Re: [PATCH net-next 4/5] selftests/bpf: check XDP attach on a nested bond slave

On 09/28, Jakub Kicinski wrote:

test_xdp_bonding_attach() already covers a flat bond both ways round:
the master is refused while a slave has a program, and a slave is
refused while the master has one. The nested test only ever checked
that attaching to the outermost master succeeds.

That left the more interesting half of the nesting untested. Only the
direct upper is consulted when deciding whether a device is already
running XDP, so with bond -> bond_nest1 -> bond_nest2 the check on
bond_nest2 looks at bond_nest1, and it only sees a program there if
bond_nest1 recorded the one it was handed. Before the preceding fix it
did not, and a second program could be attached to bond_nest2 while the
outer bond's program was already running on it.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Acked-by: Stanislav Fomichev <sdf@fomichev.me>