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Date: Thu, 23 Apr 2015 12:09:23 +0200
From: Alexander Aring <alex.aring@gmail.com>
Subject: Re: First kernel patch - checkpatch for at86rf230.c, false-positives?
Message-ID: <20150423100918.GA9284@omega>
References: <CAG9Fz+uvR29TX4-MavSqA=MPkUhsn7n0HnaDzh4PDAmrMvrsVQ@mail.gmail.com>
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To: Christoffer Holmstedt <christoffer.holmstedt@gmail.com>
Cc: linux-wpan@vger.kernel.org

On Thu, Apr 23, 2015 at 11:48:07AM +0200, Christoffer Holmstedt wrote:
> Hi
> I've access to a few raspberry pi:s with the openlabs extension board
> and I'm currently configuring my development environment for kernel
> development to help out with the wpan subsystem.
> 
> I just ran checkpatch.pl over at86rf230.c and got 109 errors most of
> them concerning macros not enclosed in parentheses. Are these
> false-positives or should I add parantheses?
> 

definitely false positiv!

what they do there is parameters for functions in a define.

Like:

#define STATIC_VALUES_PARAMETERS 1, 2, 3

void function(void *p, int first, int second, int third, void *foobar)
{
	....
}

and call later;

function(bar, STATIC_VALUES_PARAMETERS, foo);

compiler will replace it with:

function(bar, 1, 2, 3, foo);

and it's wrong to use:

function(bar, (1, 2, 3), foo);

it's not usually kernel programming and historical copy&pasted from
contiki code [0] or maybe contiki copy&pasted it from linux, I don't
know I don't programmed it.


checkpatch warnings about this because it's complicated to use logical
operations define inside another logical operations define. like:
BAR_MASK(FOO_MASK(bar)) - without brackets it's hard to understand
what's going on there.
But this isn't the case here.


btw:

There exists an code styling issue which is not shown by checkpatch.
It's the tab after every define, I have patches for this I will send
them later, it's included for the RFC to add phy capabilities dump.

- Alex

[0] https://github.com/contiki-os/contiki/blob/master/cpu/avr/radio/rf230/at86rf230_registermap.h