Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6

[net-next-2.6.git] / include / net / tcp.h

diff --git a/include/net/tcp.h b/include/net/tcp.h
index eaa9582779d029a9362c32b3816fed8c157e4d3e..914a60c7ad62070720401f6e18c66af86f7a48e8 100644 (file)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -475,8 +475,22 @@ extern unsigned int tcp_current_mss(struct sock *sk);
 /* Bound MSS / TSO packet size with the half of the window */
 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
 {
-       if (tp->max_window && pktsize > (tp->max_window >> 1))
-               return max(tp->max_window >> 1, 68U - tp->tcp_header_len);
+       int cutoff;
+
+       /* When peer uses tiny windows, there is no use in packetizing
+        * to sub-MSS pieces for the sake of SWS or making sure there
+        * are enough packets in the pipe for fast recovery.
+        *
+        * On the other hand, for extremely large MSS devices, handling
+        * smaller than MSS windows in this way does make sense.
+        */
+       if (tp->max_window >= 512)
+               cutoff = (tp->max_window >> 1);
+       else
+               cutoff = tp->max_window;
+
+       if (cutoff && pktsize > cutoff)
+               return max_t(int, cutoff, 68U - tp->tcp_header_len);
        else
                return pktsize;
 }
@@ -789,6 +803,15 @@ static inline __u32 tcp_current_ssthresh(const struct sock *sk)
 /* Use define here intentionally to get WARN_ON location shown at the caller */
 #define tcp_verify_left_out(tp)        WARN_ON(tcp_left_out(tp) > tp->packets_out)
 
+/*
+ * Convert RFC 3390 larger initial window into an equivalent number of packets.
+ * This is based on the numbers specified in RFC 5681, 3.1.
+ */
+static inline u32 rfc3390_bytes_to_packets(const u32 smss)
+{
+       return smss <= 1095 ? 4 : (smss > 2190 ? 2 : 3);
+}
+
 extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
 extern __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst);