commit 3c53ed8fef6881a864f0ee8240ed2793ef73ad0d
author Phil Sutter <phil@nwl.cc> Thu Oct 18 10:34:26 2018 +0200
committer David S. Miller <davem@davemloft.net> Thu Oct 18 16:00:02 2018 -0700
tree 919d4fbb499bbca7812fa8fb1d4a37d544eb586b
parent 6b839b6cf9eada30b086effb51e5d6076bafc761

net: sched: Fix for duplicate class dump

When dumping classes by parent, kernel would return classes twice:

| # tc qdisc add dev lo root prio
| # tc class show dev lo
| class prio 8001:1 parent 8001:
| class prio 8001:2 parent 8001:
| class prio 8001:3 parent 8001:
| # tc class show dev lo parent 8001:
| class prio 8001:1 parent 8001:
| class prio 8001:2 parent 8001:
| class prio 8001:3 parent 8001:
| class prio 8001:1 parent 8001:
| class prio 8001:2 parent 8001:
| class prio 8001:3 parent 8001:

This comes from qdisc_match_from_root() potentially returning the root
qdisc itself if its handle matched. Though in that case, root's classes
were already dumped a few lines above.

Fixes: cb395b2010879 ("net: sched: optimize class dumps")
Signed-off-by: Phil Sutter <phil@nwl.cc>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>