linux-kernel - Re: [PATCH 04/11] PM / devfreq: Remove redundant frequency adjustment from governors

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]

Date:   Mon, 28 May 2018 14:36:06 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Matthias Kaehlcke <mka@...omium.org>,
        MyungJoo Ham <myungjoo.ham@...sung.com>
Cc:     Kyungmin Park <kyungmin.park@...sung.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Brian Norris <briannorris@...omium.org>,
        Douglas Anderson <dianders@...omium.org>
Subject: Re: [PATCH 04/11] PM / devfreq: Remove redundant frequency
 adjustment from governors

Hi,

On 2018년 05월 26일 05:30, Matthias Kaehlcke wrote:
> The userspace and simpleondemand governor determine a target frequency and
> then adjust it according to the df->min/max_freq limits that might have
> been set by user space. This adjustment is redundant, it is done in
> update_devfreq() for any governor, right after returning from
> governor->get_target_freq().
> 
> Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> ---
>  drivers/devfreq/governor_simpleondemand.c |  5 -----
>  drivers/devfreq/governor_userspace.c      | 16 ++++------------
>  2 files changed, 4 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/devfreq/governor_simpleondemand.c b/drivers/devfreq/governor_simpleondemand.c
> index 278964783fa6..3da7554b4837 100644
> --- a/drivers/devfreq/governor_simpleondemand.c
> +++ b/drivers/devfreq/governor_simpleondemand.c
> @@ -84,11 +84,6 @@ static int devfreq_simple_ondemand_func(struct devfreq *df,
>  	b = div_u64(b, (dfso_upthreshold - dfso_downdifferential / 2));
>  	*freq = (unsigned long) b;
>  
> -	if (df->min_freq && *freq < df->min_freq)
> -		*freq = df->min_freq;
> -	if (df->max_freq && *freq > df->max_freq)
> -		*freq = df->max_freq;
> -
>  	return 0;
>  }
>  
> diff --git a/drivers/devfreq/governor_userspace.c b/drivers/devfreq/governor_userspace.c
> index 080607c3f34d..378d84c011df 100644
> --- a/drivers/devfreq/governor_userspace.c
> +++ b/drivers/devfreq/governor_userspace.c
> @@ -26,19 +26,11 @@ static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
>  {
>  	struct userspace_data *data = df->data;
>  
> -	if (data->valid) {
> -		unsigned long adjusted_freq = data->user_frequency;
> -
> -		if (df->max_freq && adjusted_freq > df->max_freq)
> -			adjusted_freq = df->max_freq;
> -
> -		if (df->min_freq && adjusted_freq < df->min_freq)
> -			adjusted_freq = df->min_freq;
> -
> -		*freq = adjusted_freq;
> -	} else {
> +	if (data->valid)
> +		*freq = data->user_frequency;
> +	else
>  		*freq = df->previous_freq; /* No user freq specified yet */
> -	}
> +
>  	return 0;
>  }
>  
> 

Reviewed-by: Chanwoo Choi <cw00.choi@...sung.com>

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics