[PATCH bpf 0/3] xsk: require XDP_UMEM_TX_METADATA_LEN to actuate tx_metadata_len

[Stanislav Fomichev <sdf@fomichev.me>]

Julian reports that commit 341ac980eab9 ("xsk: Support tx_metadata_len")
can break existing use cases which don't zero-initialize xdp_umem_reg
padding. Fix it (while still breaking a minority of new users of tx
metadata), update the docs, update the selftest and sprinkle some
BUILD_BUG_ONs to hopefully catch similar issues in the future.

Thank you Julian for the report and for helping to chase it down!

Reported-by: Julian Schindel <mail@arctic-alpaca.de>
Cc: Magnus Karlsson <magnus.karlsson@gmail.com>

Stanislav Fomichev (3):
  xsk: require XDP_UMEM_TX_METADATA_LEN to actuate tx_metadata_len
  selftests/bpf: Add XDP_UMEM_TX_METADATA_LEN to XSK TX metadata test
  xsk: Try to make xdp_umem_reg extension a bit more future-proof

 Documentation/networking/xsk-tx-metadata.rst  | 16 ++++++++-----
 include/uapi/linux/if_xdp.h                   |  4 ++++
 net/xdp/xdp_umem.c                            |  9 +++++---
 net/xdp/xsk.c                                 | 23 ++++++++++---------
 tools/include/uapi/linux/if_xdp.h             |  4 ++++
 .../selftests/bpf/prog_tests/xdp_metadata.c   |  3 ++-
 6 files changed, 38 insertions(+), 21 deletions(-)

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2.45.2