netdev - Re: [PATCH bpf-next 3/9] samples: bpf: refactor test_cgrp2

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Message-ID: <CAEKGpzjXUhnOVbamcysTX7KOrmEZ_JEzZMah3f9sLM2h+OkXsQ@mail.gmail.com>
Date:   Wed, 18 Nov 2020 18:03:14 +0900
From:   "Daniel T. Lee" <danieltimlee@...il.com>
To:     Martin KaFai Lau <kafai@...com>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>, brakmo <brakmo@...com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        David Ahern <dsa@...ulusnetworks.com>,
        Yonghong Song <yhs@...com>,
        Toke Høiland-Jørgensen <toke@...hat.com>,
        Ira Weiny <ira.weiny@...el.com>, Thomas Graf <tgraf@...g.ch>,
        Jakub Kicinski <kuba@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        bpf <bpf@...r.kernel.org>, netdev <netdev@...r.kernel.org>,
        Xdp <xdp-newbies@...r.kernel.org>
Subject: Re: [PATCH bpf-next 3/9] samples: bpf: refactor test_cgrp2_sock2
 program with libbpf

On Wed, Nov 18, 2020 at 2:58 PM Martin KaFai Lau <kafai@...com> wrote:
>
> On Tue, Nov 17, 2020 at 02:56:38PM +0000, Daniel T. Lee wrote:
> [ ... ]
>
> > +     err = bpf_link__pin(link, link_pin_path);
> > +     if (err < 0) {
> > +             printf("err : %d\n", err);
> > +             goto cleanup;
> > +     }
> > +
> > +     ret = EXIT_SUCCESS;
> > +
> > +cleanup:
> > +     if (ret != EXIT_SUCCESS)
> > +             bpf_link__destroy(link);
> This looks wrong.  cleanup should be done regardless.
>

At first, I thought destroying the link after the link__pin might unpin
the link, but I just tested it and confirmed that it actually didn't
and that the link kept pinned.

Thanks for pointing it out! I will stick to this method.

> > +
> > +     bpf_object__close(obj);
> > +     return ret;
> >  }



-- 
Best,
Daniel T. Lee