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

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Message-ID: <1BCA833A-4C0C-41BA-8603-E68C41C9FE60@fb.com>
Date:   Thu, 30 Jul 2020 21:50:32 +0000
From:   Song Liu <songliubraving@...com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.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 Jul 30, 2020, at 2:16 PM, Andrii Nakryiko <andrii.nakryiko@...il.com> wrote:
> 
> 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?

Ah, I see. I misunderstood "defunct state". Please ignore the comment. 

Thanks,
Song