linux-kernel - Re: [PATCH v4 3/4] powercap/drivers/dtpm: Add API for dynamic thermal power management

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Message-ID: <b26cab76-a18f-06ee-23d6-bbcc4393364e@arm.com>
Date:   Wed, 2 Dec 2020 17:19:35 +0000
From:   Lukasz Luba <lukasz.luba@....com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     rjw@...ysocki.net, ulf.hansson@...aro.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Thara Gopinath <thara.gopinath@...aro.org>,
        Lina Iyer <ilina@...eaurora.org>,
        Ram Chandrasekar <rkumbako@...eaurora.org>,
        Zhang Rui <rui.zhang@...el.com>, Arnd Bergmann <arnd@...db.de>,
        "open list:GENERIC INCLUDE/ASM HEADER FILES" 
        <linux-arch@...r.kernel.org>
Subject: Re: [PATCH v4 3/4] powercap/drivers/dtpm: Add API for dynamic thermal
 power management



On 12/2/20 12:37 PM, Lukasz Luba wrote:
> Hi Daniel,
> 
> I realized small issue when I went through this new mutex code
> (which is safer IMHO).
> 
> On 12/1/20 7:28 PM, Daniel Lezcano wrote:
> 
> [snip]
> 
>> +int dtpm_register(const char *name, struct dtpm *dtpm, struct dtpm 
>> *parent)
>> +{
>> +    struct powercap_zone *pcz;
>> +
>> +    if (!pct)
>> +        return -EAGAIN;
>> +
>> +    if (root && !parent)
>> +        return -EBUSY;
>> +
>> +    if (!root && parent)
>> +        return -EINVAL;
>> +
>> +    if (parent && parent->ops)
>> +        return -EINVAL;
>> +
> 
> Maybe it worth to add a check of dtpm pointer here, just to play safe?
> 
>      if (!dtpm)
>          return -EINVAL;
> 
> The dtpm->ops might explode when we don't capture this miss-usage during
> reviews of future drivers/shim layers. What do you think?
> 
> 
>> +    if (dtpm->ops && !(dtpm->ops->set_power_uw &&
>> +               dtpm->ops->get_power_uw &&
>> +               dtpm->ops->release))
>> +        return -EINVAL;
>> +
> 
> I am going to stress test the whole series with hotplug today
> and add review for patch 4/4.
> 

I have tested with a hotplug stress and looks OK with the mutex.
You can add again the tag:

Tested-by: Lukasz Luba <lukasz.luba@....com>

Regards,
Lukasz