Re: [PATCH 1/3] ath10k: remove ath10k_vif_to_arvif()

From: Adrian Chadd <adrian@freebsd.org>
To: "Valo, Kalle" <kvalo@qca.qualcomm.com>
Cc: "Ben Greear" <greearb@candelatech.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
	"Amadeusz Sławiński" <amadeusz.slawinski@tieto.com>,
	"ath10k@lists.infradead.org" <ath10k@lists.infradead.org>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/3] ath10k: remove ath10k_vif_to_arvif()
Date: Thu, 9 Feb 2017 23:14:40 -0800	[thread overview]
Message-ID: <CAJ-Vmom7k3Tsgs8tRHQppmL7XxADS3V24AGOQY5QgkrSgr5Qzg@mail.gmail.com> (raw)
In-Reply-To: <87tw82il32.fsf@kamboji.qca.qualcomm.com>

On 9 February 2017 at 23:03, Valo, Kalle <kvalo@qca.qualcomm.com> wrote:
> Ben Greear <greearb@candelatech.com> writes:
>
>> On 02/07/2017 01:14 AM, Valo, Kalle wrote:
>>> Adrian Chadd <adrian@freebsd.org> writes:
>>>
>>>> Removing this method makes the diff to FreeBSD larger, as "vif" in
>>>> FreeBSD is a different pointer.
>>>>
>>>> (Yes, I have ath10k on freebsd working and I'd like to find a way to
>>>> reduce the diff moving forward.)
>>>
>>> I don't like this "(void *) vif->drv_priv" style that much either but
>>> apparently it's commonly used in Linux wireless code and already parts
>>> of ath10k. So this patch just unifies the coding style.
>>
>> Surely the code compiles to the same thing, so why add a patch that
>> makes it more difficult for Adrian and makes the code no easier to read
>> for the rest of us?
>
> Because that's the coding style used already in Linux. It's great to see
> that parts of ath10k can be used also in other systems but in principle
> I'm not very fond of the idea starting to reject valid upstream patches
> because of driver forks.
>
> I think backports project is doing it right, it's not limiting upstream
> development in any way and handles all the API changes internally. Maybe
> FreeBSD could do something similar?

I tried, but ... well, imagine renaming vif->drv_priv to something
else. That's what you're suggesting. :-) You can do it with
coccinelle, but not via just backports API implementations. I'm a big
fan of light weight accessor APIs for the same reason.

(Since FreeBSD doesn't have that pointer in ieee80211vap, it's done a
different way.)

If you could convert other direct uses over to ath10k_vif_to_arvif()
then that'd make me happier. If not, it's fine, when I push this into
freebsd and fast-forward commits, I'll have to just maintain it.

For what it's worth - the linux skb accessors are the same. If there
were accessors for the skb data / len fields (like we do for mbufs)
then porting the code would've involved about 5,000 less changed
lines.

-adrian