On Wed, Sep 11, 2019 at 2:33 PM Daniel T. Lee <danieltimlee@xxxxxxxxx> wrote:
>
> Currently, at xdp_adjust_tail_kern.c, MAX_PCKT_SIZE is limited
> to 600. To make this size flexible, a new map 'pcktsz' is added.
>
> By updating new packet size to this map from the userland,
> xdp_adjust_tail_kern.o will use this value as a new max_pckt_size.
>
> If no '-P <MAX_PCKT_SIZE>' option is used, the size of maximum packet
> will be 600 as a default.
>
> Signed-off-by: Daniel T. Lee <danieltimlee@xxxxxxxxx>
>
> ---
> Changes in v2:
> - Change the helper to fetch map from 'bpf_map__next' to
> 'bpf_object__find_map_fd_by_name'.
>
> samples/bpf/xdp_adjust_tail_kern.c | 23 +++++++++++++++++++----
> samples/bpf/xdp_adjust_tail_user.c | 28 ++++++++++++++++++++++------
> 2 files changed, 41 insertions(+), 10 deletions(-)
>
> diff --git a/samples/bpf/xdp_adjust_tail_kern.c b/samples/bpf/xdp_adjust_tail_kern.c
> index 411fdb21f8bc..d6d84ffe6a7a 100644
> --- a/samples/bpf/xdp_adjust_tail_kern.c
> +++ b/samples/bpf/xdp_adjust_tail_kern.c
> @@ -25,6 +25,13 @@
> #define ICMP_TOOBIG_SIZE 98
> #define ICMP_TOOBIG_PAYLOAD_SIZE 92
>
> +struct bpf_map_def SEC("maps") pcktsz = {
> + .type = BPF_MAP_TYPE_ARRAY,
> + .key_size = sizeof(__u32),
> + .value_size = sizeof(__u32),
> + .max_entries = 1,
> +};
> +
Hey Daniel,
This looks like an ideal use case for global variables on BPF side. I
think it's much cleaner and will make BPF side of things simpler.
Would you mind giving global data a spin instead of adding this map?
> struct bpf_map_def SEC("maps") icmpcnt = {
> .type = BPF_MAP_TYPE_ARRAY,
> .key_size = sizeof(__u32),
> @@ -64,7 +71,8 @@ static __always_inline void ipv4_csum(void *data_start, int data_size,
> *csum = csum_fold_helper(*csum);
> }
>
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