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-rw-r--r--net/ipv4/tcp_input.c193
1 files changed, 118 insertions, 75 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 0a42e934034..0f0c1c9829a 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -103,7 +103,7 @@ int sysctl_tcp_abc __read_mostly;
#define FLAG_SLOWPATH 0x100 /* Do not skip RFC checks for window update.*/
#define FLAG_ONLY_ORIG_SACKED 0x200 /* SACKs only non-rexmit sent before RTO */
#define FLAG_SND_UNA_ADVANCED 0x400 /* Snd_una was changed (!= FLAG_DATA_ACKED) */
-#define FLAG_DSACKING_ACK 0x800 /* SACK blocks contained DSACK info */
+#define FLAG_DSACKING_ACK 0x800 /* SACK blocks contained D-SACK info */
#define FLAG_NONHEAD_RETRANS_ACKED 0x1000 /* Non-head rexmitted data was ACKed */
#define FLAG_ACKED (FLAG_DATA_ACKED|FLAG_SYN_ACKED)
@@ -866,7 +866,7 @@ static void tcp_disable_fack(struct tcp_sock *tp)
tp->rx_opt.sack_ok &= ~2;
}
-/* Take a notice that peer is sending DSACKs */
+/* Take a notice that peer is sending D-SACKs */
static void tcp_dsack_seen(struct tcp_sock *tp)
{
tp->rx_opt.sack_ok |= 4;
@@ -1058,7 +1058,7 @@ static void tcp_update_reordering(struct sock *sk, const int metric,
*
* With D-SACK the lower bound is extended to cover sequence space below
* SND.UNA down to undo_marker, which is the last point of interest. Yet
- * again, DSACK block must not to go across snd_una (for the same reason as
+ * again, D-SACK block must not to go across snd_una (for the same reason as
* for the normal SACK blocks, explained above). But there all simplicity
* ends, TCP might receive valid D-SACKs below that. As long as they reside
* fully below undo_marker they do not affect behavior in anyway and can
@@ -1080,7 +1080,7 @@ static int tcp_is_sackblock_valid(struct tcp_sock *tp, int is_dsack,
if (!before(start_seq, tp->snd_nxt))
return 0;
- /* In outstanding window? ...This is valid exit for DSACKs too.
+ /* In outstanding window? ...This is valid exit for D-SACKs too.
* start_seq == snd_una is non-sensical (see comments above)
*/
if (after(start_seq, tp->snd_una))
@@ -1121,7 +1121,7 @@ static int tcp_mark_lost_retrans(struct sock *sk, u32 received_upto)
struct sk_buff *skb;
int flag = 0;
int cnt = 0;
- u32 new_low_seq = 0;
+ u32 new_low_seq = tp->snd_nxt;
tcp_for_write_queue(skb, sk) {
u32 ack_seq = TCP_SKB_CB(skb)->ack_seq;
@@ -1153,7 +1153,7 @@ static int tcp_mark_lost_retrans(struct sock *sk, u32 received_upto)
NET_INC_STATS_BH(LINUX_MIB_TCPLOSTRETRANSMIT);
}
} else {
- if (!new_low_seq || before(ack_seq, new_low_seq))
+ if (before(ack_seq, new_low_seq))
new_low_seq = ack_seq;
cnt += tcp_skb_pcount(skb);
}
@@ -1204,8 +1204,8 @@ static int tcp_check_dsack(struct tcp_sock *tp, struct sk_buff *ack_skb,
* which may fail and creates some hassle (caller must handle error case
* returns).
