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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-01-20 14:01:31 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-01-20 14:01:31 -0300
commitb4b7ff4b08e691656c9d77c758fc355833128ac0 (patch)
tree82fcb00e6b918026dc9f2d1f05ed8eee83874cc0 /net/ipv4/tcp_input.c
parent35acfa0fc609f2a2cd95cef4a6a9c3a5c38f1778 (diff)
Linux-libre 4.4-gnupck-4.4-gnu
Diffstat (limited to 'net/ipv4/tcp_input.c')
-rw-r--r--net/ipv4/tcp_input.c283
1 files changed, 160 insertions, 123 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 194a8ff10..e4600e3c9 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -98,6 +98,7 @@ int sysctl_tcp_stdurg __read_mostly;
int sysctl_tcp_rfc1337 __read_mostly;
int sysctl_tcp_max_orphans __read_mostly = NR_FILE;
int sysctl_tcp_frto __read_mostly = 2;
+int sysctl_tcp_min_rtt_wlen __read_mostly = 300;
int sysctl_tcp_thin_dupack __read_mostly;
@@ -883,6 +884,7 @@ static void tcp_update_reordering(struct sock *sk, const int metric,
if (metric > 0)
tcp_disable_early_retrans(tp);
+ tp->rack.reord = 1;
}
/* This must be called before lost_out is incremented */
@@ -908,8 +910,7 @@ static void tcp_skb_mark_lost(struct tcp_sock *tp, struct sk_buff *skb)
}
}
-static void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp,
- struct sk_buff *skb)
+void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb)
{
tcp_verify_retransmit_hint(tp, skb);
@@ -1050,70 +1051,6 @@ static bool tcp_is_sackblock_valid(struct tcp_sock *tp, bool is_dsack,
return !before(start_seq, end_seq - tp->max_window);
}
-/* Check for lost retransmit. This superb idea is borrowed from "ratehalving".
- * Event "B". 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
- * highest SACK block). Also calculate the lowest snd_nxt among the remaining
- * retransmitted skbs to avoid some costly processing per ACKs.
- */
-static void tcp_mark_lost_retrans(struct sock *sk, int *flag)
-{
- const struct inet_connection_sock *icsk = inet_csk(sk);
- struct tcp_sock *tp = tcp_sk(sk);
- struct sk_buff *skb;
- int cnt = 0;
- u32 new_low_seq = tp->snd_nxt;
- u32 received_upto = tcp_highest_sack_seq(tp);
-
- if (!tcp_is_fack(tp) || !tp->retrans_out ||
- !after(received_upto, tp->lost_retrans_low) ||
- icsk->icsk_ca_state != TCP_CA_Recovery)
- return;
-
- tcp_for_write_queue(skb, sk) {
- u32 ack_seq = TCP_SKB_CB(skb)->ack_seq;
-
- if (skb == tcp_send_head(sk))
- break;
- 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))
- continue;
-
- /* TODO: We would like to get rid of tcp_is_fack(tp) only
- * constraint here (see above) but figuring out that at
- * least tp->reordering SACK blocks reside between ack_seq
- * and received_upto is not easy task to do cheaply with
- * the available datastructures.
- *
- * Whether FACK should check here for tp->reordering segs
- * in-between one could argue for either way (it would be
- * rather simple to implement as we could count fack_count
- * during the walk and do tp->fackets_out - fack_count).
- */
- if (after(received_upto, ack_seq)) {
- TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
- tp->retrans_out -= tcp_skb_pcount(skb);
- *flag |= FLAG_LOST_RETRANS;
- tcp_skb_mark_lost_uncond_verify(tp, skb);
- NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPLOSTRETRANSMIT);
- } else {
- if (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;
-}
-
static bool tcp_check_dsack(struct sock *sk, const struct sk_buff *ack_skb,
struct tcp_sack_block_wire *sp, int num_sacks,
u32 prior_snd_una)
@@ -1239,6 +1176,8 @@ static u8 tcp_sacktag_one(struct sock *sk,
return sacked;
if (!(sacked & TCPCB_SACKED_ACKED)) {
+ tcp_rack_advance(tp, xmit_time, sacked);
+
if (sacked & TCPCB_SACKED_RETRANS) {
/* If the segment is not tagged as lost,
* we do not clear RETRANS, believing
@@ -1840,7 +1779,6 @@ advance_sp:
((inet_csk(sk)->icsk_ca_state != TCP_CA_Loss) || tp->undo_marker))
tcp_update_reordering(sk, tp->fackets_out - state->reord, 0);
- tcp_mark_lost_retrans(sk, &state->flag);
tcp_verify_left_out(tp);
out:
@@ -2317,14 +2255,29 @@ static inline void tcp_moderate_cwnd(struct tcp_sock *tp)
tp->snd_cwnd_stamp = tcp_time_stamp;
}
+static bool tcp_tsopt_ecr_before(const struct tcp_sock *tp, u32 when)
+{
+ return tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr &&
+ before(tp->rx_opt.rcv_tsecr, when);
+}
+
+/* skb is spurious retransmitted if the returned timestamp echo
+ * reply is prior to the skb transmission time
+ */
+static bool tcp_skb_spurious_retrans(const struct tcp_sock *tp,
+ const struct sk_buff *skb)
+{
+ return (TCP_SKB_CB(skb)->sacked & TCPCB_RETRANS) &&
+ tcp_tsopt_ecr_before(tp, tcp_skb_timestamp(skb));
+}
+
/* Nothing was retransmitted or returned timestamp is less
* than timestamp of the first retransmission.
