net_sched: act_mpls: use RCU in tcf_mpls_dump()

Also storing tcf_action into struct tcf_mpls_params
makes sure there is no discrepancy in tcf_mpls_act().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250709090204.797558-8-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/tc_act/tc_mpls.h b/include/net/tc_act/tc_mpls.h
index d452e5e94fd0f6dfaf9510d8722f79b62c6d69bb..dd067bd4018d4bb70ca024f7997d22c7b993782a 100644 (file)
--- a/include/net/tc_act/tc_mpls.h
+++ b/include/net/tc_act/tc_mpls.h
@@ -10,6 +10,7 @@
 struct tcf_mpls_params {
        int tcfm_action;
        u32 tcfm_label;
+       int action; /* tcf_action */
        u8 tcfm_tc;
        u8 tcfm_ttl;
        u8 tcfm_bos;

diff --git a/net/sched/act_mpls.c b/net/sched/act_mpls.c
index 9f86f4e666d3363b83cfc883136b2c4a231479a4..6654011dcd2ba30769b2f52078373a834e259f88 100644 (file)
--- a/net/sched/act_mpls.c
+++ b/net/sched/act_mpls.c
@@ -57,7 +57,7 @@ TC_INDIRECT_SCOPE int tcf_mpls_act(struct sk_buff *skb,
        struct tcf_mpls *m = to_mpls(a);
        struct tcf_mpls_params *p;
        __be32 new_lse;
-       int ret, mac_len;
+       int mac_len;
 
        tcf_lastuse_update(&m->tcf_tm);
        bstats_update(this_cpu_ptr(m->common.cpu_bstats), skb);
@@ -72,8 +72,6 @@ TC_INDIRECT_SCOPE int tcf_mpls_act(struct sk_buff *skb,
                mac_len = skb_network_offset(skb);
        }
 
-       ret = READ_ONCE(m->tcf_action);
-
        p = rcu_dereference_bh(m->mpls_p);
 
        switch (p->tcfm_action) {
@@ -122,7 +120,7 @@ TC_INDIRECT_SCOPE int tcf_mpls_act(struct sk_buff *skb,
        if (skb_at_tc_ingress(skb))
                skb_pull_rcsum(skb, skb->mac_len);
 
-       return ret;
+       return p->action;
 
 drop:
        qstats_drop_inc(this_cpu_ptr(m->common.cpu_qstats));
@@ -296,6 +294,7 @@ static int tcf_mpls_init(struct net *net, struct nlattr *nla,
                                         ACT_MPLS_BOS_NOT_SET);
        p->tcfm_proto = nla_get_be16_default(tb[TCA_MPLS_PROTO],
                                             htons(ETH_P_MPLS_UC));
+       p->action = parm->action;
 
        spin_lock_bh(&m->tcf_lock);
        goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
@@ -330,8 +329,8 @@ static int tcf_mpls_dump(struct sk_buff *skb, struct tc_action *a,
                         int bind, int ref)
 {
        unsigned char *b = skb_tail_pointer(skb);
-       struct tcf_mpls *m = to_mpls(a);
-       struct tcf_mpls_params *p;
+       const struct tcf_mpls *m = to_mpls(a);
+       const struct tcf_mpls_params *p;
        struct tc_mpls opt = {
                .index    = m->tcf_index,
                .refcnt   = refcount_read(&m->tcf_refcnt) - ref,
@@ -339,10 +338,10 @@ static int tcf_mpls_dump(struct sk_buff *skb, struct tc_action *a,
        };
        struct tcf_t t;
 
-       spin_lock_bh(&m->tcf_lock);
-       opt.action = m->tcf_action;
-       p = rcu_dereference_protected(m->mpls_p, lockdep_is_held(&m->tcf_lock));
+       rcu_read_lock();
+       p = rcu_dereference(m->mpls_p);
        opt.m_action = p->tcfm_action;
+       opt.action = p->action;
 
        if (nla_put(skb, TCA_MPLS_PARMS, sizeof(opt), &opt))
                goto nla_put_failure;
@@ -370,12 +369,12 @@ static int tcf_mpls_dump(struct sk_buff *skb, struct tc_action *a,
        if (nla_put_64bit(skb, TCA_MPLS_TM, sizeof(t), &t, TCA_MPLS_PAD))
                goto nla_put_failure;
 
-       spin_unlock_bh(&m->tcf_lock);
+       rcu_read_unlock();
 
        return skb->len;
 
 nla_put_failure:
-       spin_unlock_bh(&m->tcf_lock);
+       rcu_read_unlock();
        nlmsg_trim(skb, b);
        return -EMSGSIZE;
 }