*/
-int tcp_match_skb_to_sack(struct sock *sk, struct sk_buff *skb,
- u32 start_seq, u32 end_seq)
+static int tcp_match_skb_to_sack(struct sock *sk, struct sk_buff *skb,
+ u32 start_seq, u32 end_seq)
{
int in_sack, err;
unsigned int pkt_len;
@@ -1242,12 +1242,13 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
int num_sacks = (ptr[1] - TCPOLEN_SACK_BASE)>>3;
int reord = tp->packets_out;
int prior_fackets;
- u32 highest_sack_end_seq = 0;
+ u32 highest_sack_end_seq = tp->lost_retrans_low;
int flag = 0;
int found_dup_sack = 0;
int cached_fack_count;
int i;
int first_sack_index;
+ int force_one_sack;
if (!tp->sacked_out) {
if (WARN_ON(tp->fackets_out))
@@ -1268,22 +1269,25 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
if (before(TCP_SKB_CB(ack_skb)->ack_seq, prior_snd_una - tp->max_window))
return 0;
+ if (!tp->packets_out)
+ goto out;
+
/* SACK fastpath:
* if the only SACK change is the increase of the end_seq of
* the first block then only apply that SACK block
* and use retrans queue hinting otherwise slowpath */
- flag = 1;
+ force_one_sack = 1;
for (i = 0; i < num_sacks; i++) {
__be32 start_seq = sp[i].start_seq;
__be32 end_seq = sp[i].end_seq;
if (i == 0) {
if (tp->recv_sack_cache[i].start_seq != start_seq)
- flag = 0;
+ force_one_sack = 0;
} else {
if ((tp->recv_sack_cache[i].start_seq != start_seq) ||
(tp->recv_sack_cache[i].end_seq != end_seq))
- flag = 0;
+ force_one_sack = 0;
}
tp->recv_sack_cache[i].start_seq = start_seq;
tp->recv_sack_cache[i].end_seq = end_seq;
@@ -1295,7 +1299,7 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
}
first_sack_index = 0;
- if (flag)
+ if (force_one_sack)
num_sacks = 1;
else {
int j;
@@ -1321,9 +1325,6 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
}
}
- /* clear flag as used for different purpose in following code */
- flag = 0;
-
/* Use SACK fastpath hint if valid */
cached_skb = tp->fastpath_skb_hint;
cached_fack_count = tp->fastpath_cnt_hint;
@@ -1332,12 +1333,15 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
cached_fack_count = 0;
}
- for (i=0; i<num_sacks; i++, sp++) {
+ for (i = 0; i < num_sacks; i++) {
struct sk_buff *skb;
__u32 start_seq = ntohl(sp->start_seq);
__u32 end_seq = ntohl(sp->end_seq);
int fack_count;
int dup_sack = (found_dup_sack && (i == first_sack_index));
+ int next_dup = (found_dup_sack && (i+1 == first_sack_index));
+
+ sp++;
if (!tcp_is_sackblock_valid(tp, dup_sack, start_seq, end_seq)) {
if (dup_sack) {
@@ -1363,7 +1367,7 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
flag |= FLAG_DATA_LOST;
tcp_for_write_queue_from(skb, sk) {
- int in_sack;
+ int in_sack = 0;
u8 sacked;
if (skb == tcp_send_head(sk))
@@ -1382,11 +1386,25 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
if (!before(TCP_SKB_CB(skb)->seq, end_seq))
break;
- in_sack = tcp_match_skb_to_sack(sk, skb, start_seq, end_seq);
- if (in_sack < 0)
- break;
+ dup_sack = (found_dup_sack && (i == first_sack_index));
- fack_count += tcp_skb_pcount(skb);
+ /* Due to sorting DSACK may reside within this SACK block! */
+ if (next_dup) {
+ u32 dup_start = ntohl(sp->start_seq);
+ u32 dup_end = ntohl(sp->end_seq);
+
+ if (before(TCP_SKB_CB(skb)->seq, dup_end)) {
+ in_sack = tcp_match_skb_to_sack(sk, skb, dup_start, dup_end);
+ if (in_sack > 0)
+ dup_sack = 1;
+ }
+ }
+
+ /* DSACK info lost if out-of-mem, try SACK still */
+ if (in_sack <= 0)
+ in_sack = tcp_match_skb_to_sack(sk, skb, start_seq, end_seq);
+ if (unlikely(in_sack < 0))
+ break;
sacked = TCP_SKB_CB(skb)->sacked;
@@ -1402,19 +1420,17 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
if ((dup_sack && in_sack) &&
(sacked&TCPCB_SACKED_ACKED))
reord = min(fack_count, reord);
- } else {
- /* If it was in a hole, we detected reordering. */
- if (fack_count < prior_fackets &&
- !(sacked&TCPCB_SACKED_ACKED))
- reord = min(fack_count, reord);
}
/* Nothing to do; acked frame is about to be dropped. */
+ fack_count += tcp_skb_pcount(skb);
continue;
}
- if (!in_sack)
+ if (!in_sack) {
+ fack_count += tcp_skb_pcount(skb);
continue;
+ }
if (!(sacked&TCPCB_SACKED_ACKED)) {
if (sacked & TCPCB_SACKED_RETRANS) {
@@ -1431,12 +1447,17 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
tp->retransmit_skb_hint = NULL;
}
} else {
- /* New sack for not retransmitted frame,
- * which was in hole. It is reordering.
