# \[Patch net-next 09/13\] udp: introduce tracepoint trace\_udp\_rcv()

- From: Cong Wang \<hidden\>
- Date: 2021-08-05 18:58:11 
- List: netdev
- Page: https://ratatoskr.run/netdev/2021/08/11208695
- Thread: https://ratatoskr.run/netdev/2021/08/11208686/t.md

```text
From: Qitao Xu <redacted>

Tracepoint trace_udp_rcv() is introduced to trace skb at
the entrance of UDP layer on RX side.

Reviewed-by: Cong Wang <redacted>
Signed-off-by: Qitao Xu <redacted>
---
 include/trace/events/udp.h | 17 +++++++++++++++++
 net/ipv4/udp.c             |  8 +++++++-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/include/trace/events/udp.h b/include/trace/events/udp.h
index 6af4b402237a..5008bdd546e8 100644
--- a/include/trace/events/udp.h
+++ b/include/trace/events/udp.h
@@ -27,6 +27,23 @@ TRACE_EVENT(udp_fail_queue_rcv_skb,
 	TP_printk("rc=%d port=%hu", __entry->rc, __entry->lport)
 );
 
+TRACE_EVENT(udp_rcv,
+
+	TP_PROTO(const struct sk_buff *skb),
+
+	TP_ARGS(skb),
+
+	TP_STRUCT__entry(
+		__field(const void *, skbaddr)
+	),
+
+	TP_fast_assign(
+		__entry->skbaddr = skb;
+	),
+
+	TP_printk("skbaddr=%px", __entry->skbaddr)
+);
+
 TRACE_EVENT(udp_send_skb,
 
 	TP_PROTO(const struct sock *sk, const struct sk_buff *skb),
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index daa618465a1d..4751a8f9acff 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2617,7 +2617,13 @@ int udp_v4_early_demux(struct sk_buff *skb)
 
 int udp_rcv(struct sk_buff *skb)
 {
-	return __udp4_lib_rcv(skb, &udp_table, IPPROTO_UDP);
+	int ret;
+
+	ret = __udp4_lib_rcv(skb, &udp_table, IPPROTO_UDP);
+	if (!ret)
+		trace_udp_rcv(skb);
+	return ret;
+
 }
 
 void udp_destroy_sock(struct sock *sk)
-- 
2.27.0

```