linux-kernel - Re: [PATCH v25 01/10] drivers/base: refactor cpu.c to use .is

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Message-ID: <31c1393d-4285-0032-7675-737737d21f71@oracle.com>
Date:   Mon, 3 Jul 2023 11:53:35 -0500
From:   Eric DeVolder <eric.devolder@...cle.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, david@...hat.com, osalvador@...e.de,
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        boris.ostrovsky@...cle.com
Subject: Re: [PATCH v25 01/10] drivers/base: refactor cpu.c to use
 .is_visible()

On 7/3/23 08:05, Greg KH wrote:
> On Thu, Jun 29, 2023 at 03:21:10PM -0400, Eric DeVolder wrote:
>>   - the function body of the callback functions are now wrapped with
>>     IS_ENABLED(); as the callback function must exist now that the
>>     attribute is always compiled-in (though not necessarily visible).
> 
> Why do you need to do this last thing?  Is it a code savings goal?  Or
> something else?  The file will not be present in the system if the
> option is not enabled, so it should be safe to not do this unless you
> feel it's necessary for some reason?

To accommodate the request, all DEVICE_ATTR() must be unconditionally present in this file. The 
DEVICE_ATTR() requires the .show() callback. As the callback is referenced from a data structure, 
the callback has to be present for link. All the callbacks for these attributes are in this file.

I have two basic choices for gutting the function body if the config feature is not enabled. I can 
either use #ifdef or IS_ENABLED(). Thomas has made it clear I need to use IS_ENABLED(). I can 
certainly use #ifdef (which is what I did in v24).

> 
> Not doing this would make the diff easier to read :)

I agree this is messy. I'm not really sure what this request/effort achieves as these attributes are 
not strongly related (unlike cacheinfo) and the way the file was before results in less code.

At any rate, please indicate if you'd rather I use #ifdef.
Thanks for your time!
eric

> 
> thanks,
> 
> greg k-h