/* Check for lost retransmit. This superb idea is borrowed from "ratehalving".
* Event "C". Later note: FACK people cheated me again 8), we have to account
* for reordering! Ugly, but should help.
+ *
+ * Search retransmitted skbs from write_queue that were sent when snd_nxt was
+ * less than what is now known to be received by the other end (derived from
+ * SACK blocks by the caller). Also calculate the lowest snd_nxt among the
+ * remaining retransmitted skbs to avoid some costly processing per ACKs.
*/
-static int tcp_mark_lost_retrans(struct sock *sk, u32 lost_retrans)
+static int tcp_mark_lost_retrans(struct sock *sk, u32 received_upto)
{
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *skb;
int flag = 0;
+ int cnt = 0;
+ u32 new_low_seq = 0;
tcp_for_write_queue(skb, sk) {
u32 ack_seq = TCP_SKB_CB(skb)->ack_seq;
if (skb == tcp_send_head(sk))
break;
- if (after(TCP_SKB_CB(skb)->seq, lost_retrans))
+ if (cnt == tp->retrans_out)
break;
if (!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una))
continue;
- if ((TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) &&
- after(lost_retrans, ack_seq) &&
+ if (!(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS))
+ continue;
+
+ if (after(received_upto, ack_seq) &&
(tcp_is_fack(tp) ||
- !before(lost_retrans,
+ !before(received_upto,
ack_seq + tp->reordering * tp->mss_cache))) {
TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
tp->retrans_out -= tcp_skb_pcount(skb);
flag |= FLAG_DATA_SACKED;
NET_INC_STATS_BH(LINUX_MIB_TCPLOSTRETRANSMIT);
}
+ } else {
+ if (!new_low_seq || before(ack_seq, new_low_seq))
+ new_low_seq = ack_seq;
+ cnt += tcp_skb_pcount(skb);
}
}
+
+ if (tp->retrans_out)
+ tp->lost_retrans_low = new_low_seq;
+
return flag;
}
int num_sacks = (ptr[1] - TCPOLEN_SACK_BASE)>>3;
int reord = tp->packets_out;
int prior_fackets;
- u32 lost_retrans = 0;
+ u32 highest_sack_end_seq = 0;
int flag = 0;
int found_dup_sack = 0;
int cached_fack_count;
continue;
}
- if ((sacked&TCPCB_SACKED_RETRANS) &&
- after(end_seq, TCP_SKB_CB(skb)->ack_seq) &&
- (!lost_retrans || after(end_seq, lost_retrans)))
- lost_retrans = end_seq;
-
if (!in_sack)
continue;
if (fack_count > tp->fackets_out)
tp->fackets_out = fack_count;
- if (after(TCP_SKB_CB(skb)->seq,
- tp->highest_sack))
+ if (after(TCP_SKB_CB(skb)->seq, tp->highest_sack)) {
tp->highest_sack = TCP_SKB_CB(skb)->seq;
+ highest_sack_end_seq = TCP_SKB_CB(skb)->end_seq;
+ }
} else {
if (dup_sack && (sacked&TCPCB_RETRANS))
reord = min(fack_count, reord);
}
}
- if (lost_retrans && icsk->icsk_ca_state == TCP_CA_Recovery)
- flag |= tcp_mark_lost_retrans(sk, lost_retrans);
+ if (tp->retrans_out &&
+ after(highest_sack_end_seq, tp->lost_retrans_low) &&
+ icsk->icsk_ca_state == TCP_CA_Recovery)
+ flag |= tcp_mark_lost_retrans(sk, highest_sack_end_seq);
tcp_verify_left_out(tp);
}
/* Mark head of queue up as lost. */
-static void tcp_mark_head_lost(struct sock *sk,
- int packets, u32 high_seq)
+static void tcp_mark_head_lost(struct sock *sk, int packets)
{
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *skb;
tp->lost_skb_hint = skb;
tp->lost_cnt_hint = cnt;
cnt += tcp_skb_pcount(skb);
- if (cnt > packets || after(TCP_SKB_CB(skb)->end_seq, high_seq))
+ if (cnt > packets || after(TCP_SKB_CB(skb)->end_seq, tp->high_seq))
break;
if (!(TCP_SKB_CB(skb)->sacked & (TCPCB_SACKED_ACKED|TCPCB_LOST))) {
TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
int lost = tp->fackets_out - tp->reordering;
if (lost <= 0)
lost = 1;
- tcp_mark_head_lost(sk, lost, tp->high_seq);
+ tcp_mark_head_lost(sk, lost);
} else {
- tcp_mark_head_lost(sk, 1, tp->high_seq);
+ tcp_mark_head_lost(sk, 1);
}
/* New heuristics: it is possible only after we switched
before(tp->snd_una, tp->high_seq) &&
icsk->icsk_ca_state != TCP_CA_Open &&
tp->fackets_out > tp->reordering) {
- tcp_mark_head_lost(sk, tp->fackets_out-tp->reordering, tp->high_seq);
+ tcp_mark_head_lost(sk, tp->fackets_out - tp->reordering);
NET_INC_STATS_BH(LINUX_MIB_TCPLOSS);
}