netdev - [PATCH v2 net-next 04/11] net_sched: act_ct: use RCU in tcf_ct

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Message-ID: <20250709090204.797558-5-edumazet@google.com>
Date: Wed,  9 Jul 2025 09:01:56 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: Simon Horman <horms@...nel.org>, Jamal Hadi Salim <jhs@...atatu.com>, 
	Cong Wang <xiyou.wangcong@...il.com>, Jiri Pirko <jiri@...nulli.us>, 
	Kuniyuki Iwashima <kuniyu@...gle.com>, netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH v2 net-next 04/11] net_sched: act_ct: use RCU in tcf_ct_dump()

Also storing tcf_action into struct tcf_ct_params
makes sure there is no discrepancy in tcf_ct_act().

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 include/net/tc_act/tc_ct.h |  2 +-
 net/sched/act_ct.c         | 30 +++++++++++++++---------------
 2 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/include/net/tc_act/tc_ct.h b/include/net/tc_act/tc_ct.h
index e6b45cb27ebf43d6c937fd823767ac1cc9797524..8b90c86c0b0ddd63a3eab7d59328404deb148b10 100644
--- a/include/net/tc_act/tc_ct.h
+++ b/include/net/tc_act/tc_ct.h
@@ -13,7 +13,7 @@ struct tcf_ct_params {
 	struct nf_conntrack_helper *helper;
 	struct nf_conn *tmpl;
 	u16 zone;
-
+	int action;
 	u32 mark;
 	u32 mark_mask;
 
diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c
index c02f39efc6efead9e18908bdb307872445c6b8fd..6749a4a9a9cd0a43897fcd20d228721ce057cb88 100644
--- a/net/sched/act_ct.c
+++ b/net/sched/act_ct.c
@@ -977,7 +977,7 @@ TC_INDIRECT_SCOPE int tcf_ct_act(struct sk_buff *skb, const struct tc_action *a,
 
 	p = rcu_dereference_bh(c->params);
 
-	retval = READ_ONCE(c->tcf_action);
+	retval = p->action;
 	commit = p->ct_action & TCA_CT_ACT_COMMIT;
 	clear = p->ct_action & TCA_CT_ACT_CLEAR;
 	tmpl = p->tmpl;
@@ -1409,6 +1409,7 @@ static int tcf_ct_init(struct net *net, struct nlattr *nla,
 	if (err)
 		goto cleanup;
 
+	params->action = parm->action;
 	spin_lock_bh(&c->tcf_lock);
 	goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
 	params = rcu_replace_pointer(c->params, params,
@@ -1442,8 +1443,8 @@ static void tcf_ct_cleanup(struct tc_action *a)
 }
 
 static int tcf_ct_dump_key_val(struct sk_buff *skb,
-			       void *val, int val_type,
-			       void *mask, int mask_type,
+			       const void *val, int val_type,
+			       const void *mask, int mask_type,
 			       int len)
 {
 	int err;
@@ -1464,9 +1465,9 @@ static int tcf_ct_dump_key_val(struct sk_buff *skb,
 	return 0;
 }
 
-static int tcf_ct_dump_nat(struct sk_buff *skb, struct tcf_ct_params *p)
+static int tcf_ct_dump_nat(struct sk_buff *skb, const struct tcf_ct_params *p)
 {
-	struct nf_nat_range2 *range = &p->range;
+	const struct nf_nat_range2 *range = &p->range;
 
 	if (!(p->ct_action & TCA_CT_ACT_NAT))
 		return 0;
@@ -1504,7 +1505,8 @@ static int tcf_ct_dump_nat(struct sk_buff *skb, struct tcf_ct_params *p)
 	return 0;
 }
 
-static int tcf_ct_dump_helper(struct sk_buff *skb, struct nf_conntrack_helper *helper)
+static int tcf_ct_dump_helper(struct sk_buff *skb,
+			      const struct nf_conntrack_helper *helper)
 {
 	if (!helper)
 		return 0;
@@ -1521,9 +1523,8 @@ static inline int tcf_ct_dump(struct sk_buff *skb, struct tc_action *a,
 			      int bind, int ref)
 {
 	unsigned char *b = skb_tail_pointer(skb);
-	struct tcf_ct *c = to_ct(a);
-	struct tcf_ct_params *p;
-
+	const struct tcf_ct *c = to_ct(a);
+	const struct tcf_ct_params *p;
 	struct tc_ct opt = {
 		.index   = c->tcf_index,
 		.refcnt  = refcount_read(&c->tcf_refcnt) - ref,
@@ -1531,10 +1532,9 @@ static inline int tcf_ct_dump(struct sk_buff *skb, struct tc_action *a,
 	};
 	struct tcf_t t;
 
-	spin_lock_bh(&c->tcf_lock);
-	p = rcu_dereference_protected(c->params,
-				      lockdep_is_held(&c->tcf_lock));
-	opt.action = c->tcf_action;
+	rcu_read_lock();
+	p = rcu_dereference(c->params);
+	opt.action = p->action;
 
 	if (tcf_ct_dump_key_val(skb,
 				&p->ct_action, TCA_CT_ACTION,
@@ -1579,11 +1579,11 @@ static inline int tcf_ct_dump(struct sk_buff *skb, struct tc_action *a,
 	tcf_tm_dump(&t, &c->tcf_tm);
 	if (nla_put_64bit(skb, TCA_CT_TM, sizeof(t), &t, TCA_CT_PAD))
 		goto nla_put_failure;
-	spin_unlock_bh(&c->tcf_lock);
+	rcu_read_unlock();
 
 	return skb->len;
 nla_put_failure:
-	spin_unlock_bh(&c->tcf_lock);
+	rcu_read_unlock();
 	nlmsg_trim(skb, b);
 	return -1;
 }
-- 
2.50.0.727.gbf7dc18ff4-goog