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 96c39e9a873c755611c070053fb8192f31f99148..a0eb389b4fb4bc08402c0cd899599fa12921c41d 100644 (file)
--- 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;