netdev - Re: [PATCH bpf-next v6] samples: bpf: add max_pckt_size option at xdp_adjust

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Date:   Tue, 8 Oct 2019 01:13:57 +0900
From:   "Daniel T. Lee" <danieltimlee@...il.com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc:     Yonghong Song <yhs@...com>, Song Liu <liu.song.a23@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>, bpf <bpf@...r.kernel.org>,
        Networking <netdev@...r.kernel.org>
Subject: Re: [PATCH bpf-next v6] samples: bpf: add max_pckt_size option at xdp_adjust_tail

On Tue, Oct 8, 2019 at 1:41 AM Andrii Nakryiko
<andrii.nakryiko@...il.com> wrote:
>
> On Mon, Oct 7, 2019 at 9:06 AM Daniel T. Lee <danieltimlee@...il.com> wrote:
> >
> > Currently, at xdp_adjust_tail_kern.c, MAX_PCKT_SIZE is limited
> > to 600. To make this size flexible, static global variable
> > 'max_pcktsz' is added.
> >
> > By updating new packet size from the user space, xdp_adjust_tail_kern.o
> > will use this value as a new max packet size.
> >
> > This static global variable can be accesible from .data section with
> > bpf_object__find_map* from user space, since it is considered as
> > internal map (accessible with .bss/.data/.rodata suffix).
> >
> > If no '-P <MAX_PCKT_SIZE>' option is used, the size of maximum packet
> > will be 600 as a default.
> >
> > Changed the way to test prog_fd, map_fd from '!= 0' to '< 0',
> > since fd could be 0 when stdin is closed.
> >
> > Signed-off-by: Daniel T. Lee <danieltimlee@...il.com>
> >
> > ---
> > Changes in v6:
> >     - Remove redundant error message
> > Changes in v5:
> >     - Change pcktsz map to static global variable
> > Changes in v4:
> >     - make pckt_size no less than ICMP_TOOBIG_SIZE
> >     - Fix code style
> > Changes in v2:
> >     - Change the helper to fetch map from 'bpf_map__next' to
> >     'bpf_object__find_map_fd_by_name'.
>
>
> This should go into commit message, that's netdev preference.
>
> Otherwise looks good!
>
> Acked-by: Andrii Nakryiko <andriin@...com>
>

Thanks for the feedback!

Will send the next patch with the modified commit message right away!

Thanks,
Daniel

> >
> >  samples/bpf/xdp_adjust_tail_kern.c |  7 +++++--
> >  samples/bpf/xdp_adjust_tail_user.c | 29 ++++++++++++++++++++---------
> >  2 files changed, 25 insertions(+), 11 deletions(-)
> >
> > diff --git a/samples/bpf/xdp_adjust_tail_kern.c b/samples/bpf/xdp_adjust_tail_kern.c
> > index 411fdb21f8bc..c616508befb9 100644
> > --- a/samples/bpf/xdp_adjust_tail_kern.c
> > +++ b/samples/bpf/xdp_adjust_tail_kern.c
> > @@ -25,6 +25,9 @@
> >  #define ICMP_TOOBIG_SIZE 98
> >  #define ICMP_TOOBIG_PAYLOAD_SIZE 92
> >
>
> [...]