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Date: Wed, 29 May 2013 17:20:12 -0700
From: Yuchung Cheng <ycheng@...gle.com>
To: davem@...emloft.net, ncardwell@...gle.com, edumazet@...gle.com,
nanditad@...gle.com
Cc: aterzis@...gle.com, netdev@...r.kernel.org,
Yuchung Cheng <ycheng@...gle.com>
Subject: [PATCH 2/4 net-next] tcp: refactor undo functions
Refactor and relocate various functions or variables to prepare the
undo fix. Remove some unused function arguments. Rename tcp_undo_cwr
to tcp_undo_cwnd_reduction to be consistent with the rest of
CWR related function names.
Signed-off-by: Yuchung Cheng <ycheng@...gle.com>
---
net/ipv4/tcp_input.c | 97 +++++++++++++++++++++++++++-------------------------
1 file changed, 50 insertions(+), 47 deletions(-)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 86b5fa7..fcb668d 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2243,10 +2243,23 @@ static void DBGUNDO(struct sock *sk, const char *msg)
#define DBGUNDO(x...) do { } while (0)
#endif
-static void tcp_undo_cwr(struct sock *sk, const bool undo_ssthresh)
+static void tcp_undo_cwnd_reduction(struct sock *sk, const bool undo_ssthresh,
+ bool unmark_loss)
{
struct tcp_sock *tp = tcp_sk(sk);
+ if (unmark_loss) {
+ struct sk_buff *skb;
+
+ tcp_for_write_queue(skb, sk) {
+ if (skb == tcp_send_head(sk))
+ break;
+ TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
+ }
+ tp->lost_out = 0;
+ tcp_clear_all_retrans_hints(tp);
+ }
+
if (tp->prior_ssthresh) {
const struct inet_connection_sock *icsk = inet_csk(sk);
@@ -2263,6 +2276,9 @@ static void tcp_undo_cwr(struct sock *sk, const bool undo_ssthresh)
tp->snd_cwnd = max(tp->snd_cwnd, tp->snd_ssthresh);
}
tp->snd_cwnd_stamp = tcp_time_stamp;
+
+ if (undo_ssthresh)
+ tp->undo_marker = 0;
}
static inline bool tcp_may_undo(const struct tcp_sock *tp)
@@ -2282,14 +2298,13 @@ static bool tcp_try_undo_recovery(struct sock *sk)
* or our original transmission succeeded.
*/
DBGUNDO(sk, inet_csk(sk)->icsk_ca_state == TCP_CA_Loss ? "loss" : "retrans");
- tcp_undo_cwr(sk, true);
+ tcp_undo_cwnd_reduction(sk, true, false);
if (inet_csk(sk)->icsk_ca_state == TCP_CA_Loss)
mib_idx = LINUX_MIB_TCPLOSSUNDO;
else
mib_idx = LINUX_MIB_TCPFULLUNDO;
NET_INC_STATS_BH(sock_net(sk), mib_idx);
- tp->undo_marker = 0;
}
if (tp->snd_una == tp->high_seq && tcp_is_reno(tp)) {
/* Hold old state until something *above* high_seq
@@ -2309,8 +2324,7 @@ static void tcp_try_undo_dsack(struct sock *sk)
if (tp->undo_marker && !tp->undo_retrans) {
DBGUNDO(sk, "D-SACK");
- tcp_undo_cwr(sk, true);
- tp->undo_marker = 0;
+ tcp_undo_cwnd_reduction(sk, true, false);
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPDSACKUNDO);
}
}
@@ -2344,60 +2358,20 @@ static bool tcp_any_retrans_done(const struct sock *sk)
return false;
}
-/* Undo during fast recovery after partial ACK. */
-
-static int tcp_try_undo_partial(struct sock *sk, int acked)
-{
- struct tcp_sock *tp = tcp_sk(sk);
- /* Partial ACK arrived. Force Hoe's retransmit. */
- int failed = tcp_is_reno(tp) || (tcp_fackets_out(tp) > tp->reordering);
-
- if (tcp_may_undo(tp)) {
- /* Plain luck! Hole if filled with delayed
- * packet, rather than with a retransmit.
- */
- if (!tcp_any_retrans_done(sk))
- tp->retrans_stamp = 0;
-
- tcp_update_reordering(sk, tcp_fackets_out(tp) + acked, 1);
-
- DBGUNDO(sk, "Hoe");
- tcp_undo_cwr(sk, false);
- NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPPARTIALUNDO);
-
- /* So... Do not make Hoe's retransmit yet.
- * If the first packet was delayed, the rest
- * ones are most probably delayed as well.
- */
- failed = 0;
- }
- return failed;
-}
-
/* Undo during loss recovery after partial ACK or using F-RTO. */
static bool tcp_try_undo_loss(struct sock *sk, bool frto_undo)
{
struct tcp_sock *tp = tcp_sk(sk);
if (frto_undo || tcp_may_undo(tp)) {
- struct sk_buff *skb;
- tcp_for_write_queue(skb, sk) {
- if (skb == tcp_send_head(sk))
- break;
- TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
- }
-
- tcp_clear_all_retrans_hints(tp);
+ tcp_undo_cwnd_reduction(sk, true, true);
DBGUNDO(sk, "partial loss");
- tp->lost_out = 0;
- tcp_undo_cwr(sk, true);
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPLOSSUNDO);
if (frto_undo)
NET_INC_STATS_BH(sock_net(sk),
LINUX_MIB_TCPSPURIOUSRTOS);
inet_csk(sk)->icsk_retransmits = 0;
- tp->undo_marker = 0;
if (frto_undo || tcp_is_sack(tp))
tcp_set_ca_state(sk, TCP_CA_Open);
return true;
@@ -2669,6 +2643,35 @@ static void tcp_process_loss(struct sock *sk, int flag, bool is_dupack)
tcp_xmit_retransmit_queue(sk);
}
+/* Undo during fast recovery after partial ACK. */
+static bool tcp_try_undo_partial(struct sock *sk, int acked)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ /* Partial ACK arrived. Force Hoe's retransmit. */
+ bool failed = tcp_is_reno(tp) || (tcp_fackets_out(tp) > tp->reordering);
+
+ if (tcp_may_undo(tp)) {
+ /* Plain luck! Hole if filled with delayed
+ * packet, rather than with a retransmit.
+ */
+ if (!tcp_any_retrans_done(sk))
+ tp->retrans_stamp = 0;
+
+ tcp_update_reordering(sk, tcp_fackets_out(tp) + acked, 1);
+
+ DBGUNDO(sk, "Hoe");
+ tcp_undo_cwnd_reduction(sk, false, false);
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPPARTIALUNDO);
+
+ /* So... Do not make Hoe's retransmit yet.
+ * If the first packet was delayed, the rest
+ * ones are most probably delayed as well.
+ */
+ failed = false;
+ }
+ return failed;
+}
+
/* Process an event, which can update packets-in-flight not trivially.
* Main goal of this function is to calculate new estimate for left_out,
* taking into account both packets sitting in receiver's buffer and
@@ -2686,7 +2689,7 @@ static void tcp_fastretrans_alert(struct sock *sk, const int acked,
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
- int do_lost = is_dupack || ((flag & FLAG_DATA_SACKED) &&
+ bool do_lost = is_dupack || ((flag & FLAG_DATA_SACKED) &&
(tcp_fackets_out(tp) > tp->reordering));
int fast_rexmit = 0;
--
1.8.2.1
--
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