linux-kernel - Re: [PATCH 1/3] thermal: core: Add indication for userspace usage

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: <D53454A1-5ED0-4B4D-B22F-8663C9970ECD@canonical.com>
Date:   Tue, 1 Dec 2020 02:22:21 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Cc:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        Zhang Rui <rui.zhang@...el.com>, amitk@...nel.org,
        "open list:THERMAL" <linux-pm@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] thermal: core: Add indication for userspace usage


> On Dec 1, 2020, at 02:13, Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com> wrote:

[snipped] 

>>> What about creating an new callback
>>> 
>>> enum thermal_trip_status {
>>> 	THERMAL_TRIP_DISABLED = 0,
>>> 	THERMAL_TRIP_ENABLED,
>>> };
>>> 
>>> int get_trip_status(struct thermal_zone_device *, int trip, enum
>>> thermal_trip_status *state);
>>> 
>>> Then in 
>>> static void handle_thermal_trip(struct thermal_zone_device *tz, int
>>> trip)
>>> {
>>> 
>>> /* before tz->ops->get_trip_temp(tz, trip, &trip_temp); */
>>> if (tz->ops->get_trip_status) {
>>> 	enum thermal_trip_status *status;
>>> 
>>> 	if (!tz->ops->get_trip_status(tz, trip, &status)) {
>>> 		if (status == THERMAL_TRIP_DISABLED)
>>> 			return;	
>>> 	}
>>> }
>>> ...
>>> ...
>>> 
>>> }
>>> 
>>> 
>>> This callback will help the cases:
>>> - Allows drivers to selectively disable certain trips during init
>>> state
>>> or system resume where there can be spikes or always. int340x
>>> drivers
>>> can disable always.
>> 
>> This sounds really great. This is indeed can happen on system resume,
>> before userspace process thaw.
>> 
>>> - Still give options for drivers to handle critical trip even if
>>> they
>>> are bound to user space governors. User space process may be dead,
>>> so
>>> still allow kernel to process graceful shutdown
>> 
>> To make the scenario happen, do we need a new sysfs to let usespace
>> enable it with THERMAL_TRIP_ENABLED?
> This should be drivers call not user space.

Understood. So after thermal_zone_device_register(), the driver can decide to what to return on get_trip_temp().
Let me work on a new patch if there's no other concern.

Kai-Heng

> 
> Thanks,
> Srinivas