Re: [PATCH v2 04/11] thermal: core: Manage thermal_list_lock using a mutex guard

Lukasz Luba
2024-10-22T22:49:29Z

On 10/10/24 23:10, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Switch over the thermal core to using a mutex guard for
> thermal_list_lock management.
>
> No intentional functional impact.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>
> This is a resend of
>
> https://lore.kernel.org/linux-pm/2018087.usQuhbGJ8B@rjwysocki.net/
>
> ---
> drivers/thermal/thermal_core.c | 148 ++++++++++++++++++-----------------------
> 1 file changed, 68 insertions(+), 80 deletions(-)
>
> Index: linux-pm/drivers/thermal/thermal_core.c
> ===================================================================
> --- linux-pm.orig/drivers/thermal/thermal_core.c
> +++ linux-pm/drivers/thermal/thermal_core.c
> @@ -140,7 +140,7 @@ int thermal_register_governor(struct the
> def_governor = governor;
> }
>
> - mutex_lock(&thermal_list_lock);
> + guard(mutex)(&thermal_list_lock);
>
> list_for_each_entry(pos, &thermal_tz_list, node) {
> /*
> @@ -163,7 +163,6 @@ int thermal_register_governor(struct the
> }
> }
>
> - mutex_unlock(&thermal_list_lock);
> mutex_unlock(&thermal_governor_lock);
>
> return err;
> @@ -181,7 +180,9 @@ void thermal_unregister_governor(struct
> if (!__find_governor(governor->name))
> goto exit;
>
> - mutex_lock(&thermal_list_lock);
> + list_del(&governor->governor_list);
> +
> + guard(mutex)(&thermal_list_lock);
>
> list_for_each_entry(pos, &thermal_tz_list, node) {
> if (!strncasecmp(pos->governor->name, governor->name,
> @@ -189,8 +190,6 @@ void thermal_unregister_governor(struct
> thermal_set_governor(pos, NULL);
> }
>
> - mutex_unlock(&thermal_list_lock);
> - list_del(&governor->governor_list);
> exit:
> mutex_unlock(&thermal_governor_lock);
> }
> @@ -686,51 +685,52 @@ int for_each_thermal_cooling_device(int
> void *), void *data)
> {
> struct thermal_cooling_device *cdev;
> - int ret = 0;
>
> - mutex_lock(&thermal_list_lock);
> + guard(mutex)(&thermal_list_lock);
> +
> list_for_each_entry(cdev, &thermal_cdev_list, node) {
> + int ret;
> +
> ret = cb(cdev, data);
> if (ret)
> - break;
> + return ret;
> }
> - mutex_unlock(&thermal_list_lock);
>
> - return ret;
> + return 0;
> }
>
> int for_each_thermal_zone(int (*cb)(struct thermal_zone_device *, void *),
> void *data)
> {
> struct thermal_zone_device *tz;
> - int ret = 0;
>
> - mutex_lock(&thermal_list_lock);
> + guard(mutex)(&thermal_list_lock);
> +
> list_for_each_entry(tz, &thermal_tz_list, node) {
> + int ret;
> +
> ret = cb(tz, data);
> if (ret)
> - break;
> + return ret;
> }
> - mutex_unlock(&thermal_list_lock);
>
> - return ret;
> + return 0;
> }
>
> struct thermal_zone_device *thermal_zone_get_by_id(int id)
> {
> - struct thermal_zone_device *tz, *match = NULL;
> + struct thermal_zone_device *tz;
> +
> + guard(mutex)(&thermal_list_lock);
>
> - 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;
> + return tz;
> }
> }
> - mutex_unlock(&thermal_list_lock);
>
> - return match;
> + return NULL;
> }
>
> /*
> @@ -969,14 +969,12 @@ static void thermal_cooling_device_init_
> {
> struct thermal_zone_device *tz;
>
> - mutex_lock(&thermal_list_lock);
> + guard(mutex)(&thermal_list_lock);
>
> list_add(&cdev->node, &thermal_cdev_list);
>
> list_for_each_entry(tz, &thermal_tz_list, node)
> thermal_zone_cdev_bind(tz, cdev);
> -
> - mutex_unlock(&thermal_list_lock);
> }
>
> /**
> @@ -1210,10 +1208,10 @@ void thermal_cooling_device_update(struc
> * Hold thermal_list_lock throughout the update to prevent the device
> * from going away while being updated.
> */
> - mutex_lock(&thermal_list_lock);
> + guard(mutex)(&thermal_list_lock);
>
> if (!thermal_cooling_device_present(cdev))
> - goto unlock_list;
> + return;
>
> /*
> * Update under the cdev lock to prevent the state from being set beyond
> @@ -1255,9 +1253,6 @@ void thermal_cooling_device_update(struc
>
> unlock:
> mutex_unlock(&cdev->lock);
> -
> -unlock_list:
> - mutex_unlock(&thermal_list_lock);
> }
> EXPORT_SYMBOL_GPL(thermal_cooling_device_update);
>
> @@ -1281,24 +1276,18 @@ static void thermal_zone_cdev_unbind(str
> static bool thermal_cooling_device_exit(struct thermal_cooling_device *cdev)
> {
> struct thermal_zone_device *tz;
> - bool ret = true;
>
