net/sched: Revert "net/sched: Restrict conditions for adding duplicating netems to...

net/sched: Revert "net/sched: Restrict conditions for adding duplicating netems to qdisc tree"

This reverts commit ec8e0e3d7adef940cdf9475e2352c0680189d14e.

The original patch rejects any tree containing two netems when
either has duplication set, even when they sit on unrelated classes
of the same classful parent. That broke configurations that have
worked since netem was introduced.

The re-entrancy problem the original commit was trying to solve is
handled by later patch using tc_depth flag.

Doing this revert will (re)expose the original bug with multiple
netem duplication. When this patch is backported make sure
and get the full series.

Fixes: ec8e0e3d7ade ("net/sched: Restrict conditions for adding duplicating netems to qdisc tree")
Reported-by: Ji-Soo Chung <jschung2@proton.me>
Reported-by: Gerlinde <lrGerlinde@mailfence.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220774
Reported-by: zyc zyc <zyc199902@zohomail.cn>
Closes: https://lore.kernel.org/all/19adda5a1e2.12410b78222774.9191120410578703463@zohomail.cn/
Reported-by: Manas Ghandat <ghandatmanas@gmail.com>
Closes: https://lore.kernel.org/netdev/f69b2c8f-8325-4c2e-a011-6dbc089f30e4@gmail.com/
Reviewed-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260525122556.973584-3-jhs@mojatatu.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>