netdev - Re: [PATCH v3 bpf] tools: bpftool: Add missing close before bpftool net attach exit

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Message-ID: <CAEf4BzZ_Fhzg=f437fS0rZANk5ZDAfTv_T3f9Hm6LCLO23pm-g@mail.gmail.com>
Date:   Wed, 11 Nov 2020 14:37:41 -0800
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     Wang Hai <wanghai38@...wei.com>,
        john fastabend <john.fastabend@...il.com>,
        Quentin Monnet <quentin@...valent.com>,
        Michal Rostecki <mrostecki@...nsuse.org>,
        Alexei Starovoitov <ast@...nel.org>, Martin Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andrii@...nel.org>,
        KP Singh <kpsingh@...omium.org>,
        Toke Høiland-Jørgensen <toke@...hat.com>,
        "Daniel T. Lee" <danieltimlee@...il.com>,
        bpf <bpf@...r.kernel.org>, Networking <netdev@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 bpf] tools: bpftool: Add missing close before bpftool
 net attach exit

On Wed, Nov 11, 2020 at 1:24 PM Daniel Borkmann <daniel@...earbox.net> wrote:
>
> On 11/11/20 2:54 PM, Wang Hai wrote:
> > progfd is created by prog_parse_fd(), before 'bpftool net attach' exit,
> > it should be closed.
> >
> > Fixes: 04949ccc273e ("tools: bpftool: add net attach command to attach XDP on interface")
> > Signed-off-by: Wang Hai <wanghai38@...wei.com>
> > ---
> > v2->v3: add 'err = 0' before successful return
> > v1->v2: use cleanup tag instead of repeated closes
> >   tools/bpf/bpftool/net.c | 18 +++++++++++-------
> >   1 file changed, 11 insertions(+), 7 deletions(-)
> >
> > diff --git a/tools/bpf/bpftool/net.c b/tools/bpf/bpftool/net.c
> > index 910e7bac6e9e..f927392271cc 100644
> > --- a/tools/bpf/bpftool/net.c
> > +++ b/tools/bpf/bpftool/net.c
> > @@ -578,8 +578,8 @@ static int do_attach(int argc, char **argv)
> >
> >       ifindex = net_parse_dev(&argc, &argv);
> >       if (ifindex < 1) {
> > -             close(progfd);
> > -             return -EINVAL;
> > +             err = -EINVAL;
> > +             goto cleanup;
> >       }
> >
> >       if (argc) {
> > @@ -587,8 +587,8 @@ static int do_attach(int argc, char **argv)
> >                       overwrite = true;
> >               } else {
> >                       p_err("expected 'overwrite', got: '%s'?", *argv);
> > -                     close(progfd);
> > -                     return -EINVAL;
> > +                     err = -EINVAL;
> > +                     goto cleanup;
> >               }
> >       }
> >
> > @@ -597,16 +597,20 @@ static int do_attach(int argc, char **argv)
> >               err = do_attach_detach_xdp(progfd, attach_type, ifindex,
> >                                          overwrite);
> >
> > -     if (err < 0) {
> > +     if (err) {
> >               p_err("interface %s attach failed: %s",
> >                     attach_type_strings[attach_type], strerror(-err));
> > -             return err;
> > +             goto cleanup;
> >       }
> >
> >       if (json_output)
> >               jsonw_null(json_wtr);
> >
> > -     return 0;
> > +     err = 0;
>
> Why is the 'err = 0' still needed here given we test for err != 0 earlier?
> Would just remove it, otherwise looks good.

This patch was already applied. Wang, can you please follow up with
another patch to address Daniel's feedback?

>
> > +cleanup:
> > +     close(progfd);
> > +     return err;
> >   }
> >
> >   static int do_detach(int argc, char **argv)
> >
>