[TCP]: Keep TSO enabled even during loss events.

All we need to do is resegment the queue so that
we record SACK information accurately.  The edges
of the SACK blocks guide our resegmenting decisions.

With help from Herbert Xu.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/tcp.h b/include/net/tcp.h
index d6bcf13..97af77c 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -454,6 +454,7 @@
 extern void tcp_xmit_retransmit_queue(struct sock *);
 extern void tcp_simple_retransmit(struct sock *);
 extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
+extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
 
 extern void tcp_send_probe0(struct sock *);
 extern void tcp_send_partial(struct sock *);