[PATCH net-next] net: sched: refactor flower walk to iterate over idr

[Vlad Buslov <vladbu@mellanox.com>]

Extend struct tcf_walker with additional 'cookie' field. It is intended to
be used by classifier walk implementations to continue iteration directly
from particular filter, instead of iterating 'skip' number of times.

Change flower walk implementation to save filter handle in 'cookie'. Each
time flower walk is called, it looks up filter with saved handle directly
with idr, instead of iterating over filter linked list 'skip' number of
times. This change improves complexity of dumping flower classifier from
quadratic to linearithmic. (assuming idr lookup has logarithmic complexity)

Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
---
 include/net/pkt_cls.h  |  1 +
 net/sched/cls_api.c    |  2 ++
 net/sched/cls_flower.c | 20 +++++++++-----------
 3 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h
index a3c1a2c47cd4..ff7708c40e22 100644
--- a/include/net/pkt_cls.h
+++ b/include/net/pkt_cls.h
@@ -13,6 +13,7 @@ struct tcf_walker {
 	int	stop;
 	int	skip;
 	int	count;
+	unsigned long cookie;
 	int	(*fn)(struct tcf_proto *, void *node, struct tcf_walker *);
 };
 
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index cdc3c87c53e6..9aa70e2035dc 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -1463,7 +1463,9 @@ static bool tcf_chain_dump(struct tcf_chain *chain, struct Qdisc *q, u32 parent,
 		arg.w.stop = 0;
 		arg.w.skip = cb->args[1] - 1;
 		arg.w.count = 0;
+		arg.w.cookie = cb->args[2];
 		tp->ops->walk(tp, &arg.w);
+		cb->args[2] = arg.w.cookie;
 		cb->args[1] = arg.w.count + 1;
 		if (arg.w.stop)
 			return false;
diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index 2b5be42a9f1c..754def20b432 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -1058,19 +1058,17 @@ static void fl_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 {
 	struct cls_fl_head *head = rtnl_dereference(tp->root);
 	struct cls_fl_filter *f;
-	struct fl_flow_mask *mask;
 
-	list_for_each_entry_rcu(mask, &head->masks, list) {
-		list_for_each_entry_rcu(f, &mask->filters, list) {
-			if (arg->count < arg->skip)
-				goto skip;
-			if (arg->fn(tp, f, arg) < 0) {
-				arg->stop = 1;
-				break;
-			}
-skip:
-			arg->count++;
+	arg->count = arg->skip;
+
+	while ((f = idr_get_next_ul(&head->handle_idr,
+				    &arg->cookie)) != NULL) {
+		if (arg->fn(tp, f, arg) < 0) {
+			arg->stop = 1;
+			break;
 		}
+		arg->cookie = f->handle + 1;
+		arg->count++;
 	}
 }
 
-- 
2.7.5