From: Soheil Hassas Yeganeh <soh...@google.com>

When SKBs are coalesced, we can have SKBs with different
frag sizes. Some with PAGE_SIZE and some not with PAGE_SIZE.
Since recv_skip_hint is always set to the full SKB size,
it can overestimate the amount that should be read using
normal read for coalesced packets.

Change the recv_skip_hint so that it only includes the first
frags that are not of PAGE_SIZE.

Signed-off-by: Soheil Hassas Yeganeh <soh...@google.com>
Signed-off-by: Eric Dumazet <eduma...@google.com>
---
 net/ipv4/tcp.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 3e17501fc1a1..cdbd423bdeb4 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1805,8 +1805,17 @@ static int tcp_zerocopy_receive(struct sock *sk,
                                frags++;
                        }
                }
-               if (frags->size != PAGE_SIZE || frags->page_offset)
+               if (frags->size != PAGE_SIZE || frags->page_offset) {
+                       int remaining = zc->recv_skip_hint;
+
+                       while (remaining && (frags->size != PAGE_SIZE ||
+                                            frags->page_offset)) {
+                               remaining -= frags->size;
+                               frags++;
+                       }
+                       zc->recv_skip_hint -= remaining;
                        break;
+               }
                ret = vm_insert_page(vma, address + length,
                                     skb_frag_page(frags));
                if (ret)
-- 
2.19.0.605.g01d371f741-goog

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