fancontrol does not work after sleep/wakeup

Bug filed in Debian in 2012 (!). There are comments in the Debian bug also suggesting a post-wakeup service restart, but I don't agree it's the correct solution unless there's a good reason for the service to stop before the system goes to sleep.

Below is a suitable workaround for me. How do you feel about this as solution?

--- /lib/systemd/system/fancontrol.service.orig 2020-08-19 11:46:13.779547039 -0500
+++ /lib/systemd/system/fancontrol.service 2020-08-19 11:46:51.566212436 -0500
@@ -9,6 +9,8 @@
 ExecStartPre=/usr/sbin/fancontrol --check
 ExecStart=/usr/sbin/fancontrol
 PIDFile=/var/run/fancontrol.pid
+Restart=on-failure
+RestartSec=5s

 [Install]
 WantedBy=multi-user.target

I think that a more acceptable workaround would be adding a script to

  /usr/lib/systemd/system-sleep/

that stops the service pre-sleep and starts it post-sleep. See systemd-sleep(8) on how this can be implemented. I'd then propose it to the Debian package maintainers; Ubuntu will then pickup the fix.

There's a bug in the upstream bug tracker where this is being discussed:

https://github.com/lm-sensors/lm-sensors/issues/172

but it doesn't seem they have a solution ready.

The workaround suggested by Paride [1] is available since 1:3.6.0-7 and is available since hirsute

[1] https://github.com/lm-sensors/lm-sensors/issues/172#issuecomment-677688391

Fixed in Version: 1:3.6.0-6

Ubuntu is at
 lm-sensors | 1:3.6.0-7 | impish/universe | amd64, arm64, armhf, i386, ppc64el, riscv64, s390x
 lm-sensors | 1:3.6.0-7build1 | jammy/universe | amd64, arm64, armhf, i386, ppc64el, riscv64, s390x

Thereby this is fixed in Jammy and Impish, not sure if this is important enough to SRU, but happy to be convinced.

I was testing the solution adopted in lm-sensors 3.6.0-6 and later, and there is something that is bothering me a bit.

To recap, the fix that was applied is to restart the fancontrol service in the systemd-sleep hook. That sounds find, but imagine this scenario. I installed fancontrol, it's configured and running. For some reason, I decided to disable it, but keep the package installed. I do this then:

sudo systemctl disable fancontrol.service

In this way, the service will only start if a manual start command is issued, like "sudo systemctl start fancontrol.service". It won't start on boot, for example.

Except if you have the systemd-sleep hook in place.

You boot the machine, fancontrol is not running. Then you suspend it, and when it's resumed, fancontrol will be (re)started and will be running. I think that would be surprising behavior, because I disabled the service.

You can then mask the service, so that not even "sudo systemctl start fancontrol.service" will start it, but I still find that a bit unexpected, from a user's point of view. Maybe it's best to write a better hook, one that will only issue the restart if the service is enabled.

Hello flexman, or anyone else affected,

Accepted lm-sensors into focal-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/lm-sensors/1:3.6.0-2ubuntu1.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-focal to verification-done-focal. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-focal. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

Hello flexman, or anyone else affected,

Accepted lm-sensors into bionic-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/lm-sensors/1:3.4.0-4ubuntu0.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-bionic to verification-done-bionic. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-bionic. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

Verification done in Focal. All scenarios OK:

❯ cat /etc/fancontrol

# Configuration file generated by pwmconfig, changes will be lost

INTERVAL=10
DEVPATH=hwmon5=devices/platform/qc71_laptop hwmon6=devices/platform/qc71_laptop
DEVNAME=hwmon5=qc71_laptop.hwmon.fan hwmon6=qc71_laptop.hwmon.pwm
FCTEMPS=hwmon6/pwm2=hwmon5/temp2_input
FCFANS= hwmon6/pwm2=hwmon5/fan2_input
MINTEMP=hwmon6/pwm2=20
MAXTEMP=hwmon6/pwm2=60
MINSTART=hwmon6/pwm2=150
MINSTOP=hwmon6/pwm2=100

* Scenario 1: Service is enabled and active --> is restarted

❯ systemctl status -l fancontrol
● fancontrol.service - fan speed regulator
Loaded: loaded (/lib/systemd/system/fancontrol.service; enabled; vendor preset: enabled)
Active: active (running) since Wed 2022-04-20 18:38:51 CEST; 1min 9s ago
Docs: man:fancontrol(8)
man:pwmconfig(8)
Process: 60255 ExecStartPre=/usr/sbin/fancontrol --check (code=exited, status=0/SUCCESS)
Main PID: 60352 (fancontrol)
Tasks: 2 (limit: 76978)
Memory: 1.3M
CGroup: /system.slice/fancontrol.service
├─60352 /bin/bash /usr/sbin/fancontrol
└─61653 sleep 10

