netdev - Re: [PATCH v2 bpf-next 1/2] btf: separate btf creation and loading

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Message-ID: <CAEf4Bzb92WCOpYvKbjAtFGnW7sbfuckXv437oRnX6LxJMDPBPg@mail.gmail.com>
Date:   Tue, 5 Feb 2019 21:03:09 -0800
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     Andrii Nakryiko <andriin@...com>, Song Liu <songliubraving@...com>,
        Yonghong Song <yhs@...com>, Alexei Starovoitov <ast@...com>,
        Martin Lau <kafai@...com>, netdev@...r.kernel.org,
        daniel@...earbox.next
Subject: Re: [PATCH v2 bpf-next 1/2] btf: separate btf creation and loading

On Tue, Feb 5, 2019 at 7:03 PM Alexei Starovoitov
<alexei.starovoitov@...il.com> wrote:
>
> On Tue, Feb 05, 2019 at 04:29:48PM -0800, Andrii Nakryiko wrote:
> > This change splits out previous btf__new functionality of constructing
> > struct btf and loading it into kernel into two:
> > - btf__new() just creates and initializes struct btf
> > - btf__load() attempts to load existing struct btf into kernel
> >
> > btf__free will still close BTF fd, if it was ever loaded successfully
> > into kernel.
> >
> > This change allows users of libbpf to manipulate BTF using its API,
> > without the need to unnecessarily load it into kernel.
> >
> > One of the intended use cases is pahole using libbpf to do DWARF to BTF
> > conversion and deduplication using libbpf, while handling ELF sections
> > overwrites and other concerns on its own.
> >
> > Signed-off-by: Andrii Nakryiko <andriin@...com>
> > Acked-by: Song Liu <songliubraving@...com>
>
> should it be
> Fixes: 2d3feca8c44f ("bpf: btf: print map dump and lookup with btf info")
> ?
> Even back then btf__new() was doing the loading.
> So that btf support in bpftool was silently double loading btf.
>

ok, will add that to commit message