- */
- if (!(sacked & TCPCB_RETRANS) &&
- fack_count < prior_fackets)
- reord = min(fack_count, reord);
+ if (!(sacked & TCPCB_RETRANS)) {
+ /* New sack for not retransmitted frame,
+ * which was in hole. It is reordering.
+ */
+ if (fack_count < prior_fackets)
+ 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;
@@ -1445,24 +1466,13 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
/* clear lost hint */
tp->retransmit_skb_hint = NULL;
}
- /* SACK enhanced F-RTO detection.
- * Set flag if and only if non-rexmitted
- * segments below frto_highmark are
- * SACKed (RFC4138; Appendix B).
- * Clearing correct due to in-order walk
- */
- if (after(end_seq, tp->frto_highmark)) {
- flag &= ~FLAG_ONLY_ORIG_SACKED;
- } else {
- if (!(sacked & TCPCB_RETRANS))
- flag |= FLAG_ONLY_ORIG_SACKED;
- }
}
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);
if (fack_count > tp->fackets_out)
tp->fackets_out = fack_count;
@@ -1473,6 +1483,8 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
} 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
@@ -1487,6 +1499,12 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
tp->retransmit_skb_hint = NULL;
}
}
+
+ /* SACK enhanced FRTO (RFC4138, Appendix B): Clearing correct
+ * due to in-order walk
+ */
+ if (after(end_seq, tp->frto_highmark))
+ flag &= ~FLAG_ONLY_ORIG_SACKED;
}
if (tp->retrans_out &&
@@ -1498,7 +1516,9 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
if ((reord < tp->fackets_out) && icsk->icsk_ca_state != TCP_CA_Loss &&
(!tp->frto_highmark || after(tp->snd_una, tp->frto_highmark)))
- tcp_update_reordering(sk, ((tp->fackets_out + 1) - reord), 0);
+ tcp_update_reordering(sk, tp->fackets_out - reord, 0);
+
+out:
#if FASTRETRANS_DEBUG > 0
BUG_TRAP((int)tp->sacked_out >= 0);
@@ -1615,7 +1635,7 @@ void tcp_enter_frto(struct sock *sk)
!icsk->icsk_retransmits)) {
tp->prior_ssthresh = tcp_current_ssthresh(sk);
/* Our state is too optimistic in ssthresh() call because cwnd
- * is not reduced until tcp_enter_frto_loss() when previous FRTO
+ * is not reduced until tcp_enter_frto_loss() when previous F-RTO
* recovery has not yet completed. Pattern would be this: RTO,
* Cumulative ACK, RTO (2xRTO for the same segment does not end
* up here twice).
@@ -1654,6 +1674,9 @@ void tcp_enter_frto(struct sock *sk)
}
tcp_verify_left_out(tp);
+ /* Too bad if TCP was application limited */
+ tp->snd_cwnd = min(tp->snd_cwnd, tcp_packets_in_flight(tp) + 1);
+
/* Earlier loss recovery underway (see RFC4138; Appendix B).
* The last condition is necessary at least in tp->frto_counter case.
*/
@@ -1686,6 +1709,8 @@ static void tcp_enter_frto_loss(struct sock *sk, int allowed_segments, int flag)
tcp_for_write_queue(skb, sk) {
if (skb == tcp_send_head(sk))
break;
+
+ TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
/*
* Count the retransmission made on RTO correctly (only when
* waiting for the first ACK and did not get it)...
