[TCP]: tcp_simple_retransmit can cause S+L

[linux-2.6-omap-h63xx.git] / net / ipv4 / tcp_output.c

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index ed750f9ceb07caed9ed5479740e664c6a319bc8f..d29ef79c00caf442e48562de2476e2377b6cb6ca 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -255,7 +255,7 @@ static u16 tcp_select_window(struct sock *sk)
                 *
                 * Relax Will Robinson.
                 */
-               new_win = cur_win;
+               new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale);
        }
        tp->rcv_wnd = new_win;
        tp->rcv_wup = tp->rcv_nxt;
@@ -1035,6 +1035,13 @@ static void tcp_cwnd_validate(struct sock *sk)
  * introducing MSS oddities to segment boundaries. In rare cases where
  * mss_now != mss_cache, we will request caller to create a small skb
  * per input skb which could be mostly avoided here (if desired).
+ *
+ * We explicitly want to create a request for splitting write queue tail
+ * to a small skb for Nagle purposes while avoiding unnecessary modulos,
+ * thus all the complexity (cwnd_len is always MSS multiple which we
+ * return whenever allowed by the other factors). Basically we need the
+ * modulo only when the receiver window alone is the limiting factor or
+ * when we would be allowed to send the split-due-to-Nagle skb fully.
  */
 static unsigned int tcp_mss_split_point(struct sock *sk, struct sk_buff *skb,
                                        unsigned int mss_now, unsigned int cwnd)
@@ -1048,10 +1055,11 @@ static unsigned int tcp_mss_split_point(struct sock *sk, struct sk_buff *skb,
        if (likely(cwnd_len <= window && skb != tcp_write_queue_tail(sk)))
                return cwnd_len;
 
-       if (skb == tcp_write_queue_tail(sk) && cwnd_len <= skb->len)
+       needed = min(skb->len, window);
+
+       if (skb == tcp_write_queue_tail(sk) && cwnd_len <= needed)
                return cwnd_len;
 
-       needed = min(skb->len, window);
        return needed - needed % mss_now;
 }
 
@@ -1800,6 +1808,9 @@ void tcp_simple_retransmit(struct sock *sk)
        if (!lost)
                return;
 
+       if (tcp_is_reno(tp))
+               tcp_limit_reno_sacked(tp);
+
        tcp_verify_left_out(tp);
 
        /* Don't muck with the congestion window here.