target/linux/generic/backport-4.9/100-tcp-add-tcp_ooo_try_coalesce-helper.patch

   1 From 74b120c45aebf4278e1dedc55f5fa24d8ea83cdc Mon Sep 17 00:00:00 2001
   2 From: Eric Dumazet <edumazet@google.com>
   3 Date: Mon, 23 Jul 2018 09:28:21 -0700
   4 Subject: tcp: add tcp_ooo_try_coalesce() helper
   5
   6 commit 58152ecbbcc6a0ce7fddd5bf5f6ee535834ece0c upstream.
   7
   8 In case skb in out_or_order_queue is the result of
   9 multiple skbs coalescing, we would like to get a proper gso_segs
  10 counter tracking, so that future tcp_drop() can report an accurate
  11 number.
  12
  13 I chose to not implement this tracking for skbs in receive queue,
  14 since they are not dropped, unless socket is disconnected.
  15
  16 Signed-off-by: Eric Dumazet <edumazet@google.com>
  17 Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
  18 Acked-by: Yuchung Cheng <ycheng@google.com>
  19 Signed-off-by: David S. Miller <davem@davemloft.net>
  20 Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
  21 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  22 ---
  23  net/ipv4/tcp_input.c | 23 +++++++++++++++++++++--
  24  1 file changed, 21 insertions(+), 2 deletions(-)
  25
  26 diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
  27 index a9be8df108b4..9d0b73aa649f 100644
  28 --- a/net/ipv4/tcp_input.c
  29 +++ b/net/ipv4/tcp_input.c
  30 @@ -4370,6 +4370,23 @@ static bool tcp_try_coalesce(struct sock *sk,
  31         return true;
  32  }
  33
  34 +static bool tcp_ooo_try_coalesce(struct sock *sk,
  35 +                            struct sk_buff *to,
  36 +                            struct sk_buff *from,
  37 +                            bool *fragstolen)
  38 +{
  39 +       bool res = tcp_try_coalesce(sk, to, from, fragstolen);
  40 +
  41 +       /* In case tcp_drop() is called later, update to->gso_segs */
  42 +       if (res) {
  43 +               u32 gso_segs = max_t(u16, 1, skb_shinfo(to)->gso_segs) +
  44 +                              max_t(u16, 1, skb_shinfo(from)->gso_segs);
  45 +
  46 +               skb_shinfo(to)->gso_segs = min_t(u32, gso_segs, 0xFFFF);
  47 +       }
  48 +       return res;
  49 +}
  50 +
  51  static void tcp_drop(struct sock *sk, struct sk_buff *skb)
  52  {
  53         sk_drops_add(sk, skb);
  54 @@ -4493,7 +4510,8 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
  55         /* In the typical case, we are adding an skb to the end of the list.
  56          * Use of ooo_last_skb avoids the O(Log(N)) rbtree lookup.
  57          */
  58 -       if (tcp_try_coalesce(sk, tp->ooo_last_skb, skb, &fragstolen)) {
  59 +       if (tcp_ooo_try_coalesce(sk, tp->ooo_last_skb,
  60 +                                skb, &fragstolen)) {
  61  coalesce_done:
  62                 tcp_grow_window(sk, skb);
  63                 kfree_skb_partial(skb, fragstolen);
  64 @@ -4543,7 +4561,8 @@ coalesce_done:
  65                                 tcp_drop(sk, skb1);
  66                                 goto merge_right;
  67                         }
  68 -               } else if (tcp_try_coalesce(sk, skb1, skb, &fragstolen)) {
  69 +               } else if (tcp_ooo_try_coalesce(sk, skb1,
  70 +                                               skb, &fragstolen)) {
  71                         goto coalesce_done;
  72                 }
  73                 p = &parent->rb_right;
  74 --
  75 cgit 1.2-0.3.lf.el7
  76