netdev - [PATCH net-next v3 5/5] net/sched: cls_api: conditional notification of events

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Date: Wed,  6 Dec 2023 13:44:16 -0300
From: Pedro Tammela <pctammela@...atatu.com>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	jhs@...atatu.com,
	xiyou.wangcong@...il.com,
	jiri@...nulli.us,
	marcelo.leitner@...il.com,
	vladbu@...dia.com,
	Pedro Tammela <pctammela@...atatu.com>,
	Jiri Pirko <jiri@...dia.com>
Subject: [PATCH net-next v3 5/5] net/sched: cls_api: conditional notification of events

As of today tc-filter/chain events are unconditionally built and sent to
RTNLGRP_TC. As with the introduction of rtnl_notify_needed we can check
before-hand if they are really needed. This will help to alleviate
system pressure when filters are concurrently added without the rtnl
lock as in tc-flower.

Reviewed-by: Jiri Pirko <jiri@...dia.com>
Signed-off-by: Pedro Tammela <pctammela@...atatu.com>
---
 net/sched/cls_api.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 1976bd163986..123185907ebd 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -2053,6 +2053,9 @@ static int tfilter_notify(struct net *net, struct sk_buff *oskb,
 	u32 portid = oskb ? NETLINK_CB(oskb).portid : 0;
 	int err = 0;
 
+	if (!unicast && !rtnl_notify_needed(net, n->nlmsg_flags, RTNLGRP_TC))
+		return 0;
+
 	skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOBUFS;
@@ -2082,6 +2085,9 @@ static int tfilter_del_notify(struct net *net, struct sk_buff *oskb,
 	u32 portid = oskb ? NETLINK_CB(oskb).portid : 0;
 	int err;
 
+	if (!unicast && !rtnl_notify_needed(net, n->nlmsg_flags, RTNLGRP_TC))
+		return tp->ops->delete(tp, fh, last, rtnl_held, extack);
+
 	skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOBUFS;
@@ -2906,6 +2912,9 @@ static int tc_chain_notify(struct tcf_chain *chain, struct sk_buff *oskb,
 	struct sk_buff *skb;
 	int err = 0;
 
+	if (!unicast && !rtnl_notify_needed(net, flags, RTNLGRP_TC))
+		return 0;
+
 	skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOBUFS;
@@ -2935,6 +2944,9 @@ static int tc_chain_notify_delete(const struct tcf_proto_ops *tmplt_ops,
 	struct net *net = block->net;
 	struct sk_buff *skb;
 
+	if (!unicast && !rtnl_notify_needed(net, flags, RTNLGRP_TC))
+		return 0;
+
 	skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOBUFS;
-- 
2.40.1