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From: Vincenzo Mezzela <vincenzo.mezzela@gmail.com>
To: sudeep.holla@arm.com
Cc: vincenzo.mezzela@gmail.com,
	gregkh@linuxfoundation.org,
	javier.carrasco.cruz@gmail.com,
	julia.lawall@inria.fr,
	linux-kernel@vger.kernel.org,
	rafael@kernel.org,
	skhan@linuxfoundation.org
Subject: [PATCH 2/2 v4] drivers: arch_topology: use __free attribute instead of of_node_put()
Date: Mon, 13 May 2024 10:13:04 +0200
Message-Id: <20240513081304.499915-3-vincenzo.mezzela@gmail.com>
In-Reply-To: <20240513081304.499915-1-vincenzo.mezzela@gmail.com>
References: <20240501094313.407820-1-vincenzo.mezzela@gmail.com>
 <20240513081304.499915-1-vincenzo.mezzela@gmail.com>
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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().

The declaration of the device_node used within the do-while loops is
moved directly within the loop so that the resource is automatically
freed at the end of each iteration.

Suggested-by: Julia Lawall <julia.lawall@inria.fr>
Signed-off-by: Vincenzo Mezzela <vincenzo.mezzela@gmail.com>
---
 drivers/base/arch_topology.c | 56 +++++++++++++++++-------------------
 1 file changed, 26 insertions(+), 30 deletions(-)

diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index 0115011b7a99..93c9f0499694 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -8,6 +8,7 @@
 
 #include <linux/acpi.h>
 #include <linux/cacheinfo.h>
+#include <linux/cleanup.h>
 #include <linux/cpu.h>
 #include <linux/cpufreq.h>
 #include <linux/device.h>
@@ -513,10 +514,10 @@ core_initcall(free_raw_capacity);
  */
 static int __init get_cpu_for_node(struct device_node *node)
 {
-	struct device_node *cpu_node;
 	int cpu;
+	struct device_node *cpu_node __free(device_node) =
+		of_parse_phandle(node, "cpu", 0);
 
-	cpu_node = of_parse_phandle(node, "cpu", 0);
 	if (!cpu_node)
 		return -1;
 
@@ -527,7 +528,6 @@ static int __init get_cpu_for_node(struct device_node *node)
 		pr_info("CPU node for %pOF exist but the possible cpu range is :%*pbl\n",
 			cpu_node, cpumask_pr_args(cpu_possible_mask));
 
-	of_node_put(cpu_node);
 	return cpu;
 }
 
@@ -538,11 +538,12 @@ static int __init parse_core(struct device_node *core, int package_id,
 	bool leaf = true;
 	int i = 0;
 	int cpu;
-	struct device_node *t;
 
 	do {
 		snprintf(name, sizeof(name), "thread%d", i);
-		t = of_get_child_by_name(core, name);
+		struct device_node *t __free(device_node) =
+			of_get_child_by_name(core, name);
+
 		if (!t)
 			break;
 
@@ -555,10 +556,8 @@ static int __init parse_core(struct device_node *core, int package_id,
 			cpu_topology[cpu].thread_id = i;
 		} else if (cpu != -ENODEV) {
 			pr_err("%pOF: Can't get CPU for thread\n", t);
-			of_node_put(t);
 			return -EINVAL;
 		}
-		of_node_put(t);
 		i++;
 	} while (1);
 
@@ -587,7 +586,6 @@ static int __init parse_cluster(struct device_node *cluster, int package_id,
 	char name[20];
 	bool leaf = true;
 	bool has_cores = false;
-	struct device_node *c;
 	int core_id = 0;
 	int i, ret;
 
@@ -599,7 +597,9 @@ static int __init parse_cluster(struct device_node *cluster, int package_id,
 	i = 0;
 	do {
 		snprintf(name, sizeof(name), "cluster%d", i);
-		c = of_get_child_by_name(cluster, name);
+		struct device_node *c __free(device_node) =
+			of_get_child_by_name(cluster, name);
+
 		if (!c)
 			break;
 
@@ -607,7 +607,6 @@ static int __init parse_cluster(struct device_node *cluster, int package_id,
 		ret = parse_cluster(c, package_id, i, depth + 1);
 		if (depth > 0)
 			pr_warn("Topology for clusters of clusters not yet supported\n");
-		of_node_put(c);
 		if (ret != 0)
 			return ret;
 		i++;
@@ -617,7 +616,9 @@ static int __init parse_cluster(struct device_node *cluster, int package_id,
 	i = 0;
 	do {
 		snprintf(name, sizeof(name), "core%d", i);
-		c = of_get_child_by_name(cluster, name);
+		struct device_node *c __free(device_node) =
+			of_get_child_by_name(cluster, name);
+
 		if (!c)
 			break;
 
@@ -625,21 +626,19 @@ static int __init parse_cluster(struct device_node *cluster, int package_id,
 
 		if (depth == 0) {
 			pr_err("%pOF: cpu-map children should be clusters\n", c);
-			of_node_put(c);
 			return -EINVAL;
 		}
 
 		if (leaf) {
 			ret = parse_core(c, package_id, cluster_id, core_id++);
+			if (ret != 0)
+				return ret;
 		} else {
 			pr_err("%pOF: Non-leaf cluster with core %s\n",
 			       cluster, name);
-			ret = -EINVAL;
+			return -EINVAL;
 		}
 
-		of_node_put(c);
-		if (ret != 0)
-			return ret;
 		i++;
 	} while (1);
 
@@ -652,19 +651,19 @@ static int __init parse_cluster(struct device_node *cluster, int package_id,
 static int __init parse_socket(struct device_node *socket)
 {
 	char name[20];
-	struct device_node *c;
 	bool has_socket = false;
 	int package_id = 0, ret;
 
 	do {
 		snprintf(name, sizeof(name), "socket%d", package_id);
-		c = of_get_child_by_name(socket, name);
+		struct device_node *c __free(device_node) =
+			of_get_child_by_name(socket, name);
+
 		if (!c)
 			break;
 
 		has_socket = true;
 		ret = parse_cluster(c, package_id, -1, 0);
-		of_node_put(c);
 		if (ret != 0)
 			return ret;
 
@@ -679,11 +678,11 @@ static int __init parse_socket(struct device_node *socket)
 
 static int __init parse_dt_topology(void)
 {
-	struct device_node *cn, *map;
 	int ret = 0;
 	int cpu;
+	struct device_node *cn __free(device_node) =
+		of_find_node_by_path("/cpus");
 
-	cn = of_find_node_by_path("/cpus");
 	if (!cn) {
 		pr_err("No CPU information found in DT\n");
 		return 0;
@@ -693,13 +692,15 @@ static int __init parse_dt_topology(void)
 	 * When topology is provided cpu-map is essentially a root
 	 * cluster with restricted subnodes.
 	 */
-	map = of_get_child_by_name(cn, "cpu-map");
+	struct device_node *map __free(device_node) =
+		of_get_child_by_name(cn, "cpu-map");
+
 	if (!map)
-		goto out;
+		return ret;
 
 	ret = parse_socket(map);
 	if (ret != 0)
-		goto out_map;
+		return ret;
 
 	topology_normalize_cpu_scale();
 
@@ -709,14 +710,9 @@ static int __init parse_dt_topology(void)
 	 */
 	for_each_possible_cpu(cpu)
 		if (cpu_topology[cpu].package_id < 0) {
-			ret = -EINVAL;
-			break;
+			return -EINVAL;
 		}
 
-out_map:
-	of_node_put(map);
-out:
-	of_node_put(cn);
 	return ret;
 }
 #endif
-- 
2.34.1