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

* master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6: (21 commits)
  [IPV4] SNMP: Support OutMcastPkts and OutBcastPkts
  [IPV4] SNMP: Support InMcastPkts and InBcastPkts
  [IPV4] SNMP: Support InTruncatedPkts
  [IPV4] SNMP: Support InNoRoutes
  [SNMP]: Add definitions for {In,Out}BcastPkts
  [TCP] FRTO: RFC4138 allows Nagle override when new data must be sent
  [TCP] FRTO: Delay skb available check until it's mandatory
  [XFRM]: Restrict upper layer information by bundle.
  [TCP]: Catch skb with S+L bugs earlier
  [PATCH] INET : IPV4 UDP lookups converted to a 2 pass algo
  [L2TP]: Add the ability to autoload a pppox protocol module.
  [SKB]: Introduce skb_queue_walk_safe()
  [AF_IUCV/IUCV]: smp_call_function deadlock
  [IPV6]: Fix slab corruption running ip6sic
  [TCP]: Update references in two old comments
  [XFRM]: Export SPD info
  [IPV6]: Track device renames in snmp6.
  [SCTP]: Fix sctp_getsockopt_local_addrs_old() to use local storage.
  [NET]: Remove NETIF_F_INTERNAL_STATS, default to internal stats.
  [NETPOLL]: Remove CONFIG_NETPOLL_RX
  ...

1 files changed, 18 insertions, 12 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 051f0f815f1..7641b2761a1 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1265,20 +1265,15 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
 	return flag;
 }
 
-/* F-RTO can only be used if these conditions are satisfied:
- *  - there must be some unsent new data
- *  - the advertised window should allow sending it
- *  - TCP has never retransmitted anything other than head (SACK enhanced
- *    variant from Appendix B of RFC4138 is more robust here)
+/* F-RTO can only be used if TCP has never retransmitted anything other than
+ * head (SACK enhanced variant from Appendix B of RFC4138 is more robust here)
  */
 int tcp_use_frto(struct sock *sk)
 {
 	const struct tcp_sock *tp = tcp_sk(sk);
 	struct sk_buff *skb;
 
-	if (!sysctl_tcp_frto || !tcp_send_head(sk) ||
-		after(TCP_SKB_CB(tcp_send_head(sk))->end_seq,
-		      tp->snd_una + tp->snd_wnd))
+	if (!sysctl_tcp_frto)
 		return 0;
 
 	if (IsSackFrto())
@@ -2642,7 +2637,9 @@ static void tcp_undo_spur_to_response(struct sock *sk, int flag)
  *                  algorithm is not part of the F-RTO detection algorithm
  *                  given in RFC4138 but can be selected separately).
  * Otherwise (basically on duplicate ACK), RTO was (likely) caused by a loss
- * and TCP falls back to conventional RTO recovery.
+ * and TCP falls back to conventional RTO recovery. F-RTO allows overriding
+ * of Nagle, this is done using frto_counter states 2 and 3, when a new data
+ * segment of any size sent during F-RTO, state 2 is upgraded to 3.
  *
  * Rationale: if the RTO was spurious, new ACKs should arrive from the
  * original window even after we transmit two new data segments.
@@ -2671,7 +2668,7 @@ static int tcp_process_frto(struct sock *sk, u32 prior_snd_una, int flag)
 		inet_csk(sk)->icsk_retransmits = 0;
 
 	if (!before(tp->snd_una, tp->frto_highmark)) {
-		tcp_enter_frto_loss(sk, tp->frto_counter + 1, flag);
+		tcp_enter_frto_loss(sk, (tp->frto_counter == 1 ? 2 : 3), flag);
 		return 1;
 	}
 
@@ -2697,7 +2694,7 @@ static int tcp_process_frto(struct sock *sk, u32 prior_snd_una, int flag)
 			return 1;
 		}
 
-		if ((tp->frto_counter == 2) &&
+		if ((tp->frto_counter >= 2) &&
 		    (!(flag&FLAG_FORWARD_PROGRESS) ||
 		     ((flag&FLAG_DATA_SACKED) && !(flag&FLAG_ONLY_ORIG_SACKED)))) {
 			/* RFC4138 shortcoming (see comment above) */
@@ -2710,10 +2707,19 @@ static int tcp_process_frto(struct sock *sk, u32 prior_snd_una, int flag)
 	}
 
 	if (tp->frto_counter == 1) {
+		/* Sending of the next skb must be allowed or no FRTO */
+		if (!tcp_send_head(sk) ||
+		    after(TCP_SKB_CB(tcp_send_head(sk))->end_seq,
+				     tp->snd_una + tp->snd_wnd)) {
+			tcp_enter_frto_loss(sk, (tp->frto_counter == 1 ? 2 : 3),
+					    flag);
+			return 1;
+		}
+
 		tp->snd_cwnd = tcp_packets_in_flight(tp) + 2;
 		tp->frto_counter = 2;
 		return 1;
-	} else /* frto_counter == 2 */ {
+	} else {
 		switch (sysctl_tcp_frto_response) {
 		case 2:
 			tcp_undo_spur_to_response(sk, flag);