tcp: reorganize retransmit code loops

Both loops are quite similar, so they can be combined
with little effort. As a result, forward_skb_hint becomes
obsolete as well.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index d7637c4..7672906 100644 (file)
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -342,7 +342,6 @@ struct tcp_sock {
        struct sk_buff* lost_skb_hint;
        struct sk_buff *scoreboard_skb_hint;
        struct sk_buff *retransmit_skb_hint;
-       struct sk_buff *forward_skb_hint;
 
        struct sk_buff_head     out_of_order_queue; /* Out of order segments go here */
 

diff --git a/include/net/tcp.h b/include/net/tcp.h
index d0e90c5..220f54c 100644 (file)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1042,7 +1042,6 @@ static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
        tp->lost_skb_hint = NULL;
        tp->scoreboard_skb_hint = NULL;
        tp->retransmit_skb_hint = NULL;
-       tp->forward_skb_hint = NULL;
 }
 
 /* MD5 Signature */

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 9f44be6..b5b4ddc 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2032,7 +2032,9 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
        const struct inet_connection_sock *icsk = inet_csk(sk);
        struct tcp_sock *tp = tcp_sk(sk);
        struct sk_buff *skb;
+       struct sk_buff *hole = NULL;
        int mib_idx;
+       int fwd_rexmitting = 0;
 
        if (!tp->lost_out)
                tp->retransmit_high = tp->snd_una;
@@ -2049,7 +2051,8 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
                if (skb == tcp_send_head(sk))
                        break;
                /* we could do better than to assign each time */
-               tp->retransmit_skb_hint = skb;
+               if (hole == NULL)
+                       tp->retransmit_skb_hint = skb;
 
                /* Assume this retransmit will generate
                 * only one packet for congestion window
@@ -2060,65 +2063,49 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
                 */
                if (tcp_packets_in_flight(tp) >= tp->snd_cwnd)
                        return;
-               if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high))
-                       break;
-               if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS))
-                       continue;
-
-               if (!(sacked & TCPCB_LOST))
-                       continue;
-
-               if (tcp_retransmit_skb(sk, skb)) {
-                       tp->retransmit_skb_hint = NULL;
-                       return;
-               }
-               if (icsk->icsk_ca_state != TCP_CA_Loss)
-                       mib_idx = LINUX_MIB_TCPFASTRETRANS;
-               else
-                       mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS;
-               NET_INC_STATS_BH(sock_net(sk), mib_idx);
-
-               if (skb == tcp_write_queue_head(sk))
-                       inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
-                                                 inet_csk(sk)->icsk_rto,
-                                                 TCP_RTO_MAX);
-       }
-
-       /* OK, demanded retransmission is finished. */
-       if (!tcp_can_forward_retransmit(sk))
-               return;
 
-       if (tp->forward_skb_hint)
-               skb = tp->forward_skb_hint;
-       else
-               skb = tcp_write_queue_head(sk);
+               if (fwd_rexmitting) {
+begin_fwd:
+                       if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp)))
+                               break;
+                       mib_idx = LINUX_MIB_TCPFORWARDRETRANS;
 
-       tcp_for_write_queue_from(skb, sk) {
-               if (skb == tcp_send_head(sk))
-                       break;
-               tp->forward_skb_hint = skb;
+               } else if (!before(TCP_SKB_CB(skb)->seq, tp->retransmit_high)) {
+                       if (!tcp_can_forward_retransmit(sk))
+                               break;
+                       /* Backtrack if necessary to non-L'ed skb */
+                       if (hole != NULL) {
+                               skb = hole;
+                               hole = NULL;
+                       }
+                       fwd_rexmitting = 1;
+                       goto begin_fwd;
 
-               if (!before(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp)))
-                       break;
+               } else if (!(sacked & TCPCB_LOST)) {
+                       if (hole == NULL && !(sacked & TCPCB_SACKED_RETRANS))
+                               hole = skb;
+                       continue;
 
-               if (tcp_packets_in_flight(tp) >= tp->snd_cwnd)
-                       break;
+               } else {
+                       if (icsk->icsk_ca_state != TCP_CA_Loss)
+                               mib_idx = LINUX_MIB_TCPFASTRETRANS;
+                       else
+                               mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS;
+               }
 
-               if (TCP_SKB_CB(skb)->sacked & TCPCB_TAGBITS)
+               if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS))
                        continue;
 
-               /* Ok, retransmit it. */
                if (tcp_retransmit_skb(sk, skb)) {
-                       tp->forward_skb_hint = NULL;
-                       break;
+                       tp->retransmit_skb_hint = NULL;
+                       return;
                }
+               NET_INC_STATS_BH(sock_net(sk), mib_idx);
 
                if (skb == tcp_write_queue_head(sk))
                        inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
                                                  inet_csk(sk)->icsk_rto,
                                                  TCP_RTO_MAX);
-
-               NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFORWARDRETRANS);
        }
 }