@@ -1699,7 +1724,7 @@ static void tcp_enter_frto_loss(struct sock *sk, int allowed_segments, int flag)
} else {
if (TCP_SKB_CB(skb)->sacked & TCPCB_RETRANS)
tp->undo_marker = 0;
- TCP_SKB_CB(skb)->sacked &= ~(TCPCB_LOST|TCPCB_SACKED_RETRANS);
+ TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
}
/* Don't lost mark skbs that were fwd transmitted after RTO */
@@ -1801,7 +1826,7 @@ void tcp_enter_loss(struct sock *sk, int how)
tcp_set_ca_state(sk, TCP_CA_Loss);
tp->high_seq = tp->snd_nxt;
TCP_ECN_queue_cwr(tp);
- /* Abort FRTO algorithm if one is in progress */
+ /* Abort F-RTO algorithm if one is in progress */
tp->frto_counter = 0;
}
@@ -1946,7 +1971,7 @@ static int tcp_time_to_recover(struct sock *sk)
struct tcp_sock *tp = tcp_sk(sk);
__u32 packets_out;
- /* Do not perform any recovery during FRTO algorithm */
+ /* Do not perform any recovery during F-RTO algorithm */
if (tp->frto_counter)
return 0;
@@ -1995,8 +2020,7 @@ static void tcp_verify_retransmit_hint(struct tcp_sock *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;
@@ -2019,7 +2043,7 @@ static void tcp_mark_head_lost(struct sock *sk,
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;
@@ -2040,9 +2064,9 @@ static void tcp_update_scoreboard(struct sock *sk)
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
@@ -2062,7 +2086,7 @@ static void tcp_update_scoreboard(struct sock *sk)
if (!tcp_skb_timedout(sk, skb))
break;
- if (!(TCP_SKB_CB(skb)->sacked&TCPCB_TAGBITS)) {
+ if (!(TCP_SKB_CB(skb)->sacked & (TCPCB_SACKED_ACKED|TCPCB_LOST))) {
TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
tp->lost_out += tcp_skb_pcount(skb);
tcp_verify_retransmit_hint(tp, skb);
@@ -2381,7 +2405,7 @@ tcp_fastretrans_alert(struct sock *sk, int pkts_acked, int flag)
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);
}
@@ -2614,7 +2638,8 @@ static u32 tcp_tso_acked(struct sock *sk, struct sk_buff *skb)
* is before the ack sequence we can discard it as it's confirmed to have
* arrived at the other end.
*/
-static int tcp_clean_rtx_queue(struct sock *sk, s32 *seq_rtt_p)
+static int tcp_clean_rtx_queue(struct sock *sk, s32 *seq_rtt_p,
+ int prior_fackets)
{
struct tcp_sock *tp = tcp_sk(sk);
const struct inet_connection_sock *icsk = inet_csk(sk);
@@ -2623,6 +2648,8 @@ static int tcp_clean_rtx_queue(struct sock *sk, s32 *seq_rtt_p)
int fully_acked = 1;
int flag = 0;
int prior_packets = tp->packets_out;
+ u32 cnt = 0;
+ u32 reord = tp->packets_out;
s32 seq_rtt = -1;
ktime_t last_ackt = net_invalid_timestamp();
@@ -2663,10 +2690,14 @@ static int tcp_clean_rtx_queue(struct sock *sk, s32 *seq_rtt_p)
if ((flag & FLAG_DATA_ACKED) ||
(packets_acked > 1))
flag |= FLAG_NONHEAD_RETRANS_ACKED;
- } else if (seq_rtt < 0) {
- seq_rtt = now - scb->when;
- if (fully_acked)
- last_ackt = skb->tstamp;
+ } else {
+ if (seq_rtt < 0) {
+ seq_rtt = now - scb->when;
+ if (fully_acked)
+ last_ackt = skb->tstamp;
+ }
+ if (!(sacked & TCPCB_SACKED_ACKED))
+ reord = min(cnt, reord);
}
if (sacked & TCPCB_SACKED_ACKED)
@@ -2677,12 +2708,16 @@ static int tcp_clean_rtx_queue(struct sock *sk, s32 *seq_rtt_p)
