[PATCH net-next v2 3/3] tcp: add location into reset trace process

[Jason Xing <kerneljasonxing@gmail.com>]

From: Jason Xing <kernelxing@tencent.com>

In addition to knowing the 4-tuple of the flow which generates RST,
the reason why it does so is very important because we have some
cases where the RST should be sent and have no clue which one
exactly.

Adding location of reset process can help us more, like what
trace_kfree_skb does.

Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
 include/trace/events/tcp.h | 14 ++++++++++----
 net/ipv4/tcp_ipv4.c        |  2 +-
 net/ipv4/tcp_output.c      |  2 +-
 net/ipv6/tcp_ipv6.c        |  2 +-
 4 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
index a13eb2147a02..8f6c1a07503c 100644
--- a/include/trace/events/tcp.h
+++ b/include/trace/events/tcp.h
@@ -109,13 +109,17 @@ DEFINE_EVENT(tcp_event_sk_skb, tcp_retransmit_skb,
  */
 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,
+		void *location),
 
-	TP_ARGS(sk, skb),
+	TP_ARGS(sk, skb, location),
 
 	TP_STRUCT__entry(
 		__field(const void *, skbaddr)
 		__field(const void *, skaddr)
+		__field(void *, location)
 		__field(int, state)
 		__array(__u8, saddr, sizeof(struct sockaddr_in6))
 		__array(__u8, daddr, sizeof(struct sockaddr_in6))
@@ -141,12 +145,14 @@ TRACE_EVENT(tcp_send_reset,
 			 */
 			TP_STORE_ADDR_PORTS_SKB(skb, entry->daddr, entry->saddr);
 		}
+		__entry->location = location;
 	),
 
-	TP_printk("skbaddr=%p skaddr=%p src=%pISpc dest=%pISpc state=%s",
+	TP_printk("skbaddr=%p skaddr=%p src=%pISpc dest=%pISpc state=%s location=%pS",
 		  __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->location)
 );
 
 /*
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index d5c4a969c066..fec54cfc4fb3 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -870,7 +870,7 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
 		arg.bound_dev_if = sk->sk_bound_dev_if;
 	}
 
-	trace_tcp_send_reset(sk, skb);
+	trace_tcp_send_reset(sk, skb,  __builtin_return_address(0));
 
 	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 e3167ad96567..fb613582817e 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)
 	/* 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,  __builtin_return_address(0));
 }
 
 /* Send a crossed SYN-ACK during socket establishment.
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 8e9c59b6c00c..7eba9c3d69f1 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1128,7 +1128,7 @@ 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,  __builtin_return_address(0));
 
 	tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, 1,
 			     ipv6_get_dsfield(ipv6h), label, priority, txhash,
-- 
2.37.3