linux-kernel - Re: [PATCH] atm: ambassador: remove h from printk format specifier

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Date:   Thu, 17 Dec 2020 14:03:07 -0800
From:   Tom Rix <trix@...hat.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     3chas3@...il.com, linux-atm-general@...ts.sourceforge.net,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] atm: ambassador: remove h from printk format specifier


On 12/17/20 9:28 AM, Jakub Kicinski wrote:
> On Thu, 17 Dec 2020 05:17:24 -0800 Tom Rix wrote:
>> On 12/16/20 4:45 PM, Jakub Kicinski wrote:
>>> On Tue, 15 Dec 2020 06:22:28 -0800 trix@...hat.com wrote:  
>>>> From: Tom Rix <trix@...hat.com>
>>>>
>>>> See Documentation/core-api/printk-formats.rst.
>>>> h should no longer be used in the format specifier for printk.
>>>>
>>>> Signed-off-by: Tom Rix <trix@...hat.com>  
>>> That's for new code I assume?
>>>
>>> What's the harm in leaving this ancient code be?  
>> This change is part of a tree wide cleanup.
> What's the purpose of the "clean up"? Why is it making the code better?
>
> This is a quote from your change:
>
> -  PRINTK (KERN_NOTICE, "debug bitmap is %hx", debug &= DBG_MASK);
> +  PRINTK (KERN_NOTICE, "debug bitmap is %x", debug &= DBG_MASK);
>
> Are you sure that the use of %hx is the worst part of that line?

In this case, it means this bit of code is compliant with the %h checker in checkpatch.

why you are seeing this change for %hx and not the horrible debug &= or the old PRINTK macro is because the change was mechanical.

leveraging the clang build and a special fixit for %h, an allyesconfig for x86_64 cleans this problem from most of the tree in about an hour.  atm/ was just one of the places it hit, there are about 100 more.

If you want the debug &= fixed, i can do that.

The macro is a treewide problem and i can add that to the treewide cleanups i am planning.

Tom

>
>> drivers/atm status is listed as Maintained in MAINTAINERS so changes
>> like this should be ok.
>>
>> Should drivers/atm status be changed?
> Up to Chas, but AFAIU we're probably only a few years away from ATM as 
> a whole walking into the light. So IMHO "Obsolete" would be justified.
>