[PATCH net-next 05/11] net_sched: act_ctinfo: use atomic64_t for three counters

[Eric Dumazet <edumazet@google.com>]

Commit 21c167aa0ba9 ("net/sched: act_ctinfo: use percpu stats")
missed that stats_dscp_set, stats_dscp_error and stats_cpmark_set
might be written (and read) locklessly.

Use atomic64_t for these three fields, I doubt act_ctinfo is used
heavily on big SMP hosts anyway.

Fixes: 24ec483cec98 ("net: sched: Introduce act_ctinfo action")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Pedro Tammela <pctammela@mojatatu.com>
---
 include/net/tc_act/tc_ctinfo.h |  6 +++---
 net/sched/act_ctinfo.c         | 19 +++++++++++--------
 2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/include/net/tc_act/tc_ctinfo.h b/include/net/tc_act/tc_ctinfo.h
index f071c1d70a25e14a7a68c6294563a08851fbc738..a04bcac7adf4b61b73181d5dbd2ff9eee3cf5e97 100644
--- a/include/net/tc_act/tc_ctinfo.h
+++ b/include/net/tc_act/tc_ctinfo.h
@@ -18,9 +18,9 @@ struct tcf_ctinfo_params {
 struct tcf_ctinfo {
 	struct tc_action common;
 	struct tcf_ctinfo_params __rcu *params;
-	u64 stats_dscp_set;
-	u64 stats_dscp_error;
-	u64 stats_cpmark_set;
+	atomic64_t stats_dscp_set;
+	atomic64_t stats_dscp_error;
+	atomic64_t stats_cpmark_set;
 };
 
 enum {
diff --git a/net/sched/act_ctinfo.c b/net/sched/act_ctinfo.c
index 5b1241ddc75851998d93cd533acd74d7688410ac..93ab3bcd6d3106a1561f043e078d0be5997ea277 100644
--- a/net/sched/act_ctinfo.c
+++ b/net/sched/act_ctinfo.c
@@ -44,9 +44,9 @@ static void tcf_ctinfo_dscp_set(struct nf_conn *ct, struct tcf_ctinfo *ca,
 				ipv4_change_dsfield(ip_hdr(skb),
 						    INET_ECN_MASK,
 						    newdscp);
-				ca->stats_dscp_set++;
+				atomic64_inc(&ca->stats_dscp_set);
 			} else {
-				ca->stats_dscp_error++;
+				atomic64_inc(&ca->stats_dscp_error);
 			}
 		}
 		break;
@@ -57,9 +57,9 @@ static void tcf_ctinfo_dscp_set(struct nf_conn *ct, struct tcf_ctinfo *ca,
 				ipv6_change_dsfield(ipv6_hdr(skb),
 						    INET_ECN_MASK,
 						    newdscp);
-				ca->stats_dscp_set++;
+				atomic64_inc(&ca->stats_dscp_set);
 			} else {
-				ca->stats_dscp_error++;
+				atomic64_inc(&ca->stats_dscp_error);
 			}
 		}
 		break;
@@ -72,7 +72,7 @@ static void tcf_ctinfo_cpmark_set(struct nf_conn *ct, struct tcf_ctinfo *ca,
 				  struct tcf_ctinfo_params *cp,
 				  struct sk_buff *skb)
 {
-	ca->stats_cpmark_set++;
+	atomic64_inc(&ca->stats_cpmark_set);
 	skb->mark = READ_ONCE(ct->mark) & cp->cpmarkmask;
 }
 
@@ -323,15 +323,18 @@ static int tcf_ctinfo_dump(struct sk_buff *skb, struct tc_action *a,
 	}
 
 	if (nla_put_u64_64bit(skb, TCA_CTINFO_STATS_DSCP_SET,
-			      ci->stats_dscp_set, TCA_CTINFO_PAD))
+			      atomic64_read(&ci->stats_dscp_set),
+			      TCA_CTINFO_PAD))
 		goto nla_put_failure;
 
 	if (nla_put_u64_64bit(skb, TCA_CTINFO_STATS_DSCP_ERROR,
-			      ci->stats_dscp_error, TCA_CTINFO_PAD))
+			      atomic64_read(&ci->stats_dscp_error),
+			      TCA_CTINFO_PAD))
 		goto nla_put_failure;
 
 	if (nla_put_u64_64bit(skb, TCA_CTINFO_STATS_CPMARK_SET,
-			      ci->stats_cpmark_set, TCA_CTINFO_PAD))
+			      atomic64_read(&ci->stats_cpmark_set),
+			      TCA_CTINFO_PAD))
 		goto nla_put_failure;
 
 	spin_unlock_bh(&ci->tcf_lock);
-- 
2.50.0.727.gbf7dc18ff4-goog