It was added in commit e57a784d8c ("pkt_sched: set root qdisc
before change() in attach_default_qdiscs()") to hide duplicates
from "tc qdisc show" for incative deivices.
After 59cc1f61f ("net: sched: convert qdisc linked list to hashtable")
it triggered when classful qdisc is added to inactive device because
default qdiscs are added before switching root qdisc.
Anyway after commit ea32746953 ("net: sched: avoid duplicates in
qdisc dump") duplicates are filtered right in dumper.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
c90e95147c