From: Pedro Tammela <pctammela@mojatatu.com>
Date: Fri, 8 Dec 2023 19:28:47 +0000 (-0300)
Subject: net/sched: cls_api: conditional notification of events
X-Git-Tag: v6.6.88~375
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=28f2cd143b5b2b35b83669d892b15871f2a57efe;p=thirdparty%2Fkernel%2Fstable.git

net/sched: cls_api: conditional notification of events

[ Upstream commit 93775590b1ee98bf2976b1f4a1ed24e9ff76170f ]

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@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Link: https://lore.kernel.org/r/20231208192847.714940-8-pctammela@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: 369609fc6272 ("tc: Ensure we have enough buffer space when sending filter netlink notifications")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 96c39e9a873c7..a0eb389b4fb4b 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -2038,6 +2038,9 @@ 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;
@@ -2067,6 +2070,9 @@ static int tfilter_del_notify(struct net *net, struct sk_buff *oskb,
 	u32 portid = oskb ? NETLINK_CB(oskb).portid : 0;
 	int err;
 
+	if (!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;
@@ -2891,6 +2897,9 @@ 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;
@@ -2920,6 +2929,9 @@ static int tc_chain_notify_delete(const struct tcf_proto_ops *tmplt_ops,
 	struct net *net = block->net;
 	struct sk_buff *skb;
 
+	if (!rtnl_notify_needed(net, flags, RTNLGRP_TC))
+		return 0;
+
 	skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
 	if (!skb)
 		return -ENOBUFS;