tcp: tcp_make_synack() minor changes

There is no need to allocate 15 bytes in excess for a SYNACK packet,
as it contains no data, only headers.

SYNACK are always generated in softirq context, and contain a single
segment, we can use TCP_INC_STATS_BH()

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

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 21533f5..699fb10 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2741,7 +2741,7 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
        int tcp_header_size;
        int mss;
 
-       skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15, 1, GFP_ATOMIC);
+       skb = sock_wmalloc(sk, MAX_TCP_HEADER, 1, GFP_ATOMIC);
        if (unlikely(!skb)) {
                dst_release(dst);
                return NULL;
@@ -2811,7 +2811,7 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
        th->window = htons(min(req->rcv_wnd, 65535U));
        tcp_options_write((__be32 *)(th + 1), tp, &opts);
        th->doff = (tcp_header_size >> 2);
-       TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, tcp_skb_pcount(skb));
+       TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_OUTSEGS);
 
 #ifdef CONFIG_TCP_MD5SIG
        /* Okay, we have all we need - do the md5 hash if needed */