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 17:14:16 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     Brian Vazquez <brianvv.kernel@...il.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, 24 Jun 2019 16:35:05 -0700, Brian Vazquez wrote:
> On Mon, Jun 24, 2019 at 3:46 PM Jakub Kicinski 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;
>         };

Ah, okay.