tcp: set recv_skip_hint when tcp_inq is less than PAGE_SIZE

When we have less than PAGE_SIZE of data on receive queue,
we set recv_skip_hint to 0. Instead, set it to the actual
number of bytes available.

Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 5 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index dcf51fbf5ec7..78ac4d2e3827 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1753,6 +1753,7 @@ static int tcp_zerocopy_receive(struct sock *sk,
         struct vm_area_struct *vma;
         struct sk_buff *skb = NULL;
         struct tcp_sock *tp;
+        int inq;
         int ret;
 
         if (address & (PAGE_SIZE - 1) || address != zc->address)
@@ -1773,12 +1774,15 @@ static int tcp_zerocopy_receive(struct sock *sk,
 
         tp = tcp_sk(sk);
         seq = tp->copied_seq;
-        zc->length = min_t(u32, zc->length, tcp_inq(sk));
+        inq = tcp_inq(sk);
+        zc->length = min_t(u32, zc->length, inq);
         zc->length &= ~(PAGE_SIZE - 1);
-
-        zap_page_range(vma, address, zc->length);
-
-        zc->recv_skip_hint = 0;
+        if (zc->length) {
+                zap_page_range(vma, address, zc->length);
+                zc->recv_skip_hint = 0;
+        } else {
+                zc->recv_skip_hint = inq;
+        }
         ret = 0;
         while (length + PAGE_SIZE <= zc->length) {
                 if (zc->recv_skip_hint < PAGE_SIZE) {