tcp: add tcpi_bytes_received to tcp_info

This patch tracks total number of payload bytes received on a TCP socket.
This is the sum of all changes done to tp->rcv_nxt

RFC4898 named this : tcpEStatsAppHCThruOctetsReceived

This is a 64bit field, and can be fetched both from TCP_INFO
getsockopt() if one has a handle on a TCP socket, or from inet_diag
netlink facility (iproute2/ss patch will follow)

Note that tp->bytes_received was placed near tp->rcv_nxt for
best data locality and minimal performance impact.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Matt Mathis <mattmathis@google.com>
Cc: Eric Salo <salo@google.com>
Cc: Martin Lau <kafai@fb.com>
Cc: Chris Rapier <rapier@psc.edu>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 15 insertions, 4 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 4bf0e8ca7b5b..99fcc0b22c92 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2666,6 +2666,7 @@ void tcp_get_info(struct sock *sk, struct tcp_info *info)
 
         spin_lock_bh(&sk->sk_lock.slock);
         info->tcpi_bytes_acked = tp->bytes_acked;
+        info->tcpi_bytes_received = tp->bytes_received;
         spin_unlock_bh(&sk->sk_lock.slock);
 }
 EXPORT_SYMBOL_GPL(tcp_get_info);
diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c
index e3d87aca6be8..3c673d5e6cff 100644
--- a/net/ipv4/tcp_fastopen.c
+++ b/net/ipv4/tcp_fastopen.c
@@ -206,6 +206,7 @@ static bool tcp_fastopen_create_child(struct sock *sk,
                         skb_set_owner_r(skb2, child);
                         __skb_queue_tail(&child->sk_receive_queue, skb2);
                         tp->syn_data_acked = 1;
+                        tp->bytes_received = end_seq - TCP_SKB_CB(skb)->seq - 1;
                 } else {
                         end_seq = TCP_SKB_CB(skb)->seq + 1;
                 }
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 378d3f4d4dc3..7e6962bcfc30 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3289,6 +3289,15 @@ static void tcp_snd_una_update(struct tcp_sock *tp, u32 ack)
         tp->snd_una = ack;
 }
 
+/* If we update tp->rcv_nxt, also update tp->bytes_received */
+static void tcp_rcv_nxt_update(struct tcp_sock *tp, u32 seq)
+{
+        u32 delta = seq - tp->rcv_nxt;
+
+        tp->bytes_received += delta;
+        tp->rcv_nxt = seq;
+}
+
 /* Update our send window.
  *
  * Window update algorithm, described in RFC793/RFC1122 (used in linux-2.2
@@ -4245,7 +4254,7 @@ static void tcp_ofo_queue(struct sock *sk)
 
                 tail = skb_peek_tail(&sk->sk_receive_queue);
                 eaten = tail && tcp_try_coalesce(sk, tail, skb, &fragstolen);
-                tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+                tcp_rcv_nxt_update(tp, TCP_SKB_CB(skb)->end_seq);
                 if (!eaten)
                         __skb_queue_tail(&sk->sk_receive_queue, skb);
                 if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
@@ -4413,7 +4422,7 @@ static int __must_check tcp_queue_rcv(struct sock *sk, struct sk_buff *skb, int
         __skb_pull(skb, hdrlen);
         eaten = (tail &&
                  tcp_try_coalesce(sk, tail, skb, fragstolen)) ? 1 : 0;
-        tcp_sk(sk)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+        tcp_rcv_nxt_update(tcp_sk(sk), TCP_SKB_CB(skb)->end_seq);
         if (!eaten) {
                 __skb_queue_tail(&sk->sk_receive_queue, skb);
                 skb_set_owner_r(skb, sk);
@@ -4506,7 +4515,7 @@ queue_and_out:
 
                         eaten = tcp_queue_rcv(sk, skb, 0, &fragstolen);
                 }
-                tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+                tcp_rcv_nxt_update(tp, TCP_SKB_CB(skb)->end_seq);
                 if (skb->len)
                         tcp_event_data_recv(sk, skb);
                 if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
@@ -5254,7 +5263,7 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
                                         tcp_rcv_rtt_measure_ts(sk, skb);
 
                                         __skb_pull(skb, tcp_header_len);
-                                        tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+                                        tcp_rcv_nxt_update(tp, TCP_SKB_CB(skb)->end_seq);
                                         NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPHPHITSTOUSER);
                                         eaten = 1;
                                 }