Re: [PATCH] thermal/core: update cooling device during thermal zone unregistration

[Dan Carpenter <error27@gmail.com>]

Hi Zhang,

https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Zhang-Rui/thermal-core-update-cooling-device-during-thermal-zone-unregistration/20230321-234754
base:   https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git thermal
patch link:    https://lore.kernel.org/r/20230321154627.17787-1-rui.zhang%40intel.com
patch subject: [PATCH] thermal/core: update cooling device during thermal zone unregistration
config: i386-randconfig-m021 (https://download.01.org/0day-ci/archive/20230322/202303221159.6cdRxcUo-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-8) 11.3.0

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Link: https://lore.kernel.org/r/202303221159.6cdRxcUo-lkp@intel.com/

smatch warnings:
drivers/thermal/thermal_core.c:1436 thermal_zone_device_unregister() warn: iterator used outside loop: 'ti'

vim +/ti +1436 drivers/thermal/thermal_core.c

203d3d4aa48233 drivers/thermal/thermal.c      Zhang Rui        2008-01-17  1402  void thermal_zone_device_unregister(struct thermal_zone_device *tz)
203d3d4aa48233 drivers/thermal/thermal.c      Zhang Rui        2008-01-17  1403  {
a5f785ce608caf drivers/thermal/thermal_core.c Dmitry Osipenko  2020-08-18  1404  	int i, tz_id;
7e8ee1e9d7561f drivers/thermal/thermal_sys.c  Durgadoss R      2012-09-18  1405  	const struct thermal_zone_params *tzp;
203d3d4aa48233 drivers/thermal/thermal.c      Zhang Rui        2008-01-17  1406  	struct thermal_cooling_device *cdev;
203d3d4aa48233 drivers/thermal/thermal.c      Zhang Rui        2008-01-17  1407  	struct thermal_zone_device *pos = NULL;
55a1117eebc62b drivers/thermal/thermal_core.c Zhang Rui        2023-03-21  1408  	struct thermal_instance *ti;
203d3d4aa48233 drivers/thermal/thermal.c      Zhang Rui        2008-01-17  1409  
203d3d4aa48233 drivers/thermal/thermal.c      Zhang Rui        2008-01-17  1410  	if (!tz)
203d3d4aa48233 drivers/thermal/thermal.c      Zhang Rui        2008-01-17  1411  		return;
203d3d4aa48233 drivers/thermal/thermal.c      Zhang Rui        2008-01-17  1412  
7e8ee1e9d7561f drivers/thermal/thermal_sys.c  Durgadoss R      2012-09-18  1413  	tzp = tz->tzp;
a5f785ce608caf drivers/thermal/thermal_core.c Dmitry Osipenko  2020-08-18  1414  	tz_id = tz->id;
7e8ee1e9d7561f drivers/thermal/thermal_sys.c  Durgadoss R      2012-09-18  1415  
203d3d4aa48233 drivers/thermal/thermal.c      Zhang Rui        2008-01-17  1416  	mutex_lock(&thermal_list_lock);
203d3d4aa48233 drivers/thermal/thermal.c      Zhang Rui        2008-01-17  1417  	list_for_each_entry(pos, &thermal_tz_list, node)
203d3d4aa48233 drivers/thermal/thermal.c      Zhang Rui        2008-01-17  1418  		if (pos == tz)
203d3d4aa48233 drivers/thermal/thermal.c      Zhang Rui        2008-01-17  1419  			break;
203d3d4aa48233 drivers/thermal/thermal.c      Zhang Rui        2008-01-17  1420  	if (pos != tz) {
203d3d4aa48233 drivers/thermal/thermal.c      Zhang Rui        2008-01-17  1421  		/* thermal zone device not found */
203d3d4aa48233 drivers/thermal/thermal.c      Zhang Rui        2008-01-17  1422  		mutex_unlock(&thermal_list_lock);
203d3d4aa48233 drivers/thermal/thermal.c      Zhang Rui        2008-01-17  1423  		return;
203d3d4aa48233 drivers/thermal/thermal.c      Zhang Rui        2008-01-17  1424  	}
203d3d4aa48233 drivers/thermal/thermal.c      Zhang Rui        2008-01-17  1425  	list_del(&tz->node);
7e8ee1e9d7561f drivers/thermal/thermal_sys.c  Durgadoss R      2012-09-18  1426  
7e8ee1e9d7561f drivers/thermal/thermal_sys.c  Durgadoss R      2012-09-18  1427  	/* Unbind all cdevs associated with 'this' thermal zone */
7e8ee1e9d7561f drivers/thermal/thermal_sys.c  Durgadoss R      2012-09-18  1428  	list_for_each_entry(cdev, &thermal_cdev_list, node) {
55a1117eebc62b drivers/thermal/thermal_core.c Zhang Rui        2023-03-21  1429  		mutex_lock(&tz->lock);
55a1117eebc62b drivers/thermal/thermal_core.c Zhang Rui        2023-03-21  1430  		list_for_each_entry(ti, &tz->thermal_instances, tz_node) {
55a1117eebc62b drivers/thermal/thermal_core.c Zhang Rui        2023-03-21  1431  			if (ti->cdev == cdev)
55a1117eebc62b drivers/thermal/thermal_core.c Zhang Rui        2023-03-21  1432  				break;
55a1117eebc62b drivers/thermal/thermal_core.c Zhang Rui        2023-03-21  1433  		}
55a1117eebc62b drivers/thermal/thermal_core.c Zhang Rui        2023-03-21  1434  
55a1117eebc62b drivers/thermal/thermal_core.c Zhang Rui        2023-03-21  1435  		/* The cooling device is not used by current thermal zone */
55a1117eebc62b drivers/thermal/thermal_core.c Zhang Rui        2023-03-21 @1436  		if (ti->cdev != cdev) {

Here we are testing to see if the loop exited by hitting the break.  If
the condition is != then "ti" is not a valid pointer and it's kind of an
out of bounds access.  I used to fix these with:

-	if (ti->cdev != cdev) {
+	if (list_entry_is_head(ti, &tz->thermal_instances, tz_node)) {

But these days we just prefer using a found variable:

	found = false;
	list_for_each_entry(ti, &tz->thermal_instances, tz_node) {
		if (ti->cdev == cdev) {
			found = true;
			break;
		}
	}
	if (!found) {

55a1117eebc62b drivers/thermal/thermal_core.c Zhang Rui        2023-03-21  1437  			mutex_unlock(&tz->lock);
55a1117eebc62b drivers/thermal/thermal_core.c Zhang Rui        2023-03-21  1438  			continue;
55a1117eebc62b drivers/thermal/thermal_core.c Zhang Rui        2023-03-21  1439  		}
55a1117eebc62b drivers/thermal/thermal_core.c Zhang Rui        2023-03-21  1440  		mutex_unlock(&tz->lock);
55a1117eebc62b drivers/thermal/thermal_core.c Zhang Rui        2023-03-21  1441  
7e8ee1e9d7561f drivers/thermal/thermal_sys.c  Durgadoss R      2012-09-18  1442  		if (tz->ops->unbind) {
203d3d4aa48233 drivers/thermal/thermal.c      Zhang Rui        2008-01-17  1443  			tz->ops->unbind(tz, cdev);

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