[TCP]: Create tcp_sacktag_one().

Worker function that implements the main logic of
the inner-most loop of tcp_sacktag_write_queue().

Idea was originally presented by David S. Miller.

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

1 files changed, 96 insertions, 96 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 5e01ac2c003c..a62e0f90f566 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1240,6 +1240,99 @@ static int tcp_match_skb_to_sack(struct sock *sk, struct sk_buff *skb,
         return in_sack;
 }
 
+static int tcp_sacktag_one(struct sk_buff *skb, struct tcp_sock *tp,
+                           int *reord, int dup_sack, int fack_count)
+{
+        u8 sacked = TCP_SKB_CB(skb)->sacked;
+        int flag = 0;
+
+        /* Account D-SACK for retransmitted packet. */
+        if (dup_sack && (sacked & TCPCB_RETRANS)) {
+                if (after(TCP_SKB_CB(skb)->end_seq, tp->undo_marker))
+                        tp->undo_retrans--;
+                if (!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una) &&
+                    (sacked & TCPCB_SACKED_ACKED))
+                        *reord = min(fack_count, *reord);
+        }
+
+        /* Nothing to do; acked frame is about to be dropped (was ACKed). */
+        if (!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una))
+                return flag;
+
+        if (!(sacked & TCPCB_SACKED_ACKED)) {
+                if (sacked & TCPCB_SACKED_RETRANS) {
+                        /* If the segment is not tagged as lost,
+                         * we do not clear RETRANS, believing
+                         * that retransmission is still in flight.
+                         */
+                        if (sacked & TCPCB_LOST) {
+                                TCP_SKB_CB(skb)->sacked &=
+                                        ~(TCPCB_LOST|TCPCB_SACKED_RETRANS);
+                                tp->lost_out -= tcp_skb_pcount(skb);
+                                tp->retrans_out -= tcp_skb_pcount(skb);
+
+                                /* clear lost hint */
+                                tp->retransmit_skb_hint = NULL;
+                        }
+                } else {
+                        if (!(sacked & TCPCB_RETRANS)) {
+                                /* New sack for not retransmitted frame,
+                                 * which was in hole. It is reordering.
+                                 */
+                                if (before(TCP_SKB_CB(skb)->seq,
+                                           tcp_highest_sack_seq(tp)))
+                                        *reord = min(fack_count, *reord);
+
+                                /* SACK enhanced F-RTO (RFC4138; Appendix B) */
+                                if (!after(TCP_SKB_CB(skb)->end_seq, tp->frto_highmark))
+                                        flag |= FLAG_ONLY_ORIG_SACKED;
+                        }
+
+                        if (sacked & TCPCB_LOST) {
+                                TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
+                                tp->lost_out -= tcp_skb_pcount(skb);
+
+                                /* clear lost hint */
+                                tp->retransmit_skb_hint = NULL;
+                        }
+                }
+
+                TCP_SKB_CB(skb)->sacked |= TCPCB_SACKED_ACKED;
+                flag |= FLAG_DATA_SACKED;
+                tp->sacked_out += tcp_skb_pcount(skb);
+
+                fack_count += tcp_skb_pcount(skb);
+
+                /* Lost marker hint past SACKed? Tweak RFC3517 cnt */
+                if (!tcp_is_fack(tp) && (tp->lost_skb_hint != NULL) &&
+                    before(TCP_SKB_CB(skb)->seq,
+                           TCP_SKB_CB(tp->lost_skb_hint)->seq))
+                        tp->lost_cnt_hint += tcp_skb_pcount(skb);
+
+                if (fack_count > tp->fackets_out)
+                        tp->fackets_out = fack_count;
+
+                if (after(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp)))
+                        tp->highest_sack = skb;
+
+        } else {
+                if (dup_sack && (sacked & TCPCB_RETRANS))
+                        *reord = min(fack_count, *reord);
+        }
+
+        /* D-SACK. We can detect redundant retransmission in S|R and plain R
+         * frames and clear it. undo_retrans is decreased above, L|R frames
+         * are accounted above as well.
+         */
+        if (dup_sack && (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS)) {
+                TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
+                tp->retrans_out -= tcp_skb_pcount(skb);
+                tp->retransmit_skb_hint = NULL;
+        }
+
+        return flag;
+}
+
 static int
 tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_una)
 {
@@ -1375,7 +1468,6 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
 
                 tcp_for_write_queue_from(skb, sk) {
                         int in_sack = 0;
-                        u8 sacked;
 
