mptcp: add tracepoint in subflow_check_data_avail

This patch added a tracepoint in subflow_check_data_avail() to show the
mapping status.

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/trace/events/mptcp.h

@@ -7,6 +7,14 @@
 
 #include <linux/tracepoint.h>
 
+#define show_mapping_status(status)					\
+	__print_symbolic(status,					\
+		{ 0, "MAPPING_OK" },					\
+		{ 1, "MAPPING_INVALID" },				\
+		{ 2, "MAPPING_EMPTY" },					\
+		{ 3, "MAPPING_DATA_FIN" },				\
+		{ 4, "MAPPING_DUMMY" })
+
 TRACE_EVENT(mptcp_subflow_get_send,
 
 	TP_PROTO(struct mptcp_subflow_context *subflow),
@@ -138,6 +146,27 @@ TRACE_EVENT(ack_update_msk,
 		  __entry->msk_wnd_end)
 );
 
+TRACE_EVENT(subflow_check_data_avail,
+
+	TP_PROTO(__u8 status, struct sk_buff *skb),
+
+	TP_ARGS(status, skb),
+
+	TP_STRUCT__entry(
+		__field(u8, status)
+		__field(const void *, skb)
+	),
+
+	TP_fast_assign(
+		__entry->status = status;
+		__entry->skb = skb;
+	),
+
+	TP_printk("mapping_status=%s, skb=%p",
+		  show_mapping_status(__entry->status),
+		  __entry->skb)
+);
+
 #endif /* _TRACE_MPTCP_H */
 
 /* This part must be outside protection */

net/mptcp/subflow.c

@@ -1002,8 +1002,6 @@ static bool subflow_check_data_avail(struct sock *ssk)
 	struct mptcp_sock *msk;
 	struct sk_buff *skb;
 
-	pr_debug("msk=%p ssk=%p data_avail=%d skb=%p", subflow->conn, ssk,
-		 subflow->data_avail, skb_peek(&ssk->sk_receive_queue));
 	if (!skb_peek(&ssk->sk_receive_queue))
 		subflow->data_avail = 0;
 	if (subflow->data_avail)
@@ -1015,7 +1013,7 @@ static bool subflow_check_data_avail(struct sock *ssk)
 		u64 old_ack;
 
 		status = get_mapping_status(ssk, msk);
-		pr_debug("msk=%p ssk=%p status=%d", msk, ssk, status);
+		trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue));
 		if (status == MAPPING_INVALID) {
 			ssk->sk_err = EBADMSG;
 			goto fatal;