On Thursday, July 26, 2012, Zhang Rui wrote:
> we need to go over all the thermal_instance list of a cooling device
> to decide which cooling state to put the cooling device to.
>
> But at this time, as a cooling device may be referenced in multiple
> thermal zones, we need to lock the list first in case
> another thermal zone is updating this cooling device.
>
> Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx>
Reviewed-by: Rafael J. Wysocki <rjw@xxxxxxx>
> ---
> drivers/thermal/thermal_sys.c | 8 ++++++++
> include/linux/thermal.h | 1 +
> 2 files changed, 9 insertions(+)
>
> diff --git a/drivers/thermal/thermal_sys.c b/drivers/thermal/thermal_sys.c
> index 7f3a891..356a59d 100644
> --- a/drivers/thermal/thermal_sys.c
> +++ b/drivers/thermal/thermal_sys.c
> @@ -799,6 +799,7 @@ int thermal_zone_bind_cooling_device(struct thermal_zone_device *tz,
> goto remove_symbol_link;
>
> mutex_lock(&tz->lock);
> + mutex_lock(&cdev->lock);
> list_for_each_entry(pos, &tz->thermal_instances, tz_node)
> if (pos->tz == tz && pos->trip == trip && pos->cdev == cdev) {
> result = -EEXIST;
> @@ -808,6 +809,7 @@ int thermal_zone_bind_cooling_device(struct thermal_zone_device *tz,
> list_add_tail(&dev->tz_node, &tz->thermal_instances);
> list_add_tail(&dev->cdev_node, &cdev->thermal_instances);
> }
> + mutex_unlock(&cdev->lock);
> mutex_unlock(&tz->lock);
>
> if (!result)
> @@ -840,14 +842,17 @@ int thermal_zone_unbind_cooling_device(struct thermal_zone_device *tz,
> struct thermal_instance *pos, *next;
>
> mutex_lock(&tz->lock);
> + mutex_lock(&cdev->lock);
> list_for_each_entry_safe(pos, next, &tz->thermal_instances, tz_node) {
> if (pos->tz == tz && pos->trip == trip && pos->cdev == cdev) {
> list_del(&pos->tz_node);
> list_del(&pos->cdev_node);
> + mutex_unlock(&cdev->lock);
> mutex_unlock(&tz->lock);
> goto unbind;
> }
> }
> + mutex_unlock(&cdev->lock);
> mutex_unlock(&tz->lock);
>
> return -ENODEV;
> @@ -913,6 +918,7 @@ thermal_cooling_device_register(char *type, void *devdata,
> }
>
> strcpy(cdev->type, type);
> + mutex_init(&cdev->lock);
> INIT_LIST_HEAD(&cdev->thermal_instances);
> cdev->ops = ops;
> cdev->updated = true;
> @@ -1016,6 +1022,7 @@ static void thermal_cdev_do_update(struct thermal_cooling_device *cdev)
> if (cdev->updated)
> return;
>
> + mutex_lock(&cdev->lock);
> /* Make sure cdev enters the deepest cooling state */
> list_for_each_entry(instance, &cdev->thermal_instances, cdev_node) {
> if (instance->target == THERMAL_NO_TARGET)
> @@ -1023,6 +1030,7 @@ static void thermal_cdev_do_update(struct thermal_cooling_device *cdev)
> if (instance->target > target)
> target = instance->target;
> }
> + mutex_unlock(&cdev->lock);
> cdev->ops->set_cur_state(cdev, target);
> cdev->updated = true;
> }
> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> index 06fd04d..d02d06d 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -95,6 +95,7 @@ struct thermal_cooling_device {
> void *devdata;
> const struct thermal_cooling_device_ops *ops;
> bool updated; /* true if the cooling device does not need update */
> + struct mutex lock; /* protect thermal_instances list */
> struct list_head thermal_instances;
> struct list_head node;
> };
>
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