On Thu, Jun 23, 2016 at 02:27:12PM +0200, Rafael J. Wysocki wrote:

On Wed, Jun 22, 2016 at 7:06 AM, Eduardo Valentin [off-list ref] wrote:

quoted

Because several drivers do the following pattern:
.set_mode()
   ...
   local_data->mode = new_mode;
   thermal_zone_device_update(tz);

makes sense to simply do the thermal_zone_device_update()
in thermal core, after setting the new mode.

Also, this patch also remove deadlocks on drivers that
call thermal_zone_device_update() on .set_mode(),
as .set_mode()  is now called always with tz->lock held.

To me, this part of the patch is way more important than the
optimization mentioned before.

Apparently, the problem is that drivers deadlock, because the
thermal_zone_device_update() invoked from ->set_mode() is called under
tz->lock.

So to address that problem you make the core call
thermal_zone_device_update() after ->set_mode() outside of tz->lock
and the drivers don't have to do it any more.

Is that correct?

Yes this is correct. The optimization is simply a consequence of the bug
fix, as reported by Keerthy.

Thanks,
Rafael