[PATCH v2 1/2] thermal: core: Reference count the zone in thermal_zone_get_by_id()

From: Rafael J. Wysocki
Date: Thu Oct 03 2024 - 08:28:10 EST


From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

There are places in the thermal netlink code where nothing prevents
the thermal zone object from going away while being accessed after it
has been returned by thermal_zone_get_by_id().

To address this, make thermal_zone_get_by_id() get a reference on the
thermal zone device object to be returned with the help of get_device(),
under thermal_list_lock, and adjust all of its callers to this change
with the help of the cleanup.h infrastructure.

Fixes: 1ce50e7d408e ("thermal: core: genetlink support for events/cmd/sampling")
Cc: 6.8+ <stable@xxxxxxxxxxxxxxx> # 6.8+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---

v1 -> v2: Use the cleanup.h infrastructure to reduce the amount of code changes.

---
drivers/thermal/thermal_core.c | 1 +
drivers/thermal/thermal_core.h | 3 +++
drivers/thermal/thermal_netlink.c | 9 +++------
3 files changed, 7 insertions(+), 6 deletions(-)

Index: linux-pm/drivers/thermal/thermal_core.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_core.c
+++ linux-pm/drivers/thermal/thermal_core.c
@@ -728,6 +728,7 @@ struct thermal_zone_device *thermal_zone
mutex_lock(&thermal_list_lock);
list_for_each_entry(tz, &thermal_tz_list, node) {
if (tz->id == id) {
+ get_device(&tz->device);
match = tz;
break;
}
Index: linux-pm/drivers/thermal/thermal_core.h
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_core.h
+++ linux-pm/drivers/thermal/thermal_core.h
@@ -194,6 +194,9 @@ int for_each_thermal_governor(int (*cb)(

struct thermal_zone_device *thermal_zone_get_by_id(int id);

+DEFINE_CLASS(thermal_zone_get_by_id, struct thermal_zone_device *,
+ if (_T) put_device(&_T->device), thermal_zone_get_by_id(id), int id)
+
static inline bool cdev_is_power_actor(struct thermal_cooling_device *cdev)
{
return cdev->ops->get_requested_power && cdev->ops->state2power &&
Index: linux-pm/drivers/thermal/thermal_netlink.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_netlink.c
+++ linux-pm/drivers/thermal/thermal_netlink.c
@@ -443,7 +443,6 @@ static int thermal_genl_cmd_tz_get_trip(
{
struct sk_buff *msg = p->msg;
const struct thermal_trip_desc *td;
- struct thermal_zone_device *tz;
struct nlattr *start_trip;
int id;

@@ -452,7 +451,7 @@ static int thermal_genl_cmd_tz_get_trip(

id = nla_get_u32(p->attrs[THERMAL_GENL_ATTR_TZ_ID]);

- tz = thermal_zone_get_by_id(id);
+ CLASS(thermal_zone_get_by_id, tz)(id);
if (!tz)
return -EINVAL;

@@ -488,7 +487,6 @@ out_cancel_nest:
static int thermal_genl_cmd_tz_get_temp(struct param *p)
{
struct sk_buff *msg = p->msg;
- struct thermal_zone_device *tz;
int temp, ret, id;

if (!p->attrs[THERMAL_GENL_ATTR_TZ_ID])
@@ -496,7 +494,7 @@ static int thermal_genl_cmd_tz_get_temp(

id = nla_get_u32(p->attrs[THERMAL_GENL_ATTR_TZ_ID]);

- tz = thermal_zone_get_by_id(id);
+ CLASS(thermal_zone_get_by_id, tz)(id);
if (!tz)
return -EINVAL;

@@ -514,7 +512,6 @@ static int thermal_genl_cmd_tz_get_temp(
static int thermal_genl_cmd_tz_get_gov(struct param *p)
{
struct sk_buff *msg = p->msg;
- struct thermal_zone_device *tz;
int id, ret = 0;

if (!p->attrs[THERMAL_GENL_ATTR_TZ_ID])
@@ -522,7 +519,7 @@ static int thermal_genl_cmd_tz_get_gov(s

id = nla_get_u32(p->attrs[THERMAL_GENL_ATTR_TZ_ID]);

- tz = thermal_zone_get_by_id(id);
+ CLASS(thermal_zone_get_by_id, tz)(id);
if (!tz)
return -EINVAL;