net: sched: optimize class dumps

In commit 59cc1f61f09c ("net: sched: convert qdisc linked list to
hashtable") we missed the opportunity to considerably speed up
tc_dump_tclass_root() if a qdisc handle is provided by user.

Instead of iterating all the qdiscs, use qdisc_match_from_root()
to directly get the one we look for.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index bbe57d57b67fd498692bd41db49147511f1bb091..e88342fde1bc409aed6a3c86e7a628030eaac66f 100644 (file)
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1831,6 +1831,12 @@ static int tc_dump_tclass_root(struct Qdisc *root, struct sk_buff *skb,
        if (!qdisc_dev(root))
                return 0;
 
+       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)
+                       return -1;
+               return 0;
+       }
        hash_for_each(qdisc_dev(root)->qdisc_hash, b, q, hash) {
                if (tc_dump_tclass_qdisc(q, skb, tcm, cb, t_p, s_t) < 0)
                        return -1;