netdev - Re: [PATCH 1/3] net: bgmac: allocate struct bgmac just once & don't copy it

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Message-ID: <CACna6rxuz6Ci=t5D1OGdPw4L0rLuLz6Lp7XrsviMS8C+upR=CQ@mail.gmail.com>
Date:   Fri, 27 Jan 2017 17:24:38 +0100
From:   Rafał Miłecki <zajec5@...il.com>
To:     David Miller <davem@...emloft.net>
Cc:     Felix Fietkau <nbd@....name>, Jon Mason <jon.mason@...adcom.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Felix Fietkau <nbd@...nwrt.org>,
        Network Development <netdev@...r.kernel.org>,
        Rafał Miłecki <rafal@...ecki.pl>
Subject: Re: [PATCH 1/3] net: bgmac: allocate struct bgmac just once & don't
 copy it

On 27 January 2017 at 17:14, David Miller <davem@...emloft.net> wrote:
> From: Felix Fietkau <nbd@....name>
> Date: Fri, 27 Jan 2017 17:02:33 +0100
>
>> On 2017-01-27 10:20, Rafał Miłecki wrote:
>>> From: Rafał Miłecki <rafal@...ecki.pl>
>>>
>>> To share as much code as possible in bgmac we call alloc_etherdev from
>>> bgmac.c which is used by both: platform and bcma code. The easiest
>>> solution was to use it for allocating whole struct bgmac but it doesn't
>>> work well as we already get early-filled struct bgmac as an argument.
>>>
>>> So far we were solving this by copying received struct into newly
>>> allocated one. The problem is it means storing 2 allocated structs,
>>> using only 1 of them and non-shared code not having access to it.
>>>
>>> This patch solves it by using alloc_etherdev to allocate *pointer* for
>>> the already allocated struct. The only downside of this is we have to be
>>> careful when using netdev_priv.
>>>
>>> Another solution was to call alloc_etherdev in platform/bcma specific
>>> code but Jon advised against it due to sharing less code that way.
>> How does that lead to sharing less code?
>> I find this pointer indirection rather ugly and uncommon, and I think it
>> would be much cleaner to split the probe into bgmac_enet_alloc and
>> bgmac_enet_probe (with bgmac_enet_alloc calling alloc_etherdev and doing
>> basic setup).
>
> I agree, it would be so much better if bgmac_probe() and friends
> initialized a real bgmac object which was the private of a netdev
> struct, then passed that down into bgmac_enet_probe().

I'll work on V2, thanks.

-- 
Rafał