Subject: [PATCH net-next v2 6/6] rstreason: make it work in trace world

From: Jason Xing <[email-masked]>
Date: Thu, 4 Apr 2024 15:20:47 +0800

From: Jason Xing <[email-masked]>

At last, we should let it work by introducing this reset reason in
trace world.

One of the possible expected outputs is:
... tcp_send_reset: skbaddr=xxx skaddr=xxx src=xxx dest=xxx
state=TCP_ESTABLISHED reason=NOT_SPECIFIED

Signed-off-by: Jason Xing <[email-masked]>
---
 include/trace/events/tcp.h | 37 +++++++++++++++++++++++++++++++++----
 net/ipv4/tcp_ipv4.c        |  2 +-
 net/ipv4/tcp_output.c      |  2 +-
 net/ipv6/tcp_ipv6.c        |  2 +-
 4 files changed, 36 insertions(+), 7 deletions(-)

diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
index 5c04a61a11c2..9bed9e63c9c5 100644
--- a/include/trace/events/tcp.h
+++ b/include/trace/events/tcp.h
@@ -11,6 +11,7 @@
 #include <net/ipv6.h>
 #include <net/tcp.h>
 #include <linux/sock_diag.h>
+#include <net/rstreason.h>
 
 /*
  * tcp event with arguments sk and skb
@@ -74,20 +75,38 @@ DEFINE_EVENT(tcp_event_sk_skb, tcp_retransmit_skb,
 	TP_ARGS(sk, skb)
 );
 
+#undef FN1
+#define FN1(reason)	TRACE_DEFINE_ENUM(SK_RST_REASON_##reason);
+#undef FN2
+#define FN2(reason)	TRACE_DEFINE_ENUM(SKB_DROP_REASON_##reason);
+DEFINE_RST_REASON(FN1, FN1)
+
+#undef FN1
+#undef FNe1
+#define FN1(reason)	{ SK_RST_REASON_##reason, #reason },
+#define FNe1(reason)	{ SK_RST_REASON_##reason, #reason }
+
+#undef FN2
+#undef FNe2
+#define FN2(reason)	{ SKB_DROP_REASON_##reason, #reason },
+#define FNe2(reason)	{ SKB_DROP_REASON_##reason, #reason }
 /*
  * skb of trace_tcp_send_reset is the skb that caused RST. In case of
  * active reset, skb should be NULL
  */
 TRACE_EVENT(tcp_send_reset,
 
-	TP_PROTO(const struct sock *sk, const struct sk_buff *skb),
+	TP_PROTO(const struct sock *sk,
+		 const struct sk_buff *skb,
+		 const int reason),
 
-	TP_ARGS(sk, skb),
+	TP_ARGS(sk, skb, reason),
 
 	TP_STRUCT__entry(
 		__field(const void *, skbaddr)
 		__field(const void *, skaddr)
 		__field(int, state)
+		__field(int, reason)
 		__array(__u8, saddr, sizeof(struct sockaddr_in6))
 		__array(__u8, daddr, sizeof(struct sockaddr_in6))
 	),
@@ -113,14 +132,24 @@ TRACE_EVENT(tcp_send_reset,
 			 */
 			TP_STORE_ADDR_PORTS_SKB(skb, th, entry->daddr, entry->saddr);
 		}
+		__entry->reason = reason;
 	),
 
-	TP_printk("skbaddr=%p skaddr=%p src=%pISpc dest=%pISpc state=%s",
+	TP_printk("skbaddr=%p skaddr=%p src=%pISpc dest=%pISpc state=%s reason=%s",
 		  __entry->skbaddr, __entry->skaddr,
 		  __entry->saddr, __entry->daddr,
-		  __entry->state ? show_tcp_state_name(__entry->state) : "UNKNOWN")
+		  __entry->state ? show_tcp_state_name(__entry->state) : "UNKNOWN",
+		  __entry->reason < RST_REASON_START ?
+			__print_symbolic(__entry->reason, DEFINE_DROP_REASON(FN2, FNe2)) :
+			__print_symbolic(__entry->reason, DEFINE_RST_REASON(FN1, FNe1)))
 );
 
+#undef FN1
+#undef FNe1
+
+#undef FN2
+#undef FNe2
+
 /*
  * tcp event with arguments sk
  *
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 1ae2716f0c34..9c52a4a74842 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -871,7 +871,7 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb,
 	if (sk)
 		arg.bound_dev_if = sk->sk_bound_dev_if;
 
-	trace_tcp_send_reset(sk, skb);
+	trace_tcp_send_reset(sk, skb, reason);
 
 	BUILD_BUG_ON(offsetof(struct sock, sk_bound_dev_if) !=
 		     offsetof(struct inet_timewait_sock, tw_bound_dev_if));
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 18fbbad2028a..d5a7ecfcc1b3 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3608,7 +3608,7 @@ void tcp_send_active_reset(struct sock *sk, gfp_t priority, int reason)
 	/* skb of trace_tcp_send_reset() keeps the skb that caused RST,
 	 * skb here is different to the troublesome skb, so use NULL
 	 */
-	trace_tcp_send_reset(sk, NULL);
+	trace_tcp_send_reset(sk, NULL, SK_RST_REASON_NOT_SPECIFIED);
 }
 
 /* Send a crossed SYN-ACK during socket establishment.
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 6889ea70c760..3c995eff6e52 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1131,7 +1131,7 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb,
 			label = ip6_flowlabel(ipv6h);
 	}
 
-	trace_tcp_send_reset(sk, skb);
+	trace_tcp_send_reset(sk, skb, reason);
 
 	tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, 1,
 			     ipv6_get_dsfield(ipv6h), label, priority, txhash,
-- 
2.37.3