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Message-ID: <CAJZ5v0h_tsCKpvZuHejCF4qnvJt7+=GqMGc7YgiM=Eu55bKBCg@mail.gmail.com>
Date: Mon, 14 Oct 2024 14:26:02 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc: Linux PM <linux-pm@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
Daniel Lezcano <daniel.lezcano@...aro.org>, Lukasz Luba <lukasz.luba@....com>,
Zhang Rui <rui.zhang@...el.com>,
Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject: Re: [PATCH v2 09/11] thermal: core: Add and use cooling device guard
On Fri, Oct 11, 2024 at 12:22 AM Rafael J. Wysocki <rjw@...ysocki.net> wrote:
>
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>
> Add and use a special guard for cooling devices.
>
> This allows quite a few error code paths to be simplified among
> other things and brings in code size reduction for a good measure.
>
> No intentional functional impact.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>
> This is a new iteration of
>
> https://lore.kernel.org/linux-pm/1890654.atdPhlSkOF@rjwysocki.net/
>
> v1 -> v2: Rearrange cur_state_store()
>
> ---
> drivers/thermal/gov_power_allocator.c | 21 +++++++--------
> drivers/thermal/gov_step_wise.c | 6 ++--
> drivers/thermal/thermal_core.c | 17 +++---------
> drivers/thermal/thermal_debugfs.c | 25 +++++++++++-------
> drivers/thermal/thermal_helpers.c | 19 +++-----------
> drivers/thermal/thermal_sysfs.c | 45 ++++++++++++----------------------
> include/linux/thermal.h | 3 ++
> 7 files changed, 57 insertions(+), 79 deletions(-)
>
> Index: linux-pm/drivers/thermal/thermal_core.c
> ===================================================================
> --- linux-pm.orig/drivers/thermal/thermal_core.c
> +++ linux-pm/drivers/thermal/thermal_core.c
> @@ -756,12 +756,10 @@ static int thermal_instance_add(struct t
>
> list_add_tail(&new_instance->trip_node, &td->thermal_instances);
>
> - mutex_lock(&cdev->lock);
> + guard(cooling_dev)(cdev);
>
> list_add_tail(&new_instance->cdev_node, &cdev->thermal_instances);
>
> - mutex_unlock(&cdev->lock);
> -
> return 0;
> }
>
> @@ -870,11 +868,9 @@ static void thermal_instance_delete(stru
> {
> list_del(&instance->trip_node);
>
> - mutex_lock(&instance->cdev->lock);
> + guard(cooling_dev)(instance->cdev);
>
> list_del(&instance->cdev_node);
> -
> - mutex_unlock(&instance->cdev->lock);
> }
>
> /**
> @@ -1237,10 +1233,10 @@ void thermal_cooling_device_update(struc
> * Update under the cdev lock to prevent the state from being set beyond
> * the new limit concurrently.
> */
> - mutex_lock(&cdev->lock);
> + guard(cooling_dev)(cdev);
>
> if (cdev->ops->get_max_state(cdev, &cdev->max_state))
> - goto unlock;
> + return;
>
> thermal_cooling_device_stats_reinit(cdev);
>
> @@ -1267,12 +1263,9 @@ void thermal_cooling_device_update(struc
> }
>
> if (cdev->ops->get_cur_state(cdev, &state) || state > cdev->max_state)
> - goto unlock;
> + return;
>
> thermal_cooling_device_stats_update(cdev, state);
> -
> -unlock:
> - mutex_unlock(&cdev->lock);
> }
> EXPORT_SYMBOL_GPL(thermal_cooling_device_update);
>
> Index: linux-pm/include/linux/thermal.h
