On Fri, 2023-03-03 at 20:23 +0100, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > Introduce a core thermal API function, > thermal_cooling_device_update(), > for updating the max_state value for a cooling device and rearranging > its statistics in sysfs after a possible change of its > ->get_max_state() > callback return value. > > That callback is now invoked only once, during cooling device > registration, to populate the max_state field in the cooling device > object, so if its return value changes, it needs to be invoked again > and the new return value needs to be stored as max_state. Moreover, > the statistics presented in sysfs need to be rearranged in general, > because there may not be enough room in them to store data for all > of the possible states (in the case when max_state grows). > > The new function takes care of that (and some other minor things > related to it), but some extra locking and lockdep annotations are > added in several places too to protect against crashes in the cases > when the statistics are not present or when a stale max_state value > might be used by sysfs attributes. > > Note that the actual user of the new function will be added > separately. > > Link: > https://lore.kernel.org/linux-pm/53ec1f06f61c984100868926f282647e57ecfb2d.camel@xxxxxxxxx/ > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > --- > drivers/thermal/thermal_core.c | 47 ++++++++++++++++++++++++++ > drivers/thermal/thermal_core.h | 1 > drivers/thermal/thermal_sysfs.c | 72 > +++++++++++++++++++++++++++++++++++----- > include/linux/thermal.h | 1 > 4 files changed, 113 insertions(+), 8 deletions(-) > > Index: linux-pm/drivers/thermal/thermal_core.c > =================================================================== > --- linux-pm.orig/drivers/thermal/thermal_core.c > +++ linux-pm/drivers/thermal/thermal_core.c > @@ -1057,6 +1057,53 @@ static bool thermal_cooling_device_prese > return false; > } > > +void thermal_cooling_device_update(struct thermal_cooling_device > *cdev) > +{ > + unsigned long state; > + > + if (!cdev) > + return; > + > + /* > + * Hold thermal_list_lock throughout the update to prevent the > device > + * from going away while being updated. > + */ > + mutex_lock(&thermal_list_lock); > + > + if (!thermal_cooling_device_present(cdev)) > + goto unlock_list; > + > + /* > + * Update under the cdev lock to prevent the state from being > set beyond > + * the new limit concurrently. > + */ > + mutex_lock(&cdev->lock); > + > + if (cdev->ops->get_max_state(cdev, &cdev->max_state)) > + goto unlock; > + > + thermal_cooling_device_stats_reinit(cdev); > + > + if (cdev->ops->get_cur_state(cdev, &state)) > + goto unlock; > + > + if (state <= cdev->max_state) > + goto update_stats; > + how could the .get_cur_state() callback returns a value higher than .get_max_state()? Isn't this a driver problem? > + if (cdev->ops->set_cur_state(cdev, state)) > + goto unlock; even if we don't error out, should we reevaluate .get_max_state() and update cdev->max_state? thanks, rui > + > +update_stats: > + thermal_cooling_device_stats_update(cdev, state); > + > +unlock: > + mutex_unlock(&cdev->lock); > + > +unlock_list: > + mutex_unlock(&thermal_list_lock); > +} > +EXPORT_SYMBOL_GPL(thermal_cooling_device_update); > + > static void __unbind(struct thermal_zone_device *tz, int mask, > struct thermal_cooling_device *cdev) > { > Index: linux-pm/drivers/thermal/thermal_sysfs.c > =================================================================== > --- linux-pm.orig/drivers/thermal/thermal_sysfs.c > +++ linux-pm/drivers/thermal/thermal_sysfs.c > @@ -685,6 +685,8 @@ void thermal_cooling_device_stats_update > { > struct cooling_dev_stats *stats = cdev->stats; > > + lockdep_assert_held(&cdev->lock); > + > if (!stats) > return; > > @@ -706,13 +708,22 @@ static ssize_t total_trans_show(struct d > struct device_attribute *attr, char > *buf) > { > struct thermal_cooling_device *cdev = to_cooling_device(dev); > - struct cooling_dev_stats *stats = cdev->stats; > + struct cooling_dev_stats *stats; > int ret; > > + mutex_lock(&cdev->lock); > + > + stats = cdev->stats; > + if (!stats) > + goto unlock; > + > spin_lock(&stats->lock); > ret = sprintf(buf, "%u\n", stats->total_trans); > spin_unlock(&stats->lock); > > +unlock: > + mutex_unlock(&cdev->lock); > + > return ret; > } > > @@ -721,11 +732,18 @@ time_in_state_ms_show(struct device *dev > char *buf) > { > struct thermal_cooling_device *cdev = to_cooling_device(dev); > - struct cooling_dev_stats *stats = cdev->stats; > + struct cooling_dev_stats *stats; > ssize_t len = 