net: mention the convention for .ndo_setup_tc()

qdisc_offload_dump_helper(), originated from commit 602f3baf2218
("net_sch: red: Add offload ability to RED qdisc"), is designed to that

    Whether RED is being offloaded is being determined every time dump
    action is being called because parent change of this qdisc could
    change its offload state but doesn't require any RED function to be
    called.

and returning -EOPNOTSUPP (for dump queries) does not mean "I don't have
any statistics", but "I don't offload this qdisc anymore". At least two
existing drivers did it wrong, so it is worth mentioning.

Signed-off-by: David Yang <mmyangfl@gmail.com>
Link: https://patch.msgid.link/20260507214054.2539790-1-mmyangfl@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions