Merge branch 'bpf-xdp-bcast'

Merge branch 'bpf-xdp-bcast'

Hangbin Liu says:

====================
This patchset is a new implementation for XDP multicast support based
on my previous 2 maps implementation[1]. The reason is that Daniel thinks
the exclude map implementation is missing proper bond support in XDP
context. And there is a plan to add native XDP bonding support. Adding
a exclude map in the helper also increases the complexity of verifier and
has drawbacks on performance.

The new implementation just add two new flags BPF_F_BROADCAST and
BPF_F_EXCLUDE_INGRESS to extend xdp_redirect_map for broadcast support.

With BPF_F_BROADCAST the packet will be broadcasted to all the interfaces
in the map. with BPF_F_EXCLUDE_INGRESS the ingress interface will be
excluded when do broadcasting.

The patchv11 link is here [2].

  [1] https://lore.kernel.org/bpf/20210223125809.1376577-1-liuhangbin@gmail.com
  [2] https://lore.kernel.org/bpf/20210513070447.1878448-1-liuhangbin@gmail.com

v12: As Daniel pointed out:
  a) defined as const u64 for flag_mask and action_mask in
     __bpf_xdp_redirect_map()
  b) remove BPF_F_ACTION_MASK in uapi header
  c) remove EXPORT_SYMBOL_GPL for xdpf_clone()

v11:
  a) Use unlikely() when checking if this is for broadcast redirecting.
  b) Fix a tracepoint NULL pointer issue Jesper found
  c) Remove BPF_F_REDIR_MASK and just use OR flags to make the reader more
     clear about what's flags we are using
  d) Add the performace number with multi veth interfaces in patch 01
     description.
  e) remove some sleeps to reduce the testing time in patch04. Re-struct the
     test and make clear what flags we are testing.

v10: use READ/WRITE_ONCE when read/write map instead of xchg()
v9: Update patch 01 commit description
v8: use hlist_for_each_entry_rcu() when looping the devmap hash ojbs
v7: No need to free xdpf in dev_map_enqueue_clone() if xdpf_clone failed.
v6: Fix a skb leak in the error path for generic XDP
v5: Just walk the map directly to get interfaces as get_next_key() of devmap
    hash may restart looping from the first key if the device get removed.
    After update the performace has improved 10% compired with v4.
v4: Fix flags never cleared issue in patch 02. Update selftest to cover this.
v3: Rebase the code based on latest bpf-next
v2: fix flag renaming issue in patch 02
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>