[thermal: thermal/next] thermal/core: Emit a warning if the thermal zone is updated without ops

[thermal-bot for Daniel Lezcano]

The following commit has been merged into the thermal/next branch of thermal:

Commit-ID:     433178e75834dc35f1ae79b56ec2cf396f2c6f3c
Gitweb:        https://git.kernel.org/pub/scm/linux/kernel/git/thermal/linux.git//433178e75834dc35f1ae79b56ec2cf396f2c6f3c
Author:        Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
AuthorDate:    Thu, 10 Dec 2020 13:15:10 +01:00
Committer:     Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
CommitterDate: Fri, 11 Dec 2020 14:11:13 +01:00

thermal/core: Emit a warning if the thermal zone is updated without ops

The actual code is silently ignoring a thermal zone update when a
driver is requesting it without a get_temp ops set.

That looks not correct, as the caller should not have called this
function if the thermal zone is unable to read the temperature.

That makes the code less robust as the check won't detect the driver
is inconsistently using the thermal API and that does not help to
improve the framework as these circumvolutions hide the problem at the
source.

In order to detect the situation when it happens, let's add a warning
when the update is requested without the get_temp() ops set.

Any warning emitted will have to be fixed at the source of the
problem: the caller must not call thermal_zone_device_update if there
is not get_temp callback set.

Cc: Thara Gopinath <thara.gopinath@xxxxxxxxxx>
Cc: Amit Kucheria <amitk@xxxxxxxxxx>
Cc: linux-pm@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Reviewed-by: Lukasz Luba <lukasz.luba@xxxxxxx>
Link: https://lore.kernel.org/r/20201210121514.25760-1-daniel.lezcano@xxxxxxxxxx
---
 drivers/thermal/thermal_core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 90e38cc..64de098 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -553,7 +553,8 @@ void thermal_zone_device_update(struct thermal_zone_device *tz,
 	if (atomic_read(&in_suspend))
 		return;
 
-	if (!tz->ops->get_temp)
+	if (WARN_ONCE(!tz->ops->get_temp, "'%s' must not be called without "
+		      "'get_temp' ops set\n", __func__))
 		return;
 
 	update_temperature(tz);