linux-kernel - Re: [PATCH v2] thermal: core: Call monitor_thermal

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <fdbdfdc3-d87c-4b95-8fc9-7b2331d1b684@linaro.org>
Date: Wed, 3 Jul 2024 14:43:55 +0200
From: neil.armstrong@...aro.org
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>,
 Linux PM <linux-pm@...r.kernel.org>,
 Daniel Lezcano <daniel.lezcano@...aro.org>,
 LKML <linux-kernel@...r.kernel.org>, Lukasz Luba <lukasz.luba@....com>,
 Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
 Zhang Rui <rui.zhang@...el.com>,
 linux-arm-msm <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH v2] thermal: core: Call monitor_thermal_zone() if zone
 temperature is invalid

Hi,

On 03/07/2024 13:29, Rafael J. Wysocki wrote:
> Hi,
> 
> On Wed, Jul 3, 2024 at 1:04 PM Neil Armstrong <neil.armstrong@...aro.org> wrote:
>>
>> Hi,
>>
>> On 28/06/2024 14:10, Rafael J. Wysocki wrote:
>>> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>>>
>>> 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 has to be provided with valid
>>> boundaries and that can only happen 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.
>>>
>>> Fixes: 202aa0d4bb53 ("thermal: core: Do not call handle_thermal_trip() if zone temperature is invalid")
>>> Reported-by: Daniel Lezcano <daniel.lezcano@...aro.org>
>>> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>>> ---
>>>    drivers/thermal/thermal_core.c |    5 ++++-
>>>    drivers/thermal/thermal_core.h |    6 ++++++
>>>    2 files changed, 10 insertions(+), 1 deletion(-)
>>>
>>> Index: linux-pm/drivers/thermal/thermal_core.c
>>> ===================================================================
>>> --- linux-pm.orig/drivers/thermal/thermal_core.c
>>> +++ linux-pm/drivers/thermal/thermal_core.c
>>> @@ -300,6 +300,8 @@ static void monitor_thermal_zone(struct
>>>                thermal_zone_device_set_polling(tz, tz->passive_delay_jiffies);
>>>        else if (tz->polling_delay_jiffies)
>>>                thermal_zone_device_set_polling(tz, tz->polling_delay_jiffies);
>>> +     else if (tz->temperature == THERMAL_TEMP_INVALID)
>>> +             thermal_zone_device_set_polling(tz, msecs_to_jiffies(THERMAL_RECHECK_DELAY_MS));
>>>    }
>>>
>>>    static struct thermal_governor *thermal_get_tz_governor(struct thermal_zone_device *tz)
>>> @@ -514,7 +516,7 @@ void __thermal_zone_device_update(struct
>>>        update_temperature(tz);
>>>
>>>        if (tz->temperature == THERMAL_TEMP_INVALID)
>>> -             return;
>>> +             goto monitor;
>>>
>>>        tz->notify_event = event;
>>>
>>> @@ -536,6 +538,7 @@ void __thermal_zone_device_update(struct
>>>
>>>        thermal_debug_update_trip_stats(tz);
>>>
>>> +monitor:
>>>        monitor_thermal_zone(tz);
>>>    }
>>>
>>> Index: linux-pm/drivers/thermal/thermal_core.h
>>> ===================================================================
>>> --- linux-pm.orig/drivers/thermal/thermal_core.h
>>> +++ linux-pm/drivers/thermal/thermal_core.h
>>> @@ -133,6 +133,12 @@ struct thermal_zone_device {
>>>        struct thermal_trip_desc trips[] __counted_by(num_trips);
>>>    };
>>>
>>> +/*
>>> + * Default delay after a failing thermal zone temperature check before
>>> + * attempting to check it again.
>>> + */
>>> +#define THERMAL_RECHECK_DELAY_MS     100
>>> +
>>>    /* Default Thermal Governor */
>>>    #if defined(CONFIG_THERMAL_DEFAULT_GOV_STEP_WISE)
>>>    #define DEFAULT_THERMAL_GOVERNOR       "step_wise"
>>>
>>>
>>>
>>>
>>
>> This patch on next-20240702 makes Qualcomm HDK8350, HDK8450, QRD8550, HDK8560, QRD8650 & HDK8650 output in loop:
>>
>> thermal thermal_zoneXX: failed to read out thermal zone (-19)
> 
> Is the loop endless?  If not, how many times does the message get printed?

It get printed indefinitely

> 
> If I'm not mistaken, it would be printed at least once without the
> commit in question.  Can you please check that?
> 
> Also, can you check the previous version of the patch in question:
> 
> https://lore.kernel.org/linux-pm/2745114.mvXUDI8C0e@rjwysocki.net/
> 
> and see if it has the same problem (just apply it instead of the $subject one).

I reverted this one a applied v1 and the message disappeared completely.

Neil

> 
> Thanks!