From: Vlad Buslov <vladbu@mellanox.com>
Date: Mon, 9 Jul 2018 13:29:11 +0300
Subject: net: sched: refactor flower walk to iterate over idr
Patch-mainline: v4.19-rc1
Git-commit: 01683a1469995cc7aaf833d6f8b3f1c1d2fc3b92
References: bsc#1109837

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>
Reported-by: Simon Horman <simon.horman@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 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(-)

--- a/include/net/pkt_cls.h
+++ b/include/net/pkt_cls.h
@@ -12,6 +12,7 @@ struct tcf_walker {
 	int	stop;
 	int	skip;
 	int	count;
+	unsigned long cookie;
 	int	(*fn)(struct tcf_proto *, void *node, struct tcf_walker *);
 };
 
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -1508,7 +1508,9 @@ static bool tcf_chain_dump(struct tcf_ch
 		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;
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -1099,19 +1099,17 @@ static void fl_walk(struct tcf_proto *tp
 {
 	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++;
 	}
 }