                         if (skb == tcp_send_head(sk))
                                 break;
@@ -1413,102 +1505,10 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
                         if (unlikely(in_sack < 0))
                                 break;
 
-                        if (!in_sack) {
-                                fack_count += tcp_skb_pcount(skb);
-                                continue;
-                        }
-
-                        sacked = TCP_SKB_CB(skb)->sacked;
-
-                        /* Account D-SACK for retransmitted packet. */
-                        if (dup_sack && (sacked & TCPCB_RETRANS)) {
-                                if (after(TCP_SKB_CB(skb)->end_seq, tp->undo_marker))
-                                        tp->undo_retrans--;
-                                if (!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una) &&
-                                    (sacked & TCPCB_SACKED_ACKED))
-                                        reord = min(fack_count, reord);
-                        }
-
-
-                        /* Nothing to do; acked frame is about to be dropped (was ACKed). */
-                        if (!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) {
-                                fack_count += tcp_skb_pcount(skb);
-                                continue;
-                        }
-
-                        if (!(sacked&TCPCB_SACKED_ACKED)) {
-                                if (sacked & TCPCB_SACKED_RETRANS) {
-                                        /* If the segment is not tagged as lost,
-                                         * we do not clear RETRANS, believing
-                                         * that retransmission is still in flight.
-                                         */
-                                        if (sacked & TCPCB_LOST) {
-                                                TCP_SKB_CB(skb)->sacked &= ~(TCPCB_LOST|TCPCB_SACKED_RETRANS);
-                                                tp->lost_out -= tcp_skb_pcount(skb);
-                                                tp->retrans_out -= tcp_skb_pcount(skb);
-
-                                                /* clear lost hint */
-                                                tp->retransmit_skb_hint = NULL;
-                                        }
-                                } else {
-                                        if (!(sacked & TCPCB_RETRANS)) {
-                                                /* New sack for not retransmitted frame,
-                                                 * which was in hole. It is reordering.
-                                                 */
-                                                if (before(TCP_SKB_CB(skb)->seq,
-                                                           tcp_highest_sack_seq(tp)))
-                                                        reord = min(fack_count, reord);
-
-                                                /* SACK enhanced F-RTO (RFC4138; Appendix B) */
-                                                if (!after(TCP_SKB_CB(skb)->end_seq, tp->frto_highmark))
-                                                        flag |= FLAG_ONLY_ORIG_SACKED;
-                                        }
-
-                                        if (sacked & TCPCB_LOST) {
-                                                TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
-                                                tp->lost_out -= tcp_skb_pcount(skb);
-
-                                                /* clear lost hint */
-                                                tp->retransmit_skb_hint = NULL;
-                                        }
-                                }
-
-                                TCP_SKB_CB(skb)->sacked |= TCPCB_SACKED_ACKED;
-                                flag |= FLAG_DATA_SACKED;
-                                tp->sacked_out += tcp_skb_pcount(skb);
-
-                                fack_count += tcp_skb_pcount(skb);
-
-                                /* Lost marker hint past SACKed? Tweak RFC3517 cnt */
-                                if (!tcp_is_fack(tp) && (tp->lost_skb_hint != NULL) &&
-                                    before(TCP_SKB_CB(skb)->seq,
-                                           TCP_SKB_CB(tp->lost_skb_hint)->seq))
-                                        tp->lost_cnt_hint += tcp_skb_pcount(skb);
-
-                                if (fack_count > tp->fackets_out)
-                                        tp->fackets_out = fack_count;
+                        if (in_sack)
+                                flag |= tcp_sacktag_one(skb, tp, &reord, dup_sack, fack_count);
 
-                                if (after(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp)))
-                                        tp->highest_sack = skb;
-
-                        } else {
-                                if (dup_sack && (sacked&TCPCB_RETRANS))
-                                        reord = min(fack_count, reord);
-
-                                fack_count += tcp_skb_pcount(skb);
-                        }
-
-                        /* D-SACK. We can detect redundant retransmission
-                         * in S|R and plain R frames and clear it.
-                         * undo_retrans is decreased above, L|R frames
-                         * are accounted above as well.
-                         */
-                        if (dup_sack &&
-                            (TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_RETRANS)) {
-                                TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
-                                tp->retrans_out -= tcp_skb_pcount(skb);
-                                tp->retransmit_skb_hint = NULL;
-                        }
+                        fack_count += tcp_skb_pcount(skb);
                 }
 
                 /* SACK enhanced FRTO (RFC4138, Appendix B): Clearing correct