netdev - Re: [PATCH bpf-next 5/5] tools/bpftool: add documentation and bash-completion for `link detach`

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Message-ID: <CAEf4BzYOmtjmYRPjA_Crbt8TjQZpTG12YZSp1xTrr4d4dADcNA@mail.gmail.com>
Date:   Thu, 30 Jul 2020 14:16:09 -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 5/5] tools/bpftool: add documentation and
 bash-completion for `link detach`

On Thu, Jul 30, 2020 at 2:13 PM Song Liu <songliubraving@...com> wrote:
>
>
>
> > On Jul 29, 2020, at 4:05 PM, Andrii Nakryiko <andriin@...com> wrote:
> >
> > Add info on link detach sub-command to man page. Add detach to bash-completion
> > as well.
> >
> > Signed-off-by: Andrii Nakryiko <andriin@...com>
>
> Acked-by: Song Liu <songliubraving@...com>
>
> With one nitpick below.
>
> > ---
>
> [...]
>
> > @@ -49,6 +50,13 @@ DESCRIPTION
> >                 contain a dot character ('.'), which is reserved for future
> >                 extensions of *bpffs*.
> >
> > +     **bpftool link detach** *LINK*
> > +               Force-detach link *LINK*. BPF link and its underlying BPF
> > +               program will stay valid, but they will be detached from the
> > +               respective BPF hook and BPF link will transition into
> > +               a defunct state until last open file descriptor for that
>
> Shall we say "a defunct state when the last open file descriptor for that..."?


No-no, it is in defunc state between LINK_DETACH and last FD being
closed. Once last FD is closed, BPF link will get destructed and freed
in kernel. So I think until is more precise here?

>
>
> > +               link is closed.
> > +
> >       **bpftool link help**
> >                 Print short help message.
> >
>
> [...]