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From:   jackygam2001 <jacky_gam_2001@163.com>
To:     edumazet@google.com, davem@davemloft.net, kuba@kernel.org,
        pabeni@redhat.com, rostedt@goodmis.org, mingo@redhat.com,
        yoshfuji@linux-ipv6.org, dsahern@kernel.org
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        ping.gan@dell.com, jackygam2001 <jacky_gam_2001@163.com>
Subject: [PATCH] tcp: Add tracepoint for tcp_set_ca_state
Date:   Wed, 30 Mar 2022 21:01:28 +0800
Message-Id: <20220330130128.10256-1-jacky_gam_2001@163.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The congestion status of a tcp flow may be updated since there
is congestion between tcp sender and receiver. It makes sense for
adding tracepoint for congestion status update function to evaluate
the performance of network and congestion algorithm.

Link: https://github.com/iovisor/bcc/pull/3899

Signed-off-by: jackygam2001 <jacky_gam_2001@163.com>
---
 include/net/tcp.h          | 12 +++---------
 include/trace/events/tcp.h | 45 +++++++++++++++++++++++++++++++++++++++++++++
 net/ipv4/tcp_cong.c        | 12 ++++++++++++
 3 files changed, 60 insertions(+), 9 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 70ca4a5e330a..9a3786f33798 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1139,15 +1139,6 @@ static inline bool tcp_ca_needs_ecn(const struct sock *sk)
 	return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
 }
 
-static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
-{
-	struct inet_connection_sock *icsk = inet_csk(sk);
-
-	if (icsk->icsk_ca_ops->set_state)
-		icsk->icsk_ca_ops->set_state(sk, ca_state);
-	icsk->icsk_ca_state = ca_state;
-}
-
 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
 {
 	const struct inet_connection_sock *icsk = inet_csk(sk);
@@ -1156,6 +1147,9 @@ static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
 		icsk->icsk_ca_ops->cwnd_event(sk, event);
 }
 
+/* From tcp_cong.c */
+void tcp_set_ca_state(struct sock *sk, const u8 ca_state);
+
 /* From tcp_rate.c */
 void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
 void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
index 521059d8dc0a..69a68b01c1de 100644
--- a/include/trace/events/tcp.h
+++ b/include/trace/events/tcp.h
@@ -371,6 +371,51 @@ DEFINE_EVENT(tcp_event_skb, tcp_bad_csum,
 	TP_ARGS(skb)
 );
 
+TRACE_EVENT(tcp_cong_state_set,
+
+	TP_PROTO(struct sock *sk, const u8 ca_state),
+
+	TP_ARGS(sk, ca_state),
+
+	TP_STRUCT__entry(
+		__field(const void *, skaddr)
+		__field(__u16, sport)
+		__field(__u16, dport)
+		__array(__u8, saddr, 4)
+		__array(__u8, daddr, 4)
+		__array(__u8, saddr_v6, 16)
+		__array(__u8, daddr_v6, 16)
+		__field(__u8, cong_state)
+	),
+
+	TP_fast_assign(
+		struct inet_sock *inet = inet_sk(sk);
+		__be32 *p32;
+
+		__entry->skaddr = sk;
+
+		__entry->sport = ntohs(inet->inet_sport);
+		__entry->dport = ntohs(inet->inet_dport);
+
+		p32 = (__be32 *) __entry->saddr;
+		*p32 = inet->inet_saddr;
+
+		p32 = (__be32 *) __entry->daddr;
+		*p32 =  inet->inet_daddr;
+
+		TP_STORE_ADDRS(__entry, inet->inet_saddr, inet->inet_daddr,
+			   sk->sk_v6_rcv_saddr, sk->sk_v6_daddr);
+
+		__entry->cong_state = ca_state;
+	),
+
+	TP_printk("sport=%hu dport=%hu saddr=%pI4 daddr=%pI4 saddrv6=%pI6c daddrv6=%pI6c cong_state=%u",
+		  __entry->sport, __entry->dport,
+		  __entry->saddr, __entry->daddr,
+		  __entry->saddr_v6, __entry->daddr_v6,
+		  __entry->cong_state)
+);
+
 #endif /* _TRACE_TCP_H */
 
 /* This part must be outside protection */
diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index dc95572163df..98b48bdb8be7 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -16,6 +16,7 @@
 #include <linux/gfp.h>
 #include <linux/jhash.h>
 #include <net/tcp.h>
+#include <trace/events/tcp.h>
 
 static DEFINE_SPINLOCK(tcp_cong_list_lock);
 static LIST_HEAD(tcp_cong_list);
@@ -33,6 +34,17 @@ struct tcp_congestion_ops *tcp_ca_find(const char *name)
 	return NULL;
 }
 
+void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
+{
+	struct inet_connection_sock *icsk = inet_csk(sk);
+
+	trace_tcp_cong_state_set(sk, ca_state);
+
+	if (icsk->icsk_ca_ops->set_state)
+		icsk->icsk_ca_ops->set_state(sk, ca_state);
+	icsk->icsk_ca_state = ca_state;
+}
+
 /* Must be called with rcu lock held */
 static struct tcp_congestion_ops *tcp_ca_find_autoload(struct net *net,
 						       const char *name)
-- 
2.15.0