0; > int i; > > + mutex_lock(&cdev->lock); > + > + stats = cdev->stats; > + if (!stats) > + goto unlock; > + > spin_lock(&stats->lock); > + > update_time_in_state(stats); > > for (i = 0; i <= cdev->max_state; i++) { > @@ -734,6 +752,9 @@ time_in_state_ms_show(struct device *dev > } > spin_unlock(&stats->lock); > > +unlock: > + mutex_unlock(&cdev->lock); > + > return len; > } > > @@ -742,8 +763,16 @@ reset_store(struct device *dev, struct d > size_t count) > { > struct thermal_cooling_device *cdev = to_cooling_device(dev); > - struct cooling_dev_stats *stats = cdev->stats; > - int i, states = cdev->max_state + 1; > + struct cooling_dev_stats *stats; > + int i, states; > + > + mutex_lock(&cdev->lock); > + > + stats = cdev->stats; > + if (!stats) > + goto unlock; > + > + states = cdev->max_state + 1; > > spin_lock(&stats->lock); > > @@ -757,6 +786,9 @@ reset_store(struct device *dev, struct d > > spin_unlock(&stats->lock); > > +unlock: > + mutex_unlock(&cdev->lock); > + > return count; > } > > @@ -764,10 +796,18 @@ static ssize_t trans_table_show(struct d > struct device_attribute *attr, char > *buf) > { > struct thermal_cooling_device *cdev = to_cooling_device(dev); > - struct cooling_dev_stats *stats = cdev->stats; > + struct cooling_dev_stats *stats; > ssize_t len = 0; > int i, j; > > + mutex_lock(&cdev->lock); > + > + stats = cdev->stats; > + if (!stats) { > + len = -ENODATA; > + goto unlock; > + } > + > len += snprintf(buf + len, PAGE_SIZE - len, " > From : To\n"); > len += snprintf(buf + len, PAGE_SIZE - len, " : "); > for (i = 0; i <= cdev->max_state; i++) { > @@ -775,8 +815,10 @@ static ssize_t trans_table_show(struct d > break; > len += snprintf(buf + len, PAGE_SIZE - len, > "state%2u ", i); > } > - if (len >= PAGE_SIZE) > - return PAGE_SIZE; > + if (len >= PAGE_SIZE) { > + len = PAGE_SIZE; > + goto unlock; > + } > > len += snprintf(buf + len, PAGE_SIZE - len, "\n"); > > @@ -799,8 +841,12 @@ static ssize_t trans_table_show(struct d > > if (len >= PAGE_SIZE) { > pr_warn_once("Thermal transition table exceeds > PAGE_SIZE. Disabling\n"); > - return -EFBIG; > + len = -EFBIG; > } > + > +unlock: > + mutex_unlock(&cdev->lock); > + > return len; > } > > @@ -830,6 +876,8 @@ static void cooling_device_stats_setup(s > unsigned long states = cdev->max_state + 1; > int var; > > + lockdep_assert_held(&cdev->lock); > + > var = sizeof(*stats); > var += sizeof(*stats->time_in_state) * states; > var += sizeof(*stats->trans_table) * states * states; > @@ -855,6 +903,8 @@ out: > > static void cooling_device_stats_destroy(struct > thermal_cooling_device *cdev) > { > + lockdep_assert_held(&cdev->lock); > + > kfree(cdev->stats); > cdev->stats = NULL; > } > @@ -879,6 +929,12 @@ void thermal_cooling_device_destroy_sysf > cooling_device_stats_destroy(cdev); > } > > +void thermal_cooling_device_stats_reinit(struct > thermal_cooling_device *cdev) > +{ > + cooling_device_stats_destroy(cdev); > + cooling_device_stats_setup(cdev); > +} > + > /* these helper will be used only at the time of bindig */ > ssize_t > trip_point_show(struct device *dev, struct device_attribute *attr, > char *buf) > Index: linux-pm/drivers/thermal/thermal_core.h > =================================================================== > --- linux-pm.orig/drivers/thermal/thermal_core.h > +++ linux-pm/drivers/thermal/thermal_core.h > @@ -127,6 +127,7 @@ int thermal_zone_create_device_groups(st > void thermal_zone_destroy_device_groups(struct thermal_zone_device > *); > void thermal_cooling_device_setup_sysfs(struct > thermal_cooling_device *); > void thermal_cooling_device_destroy_sysfs(struct > thermal_cooling_device *cdev); > +void thermal_cooling_device_stats_reinit(struct > thermal_cooling_device *cdev); > /* used only at binding time */ > ssize_t trip_point_show(struct device *, struct device_attribute *, > char *); > ssize_t weight_show(struct device *, struct device_attribute *, char > *); > Index: linux-pm/include/linux/thermal.h > =================================================================== > --- linux-pm.orig/include/linux/thermal.h > +++ linux-pm/include/linux/thermal.h > @@ -384,6 +384,7 @@ devm_thermal_of_cooling_device_register( > struct device_node *np, > char *type, void *devdata, > const struct thermal_cooling_device_ops > *ops); > +void thermal_cooling_device_update(struct thermal_cooling_device *); > void thermal_cooling_device_unregister(struct thermal_cooling_device > *); > struct thermal_zone_device *thermal_zone_get_zone_by_name(const char > *name); > int thermal_zone_get_temp(struct thermal_zone_device *tz, int > *temp); > > >
