net: XDP-generic determining XDP frame size

The SKB "head" pointer points to the data area that contains
skb_shared_info, that can be found via skb_end_pointer(). Given
xdp->data_hard_start have been established (basically pointing to
skb->head), frame size is between skb_end_pointer() and data_hard_start,
plus the size reserved to skb_shared_info.

Change the bpf_xdp_adjust_tail offset adjust of skb->len, to be a positive
offset number on grow, and negative number on shrink.  As this seems more
natural when reading the code.

Signed-off-by: Jesper Dangaard Brouer <[email protected]>
Signed-off-by: Alexei Starovoitov <[email protected]>
Acked-by: Toke Høiland-Jørgensen <[email protected]>
Link: https://lore.kernel.org/bpf/158945336804.97035.7164852191163722056.stgit@firesoul

0 files changed, 0 insertions, 0 deletions