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Subject: Re: [PATCH bpf] bpf: fix unused-var without NETDEVICES
To:     Ferenc Fejes <fejes@inf.elte.hu>
Cc:     netdev@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        Andrii Nakryiko <andriin@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@chromium.org>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>, bpf@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20200603081124.1627600-1-matthieu.baerts@tessares.net>
 <CAAej5NZZNg+0EbZsa-SrP0S_sOPMqdzgQ9hS8z6DYpQp9G+yhw@mail.gmail.com>
From:   Matthieu Baerts <matthieu.baerts@tessares.net>
Message-ID: <1cb3266c-7c8c-ebe6-0b6e-6d970e0adbd1@tessares.net>
Date:   Wed, 3 Jun 2020 11:12:01 +0200
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Hi Ferenc,

On 03/06/2020 10:56, Ferenc Fejes wrote:
> Matthieu Baerts <matthieu.baerts@tessares.net> ezt írta (időpont:
> 2020. jún. 3., Sze, 10:11):
>>
>> A recent commit added new variables only used if CONFIG_NETDEVICES is
>> set.
> 
> Thank you for noticing and fixed this!
> 
>> A simple fix is to only declare these variables if the same
>> condition is valid.
>>
>> Other solutions could be to move the code related to SO_BINDTODEVICE
>> option from _bpf_setsockopt() function to a dedicated one or only
>> declare these variables in the related "case" section.
> 
> Yes thats indeed a cleaner way to approach this. I will prepare a fix for that.

I should have maybe added that I didn't take this approach because in 
the rest of the code, I don't see that variables are declared only in a 
"case" section (no "{" ... "}" after "case") and code is generally not 
moved into a dedicated function in these big switch/cases. But maybe it 
makes sense here because of the #ifdef!
At the end, I took the simple approach because it is for -net.

In other words, I don't know what maintainers would prefer here but I am 
happy to see any another solutions implemented to remove these compiler 
warnings :)

Cheers,
Matt
-- 
Matthieu Baerts | R&D Engineer
matthieu.baerts@tessares.net
Tessares SA | Hybrid Access Solutions
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