netdev - Re: [RFC PATCH 2/6] bpf: add BPF_MAP_DUMP command to access more than one entry per call

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Date:   Mon, 24 Jun 2019 16:35:05 -0700
From:   Brian Vazquez <brianvv.kernel@...il.com>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>
Cc:     Brian Vazquez <brianvv@...gle.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S . Miller" <davem@...emloft.net>,
        Stanislav Fomichev <sdf@...gle.com>,
        Willem de Bruijn <willemb@...gle.com>,
        Petar Penkov <ppenkov@...gle.com>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Subject: Re: [RFC PATCH 2/6] bpf: add BPF_MAP_DUMP command to access more than
 one entry per call

On Mon, Jun 24, 2019 at 3:46 PM Jakub Kicinski
<jakub.kicinski@...ronome.com> wrote:
>
> On Fri, 21 Jun 2019 16:16:46 -0700, Brian Vazquez wrote:
> > @@ -385,6 +386,14 @@ union bpf_attr {
> >               __u64           flags;
> >       };
> >
> > +     struct { /* struct used by BPF_MAP_DUMP command */
> > +             __u32           map_fd;
>
> There is a hole here, perhaps flags don't have to be 64 bit?
The command implementation is wrapping BPF_MAP_*_ELEM commands, I
would expect this one to handle the same flags which are 64 bit.
Note that there's a hole in the anonymous structure used by the other
commands too:
        struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */
                __u32           map_fd;
                __aligned_u64   key;
                union {
                        __aligned_u64 value;
                        __aligned_u64 next_key;
                };
                __u64           flags;
        };