linux-kernel - Re: [PATCH v3] thermal/core: Clear all mitigation when thermal zone is disabled

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] [day] [month] [year] [list]

Message-ID: <d0ecfe37-b8f8-c6f8-49d7-0bdbc2bde47e@quicinc.com>
Date:   Tue, 25 Jan 2022 21:18:42 +0530
From:   Manaf Meethalavalappu Pallikunhi <quic_manafm@...cinc.com>
To:     "Pandruvada, Srinivas" <srinivas.pandruvada@...el.com>,
        "Zhang, Rui" <rui.zhang@...el.com>,
        "thara.gopinath@...aro.org" <thara.gopinath@...aro.org>,
        "mka@...omium.org" <mka@...omium.org>,
        "daniel.lezcano@...aro.org" <daniel.lezcano@...aro.org>,
        "rafael@...nel.org" <rafael@...nel.org>,
        "amitk@...nel.org" <amitk@...nel.org>
CC:     "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] thermal/core: Clear all mitigation when thermal zone
 is disabled

HI Daniel,

On 1/24/2022 6:35 AM, Pandruvada, Srinivas wrote:
> On Sun, 2022-01-23 at 21:51 +0100, Daniel Lezcano wrote:
>> Hi Manaf,
>>
>> semantically speaking disabling a thermal zone would be to detach the
>> thermal zone from its governor and stop the monitoring.
>>
>> May be add the functions
>>
>>   - thermal_governor_attach(struct thermal_zone_device *tzd)
>>     {
>>          ...
>>          if (tz->governor && tz->governor->bind_to_tz) {
>>                  if (tz->governor->bind_to_tz(tz)) {
>>          }
>>          ...
>>     }
>>
>>   - thermal_governor_detach(struct thermal_zone_device *tzd)
>>     {
>>          ...
>>          if (tz->governor && tz->governor->unbind_from_tz)
>>                  tz->governor->unbind_from_tz(tz);
>>          ...
>>     }
>>
>> And add in the step_wise and power_allocator the reset of the
>> governor's
>> data as well as the cooling device instances in the unbind_from_tz()
>> callback
>>
>> Then, thermal_zone_device_enable() attaches and
>> thermal_zone_device_disable() detaches the governor.
>>
>> Does it make sense ?
> This is better.
>
> Thanks,
> Srinivas
Yes, it makes sense. I will update it in v4
>
>>
>> On 07/01/2022 19:56, Manaf Meethalavalappu Pallikunhi wrote:
>>> Whenever a thermal zone is in trip violated state, there is a
>>> chance
>>> that the same thermal zone mode can be disabled either via thermal
>>> core API or via thermal zone sysfs. Once it is disabled, the
>>> framework
>>> bails out any re-evaluation of thermal zone. It leads to a case
>>> where
>>> if it is already in mitigation state, it will stay the same state
>>> until it is re-enabled.
>>>
>>> To avoid above mentioned issue, on thermal zone disable request
>>> reset thermal zone and clear mitigation for each trip explicitly.
>>>
>>> Signed-off-by: Manaf Meethalavalappu Pallikunhi
>>> <quic_manafm@...cinc.com>
>>> ---
>>>   drivers/thermal/thermal_core.c | 12 ++++++++++--
>>>   1 file changed, 10 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/thermal/thermal_core.c
>>> b/drivers/thermal/thermal_core.c
>>> index 51374f4..e288c82 100644
>>> --- a/drivers/thermal/thermal_core.c
>>> +++ b/drivers/thermal/thermal_core.c
>>> @@ -447,10 +447,18 @@ static int
>>> thermal_zone_device_set_mode(struct thermal_zone_device *tz,
>>>   
>>>          thermal_zone_device_update(tz, THERMAL_EVENT_UNSPECIFIED);
>>>   
>>> -       if (mode == THERMAL_DEVICE_ENABLED)
>>> +       if (mode == THERMAL_DEVICE_ENABLED) {
>>>                  thermal_notify_tz_enable(tz->id);
>>> -       else
>>> +       } else {
>>> +               int trip;
>>> +
>>> +               /* make sure all previous throttlings are cleared
>>> */
>>> +               thermal_zone_device_init(tz);
>>> +               for (trip = 0; trip < tz->trips; trip++)
>>> +                       handle_thermal_trip(tz, trip);
>>> +
>>>                  thermal_notify_tz_disable(tz->id);
>>> +       }
>>>   
>>>          return ret;
>>>   }
>>>
>>