if ((sacked & TCPCB_URG) && tp->urg_mode &&
!before(end_seq, tp->snd_up))
tp->urg_mode = 0;
- } else if (seq_rtt < 0) {
- seq_rtt = now - scb->when;
- if (fully_acked)
- last_ackt = skb->tstamp;
+ } else {
+ if (seq_rtt < 0) {
+ seq_rtt = now - scb->when;
+ if (fully_acked)
+ last_ackt = skb->tstamp;
+ }
+ reord = min(cnt, reord);
}
tp->packets_out -= packets_acked;
+ cnt += packets_acked;
/* Initial outgoing SYN's get put onto the write_queue
* just like anything else we transmit. It is not
@@ -2714,13 +2749,18 @@ static int tcp_clean_rtx_queue(struct sock *sk, s32 *seq_rtt_p)
tcp_ack_update_rtt(sk, flag, seq_rtt);
tcp_rearm_rto(sk);
+ if (tcp_is_reno(tp)) {
+ tcp_remove_reno_sacks(sk, pkts_acked);
+ } else {
+ /* Non-retransmitted hole got filled? That's reordering */
+ if (reord < prior_fackets)
+ tcp_update_reordering(sk, tp->fackets_out - reord, 0);
+ }
+
tp->fackets_out -= min(pkts_acked, tp->fackets_out);
/* hint's skb might be NULL but we don't need to care */
tp->fastpath_cnt_hint -= min_t(u32, pkts_acked,
tp->fastpath_cnt_hint);
- if (tcp_is_reno(tp))
- tcp_remove_reno_sacks(sk, pkts_acked);
-
if (ca_ops->pkts_acked) {
s32 rtt_us = -1;
@@ -2963,7 +3003,7 @@ static int tcp_process_frto(struct sock *sk, int flag)
}
if (tp->frto_counter == 1) {
- /* Sending of the next skb must be allowed or no FRTO */
+ /* Sending of the next skb must be allowed or no F-RTO */
if (!tcp_send_head(sk) ||
after(TCP_SKB_CB(tcp_send_head(sk))->end_seq,
tp->snd_una + tp->snd_wnd)) {
@@ -3003,6 +3043,7 @@ static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag)
u32 ack_seq = TCP_SKB_CB(skb)->seq;
u32 ack = TCP_SKB_CB(skb)->ack_seq;
u32 prior_in_flight;
+ u32 prior_fackets;
s32 seq_rtt;
int prior_packets;
int frto_cwnd = 0;
@@ -3027,6 +3068,8 @@ static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag)
tp->bytes_acked += min(ack - prior_snd_una, tp->mss_cache);
}
+ prior_fackets = tp->fackets_out;
+
if (!(flag&FLAG_SLOWPATH) && after(ack, prior_snd_una)) {
/* Window is constant, pure forward advance.
* No more checks are required.
@@ -3068,13 +3111,13 @@ static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag)
prior_in_flight = tcp_packets_in_flight(tp);
/* See if we can take anything off of the retransmit queue. */
- flag |= tcp_clean_rtx_queue(sk, &seq_rtt);
+ flag |= tcp_clean_rtx_queue(sk, &seq_rtt, prior_fackets);
+ if (tp->frto_counter)
+ frto_cwnd = tcp_process_frto(sk, flag);
/* Guarantee sacktag reordering detection against wrap-arounds */
if (before(tp->frto_highmark, tp->snd_una))
tp->frto_highmark = 0;
- if (tp->frto_counter)
- frto_cwnd = tcp_process_frto(sk, flag);
if (tcp_ack_is_dubious(sk, flag)) {
/* Advance CWND, if state allows this. */
@@ -3910,7 +3953,7 @@ tcp_collapse(struct sock *sk, struct sk_buff_head *list,
while (before(start, end)) {
struct sk_buff *nskb;
- int header = skb_headroom(skb);
+ unsigned int header = skb_headroom(skb);
int copy = SKB_MAX_ORDER(header, 0);
/* Too big header? This can happen with IPv6. */
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2025-04-12 15:12:10 +0000