mptcp: add tracepoint in ack_update_msk

This patch added a tracepoint in ack_update_msk() to track the
incoming data_ack and window/snd_una updates.

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

@@ -106,6 +106,38 @@ DEFINE_EVENT(mptcp_dump_mpext, get_mapping_status,
 	TP_PROTO(struct mptcp_ext *mpext),
 	TP_ARGS(mpext));
 
+TRACE_EVENT(ack_update_msk,
+
+	TP_PROTO(u64 data_ack, u64 old_snd_una,
+		 u64 new_snd_una, u64 new_wnd_end,
+		 u64 msk_wnd_end),
+
+	TP_ARGS(data_ack, old_snd_una,
+		new_snd_una, new_wnd_end,
+		msk_wnd_end),
+
+	TP_STRUCT__entry(
+		__field(u64, data_ack)
+		__field(u64, old_snd_una)
+		__field(u64, new_snd_una)
+		__field(u64, new_wnd_end)
+		__field(u64, msk_wnd_end)
+	),
+
+	TP_fast_assign(
+		__entry->data_ack = data_ack;
+		__entry->old_snd_una = old_snd_una;
+		__entry->new_snd_una = new_snd_una;
+		__entry->new_wnd_end = new_wnd_end;
+		__entry->msk_wnd_end = msk_wnd_end;
+	),
+
+	TP_printk("data_ack=%llu old_snd_una=%llu new_snd_una=%llu new_wnd_end=%llu msk_wnd_end=%llu",
+		  __entry->data_ack, __entry->old_snd_una,
+		  __entry->new_snd_una, __entry->new_wnd_end,
+		  __entry->msk_wnd_end)
+);
+
 #endif /* _TRACE_MPTCP_H */
 
 /* This part must be outside protection */

net/mptcp/options.c

@@ -13,6 +13,8 @@
 #include "protocol.h"
 #include "mib.h"
 
+#include <trace/events/mptcp.h>
+
 static bool mptcp_cap_flag_sha256(u8 flags)
 {
 	return (flags & MPTCP_CAP_FLAG_MASK) == MPTCP_CAP_HMAC_SHA256;
@@ -943,6 +945,10 @@ static void ack_update_msk(struct mptcp_sock *msk,
 		__mptcp_data_acked(sk);
 	}
 	mptcp_data_unlock(sk);
+
+	trace_ack_update_msk(mp_opt->data_ack,
+			     old_snd_una, new_snd_una,
+			     new_wnd_end, msk->wnd_end);
 }
 
 bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool use_64bit)