net: make dev_xdp_sb_prog_count() see programs attached through a link

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ethtool refuses to enable tcp-data-split on a device running
a single-buffer XDP program (which can't deal with the payload
landing in a separate buffer). dev_xdp_sb_prog_count() only looks
at xdp_state[].prog though, ignoring bpf_link integration.
Get the prog pointer from dev_xdp_prog(), which will consult both.

bpf_xdp_link_update() needs a bit of a touch-up, too, since
ethtool calls dev_xdp_sb_prog_count() with just the instance
lock (for ops-locked devices) - we now have to make sure the
link updates happen under that lock.

Spotted by AI while reviewing the XDP propagation series,
verified and tested on netdevsim with a C test along these lines:

  link = bpf_program__attach_xdp(prog, ifindex);
  system("ethtool -G eth0 tcp-data-split on")

Fixes: 197258f0ef ("net: ethtool: add hds_config member in ethtool_netdev_state")
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20261001012559.297751-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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This commit is contained in:

Jakub Kicinski 2026-09-30 18:25:59 -07:00

parent aaaaf87ea9

commit d333c8bca6

1 changed files with 7 additions and 4 deletions

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net/core/dev.c

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