netdev - Re: [PATCH v2 net-next 2/3] ipvlan: Common code from v6/v4 validator

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Message-ID: <a4a16ead-a534-47e6-8468-58898350415c@huawei.com>
Date: Tue, 27 Jan 2026 08:56:40 +0300
From: Dmitry Skorodumov <skorodumov.dmitry@...wei.com>
To: Kuniyuki Iwashima <kuniyu@...gle.com>, Dmitry Skorodumov
	<dskr99@...il.com>
CC: <netdev@...r.kernel.org>, Jakub Kicinski <kuba@...nel.org>, Stanislav
 Fomichev <sdf@...ichev.me>, Xiao Liang <shaw.leon@...il.com>,
	<linux-kernel@...r.kernel.org>, Andrew Lunn <andrew+netdev@...n.ch>, "David
 S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Paolo
 Abeni <pabeni@...hat.com>
Subject: Re: [PATCH v2 net-next 2/3] ipvlan: Common code from v6/v4
 validator_event

On 1/26/2026 9:01 PM, Kuniyuki Iwashima wrote:
> On Fri, Jan 23, 2026 at 9:04 AM Dmitry Skorodumov <dskr99@...il.com> wrote:

>> +static int ipvlan_addr_validator_event_cb(struct notifier_block *nblock,
>> +                                         unsigned long event, void *ptr)
>> +{
>> +       struct in6_validator_info *i6vi;
>> +       struct net_device *dev;
>> +
>> +       if (nblock == &ipvlan_addr4_vtor_notifier_block) {
> 
> If you check this against the v6 one instead, the if block
> and the i6vi definition can be guarded with
> #if IS_ENABLED(CONFIG_IPV6)

Hm... Few months ago, I had a conversation here that convinced me: avoid 
#ifdef whenever possible. They overburden code and reduce readability.

It even might be a good idea to replace wherever possible preprocessor 
checks with runtime checks. Use
if (IS_ENABLED(CONFIG_IPV6)) { ... }

instead of #if IS_ENABLED(CONFIG_IPV6) ... #endif

--

I'm ok with both approaches (though i tend to like runtime checks) - but 
unsure what is a common practice in bpf-net

Dmitry