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

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Message-ID: <9db21e5e-ede0-87c3-a556-8a5e666d52bc@arm.com>
Date:   Wed, 2 Dec 2020 12:37:38 +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

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.

Regards,
Lukasz