4.18-stable review patch. If anyone has any objections, please let me know.
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From: Phil Sutter phil@nwl.cc
[ Upstream commit 3c53ed8fef6881a864f0ee8240ed2793ef73ad0d ]
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sched/sch_api.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/net/sched/sch_api.c +++ b/net/sched/sch_api.c @@ -2052,7 +2052,8 @@ static int tc_dump_tclass_root(struct Qd
if (tcm->tcm_parent) { q = qdisc_match_from_root(root, TC_H_MAJ(tcm->tcm_parent)); - if (q && tc_dump_tclass_qdisc(q, skb, tcm, cb, t_p, s_t) < 0) + if (q && q != root && + tc_dump_tclass_qdisc(q, skb, tcm, cb, t_p, s_t) < 0) return -1; return 0; }