[PATCH net v3 0/2] xsk: fix multi-buffer TX software checksum
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From: Rongzheng Wang <hidden>
Date: 2026-10-28 02:50:36
Also in:
bpf, lkml, stable
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [selftests] (test runners & infrastructure), kernel selftest framework, networking [general], the rest, xdp (express data path), xdp sockets (af_xdp) · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Shuah Khan, Shuah Khan, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Jesper Dangaard Brouer, John Fastabend, Magnus Karlsson, Maciej Fijalkowski
Revision v3 (2 revisions archived).
Revisions (2)
- v2
- v3 current [diff against previous]
This is v3 of the AF_XDP multi-buffer TX software checksum fix. I found this while testing multi-buffer TX with XDP_UMEM_TX_SW_CSUM: a two-descriptor packet had a bad wire checksum, while a single descriptor was correct. There was no production or syzbot report. Patch 1 moves the software checksum calculation from xsk_skb_metadata() to the point where the last descriptor has been added to the skb. The old code calculated the checksum after the first descriptor, so multi-buffer packets only included the first fragment in the checksum. Patch 2 extends test_xdp_metadata to cover the single-descriptor and multi-buffer TX cases. The updated selftest passes on the v3 kernel in a local QEMU run. v3: - preserve unlikely() around pool->tx_sw_csum (Maciej) - restore the binary MAC literals in the selftest (Sashiko) - keep a distinct malformed-packet counter out of this stable fix; if it is useful, it can be added separately for net-next later (Magnus) v2: https://lore.kernel.org/all/20261024141157.59301-1-testwrzwrz@gmail.com/ (local) v1: https://lore.kernel.org/all/20261024091256.17918-1-testwrzwrz@gmail.com/ (local) Rongzheng Wang (2): xsk: defer software checksum until the skb is complete selftests/bpf: cover AF_XDP multi-buffer TX software checksum net/xdp/xsk.c | 23 ++-- .../selftests/bpf/prog_tests/xdp_metadata.c | 122 ++++++++++++------ 2 files changed, 99 insertions(+), 46 deletions(-) -- 2.39.5 (Apple Git-154)