linux-kernel - [PATCH 1/1 RFC] drivers: cacheinfo: use __free attribute instead of of_node

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Date: Sat, 22 Jun 2024 17:25:26 +0200
From: Vincenzo Mezzela <vincenzo.mezzela@...il.com>
To: gregkh@...uxfoundation.org,
	rafael@...nel.org
Cc: linux-kernel@...r.kernel.org,
	javier.carrasco.cruz@...il.com,
	julia.lawall@...ia.fr,
	skhan@...uxfoundation.org,
	Vincenzo Mezzela <vincenzo.mezzela@...il.com>
Subject: [PATCH 1/1 RFC] drivers: cacheinfo: use __free attribute instead of of_node_put()

Introduce the __free attribute for scope-based resource management.
Resources allocated with __free are automatically released at the end of
the scope. This enhancement aims to mitigate memory management issues
associated with forgetting to release resources by utilizing __free
instead of of_node_put().

Suggested-by: Julia Lawall <julia.lawall@...ia.fr>
Signed-off-by: Vincenzo Mezzela <vincenzo.mezzela@...il.com>
---
 drivers/base/cacheinfo.c | 41 +++++++++++++---------------------------
 1 file changed, 13 insertions(+), 28 deletions(-)

diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index 23b8cba4a2a3..acab52dd7fb8 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -202,29 +202,24 @@ static void cache_of_set_props(struct cacheinfo *this_leaf,
 
 static int cache_setup_of_node(unsigned int cpu)
 {
-	struct device_node *np, *prev;
 	struct cacheinfo *this_leaf;
 	unsigned int index = 0;
 
-	np = of_cpu_device_node_get(cpu);
+	struct device_node __free(device_node) *np = of_cpu_device_node_get(cpu);
 	if (!np) {
 		pr_err("Failed to find cpu%d device node\n", cpu);
 		return -ENOENT;
 	}
 
 	if (!of_check_cache_nodes(np)) {
-		of_node_put(np);
 		return -ENOENT;
 	}
 
-	prev = np;
-
 	while (index < cache_leaves(cpu)) {
 		this_leaf = per_cpu_cacheinfo_idx(cpu, index);
 		if (this_leaf->level != 1) {
+			struct device_node __free(device_node) *prev = np;
 			np = of_find_next_cache_node(np);
-			of_node_put(prev);
-			prev = np;
 			if (!np)
 				break;
 		}
@@ -233,8 +228,6 @@ static int cache_setup_of_node(unsigned int cpu)
 		index++;
 	}
 
-	of_node_put(np);
-
 	if (index != cache_leaves(cpu)) /* not all OF nodes populated */
 		return -ENOENT;
 
@@ -243,17 +236,14 @@ static int cache_setup_of_node(unsigned int cpu)
 
 static bool of_check_cache_nodes(struct device_node *np)
 {
-	struct device_node *next;
-
 	if (of_property_present(np, "cache-size")   ||
 	    of_property_present(np, "i-cache-size") ||
 	    of_property_present(np, "d-cache-size") ||
 	    of_property_present(np, "cache-unified"))
 		return true;
 
-	next = of_find_next_cache_node(np);
+	struct device_node __free(device_node) *next = of_find_next_cache_node(np);
 	if (next) {
-		of_node_put(next);
 		return true;
 	}
 
@@ -287,12 +277,10 @@ static int of_count_cache_leaves(struct device_node *np)
 int init_of_cache_level(unsigned int cpu)
 {
 	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
-	struct device_node *np = of_cpu_device_node_get(cpu);
-	struct device_node *prev = NULL;
+	struct device_node __free(device_node) *np = of_cpu_device_node_get(cpu);
 	unsigned int levels = 0, leaves, level;
 
 	if (!of_check_cache_nodes(np)) {
-		of_node_put(np);
 		return -ENOENT;
 	}
 
@@ -300,30 +288,27 @@ int init_of_cache_level(unsigned int cpu)
 	if (leaves > 0)
 		levels = 1;
 
-	prev = np;
-	while ((np = of_find_next_cache_node(np))) {
-		of_node_put(prev);
-		prev = np;
+	while (1) {
+		struct device_node __free(device_node) *prev = np;
+		np = of_find_next_cache_node(np);
+		if (!np)
+			break;
+
 		if (!of_device_is_compatible(np, "cache"))
-			goto err_out;
+			return -EINVAL;
 		if (of_property_read_u32(np, "cache-level", &level))
-			goto err_out;
+			return -EINVAL;
 		if (level <= levels)
-			goto err_out;
+			return -EINVAL;
 
 		leaves += of_count_cache_leaves(np);
 		levels = level;
 	}
 
-	of_node_put(np);
 	this_cpu_ci->num_levels = levels;
 	this_cpu_ci->num_leaves = leaves;
 
 	return 0;
-
-err_out:
-	of_node_put(np);
-	return -EINVAL;
 }
 
 #else
-- 
2.43.0