netdev - Re: [PATCH net-next v2 1/2] libbpf: parse maps sections of varying size

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Date:   Wed, 4 Oct 2017 09:58:17 -0400
From:   Craig Gallek <kraigatgoog@...il.com>
To:     Jesper Dangaard Brouer <brouer@...hat.com>
Cc:     Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S . Miller" <davem@...emloft.net>,
        Chonggang Li <chonggangli@...gle.com>,
        netdev <netdev@...r.kernel.org>, Eric Leblond <eric@...it.org>,
        "Wangnan (F)" <wangnan0@...wei.com>
Subject: Re: [PATCH net-next v2 1/2] libbpf: parse maps sections of varying size

On Tue, Oct 3, 2017 at 10:03 AM, Jesper Dangaard Brouer
<brouer@...hat.com> wrote:
>
>
> First of all, thank you Craig for working on this.  As Alexei says, we
> need to improve tools/lib/bpf/libbpf and move towards converting users
> of bpf_load.c to this lib instead.
>
> Comments inlined below.
>
>> +                     obj->maps[map_idx].def = *def;
>
> I'm not too happy/comfortable with this way of copying the memory of
> "def" (the type-cased struct bpf_map_def).  I guess it works, and is
> part of the C-standard(?).

I believe this is a C++-ism.  I'm not sure if it was pulled into the
C99 standard or if it's just a gcc 'feature' now.  I kept it because
it was in the initial code, but I'm happy to do an explicit copy for
v3 if that looks better.