abr 20 18:38:51 Camelot-TITAN fancontrol[60352]: Controls hwmon5/fan2_input
abr 20 18:38:51 Camelot-TITAN fancontrol[60352]: MINTEMP=20
abr 20 18:38:51 Camelot-TITAN fancontrol[60352]: MAXTEMP=60
abr 20 18:38:51 Camelot-TITAN fancontrol[60352]: MINSTART=150
abr 20 18:38:51 Camelot-TITAN fancontrol[60352]: MINSTOP=100
abr 20 18:38:51 Camelot-TITAN fancontrol[60352]: MINPWM=0
abr 20 18:38:51 Camelot-TITAN fancontrol[60352]: MAXPWM=255
abr 20 18:38:51 Camelot-TITAN fancontrol[60352]: AVERAGE=1
abr 20 18:38:52 Camelot-TITAN fancontrol[60352]: Enabling PWM on fans...
abr 20 18:38:52 Camelot-TITAN fancontrol[60352]: Starting automatic fan control...

[Suspend]

abr 20 18:42:44 Camelot-TITAN fancontrol[60352]: Aborting, restoring fans...
abr 20 18:42:44 Camelot-TITAN systemd[1]: Stopping fan speed regulator...
abr 20 18:42:44 Camelot-TITAN fancontrol[60352]: Verify fans have returned to full speed
abr 20 18:42:44 Camelot-TITAN systemd[1]: fancontrol.service: Succeeded.
abr 20 18:42:44 Camelot-TITAN systemd[1]: Stopped fan speed regulator.
abr 20 18:42:44 Camelot-TITAN systemd[1]: Starting fan speed regulator...
abr 20 18:42:44 Camelot-TITAN fancontrol[62467]: Loading configuration from /etc/fancontrol ...
abr 20 18:42:44 Camelot-TITAN fancontrol[62467]: Common settings:
abr 20 18:42:44 Camelot-TITAN fancontrol[62467]: INTERVAL=10
abr 20 18:42:44 Camelot-TITAN fancontrol[62467]: Settings for hwmon6/pwm2:
abr 20 18:42:44 Camelot-TITAN fancontrol[62467]: Depends on hwmon5/temp2_input
abr 20 18:42:44 Camelot-TITAN fancontrol[62467]: Controls hwmon5/fan2_input
abr 20 18:42:44 Camelot-TITAN fancontrol[62467]: MINTEMP=20
abr 20 18:42:44 Camelot-TITAN fancontrol[62467]: MAXTEMP=60
abr 20 18:42:44 Camelot-TITAN fancontrol[62467]: MINSTART=150
abr 20 18:42:44 Camelot-TITAN fancontrol[62467]: MINSTOP=100
abr 20 18:42:44 Camelot-TITAN fancontrol[62467]: MINPWM=0
abr 20 18:42:44 Camelot-TITAN fancontrol[62467]: MAXPWM=255
abr 20 18:42:44 Camelot-TITAN fancontrol[62467]: AVERAGE=1
abr 20 18:42:44 Camelot-TITAN systemd[1]: Started fan speed regulator.

* Scenario 2: Service is disabled ...

This bug was fixed in the package lm-sensors - 1:3.6.0-2ubuntu1.1

---------------
lm-sensors (1:3.6.0-2ubuntu1.1) focal; urgency=medium

  * d/fancontrol/systemd-sleep, d/rules: Restart fancontrol.service
    after power sleep if it is active (LP: #1882272)

 -- Andreas Hasenack <email address hidden> Thu, 31 Mar 2022 17:52:36 -0300

The verification of the Stable Release Update for lm-sensors has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

This is difficult to reproduce without the appropriate hardware. In particular, I found no way to do it in a VM.

So here is my attempt with a twist.

In a Bionic laptop, I create this file:
# cat /lib/systemd/system-sleep/rsync
#!/bin/sh

case "$1" in
  post)
    if /bin/systemctl --quiet is-active rsync.service; then
      /bin/systemctl restart rsync.service
    fi
    exit 0
    ;;
esac

Notice it's the same thing as the new fancontrol one, but with just the service name replaced.

I then installed rsync, and created an empty /etc/rsyncd.conf to satisfy the service's path condition, so it would start.

Lastly, I went through the conditions asked for in the test case for the resume case:
Service is enabled and active --> is restarted
Service is disabled and active --> is restarted
Service is enabled and inactive --> is not restarted
Service is disabled and inactive --> is not restarted

And verified that rsync was only restarted in the "enabled and active" and "disabled and active" cases, being left untouched in the other two scenarios.

This verified the logic and actions of the script, just not the actual hardware interaction with fans.

I will mark the bug as verified for bionic, with the above caveat. If this is not acceptable by the SRU team, then please reset the tag and we can continue waiting from someone from the community to test it with appropriate hardware.

This bug was fixed in the package lm-sensors - 1:3.4.0-4ubuntu0.1

---------------
lm-sensors (1:3.4.0-4ubuntu0.1) bionic; urgency=medium

  * d/fancontrol-systemd-sleep, d/rules: Restart fancontrol.service
    after power sleep if it is active (LP: #1882272)

 -- Andreas Hasenack <email address hidden> Thu, 31 Mar 2022 17:53:20 -0300