netdev - Re: [PATCH bpf-next 4/5] tools/bpftool: add `link detach` subcommand

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Message-ID: <CAEf4BzbTtP8_EvOq7HPpXCi604Je82r88L8YusGr8LogoOfk4A@mail.gmail.com>
Date:   Thu, 30 Jul 2020 14:14:46 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Song Liu <songliubraving@...com>
Cc:     Andrii Nakryiko <andriin@...com>, bpf <bpf@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...com>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        Kernel Team <Kernel-team@...com>,
        Toke Høiland-Jørgensen <toke@...hat.com>
Subject: Re: [PATCH bpf-next 4/5] tools/bpftool: add `link detach` subcommand

On Thu, Jul 30, 2020 at 2:02 PM Song Liu <songliubraving@...com> wrote:
>
>
>
> > On Jul 29, 2020, at 4:05 PM, Andrii Nakryiko <andriin@...com> wrote:
> >
> > Add ability to force-detach BPF link. Also add missing error message, if
> > specified link ID is wrong.
> >
> > Signed-off-by: Andrii Nakryiko <andriin@...com>
>
> Acked-by: Song Liu <songliubraving@...com>
>
> With two nitpicks below.
>
> [...]
>
> > static int link_parse_fd(int *argc, char ***argv)
> > {
> > +     int fd;
> > +
> >       if (is_prefix(**argv, "id")) {
> >               unsigned int id;
> >               char *endptr;
> > @@ -35,7 +37,10 @@ static int link_parse_fd(int *argc, char ***argv)
> >               }
> >               NEXT_ARGP();
> >
> > -             return bpf_link_get_fd_by_id(id);
> > +             fd = bpf_link_get_fd_by_id(id);
> > +             if (fd < 0)
> > +                     p_err("failed to get link with ID %d: %d", id, -errno);
>
> How about we print strerror(errno) to match the rest of link.c?

sure, will do, was lazy :)

>
> [...]
>
> > +static int do_detach(int argc, char **argv)
> > +{
> > +     int err, fd;
> > +
> > +     if (argc != 2)
> > +             return BAD_ARG();
> > +
> > +     fd = link_parse_fd(&argc, &argv);
> > +     if (fd < 0)
> > +             return 1;
> > +
> > +     err = bpf_link_detach(fd);
> > +     if (err)
> > +             err = -errno;
> > +     close(fd);
> > +     if (err) {
> > +             p_err("failed link detach: %d", err);
>
> And strerror(err) here.
>
>