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authorYuchung Cheng <ycheng@google.com>2017-10-04 13:00:00 -0700
committerDavid S. Miller <davem@davemloft.net>2017-10-05 21:24:47 -0700
commitbef06223083b81d2064824afe2bc85be416ab73a (patch)
treecb70c1552a2c58cc5b8f63bd8e85b7fdc3b33497 /net/ipv4/tcp_recovery.c
parent043b87d7599ed8e86a33f4cbc3f062d57e263711 (diff)
downloadlinux-bef06223083b81d2064824afe2bc85be416ab73a.tar.bz2
tcp: a small refactor of RACK loss detection
Refactor the RACK loop to improve readability and speed up the checks. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_recovery.c')
-rw-r--r--net/ipv4/tcp_recovery.c40
1 files changed, 18 insertions, 22 deletions
diff --git a/net/ipv4/tcp_recovery.c b/net/ipv4/tcp_recovery.c
index 8aa56caefde8..cda6074a429a 100644
--- a/net/ipv4/tcp_recovery.c
+++ b/net/ipv4/tcp_recovery.c
@@ -61,32 +61,28 @@ static void tcp_rack_detect_loss(struct sock *sk, u32 *reo_timeout)
list_for_each_entry_safe(skb, n, &tp->tsorted_sent_queue,
tcp_tsorted_anchor) {
struct tcp_skb_cb *scb = TCP_SKB_CB(skb);
+ s32 remaining;
- if (tcp_rack_sent_after(tp->rack.mstamp, skb->skb_mstamp,
- tp->rack.end_seq, scb->end_seq)) {
- /* Step 3 in draft-cheng-tcpm-rack-00.txt:
- * A packet is lost if its elapsed time is beyond
- * the recent RTT plus the reordering window.
- */
- u32 elapsed = tcp_stamp_us_delta(tp->tcp_mstamp,
- skb->skb_mstamp);
- s32 remaining = tp->rack.rtt_us + reo_wnd - elapsed;
-
- if (remaining < 0) {
- tcp_rack_mark_skb_lost(sk, skb);
- list_del_init(&skb->tcp_tsorted_anchor);
- continue;
- }
-
- /* Skip ones marked lost but not yet retransmitted */
- if ((scb->sacked & TCPCB_LOST) &&
- !(scb->sacked & TCPCB_SACKED_RETRANS))
- continue;
+ /* Skip ones marked lost but not yet retransmitted */
+ if ((scb->sacked & TCPCB_LOST) &&
+ !(scb->sacked & TCPCB_SACKED_RETRANS))
+ continue;
+ if (!tcp_rack_sent_after(tp->rack.mstamp, skb->skb_mstamp,
+ tp->rack.end_seq, scb->end_seq))
+ break;
+
+ /* A packet is lost if it has not been s/acked beyond
+ * the recent RTT plus the reordering window.
+ */
+ remaining = tp->rack.rtt_us + reo_wnd -
+ tcp_stamp_us_delta(tp->tcp_mstamp, skb->skb_mstamp);
+ if (remaining < 0) {
+ tcp_rack_mark_skb_lost(sk, skb);
+ list_del_init(&skb->tcp_tsorted_anchor);
+ } else {
/* Record maximum wait time (+1 to avoid 0) */
*reo_timeout = max_t(u32, *reo_timeout, 1 + remaining);
- } else {
- break;
}
}
}