linux-kernel - Re: [PATCH] sched/uclamp: Fix overzealous type replacement

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Message-ID: <4b702b68-997b-da33-660c-db4313ac6dc5@arm.com>
Date:   Fri, 15 Nov 2019 00:05:40 +0000
From:   Valentin Schneider <valentin.schneider@....com>
To:     Qais Yousef <qais.yousef@....com>
Cc:     linux-kernel@...r.kernel.org, mingo@...nel.org,
        peterz@...radead.org, vincent.guittot@...aro.org,
        Dietmar.Eggemann@....com, tj@...nel.org,
        patrick.bellasi@...bug.net, surenb@...gle.com, qperret@...gle.com
Subject: Re: [PATCH] sched/uclamp: Fix overzealous type replacement

On 14/11/2019 20:28, Qais Yousef wrote:
> On 11/13/19 16:53, Valentin Schneider wrote:
>> Some uclamp helpers had their return type changed from 'unsigned int' to
>> 'enum uclamp_id' by commit
>>
>>   0413d7f33e60 ("sched/uclamp: Always use 'enum uclamp_id' for clamp_id values")
>>
>> but it happens that some *actually* do return an unsigned int value. Those
>> are the helpers that return a utilization value: uclamp_rq_max_value() and
>> uclamp_eff_value(). Fix those up.
>>
>> Note that this doesn't lead to any obj diff using a relatively recent
>> aarch64 compiler (8.3-2019.03). The current code of e.g. uclamp_eff_value()
>> already figures out that the return value is 11 bits (bits_per(1024)) and
>> doesn't seem to do anything funny. I'm still marking this as fixing the
>> above commit to be on the safe side.
>>
>> Fixes: 0413d7f33e60 ("sched/uclamp: Always use 'enum uclamp_id' for clamp_id values")
>> Signed-off-by: Valentin Schneider <valentin.schneider@....com>
>> ---
> 
> The changelog could be a bit simpler and more explicitly say 0413d7f33e60
> wrongly changed the return type of some functions. For a second I thought
> something weird is going inside these functions.
> 

The first paragraph is exactly that, no? The rest (that starts with "Note
that") is just optional stuff I look into because I was curious.

> But that could be just me :-)
> 
> Reviewed-by: Qais Yousef <qais.yousef@....com>
> 
> Thanks!
> 
> --
> Qais Yousef
>