2 files changed, 5 insertions, 1 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 349204130d84..1aa9628ae608 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -917,6 +917,8 @@ struct tcp_congestion_ops {
         void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
         /* suggest number of segments for each skb to transmit (optional) */
         u32 (*tso_segs_goal)(struct sock *sk);
+        /* returns the multiplier used in tcp_sndbuf_expand (optional) */
+        u32 (*sndbuf_expand)(struct sock *sk);
         /* get info for inet_diag (optional) */
         size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
                            union tcp_cc_info *info);
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index d9ed4bb96f74..13a2e70141f5 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -289,6 +289,7 @@ static bool tcp_ecn_rcv_ecn_echo(const struct tcp_sock *tp, const struct tcphdr
 static void tcp_sndbuf_expand(struct sock *sk)
 {
         const struct tcp_sock *tp = tcp_sk(sk);
+        const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
         int sndmem, per_mss;
         u32 nr_segs;
 
@@ -309,7 +310,8 @@ static void tcp_sndbuf_expand(struct sock *sk)
          * Cubic needs 1.7 factor, rounded to 2 to include
          * extra cushion (application might react slowly to POLLOUT)
          */
-        sndmem = 2 * nr_segs * per_mss;
+        sndmem = ca_ops->sndbuf_expand ? ca_ops->sndbuf_expand(sk) : 2;
+        sndmem *= nr_segs * per_mss;
 
         if (sk->sk_sndbuf < sndmem)
                 sk->sk_sndbuf = min(sndmem, sysctl_tcp_wmem[2]);