On 一, 2012-08-20 at 18:45 +0300, Eduardo Valentin wrote:
> Hello Rui,
>
> On Thu, Jul 26, 2012 at 04:41:23PM +0800, 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: Eduardo Valentin <eduardo.valentin@xxxxxx>
>
> A minor comment bellow.
>
> > ---
> > 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);
>
> Why do you need to lock while going through the tz thermal_instances?
>
> > 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);
>
> Locking the above operation should be enough, no?
>
we need to add this thermal_instance to the cooling device
thermal_instance list.
say, what if another thermal zone that references this cooling device is
being unregistered at the same time?
thanks,
rui
> > }
> > + 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;
> > };
> > --
> > 1.7.9.5
> >
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