tcp: add tracepoint trace_tcp_destroy_sock

This patch adds trace event trace_tcp_destroy_sock.
Signed-off-by: NSong Liu <songliubraving@fb.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/trace/events/tcp.h

@@ -154,6 +154,13 @@ DEFINE_EVENT(tcp_event_sk, tcp_receive_reset,
 	TP_ARGS(sk)
 );
 
+DEFINE_EVENT(tcp_event_sk, tcp_destroy_sock,
+
+	TP_PROTO(const struct sock *sk),
+
+	TP_ARGS(sk)
+);
+
 #endif /* _TRACE_TCP_H */
 
 /* This part must be outside protection */

net/ipv4/tcp_ipv4.c

@@ -1869,6 +1869,8 @@ void tcp_v4_destroy_sock(struct sock *sk)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
+	trace_tcp_destroy_sock(sk);
+
 	tcp_clear_xmit_timers(sk);
 
 	tcp_cleanup_congestion_control(sk);