selftests/tc-testing: Add tests that force multiq and taprio to enqueue to child's gso_skb

Add test cases to reproduce scenarios fixed recently [1] where
multiqueue and taprio forced their children into enqueueing an skb to
gso_skb (during peek), but failed to dequeue from gso_skb because they
called the child's dequeue callback directly. This causes a desync in the
child's qlen/backlog and results in an eventual null-ptr-deref (with a
qfq or dualpi2 child).

Test cases are the following:

- Force multiq to dequeue from its child's gso_skb with qfq leaf (fb6c)
- Force multiq to dequeue from its child's gso_skb with dualpi2 leaf (1922)
- Force taprio to dequeue from its child's gso_skb with qfq leaf (476f)
- Force taprio to dequeue from its child's gso_skb with dualpi2 leaf (0235)

[1] https://lore.kernel.org/netdev/20260625-b4-disp-31bcb279-v1-0-85c40b83c529@proton.me/

Signed-off-by: Victor Nogueira <victor@mojatatu.com>
Reviewed-by: Pedro Tammela <pctammela@mojatatu.com>
Link: https://patch.msgid.link/20260630153651.249752-1-victor@mojatatu.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

0 files changed, 0 insertions, 0 deletions