> ===================================================================
> --- linux-pm.orig/include/linux/thermal.h
> +++ linux-pm/include/linux/thermal.h
> @@ -137,6 +137,9 @@ struct thermal_cooling_device {
> #endif
> };
>
> +DEFINE_GUARD(cooling_dev, struct thermal_cooling_device *, mutex_lock(&_T->lock),
> + mutex_unlock(&_T->lock))
> +
> /* Structure to define Thermal Zone parameters */
> struct thermal_zone_params {
> const char *governor_name;
> Index: linux-pm/drivers/thermal/thermal_sysfs.c
> ===================================================================
> --- linux-pm.orig/drivers/thermal/thermal_sysfs.c
> +++ linux-pm/drivers/thermal/thermal_sysfs.c
> @@ -544,14 +544,15 @@ cur_state_store(struct device *dev, stru
> if (state > cdev->max_state)
> return -EINVAL;
>
> - mutex_lock(&cdev->lock);
> + guard(cooling_dev)(cdev);
>
> result = cdev->ops->set_cur_state(cdev, state);
> - if (!result)
> - thermal_cooling_device_stats_update(cdev, state);
> + if (result)
> + return result;
>
> - mutex_unlock(&cdev->lock);
> - return result ? result : count;
> + thermal_cooling_device_stats_update(cdev, state);
> +
> + return count;
> }
>
> static struct device_attribute
> @@ -625,21 +626,18 @@ static ssize_t total_trans_show(struct d
> {
> struct thermal_cooling_device *cdev = to_cooling_device(dev);
> struct cooling_dev_stats *stats;
> - int ret = 0;
> + int ret;
>
> - mutex_lock(&cdev->lock);
> + guard(cooling_dev)(cdev);
>
> stats = cdev->stats;
> if (!stats)
> - goto unlock;
> + return 0;
>
> spin_lock(&stats->lock);
> ret = sprintf(buf, "%u\n", stats->total_trans);
> spin_unlock(&stats->lock);
>
> -unlock:
> - mutex_unlock(&cdev->lock);
> -
> return ret;
> }
>
> @@ -652,11 +650,11 @@ time_in_state_ms_show(struct device *dev
> ssize_t len = 0;
> int i;
>
> - mutex_lock(&cdev->lock);
> + guard(cooling_dev)(cdev);
>
> stats = cdev->stats;
> if (!stats)
> - goto unlock;
> + return 0;
>
> spin_lock(&stats->lock);
>
> @@ -668,9 +666,6 @@ time_in_state_ms_show(struct device *dev
> }
> spin_unlock(&stats->lock);
>
> -unlock:
> - mutex_unlock(&cdev->lock);
> -
> return len;
> }
>
> @@ -682,11 +677,11 @@ reset_store(struct device *dev, struct d
> struct cooling_dev_stats *stats;
> int i, states;
>
> - mutex_lock(&cdev->lock);
> + guard(cooling_dev)(cdev);
>
> stats = cdev->stats;
> if (!stats)
> - goto unlock;
> + return count;
>
> states = cdev->max_state + 1;
>
> @@ -702,9 +697,6 @@ reset_store(struct device *dev, struct d
>
> spin_unlock(&stats->lock);
>
> -unlock:
> - mutex_unlock(&cdev->lock);
> -
> return count;
> }
>
> @@ -716,13 +708,11 @@ static ssize_t trans_table_show(struct d
> ssize_t len = 0;
> int i, j;
>
> - mutex_lock(&cdev->lock);
> + guard(cooling_dev)(cdev);
>
> stats = cdev->stats;
> - if (!stats) {
> - len = -ENODATA;
> - goto unlock;
> - }
> + if (!stats)
> + return -ENODATA;
>
> len += snprintf(buf + len, PAGE_SIZE - len, " From : To\n");
> len += snprintf(buf + len, PAGE_SIZE - len, " : ");
There is one more "goto unlock" statement in this function that needs
to be replaced with "return".
I'll send an update of it shortly.
