Re: [PATCH v3] thermal: core: Call monitor_thermal_zone() if zone temperature is invalid

[Rafael J. Wysocki]

On Mon, Jul 15, 2024 at 6:45 AM Eric Biggers <ebiggers@xxxxxxxxxx> wrote:
>
> Hello,
>
> On Thu, Jul 04, 2024 at 01:46:26PM +0200, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> >
> > Commit 202aa0d4bb53 ("thermal: core: Do not call handle_thermal_trip()
> > if zone temperature is invalid") caused __thermal_zone_device_update()
> > to return early if the current thermal zone temperature was invalid.
> >
> > This was done to avoid running handle_thermal_trip() and governor
> > callbacks in that case which led to confusion.  However, it went too
> > far because monitor_thermal_zone() still needs to be called even when
> > the zone temperature is invalid to ensure that it will be updated
> > eventually in case thermal polling is enabled and the driver has no
> > other means to notify the core of zone temperature changes (for example,
> > it does not register an interrupt handler or ACPI notifier).
> >
> > Also if the .set_trips() zone callback is expected to set up monitoring
> > interrupts for a thermal zone, it needs to be provided with valid
> > boundaries and that can only be done if the zone temperature is known.
> >
> > Accordingly, to ensure that __thermal_zone_device_update() will
> > run again after a failing zone temperature check, make it call
> > monitor_thermal_zone() regardless of whether or not the zone
> > temperature is valid and make the latter schedule a thermal zone
> > temperature update if the zone temperature is invalid even if
> > polling is not enabled for the thermal zone (however, if this
> > continues to fail, give up after some time).
> >
> > Fixes: 202aa0d4bb53 ("thermal: core: Do not call handle_thermal_trip() if zone temperature is invalid")
> > Reported-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
> > Link: https://lore.kernel.org/linux-pm/dc1e6cba-352b-4c78-93b5-94dd033fca16@xxxxxxxxxx
> > Link: https://lore.kernel.org/linux-pm/2764814.mvXUDI8C0e@xxxxxxxxxxxxx
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> On v6.10 I'm seeing the following messages spammed to the kernel log endlessly,
> and reverting this commit fixes it.
>
>     [  156.410567] thermal thermal_zone0: failed to read out thermal zone (-61)
>     [  156.666583] thermal thermal_zone0: failed to read out thermal zone (-61)
>     [  156.922598] thermal thermal_zone0: failed to read out thermal zone (-61)
>     [  157.178613] thermal thermal_zone0: failed to read out thermal zone (-61)
>     [  157.434636] thermal thermal_zone0: failed to read out thermal zone (-61)
>     [  157.690774] thermal thermal_zone0: failed to read out thermal zone (-61)
>     [  157.946659] thermal thermal_zone0: failed to read out thermal zone (-61)
>     [  158.202717] thermal thermal_zone0: failed to read out thermal zone (-61)
>     [  158.458697] thermal thermal_zone0: failed to read out thermal zone (-61)
>
> /sys/class/thermal/thermal_zone0/type contains "iwlwifi_1".

thermal_zone0 is useless on your system and hence the message (note
that it is a debug-level one).  That thermal zone certainly shouldn't
have been enabled and it probably shouldn't have been registered
either.

Previously, the core would just leave it alone and now it is poked at
periodically.

You can make the message go away by echoing "disabled" to the mode
attribute of thermal_zone0.

I think we'll see more of this, so we'll probably need to add some
kind of a backoff to it.