[PATCH 2/2 v3] drivers: use __free attribute instead of of_node_put()

From: Vincenzo Mezzela
Date: Wed May 01 2024 - 05:43:54 EST


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@xxxxxxxx>
Signed-off-by: Vincenzo Mezzela <vincenzo.mezzela@xxxxxxxxx>
---
drivers/base/arch_topology.c | 51 +++++++++++++++---------------------
1 file changed, 21 insertions(+), 30 deletions(-)

diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index ea8836f0bb4b..eef26e304018 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;

- cpu_node = of_parse_phandle(node, "cpu", 0);
+ struct device_node *cpu_node __free(device_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 +538,11 @@ 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 +555,8 @@ 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 +585,6 @@ 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 +596,8 @@ 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 +605,6 @@ 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 +614,8 @@ 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 +623,19 @@ 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 +648,18 @@ 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 +674,11 @@ 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;

- cn = of_find_node_by_path("/cpus");
+ struct device_node *cn __free(device_node) =
+ of_find_node_by_path("/cpus");
if (!cn) {
pr_err("No CPU information found in DT\n");
return 0;
@@ -693,13 +688,14 @@ 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 +705,9 @@ 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