> @@ -760,9 +750,6 @@ static ssize_t trans_table_show(struct d
> len = -EFBIG;
> }
>
> -unlock:
> - mutex_unlock(&cdev->lock);
> -
> return len;
> }
>
> Index: linux-pm/drivers/thermal/thermal_helpers.c
> ===================================================================
> --- linux-pm.orig/drivers/thermal/thermal_helpers.c
> +++ linux-pm/drivers/thermal/thermal_helpers.c
> @@ -58,17 +58,10 @@ bool thermal_trip_is_bound_to_cdev(struc
> const struct thermal_trip *trip,
> struct thermal_cooling_device *cdev)
> {
> - bool ret;
> -
> guard(thermal_zone)(tz);
> + guard(cooling_dev)(cdev);
>
> - mutex_lock(&cdev->lock);
> -
> - ret = thermal_instance_present(tz, cdev, trip);
> -
> - mutex_unlock(&cdev->lock);
> -
> - return ret;
> + return thermal_instance_present(tz, cdev, trip);
> }
> EXPORT_SYMBOL_GPL(thermal_trip_is_bound_to_cdev);
>
> @@ -197,12 +190,12 @@ void __thermal_cdev_update(struct therma
> */
> void thermal_cdev_update(struct thermal_cooling_device *cdev)
> {
> - mutex_lock(&cdev->lock);
> + guard(cooling_dev)(cdev);
> +
> if (!cdev->updated) {
> __thermal_cdev_update(cdev);
> cdev->updated = true;
> }
> - mutex_unlock(&cdev->lock);
> }
>
> /**
> @@ -211,11 +204,9 @@ void thermal_cdev_update(struct thermal_
> */
> void thermal_cdev_update_nocheck(struct thermal_cooling_device *cdev)
> {
> - mutex_lock(&cdev->lock);
> + guard(cooling_dev)(cdev);
>
> __thermal_cdev_update(cdev);
> -
> - mutex_unlock(&cdev->lock);
> }
>
> /**
> Index: linux-pm/drivers/thermal/thermal_debugfs.c
> ===================================================================
> --- linux-pm.orig/drivers/thermal/thermal_debugfs.c
> +++ linux-pm/drivers/thermal/thermal_debugfs.c
> @@ -516,6 +516,19 @@ void thermal_debug_cdev_add(struct therm
> cdev->debugfs = thermal_dbg;
> }
>
> +static struct thermal_debugfs *thermal_debug_cdev_clear(struct thermal_cooling_device *cdev)
> +{
> + struct thermal_debugfs *thermal_dbg;
> +
> + guard(cooling_dev)(cdev);
> +
> + thermal_dbg = cdev->debugfs;
> + if (thermal_dbg)
> + cdev->debugfs = NULL;
> +
> + return thermal_dbg;
> +}
> +
> /**
> * thermal_debug_cdev_remove - Remove a cooling device debugfs entry
> *
> @@ -527,17 +540,9 @@ void thermal_debug_cdev_remove(struct th
> {
> struct thermal_debugfs *thermal_dbg;
>
> - mutex_lock(&cdev->lock);
> -
> - thermal_dbg = cdev->debugfs;
> - if (!thermal_dbg) {
> - mutex_unlock(&cdev->lock);
> + thermal_dbg = thermal_debug_cdev_clear(cdev);
> + if (!thermal_dbg)
> return;
> - }
> -
> - cdev->debugfs = NULL;
> -
> - mutex_unlock(&cdev->lock);
>
> mutex_lock(&thermal_dbg->lock);
>
> Index: linux-pm/drivers/thermal/gov_power_allocator.c
> ===================================================================
> --- linux-pm.orig/drivers/thermal/gov_power_allocator.c
> +++ linux-pm/drivers/thermal/gov_power_allocator.c
> @@ -549,18 +549,17 @@ static void allow_maximum_power(struct t
> cdev = instance->cdev;
>
> instance->target = 0;
> - mutex_lock(&cdev->lock);
> - /*
> - * Call for updating the cooling devices local stats and avoid
> - * periods of dozen of seconds when those have not been
> - * maintained.
> - */
> - cdev->ops->get_requested_power(cdev, &req_power);
> + scoped_guard(cooling_dev, cdev) {
> + /*
> + * Call for updating the cooling devices local stats and
> + * avoid periods of dozen of seconds when those have not
> + * been maintained.
> + */
> + cdev->ops->get_requested_power(cdev, &req_power);
>
> - if (params->update_cdevs)
> - __thermal_cdev_update(cdev);
> -
> - mutex_unlock(&cdev->lock);
> + if (params->update_cdevs)
> + __thermal_cdev_update(cdev);
> + }
> }
> }
>
> Index: linux-pm/drivers/thermal/gov_step_wise.c
> ===================================================================
> --- linux-pm.orig/drivers/thermal/gov_step_wise.c
> +++ linux-pm/drivers/thermal/gov_step_wise.c
> @@ -97,9 +97,9 @@ static void thermal_zone_trip_update(str
>
> instance->initialized = true;
>
> - mutex_lock(&instance->cdev->lock);
> - instance->cdev->updated = false; /* cdev needs update */
> - mutex_unlock(&instance->cdev->lock);
> + scoped_guard(cooling_dev, instance->cdev) {
> + instance->cdev->updated = false; /* cdev needs update */
> + }
> }
> }
>
>
>
>
>
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