> - mutex_lock(&thermal_list_lock);
> + guard(mutex)(&thermal_list_lock);
>
> - if (!thermal_cooling_device_present(cdev)) {
> - ret = false;
> - goto unlock;
> - }
> + if (!thermal_cooling_device_present(cdev))
> + return false;
>
> list_del(&cdev->node);
>
> list_for_each_entry(tz, &thermal_tz_list, node)
> thermal_zone_cdev_unbind(tz, cdev);
>
> -unlock:
> - mutex_unlock(&thermal_list_lock);
> -
> - return ret;
> + return true;
> }
>
> /**
> @@ -1345,7 +1334,7 @@ static void thermal_zone_init_complete(s
> {
> struct thermal_cooling_device *cdev;
>
> - mutex_lock(&thermal_list_lock);
> + guard(mutex)(&thermal_list_lock);
>
> list_add_tail(&tz->node, &thermal_tz_list);
>
> @@ -1365,8 +1354,6 @@ static void thermal_zone_init_complete(s
> tz->state |= TZ_STATE_FLAG_SUSPENDED;
>
> __thermal_zone_device_update(tz, THERMAL_EVENT_UNSPECIFIED);
> -
> - mutex_unlock(&thermal_list_lock);
> }
>
> /**
> @@ -1587,14 +1574,11 @@ EXPORT_SYMBOL_GPL(thermal_zone_device);
> static bool thermal_zone_exit(struct thermal_zone_device *tz)
> {
> struct thermal_cooling_device *cdev;
> - bool ret = true;
>
> - mutex_lock(&thermal_list_lock);
> + guard(mutex)(&thermal_list_lock);
>
> - if (list_empty(&tz->node)) {
> - ret = false;
> - goto unlock;
> - }
> + if (list_empty(&tz->node))
> + return false;
>
> guard(thermal_zone)(tz);
>
> @@ -1605,10 +1589,7 @@ static bool thermal_zone_exit(struct the
> list_for_each_entry(cdev, &thermal_cdev_list, node)
> __thermal_zone_cdev_unbind(tz, cdev);
>
> -unlock:
> - mutex_unlock(&thermal_list_lock);
> -
> - return ret;
> + return true;
> }
>
> /**
> @@ -1660,24 +1641,23 @@ struct thermal_zone_device *thermal_zone
> unsigned int found = 0;
>
> if (!name)
> - goto exit;
> + return ERR_PTR(-EINVAL);
> +
> + guard(mutex)(&thermal_list_lock);
>
> - mutex_lock(&thermal_list_lock);
> list_for_each_entry(pos, &thermal_tz_list, node)
> if (!strncasecmp(name, pos->type, THERMAL_NAME_LENGTH)) {
> found++;
> ref = pos;
> }
> - mutex_unlock(&thermal_list_lock);
>
> - /* nothing has been found, thus an error code for it */
> - if (found == 0)
> - ref = ERR_PTR(-ENODEV);
> - else if (found > 1)
> - /* Success only when an unique zone is found */
> - ref = ERR_PTR(-EEXIST);
> + if (!found)
> + return ERR_PTR(-ENODEV);
> +
> + /* Success only when one zone is found. */
> + if (found > 1)
> + return ERR_PTR(-EEXIST);
>
> -exit:
> return ref;
> }
> EXPORT_SYMBOL_GPL(thermal_zone_get_zone_by_name);
> @@ -1718,6 +1698,18 @@ static void thermal_zone_pm_prepare(stru
> tz->state |= TZ_STATE_FLAG_SUSPENDED;
> }
>
> +static void thermal_pm_notify_prepare(void)
> +{
> + struct thermal_zone_device *tz;
> +
> + guard(mutex)(&thermal_list_lock);
> +
> + thermal_pm_suspended = true;
> +
> + list_for_each_entry(tz, &thermal_tz_list, node)
> + thermal_zone_pm_prepare(tz);
> +}
> +
> static void thermal_zone_pm_complete(struct thermal_zone_device *tz)
> {
> guard(thermal_zone)(tz);
> @@ -1736,35 +1728,31 @@ static void thermal_zone_pm_complete(str
> mod_delayed_work(system_freezable_power_efficient_wq, &tz->poll_queue, 0);
> }
>
> -static int thermal_pm_notify(struct notifier_block *nb,
> - unsigned long mode, void *_unused)
> +static void thermal_pm_notify_complete(void)
> {
> struct thermal_zone_device *tz;
>
> + guard(mutex)(&thermal_list_lock);
> +
> + thermal_pm_suspended = false;
> +
> + list_for_each_entry(tz, &thermal_tz_list, node)
> + thermal_zone_pm_complete(tz);
> +}
> +
> +static int thermal_pm_notify(struct notifier_block *nb,
> + unsigned long mode, void *_unused)
> +{
> switch (mode) {
> case PM_HIBERNATION_PREPARE:
> case PM_RESTORE_PREPARE:
> case PM_SUSPEND_PREPARE:
> - mutex_lock(&thermal_list_lock);
> -
> - thermal_pm_suspended = true;
> -
> - list_for_each_entry(tz, &thermal_tz_list, node)
> - thermal_zone_pm_prepare(tz);
> -
> - mutex_unlock(&thermal_list_lock);
> + thermal_pm_notify_prepare();
> break;
> case PM_POST_HIBERNATION:
> case PM_POST_RESTORE:
> case PM_POST_SUSPEND:
> - mutex_lock(&thermal_list_lock);
> -
> - thermal_pm_suspended = false;
> -
> - list_for_each_entry(tz, &thermal_tz_list, node)
> - thermal_zone_pm_complete(tz);
> -
> - mutex_unlock(&thermal_list_lock);
> + thermal_pm_notify_complete();
> break;
> default:
> break;
>
>
>

Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>