[PATCH 4.19 081/313] thermal: Fix locking in cooling device sysfs update cur_state

Greg Kroah-Hartman
2019-02-11T15:46:55Z

[ Upstream commit 68000a0d983f539c95ebe5dccd4f29535c7ac0af ]

Sysfs interface to update cooling device cur_state does not
currently holding cooling device lock sometimes leading to
stale values in cur_state if getting updated simultanelously
from user space and thermal framework. Adding the proper locking
code fixes this issue.

Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/thermal/thermal_sysfs.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c
index 2241ceae7d7f..aa99edb4dff7 100644
--- a/drivers/thermal/thermal_sysfs.c
+++ b/drivers/thermal/thermal_sysfs.c
@@ -712,11 +712,14 @@ cur_state_store(struct device *dev, struct device_attribute *attr,
if ((long)state < 0)
return -EINVAL;

+ mutex_lock(&cdev->lock);
+
result = cdev->ops->set_cur_state(cdev, state);
- if (result)
- return result;
- thermal_cooling_device_stats_update(cdev, state);
- return count;
+ if (!result)
+ thermal_cooling_device_stats_update(cdev, state);
+
+ mutex_unlock(&cdev->lock);
+ return result ? result : count;
}

static struct device_attribute
--
2.19.1