[RFC v2 01/14] tcp: Write options after the header has been fully done

[Christoph Paasch]

The generic TCP-option framework will need to have access to the full
TCP-header (e.g., if we want to compute a checksum for TCP-MD5).

Thus, we move the call to tcp_options_write() to after all the fields in
the header have been filled out.

Signed-off-by: Christoph Paasch <cpaa...@apple.com>
Reviewed-by: Mat Martineau <mathew.j.martin...@linux.intel.com>
---
 net/ipv4/tcp_output.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index e9f985e42405..df50c7dc1a43 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1126,7 +1126,6 @@ static int tcp_transmit_skb(struct sock *sk, struct 
sk_buff *skb, int clone_it,
                }
        }
 
-       tcp_options_write((__be32 *)(th + 1), tp, &opts);
        skb_shinfo(skb)->gso_type = sk->sk_gso_type;
        if (likely(!(tcb->tcp_flags & TCPHDR_SYN))) {
                th->window      = htons(tcp_select_window(sk));
@@ -1137,6 +1136,7 @@ static int tcp_transmit_skb(struct sock *sk, struct 
sk_buff *skb, int clone_it,
                 */
                th->window      = htons(min(tp->rcv_wnd, 65535U));
        }
+       tcp_options_write((__be32 *)(th + 1), tp, &opts);
 #ifdef CONFIG_TCP_MD5SIG
        /* Calculate the MD5 hash, as we have all we need now */
        if (md5) {
@@ -3247,8 +3247,8 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, 
struct dst_entry *dst,
 
        /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */
        th->window = htons(min(req->rsk_rcv_wnd, 65535U));
-       tcp_options_write((__be32 *)(th + 1), NULL, &opts);
        th->doff = (tcp_header_size >> 2);
+       tcp_options_write((__be32 *)(th + 1), NULL, &opts);
        __TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTSEGS);
 
 #ifdef CONFIG_TCP_MD5SIG
-- 
2.16.1