[TCP]: NewReno must count every skb while marking losses

NewReno should add cnt per skb (as with FACK) instead of depending on
SACKED_ACKED bits which won't be set with it at all.  Effectively,
NewReno should always exists after the first iteration anyway (or
immediately if there's already head in lost_out.

This was fixed earlier in net-2.6.25 but got reverted among other
stuff and I didn't notice that this is still necessary (actually
wasn't even considering this case while trying to figure out the
reports because I lived with different kind of code than it in reality
was).

This should solve the WARN_ONs in TCP code that as a result of this
triggered multiple times in every place we check for this invariant.

Special thanks to Dave Young <hidave.darkstar@gmail.com> and Krishna
Kumar2 <krkumar2@in.ibm.com> for trying with my debug patches.
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Tested-by: NDave Young <hidave.darkstar@gmail.com>
Tested-by: NKrishna Kumar2 <krkumar2@in.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp_input.c

@@ -2153,7 +2153,7 @@ static void tcp_mark_head_lost(struct sock *sk, int packets, int fast_rexmit)
 		tp->lost_skb_hint = skb;
 		tp->lost_cnt_hint = cnt;
 
-		if (tcp_is_fack(tp) ||
+		if (tcp_is_fack(tp) || tcp_is_reno(tp) ||
 		    (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))
 			cnt += tcp_skb_pcount(skb);