linux-kernel - RE: [PATCH v3 6/8] PM / devfreq: Remove unneeded conditional statement

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Date:   Wed, 11 Oct 2017 11:36:35 +0000
From:   MyungJoo Ham <myungjoo.ham@...sung.com>
To:     Chanwoo Choi <cw00.choi@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>
CC:     "rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
        "chanwoo@...nel.org" <chanwoo@...nel.org>,
        Inki Dae <inki.dae@...sung.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>
Subject: RE: [PATCH v3 6/8] PM / devfreq: Remove unneeded conditional
 statement

> The commit 0ec09ac2cebe9 ("PM / devfreq: Set the freq_table of devfreq
> device") initializes the freq_table array of each devfreq device always.
> In result, it is unneeded to check whether profile->freq_table is NULL
> or not.
> 
> Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
> ---
>  drivers/devfreq/devfreq.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 3b9662ffe603..b28810cae7ee 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -315,10 +315,9 @@ int update_devfreq(struct devfreq *devfreq)
>  	freqs.new = freq;
>  	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
>  
> -	if (devfreq->profile->freq_table)
> -		if (devfreq_update_status(devfreq, freq))
> -			dev_err(&devfreq->dev,
> -				"Couldn't update frequency transition information.\n");
> +	if (devfreq_update_status(devfreq, freq))
> +		dev_err(&devfreq->dev,
> +			"Couldn't update frequency transition information.\n");

To make this commit really safe,
in this commit, please make devfreq_set_freq_table to return error
and let add_device fails when it returns error.

In the current code, we cannot guarantee that there will be
freq_table and trans_table available when it hits this line.

Cheers,
MyungJoo

>  
>  	devfreq->previous_freq = freq;
>  	return err;
> -- 
> 1.9.1