21.02.2022 15:01, Jon Hunter пишет:
Hi Dmitry,
On 18/06/2021 22:54, Dmitry Osipenko wrote:
Use hwmon_notify_event() to notify userspace and thermal core about
temperature changes.
Suggested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
---
drivers/hwmon/lm90.c | 44 +++++++++++++++++++++++++++++++++-----------
1 file changed, 33 insertions(+), 11 deletions(-)
diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
index 2e057fad05b4..e7b678a40b39 100644
--- a/drivers/hwmon/lm90.c
+++ b/drivers/hwmon/lm90.c
@@ -465,6 +465,7 @@ enum lm90_temp11_reg_index {
struct lm90_data {
struct i2c_client *client;
+ struct device *hwmon_dev;
u32 channel_config[4];
struct hwmon_channel_info temp_info;
const struct hwmon_channel_info *info[3];
@@ -1731,22 +1732,41 @@ static bool lm90_is_tripped(struct i2c_client
*client, u16 *status)
if ((st & (LM90_STATUS_LLOW | LM90_STATUS_LHIGH |
LM90_STATUS_LTHRM)) ||
(st2 & MAX6696_STATUS2_LOT2))
- dev_warn(&client->dev,
- "temp%d out of range, please check!\n", 1);
+ dev_dbg(&client->dev,
+ "temp%d out of range, please check!\n", 1);
if ((st & (LM90_STATUS_RLOW | LM90_STATUS_RHIGH |
LM90_STATUS_RTHRM)) ||
(st2 & MAX6696_STATUS2_ROT2))
- dev_warn(&client->dev,
- "temp%d out of range, please check!\n", 2);
+ dev_dbg(&client->dev,
+ "temp%d out of range, please check!\n", 2);
if (st & LM90_STATUS_ROPEN)
- dev_warn(&client->dev,
- "temp%d diode open, please check!\n", 2);
+ dev_dbg(&client->dev,
+ "temp%d diode open, please check!\n", 2);
if (st2 & (MAX6696_STATUS2_R2LOW | MAX6696_STATUS2_R2HIGH |
MAX6696_STATUS2_R2THRM | MAX6696_STATUS2_R2OT2))
- dev_warn(&client->dev,
- "temp%d out of range, please check!\n", 3);
+ dev_dbg(&client->dev,
+ "temp%d out of range, please check!\n", 3);
if (st2 & MAX6696_STATUS2_R2OPEN)
- dev_warn(&client->dev,
- "temp%d diode open, please check!\n", 3);
+ dev_dbg(&client->dev,
+ "temp%d diode open, please check!\n", 3);
+
+ if (st & LM90_STATUS_LLOW)
+ hwmon_notify_event(data->hwmon_dev, hwmon_temp,
+ hwmon_temp_min, 0);
+ if (st & LM90_STATUS_RLOW)
+ hwmon_notify_event(data->hwmon_dev, hwmon_temp,
+ hwmon_temp_min, 1);
+ if (st2 & MAX6696_STATUS2_R2LOW)
+ hwmon_notify_event(data->hwmon_dev, hwmon_temp,
+ hwmon_temp_min, 2);
+ if (st & LM90_STATUS_LHIGH)
+ hwmon_notify_event(data->hwmon_dev, hwmon_temp,
+ hwmon_temp_max, 0);
+ if (st & LM90_STATUS_RHIGH)
+ hwmon_notify_event(data->hwmon_dev, hwmon_temp,
+ hwmon_temp_max, 1);
+ if (st2 & MAX6696_STATUS2_R2HIGH)
+ hwmon_notify_event(data->hwmon_dev, hwmon_temp,
+ hwmon_temp_max, 2);
We observed a random null pointer deference crash somewhere in the
thermal core (crash log below is not very helpful) when calling
mutex_lock(). It looks like we get an interrupt when this crash
happens.
Looking at the lm90 driver, per the above, I now see we are calling
hwmon_notify_event() from the lm90 interrupt handler. Looking at
hwmon_notify_event() I see that ...
hwmon_notify_event()
--> hwmon_thermal_notify()
--> thermal_zone_device_update()
--> update_temperature()
--> mutex_lock()
So although I don't completely understand the crash, it does seem
that we should not be calling hwmon_notify_event() from the
interrupt handler.
BTW I have not reproduced this myself yet, so I have just been
reviewing the code to try and understand this.
Matt Merhar was experiencing a similar issue on T30 Ouya, but I never
managed to reproduce it on Nexus 7 and Acer A500 tablets, and couldn't
spot any problem in the code. IIRC, it was a NULL dereference of another
pointer within that code.