tcp: Add skb addr and sock addr to arguments of tracepoint tcp_probe.

It is useful to expose skb addr and sock addr to user in tracepoint
tcp_probe, so that we can get more information while monitoring
receiving of tcp data, by ebpf or other ways.

For example, we need to identify a packet by seq and end_seq when
calculate transmit latency between layer 2 and layer 4 by ebpf, but which is
not available in tcp_probe, so we can only use kprobe hooking
tcp_rcv_established to get them. But we can use tcp_probe directly if skb
addr and sock addr are available, which is more efficient.

Signed-off-by: fuyuanli <[email protected]>
Reviewed-by: Jason Xing <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: fuyuanli

include/trace/events/tcp.h

@@ -259,6 +259,8 @@ TRACE_EVENT(tcp_probe,
 		__field(__u32, srtt)
 		__field(__u32, rcv_wnd)
 		__field(__u64, sock_cookie)
+		__field(const void *, skbaddr)
+		__field(const void *, skaddr)
 	),
 
 	TP_fast_assign(
@@ -286,14 +288,18 @@ TRACE_EVENT(tcp_probe,
 		__entry->ssthresh = tcp_current_ssthresh(sk);
 		__entry->srtt = tp->srtt_us >> 3;
 		__entry->sock_cookie = sock_gen_cookie(sk);
+
+		__entry->skbaddr = skb;
+		__entry->skaddr = sk;
 	),
 
-	TP_printk("family=%s src=%pISpc dest=%pISpc mark=%#x data_len=%d snd_nxt=%#x snd_una=%#x snd_cwnd=%u ssthresh=%u snd_wnd=%u srtt=%u rcv_wnd=%u sock_cookie=%llx",
+	TP_printk("family=%s src=%pISpc dest=%pISpc mark=%#x data_len=%d snd_nxt=%#x snd_una=%#x snd_cwnd=%u ssthresh=%u snd_wnd=%u srtt=%u rcv_wnd=%u sock_cookie=%llx skbaddr=%p skaddr=%p",
 		  show_family_name(__entry->family),
 		  __entry->saddr, __entry->daddr, __entry->mark,
 		  __entry->data_len, __entry->snd_nxt, __entry->snd_una,
 		  __entry->snd_cwnd, __entry->ssthresh, __entry->snd_wnd,
-		  __entry->srtt, __entry->rcv_wnd, __entry->sock_cookie)
+		  __entry->srtt, __entry->rcv_wnd, __entry->sock_cookie,
+		  __entry->skbaddr, __entry->skaddr)
 );
 
 #define TP_STORE_ADDR_PORTS_SKB_V4(__entry, skb)			\