linux-kernel - Re: [PATCH v1 07/17] thermal/hwmon: Use the thermal API instead tampering the internals

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: <20230220141154.GB4009286@roeck-us.net>
Date:   Mon, 20 Feb 2023 06:11:54 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Amit Kucheria <amitk@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>, rafael@...nel.org
Subject: Re: [PATCH v1 07/17] thermal/hwmon: Use the thermal API instead
 tampering the internals

On Mon, Feb 20, 2023 at 02:34:08PM +0100, Daniel Lezcano wrote:
> Hi Guenter,
> 
> my script should have Cc'ed you but it didn't, so just a heads up this patch
> ;)
> 
> On 19/02/2023 15:36, Daniel Lezcano wrote:
> > In this function, there is a guarantee the thermal zone is registered.
> > 
> > The sysfs hwmon unregistering will be blocked until we exit the
> > function. The thermal zone is unregistered after the sysfs hwmon is
> > unregistered.
> > 
> > When we are in this function, the thermal zone is registered.
> > 
> > We can call the thermal_zone_get_crit_temp() function safely and let
> > the function use the lock which is private the thermal core code.
> > 

Hmm, if you say so. That very same call used to cause a crash in
Chromebooks, which is why I had added the locking.

Guenter

> > Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
> > ---
> >   drivers/thermal/thermal_hwmon.c | 10 +---------
> >   1 file changed, 1 insertion(+), 9 deletions(-)
> > 
> > diff --git a/drivers/thermal/thermal_hwmon.c b/drivers/thermal/thermal_hwmon.c
> > index bc02095b314c..15158715b967 100644
> > --- a/drivers/thermal/thermal_hwmon.c
> > +++ b/drivers/thermal/thermal_hwmon.c
> > @@ -77,15 +77,7 @@ temp_crit_show(struct device *dev, struct device_attribute *attr, char *buf)
> >   	int temperature;
> >   	int ret;
> > -	mutex_lock(&tz->lock);
> > -
> > -	if (device_is_registered(&tz->device))
> > -		ret = tz->ops->get_crit_temp(tz, &temperature);
> > -	else
> > -		ret = -ENODEV;
> > -
> > -	mutex_unlock(&tz->lock);
> > -
> > +	ret = thermal_zone_get_crit_temp(tz, &temperature);
> >   	if (ret)
> >   		return ret;
> 
> -- 
> <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs
> 
> Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
> <http://twitter.com/#!/linaroorg> Twitter |
> <http://www.linaro.org/linaro-blog/> Blog
>