3 files changed, 24 insertions, 3 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 913f9bbfc030..259ffb50e429 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -996,8 +996,11 @@ do_error:
                 goto out;
 out_err:
         /* make sure we wake any epoll edge trigger waiter */
-        if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
+        if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 &&
+                     err == -EAGAIN)) {
                 sk->sk_write_space(sk);
+                tcp_chrono_stop(sk, TCP_CHRONO_SNDBUF_LIMITED);
+        }
         return sk_stream_error(sk, flags, err);
 }
 
@@ -1331,8 +1334,11 @@ do_error:
 out_err:
         err = sk_stream_error(sk, flags, err);
         /* make sure we wake any epoll edge trigger waiter */
-        if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
+        if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 &&
+                     err == -EAGAIN)) {
                 sk->sk_write_space(sk);
+                tcp_chrono_stop(sk, TCP_CHRONO_SNDBUF_LIMITED);
+        }
         release_sock(sk);
         return err;
 }
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index a5d172761610..56fe736fd64d 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5059,8 +5059,11 @@ static void tcp_check_space(struct sock *sk)
                 /* pairs with tcp_poll() */
                 smp_mb__after_atomic();
                 if (sk->sk_socket &&
-                    test_bit(SOCK_NOSPACE, &sk->sk_socket->flags))
+                    test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
                         tcp_new_space(sk);
+                        if (!test_bit(SOCK_NOSPACE, &sk->sk_socket->flags))
+                                tcp_chrono_stop(sk, TCP_CHRONO_SNDBUF_LIMITED);
+                }
         }
 }
 
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index b74444cee24d..d3545d0cff75 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1514,6 +1514,18 @@ static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited)
                 if (sysctl_tcp_slow_start_after_idle &&
                     (s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto)
                         tcp_cwnd_application_limited(sk);
+
+                /* The following conditions together indicate the starvation
+                 * is caused by insufficient sender buffer:
+                 * 1) just sent some data (see tcp_write_xmit)
+                 * 2) not cwnd limited (this else condition)
+                 * 3) no more data to send (null tcp_send_head )
+                 * 4) application is hitting buffer limit (SOCK_NOSPACE)
+                 */
+                if (!tcp_send_head(sk) && sk->sk_socket &&
+                    test_bit(SOCK_NOSPACE, &sk->sk_socket->flags) &&
+                    (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
+                        tcp_chrono_start(sk, TCP_CHRONO_SNDBUF_LIMITED);
         }
 }