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>

2 files changed, 9 insertions, 0 deletions

diff --git a/drivers/thermal/thermal_sys.c b/drivers/thermal/thermal_sys.c
index 6e9d3dc9d89b..5be8728c88a3 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 76d0fe88eb1c..91b34812cd84 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;
 };