net_sched: act_police: use RCU in tcf_police_dump()

Also storing tcf_action into struct tcf_police_params
makes sure there is no discrepancy in tcf_police_act().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250709090204.797558-11-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/tc_act/tc_police.h b/include/net/tc_act/tc_police.h
index 490d88cb52338592f57e43fb79d1c6955a9684eb..a89fc8e68b1e4343bb3f6ecfc06737ebbc385f0c 100644 (file)
--- a/include/net/tc_act/tc_police.h
+++ b/include/net/tc_act/tc_police.h
@@ -5,10 +5,11 @@
 #include <net/act_api.h>
 
 struct tcf_police_params {
+       int                     action;
        int                     tcfp_result;
        u32                     tcfp_ewma_rate;
-       s64                     tcfp_burst;
        u32                     tcfp_mtu;
+       s64                     tcfp_burst;
        s64                     tcfp_mtu_ptoks;
        s64                     tcfp_pkt_burst;
        struct psched_ratecfg   rate;

diff --git a/net/sched/act_police.c b/net/sched/act_police.c
index a214ed68114206ed0770725ab91d867bab35aa09..0e1c611833790b4b1d941faf0a05ef1bde2adcb9 100644 (file)
--- a/net/sched/act_police.c
+++ b/net/sched/act_police.c
@@ -198,6 +198,7 @@ static int tcf_police_init(struct net *net, struct nlattr *nla,
                psched_ppscfg_precompute(&new->ppsrate, pps);
        }
 
+       new->action = parm->action;
        spin_lock_bh(&police->tcf_lock);
        spin_lock_bh(&police->tcfp_lock);
        police->tcfp_t_c = ktime_get_ns();
@@ -254,8 +255,8 @@ TC_INDIRECT_SCOPE int tcf_police_act(struct sk_buff *skb,
        tcf_lastuse_update(&police->tcf_tm);
        bstats_update(this_cpu_ptr(police->common.cpu_bstats), skb);
 
-       ret = READ_ONCE(police->tcf_action);
        p = rcu_dereference_bh(police->params);
+       ret = p->action;
 
        if (p->tcfp_ewma_rate) {
                struct gnet_stats_rate_est64 sample;
@@ -338,9 +339,9 @@ static void tcf_police_stats_update(struct tc_action *a,
 static int tcf_police_dump(struct sk_buff *skb, struct tc_action *a,
                               int bind, int ref)
 {
+       const struct tcf_police *police = to_police(a);
        unsigned char *b = skb_tail_pointer(skb);
-       struct tcf_police *police = to_police(a);
-       struct tcf_police_params *p;
+       const struct tcf_police_params *p;
        struct tc_police opt = {
                .index = police->tcf_index,
                .refcnt = refcount_read(&police->tcf_refcnt) - ref,
@@ -348,10 +349,9 @@ static int tcf_police_dump(struct sk_buff *skb, struct tc_action *a,
        };
        struct tcf_t t;
 
-       spin_lock_bh(&police->tcf_lock);
-       opt.action = police->tcf_action;
-       p = rcu_dereference_protected(police->params,
-                                     lockdep_is_held(&police->tcf_lock));
+       rcu_read_lock();
+       p = rcu_dereference(police->params);
+       opt.action = p->action;
        opt.mtu = p->tcfp_mtu;
        opt.burst = PSCHED_NS2TICKS(p->tcfp_burst);
        if (p->rate_present) {
@@ -392,12 +392,12 @@ static int tcf_police_dump(struct sk_buff *skb, struct tc_action *a,
        tcf_tm_dump(&t, &police->tcf_tm);
        if (nla_put_64bit(skb, TCA_POLICE_TM, sizeof(t), &t, TCA_POLICE_PAD))
                goto nla_put_failure;
-       spin_unlock_bh(&police->tcf_lock);
+       rcu_read_unlock();
 
        return skb->len;
 
 nla_put_failure:
-       spin_unlock_bh(&police->tcf_lock);
+       rcu_read_unlock();
        nlmsg_trim(skb, b);
        return -1;
 }