Thermal: Introduce locking for cdev.thermal_instances list.

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@intel.com>
Reviewed-by: Rafael J. Wysocki <rjw@sisk.pl>
Reviewed-by: Eduardo Valentin <eduardo.valentin@ti.com>

diff --git a/drivers/thermal/thermal_sys.c b/drivers/thermal/thermal_sys.c
index 6e9d3dc..5be8728 100644 (file)
--- 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 76d0fe8..91b3481 100644 (file)
--- 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;
 };