linux-kernel - Re: [PATCH v3] PM / OPP: discard duplicate OPPs

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Message-ID: <CAKohpoknoFuz8qnDpunA7oxr5E_18=+EQsFEy0P39fcU=4Ps9w@mail.gmail.com>
Date:	Tue, 20 May 2014 09:30:02 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Nishanth Menon <nm@...com>
Cc:	Chander Kashyap <chander.kashyap@...aro.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Pavel Machek <pavel@....cz>,
	"Brown, Len" <len.brown@...el.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Chander Kashyap <k.chander@...sung.com>,
	Inderpal Singh <inderpal.s@...sung.com>
Subject: Re: [PATCH v3] PM / OPP: discard duplicate OPPs

On 19 May 2014 18:38, Nishanth Menon <nm@...com> wrote:

>> +     if (new_opp->rate == opp->rate) {
>> +             mutex_unlock(&dev_opp_list_lock);
>> +             kfree(new_opp);
>> +             return 0;
>
> IF we decide on ensuring that the OPP additions are done one time[1] -

Fingers crossed :)

But that doesn't mean we covered everything. First of all platforms can
still add OPPs directly and then there are other OPPs than CPU's.

> then returning -EEXIST is appropriate here. we want to be able to
> catch warnings of sequencing errors, and returning 0 is not the way to
> do it.

I have asked this on the earlier thread as well, let me ask it again.
What would callers do on return value of EEXIST ? Is there anything
special we may want to handle ?

Yes, we shouldn't fix everything silently and so a pr_warn() can/should
be added here. But returning is zero is better in order not to complicate
error handling at callers side.

Isn't it ?
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