Module loading order is unstable

[khali]

With some hwmon drivers auto-loading, the order of the hwmon class devices is different when starting the lm_sensors service at boot and when restarting it later. While libsensors-based applications do not care, applications which access the hwmon class devices directly such as fancontrol are adversely affected.

See the discussion at:  http://lists.lm-sensors.org/pipermail/lm-sensors/2009-January/025197.html

Proposed solution:

1. Make sure sensors-detect stops the lm_sensors service before scanning the system.
2. Exclude the already loaded hwmon drivers from the list of drivers recommended by sensors-detect.

This will not fix systems already affected by the system, but will prevent more systems from being affected in the future.

[khali]

An alternative approach proposed by Volker Kuhlmann would be to unload all the hwmon drivers before reloading them when starting the lm_sensors service. This approach has the advantage that it doesn't depend on the initial state of the system. However it incurs a minor performance penalty, and might have unexpected side effects.

[khali]

Kay Sievers suggests that we can use the modalias files in sysfs together with "modprobe -n" to figure out whether a given hwmon driver was auto-loaded or not. This is much more robust than my initial proposal of relying on the initial system state to make the decision.

[khali]

Hopefully addressed by r5635.