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Subject[PATCH] drivers: use __free attribute instead of of_node_put()
Date
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 | 41 ++++++++++++++----------------------
1 file changed, 16 insertions(+), 25 deletions(-)

diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index 024b78a0cfc1..58eeb8183747 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -513,10 +513,10 @@ 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 +527,6 @@ 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 +537,11 @@ 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) {
leaf = false;
cpu = get_cpu_for_node(t);
@@ -553,10 +552,8 @@ 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 (t);
@@ -586,7 +583,6 @@ 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;

@@ -598,13 +594,13 @@ 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) {
leaf = false;
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;
}
@@ -615,14 +611,14 @@ 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) {
has_cores = true;

if (depth == 0) {
pr_err("%pOF: cpu-map children should be clusters\n",
c);
- of_node_put(c);
return -EINVAL;
}

@@ -635,7 +631,6 @@ static int __init parse_cluster(struct device_node *cluster, int package_id,
ret = -EINVAL;
}

- of_node_put(c);
if (ret != 0)
return ret;
}
@@ -651,17 +646,16 @@ 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) {
has_socket = true;
ret = parse_cluster(c, package_id, -1, 0);
- of_node_put(c);
if (ret != 0)
return ret;
}
@@ -676,11 +670,11 @@ 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;
@@ -690,13 +684,14 @@ 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(devide_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();

@@ -710,10 +705,6 @@ static int __init parse_dt_topology(void)
break;
}

-out_map:
- of_node_put(map);
-out:
- of_node_put(cn);
return ret;
}
#endif
--
2.34.1

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