net_sched: act_csum: use RCU in tcf_csum_dump()

Also storing tcf_action into struct tcf_csum_params
makes sure there is no discrepancy in tcf_csum_act().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250709090204.797558-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/tc_act/tc_csum.h b/include/net/tc_act/tc_csum.h
index 2515da0142a671be82f873183077a12b5c8600b2..8d0c7a9f934525cc5fa5fd2d5ea9808629b4a550 100644 (file)
--- a/include/net/tc_act/tc_csum.h
+++ b/include/net/tc_act/tc_csum.h
@@ -8,6 +8,7 @@
 
 struct tcf_csum_params {
        u32 update_flags;
+       int action;
        struct rcu_head rcu;
 };
 

diff --git a/net/sched/act_csum.c b/net/sched/act_csum.c
index 5cc8e407e7911c6c9f252d58b458728174913317..0939e6b2ba4d1947df0f3dcfc09bfaa339a6ace2 100644 (file)
--- a/net/sched/act_csum.c
+++ b/net/sched/act_csum.c
@@ -99,6 +99,7 @@ static int tcf_csum_init(struct net *net, struct nlattr *nla,
                goto put_chain;
        }
        params_new->update_flags = parm->update_flags;
+       params_new->action = parm->action;
 
        spin_lock_bh(&p->tcf_lock);
        goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
@@ -580,7 +581,7 @@ TC_INDIRECT_SCOPE int tcf_csum_act(struct sk_buff *skb,
        tcf_lastuse_update(&p->tcf_tm);
        tcf_action_update_bstats(&p->common, skb);
 
-       action = READ_ONCE(p->tcf_action);
+       action = params->action;
        if (unlikely(action == TC_ACT_SHOT))
                goto drop;
 
@@ -631,9 +632,9 @@ drop:
 static int tcf_csum_dump(struct sk_buff *skb, struct tc_action *a, int bind,
                         int ref)
 {
+       const struct tcf_csum *p = to_tcf_csum(a);
        unsigned char *b = skb_tail_pointer(skb);
-       struct tcf_csum *p = to_tcf_csum(a);
-       struct tcf_csum_params *params;
+       const struct tcf_csum_params *params;
        struct tc_csum opt = {
                .index   = p->tcf_index,
                .refcnt  = refcount_read(&p->tcf_refcnt) - ref,
@@ -641,10 +642,9 @@ static int tcf_csum_dump(struct sk_buff *skb, struct tc_action *a, int bind,
        };
        struct tcf_t t;
 
-       spin_lock_bh(&p->tcf_lock);
-       params = rcu_dereference_protected(p->params,
-                                          lockdep_is_held(&p->tcf_lock));
-       opt.action = p->tcf_action;
+       rcu_read_lock();
+       params = rcu_dereference(p->params);
+       opt.action = params->action;
        opt.update_flags = params->update_flags;
 
        if (nla_put(skb, TCA_CSUM_PARMS, sizeof(opt), &opt))
@@ -653,12 +653,12 @@ static int tcf_csum_dump(struct sk_buff *skb, struct tc_action *a, int bind,
        tcf_tm_dump(&t, &p->tcf_tm);
        if (nla_put_64bit(skb, TCA_CSUM_TM, sizeof(t), &t, TCA_CSUM_PAD))
                goto nla_put_failure;
-       spin_unlock_bh(&p->tcf_lock);
+       rcu_read_unlock();
 
        return skb->len;
 
 nla_put_failure:
-       spin_unlock_bh(&p->tcf_lock);
+       rcu_read_unlock();
        nlmsg_trim(skb, b);
        return -1;
 }