(struct device_driver *driver,
 {
 	struct gpio_aggregator *aggr;
 	struct platform_device *pdev;
-	int res, id;
+	int res;
 
 	if (!try_module_get(THIS_MODULE))
 		return -ENOENT;
 
 	/* kernfs guarantees string termination, so count + 1 is safe */
-	aggr = kzalloc(sizeof(*aggr) + count + 1, GFP_KERNEL);
-	if (!aggr) {
-		res = -ENOMEM;
+	res = gpio_aggregator_alloc(&aggr, count + 1);
+	if (res)
 		goto put_module;
-	}
 
 	memcpy(aggr->args, buf, count + 1);
 
@@ -367,19 +396,10 @@ static ssize_t gpio_aggregator_new_device_store(struct device_driver *driver,
 		goto free_ga;
 	}
 
-	mutex_lock(&gpio_aggregator_lock);
-	id = idr_alloc(&gpio_aggregator_idr, aggr, 0, 0, GFP_KERNEL);
-	mutex_unlock(&gpio_aggregator_lock);
-
-	if (id < 0) {
-		res = id;
-		goto free_table;
-	}
-
-	aggr->lookups->dev_id = kasprintf(GFP_KERNEL, "%s.%d", DRV_NAME, id);
+	aggr->lookups->dev_id = kasprintf(GFP_KERNEL, "%s.%d", DRV_NAME, aggr->id);
 	if (!aggr->lookups->dev_id) {
 		res = -ENOMEM;
-		goto remove_idr;
+		goto free_table;
 	}
 
 	res = gpio_aggregator_parse(aggr);
@@ -388,7 +408,7 @@ static ssize_t gpio_aggregator_new_device_store(struct device_driver *driver,
 
 	gpiod_add_lookup_table(aggr->lookups);
 
-	pdev = platform_device_register_simple(DRV_NAME, id, NULL, 0);
+	pdev = platform_device_register_simple(DRV_NAME, aggr->id, NULL, 0);
 	if (IS_ERR(pdev)) {
 		res = PTR_ERR(pdev);
 		goto remove_table;
@@ -402,14 +422,10 @@ static ssize_t gpio_aggregator_new_device_store(struct device_driver *driver,
 	gpiod_remove_lookup_table(aggr->lookups);
 free_dev_id:
 	kfree(aggr->lookups->dev_id);
-remove_idr:
-	mutex_lock(&gpio_aggregator_lock);
-	idr_remove(&gpio_aggregator_idr, id);
-	mutex_unlock(&gpio_aggregator_lock);
 free_table:
 	kfree(aggr->lookups);
 free_ga:
-	kfree(aggr);
+	gpio_aggregator_free(aggr);
 put_module:
 	module_put(THIS_MODULE);
 	return res;
-- 
2.45.2