net_sched: act: remove tcfa_qstats

tcfa_qstats is currently only used to hold drops and overlimits counters.

tcf_action_inc_drop_qstats() and tcf_action_inc_overlimit_qstats()
currently acquire a->tcfa_lock to increment these counters.

Switch to two atomic_t to get lock-free accounting.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20250901093141.2093176-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/act_api.h b/include/net/act_api.h
index 2894cfff2da3fba2b6e197dea35134e2aad5af80..91a24b5e0b93e451e4bc333a18972a8b28db1754 100644 (file)
--- a/include/net/act_api.h
+++ b/include/net/act_api.h
@@ -33,7 +33,10 @@ struct tc_action {
        struct tcf_t                    tcfa_tm;
        struct gnet_stats_basic_sync    tcfa_bstats;
        struct gnet_stats_basic_sync    tcfa_bstats_hw;
-       struct gnet_stats_queue         tcfa_qstats;
+
+       atomic_t                        tcfa_drops;
+       atomic_t                        tcfa_overlimits;
+
        struct net_rate_estimator __rcu *tcfa_rate_est;
        spinlock_t                      tcfa_lock;
        struct gnet_stats_basic_sync __percpu *cpu_bstats;
@@ -53,7 +56,6 @@ struct tc_action {
 #define tcf_action     common.tcfa_action
 #define tcf_tm         common.tcfa_tm
 #define tcf_bstats     common.tcfa_bstats
-#define tcf_qstats     common.tcfa_qstats
 #define tcf_rate_est   common.tcfa_rate_est
 #define tcf_lock       common.tcfa_lock
 
@@ -241,9 +243,7 @@ static inline void tcf_action_inc_drop_qstats(struct tc_action *a)
                qstats_drop_inc(this_cpu_ptr(a->cpu_qstats));
                return;
        }
-       spin_lock(&a->tcfa_lock);
-       qstats_drop_inc(&a->tcfa_qstats);
-       spin_unlock(&a->tcfa_lock);
+       atomic_inc(&a->tcfa_drops);
 }
 
 static inline void tcf_action_inc_overlimit_qstats(struct tc_action *a)
@@ -252,9 +252,7 @@ static inline void tcf_action_inc_overlimit_qstats(struct tc_action *a)
                qstats_overlimit_inc(this_cpu_ptr(a->cpu_qstats));
                return;
        }
-       spin_lock(&a->tcfa_lock);
-       qstats_overlimit_inc(&a->tcfa_qstats);
-       spin_unlock(&a->tcfa_lock);
+       atomic_inc(&a->tcfa_overlimits);
 }
 
 void tcf_action_update_stats(struct tc_action *a, u64 bytes, u64 packets,

diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 9e468e46346710c85c3a85b905d27dfe3972916a..ff6be5cfe2b0503a46a7cc8d657437fca6d0dac7 100644 (file)
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -1585,7 +1585,7 @@ void tcf_action_update_stats(struct tc_action *a, u64 bytes, u64 packets,
        }
 
        _bstats_update(&a->tcfa_bstats, bytes, packets);
-       a->tcfa_qstats.drops += drops;
+       atomic_add(drops, &a->tcfa_drops);
        if (hw)
                _bstats_update(&a->tcfa_bstats_hw, bytes, packets);
 }
@@ -1594,8 +1594,9 @@ EXPORT_SYMBOL(tcf_action_update_stats);
 int tcf_action_copy_stats(struct sk_buff *skb, struct tc_action *p,
                          int compat_mode)
 {
-       int err = 0;
+       struct gnet_stats_queue qstats = {0};
        struct gnet_dump d;
+       int err = 0;
 
        if (p == NULL)
                goto errout;
@@ -1619,14 +1620,17 @@ int tcf_action_copy_stats(struct sk_buff *skb, struct tc_action *p,
        if (err < 0)
                goto errout;
 
+       qstats.drops = atomic_read(&p->tcfa_drops);
+       qstats.overlimits = atomic_read(&p->tcfa_overlimits);
+
        if (gnet_stats_copy_basic(&d, p->cpu_bstats,
                                  &p->tcfa_bstats, false) < 0 ||
            gnet_stats_copy_basic_hw(&d, p->cpu_bstats_hw,
                                     &p->tcfa_bstats_hw, false) < 0 ||
            gnet_stats_copy_rate_est(&d, &p->tcfa_rate_est) < 0 ||
            gnet_stats_copy_queue(&d, p->cpu_qstats,
-                                 &p->tcfa_qstats,
-                                 p->tcfa_qstats.qlen) < 0)
+                                 &qstats,
+                                 qstats.qlen) < 0)
                goto errout;
 
        if (gnet_stats_finish_copy(&d) < 0)