*/
static inline bool tcp_packet_delayed(const struct tcp_sock *tp)
{
return !tp->retrans_stamp ||
- (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr &&
- before(tp->rx_opt.rcv_tsecr, tp->retrans_stamp));
+ tcp_tsopt_ecr_before(tp, tp->retrans_stamp);
}
/* Undo procedures. */
@@ -2528,6 +2481,9 @@ static void tcp_cwnd_reduction(struct sock *sk, const int prior_unsacked,
int newly_acked_sacked = prior_unsacked -
(tp->packets_out - tp->sacked_out);
+ if (newly_acked_sacked <= 0 || WARN_ON_ONCE(!tp->prior_cwnd))
+ return;
+
tp->prr_delivered += newly_acked_sacked;
if (delta < 0) {
u64 dividend = (u64)tp->snd_ssthresh * tp->prr_delivered +
@@ -2856,6 +2812,11 @@ static void tcp_fastretrans_alert(struct sock *sk, const int acked,
}
}
+ /* Use RACK to detect loss */
+ if (sysctl_tcp_recovery & TCP_RACK_LOST_RETRANS &&
+ tcp_rack_mark_lost(sk))
+ flag |= FLAG_LOST_RETRANS;
+
/* E. Process state. */
switch (icsk->icsk_ca_state) {
case TCP_CA_Recovery:
@@ -2918,8 +2879,69 @@ static void tcp_fastretrans_alert(struct sock *sk, const int acked,
tcp_xmit_retransmit_queue(sk);
}
+/* Kathleen Nichols' algorithm for tracking the minimum value of
+ * a data stream over some fixed time interval. (E.g., the minimum
+ * RTT over the past five minutes.) It uses constant space and constant
+ * time per update yet almost always delivers the same minimum as an
+ * implementation that has to keep all the data in the window.
+ *
+ * The algorithm keeps track of the best, 2nd best & 3rd best min
+ * values, maintaining an invariant that the measurement time of the
+ * n'th best >= n-1'th best. It also makes sure that the three values
+ * are widely separated in the time window since that bounds the worse
+ * case error when that data is monotonically increasing over the window.
+ *
+ * Upon getting a new min, we can forget everything earlier because it
+ * has no value - the new min is <= everything else in the window by
+ * definition and it's the most recent. So we restart fresh on every new min
+ * and overwrites 2nd & 3rd choices. The same property holds for 2nd & 3rd
+ * best.
+ */
+static void tcp_update_rtt_min(struct sock *sk, u32 rtt_us)
+{
+ const u32 now = tcp_time_stamp, wlen = sysctl_tcp_min_rtt_wlen * HZ;
+ struct rtt_meas *m = tcp_sk(sk)->rtt_min;
+ struct rtt_meas rttm = { .rtt = (rtt_us ? : 1), .ts = now };
+ u32 elapsed;
+
+ /* Check if the new measurement updates the 1st, 2nd, or 3rd choices */
+ if (unlikely(rttm.rtt <= m[0].rtt))
+ m[0] = m[1] = m[2] = rttm;
+ else if (rttm.rtt <= m[1].rtt)
+ m[1] = m[2] = rttm;
+ else if (rttm.rtt <= m[2].rtt)
+ m[2] = rttm;
+
+ elapsed = now - m[0].ts;
+ if (unlikely(elapsed > wlen)) {
+ /* Passed entire window without a new min so make 2nd choice
+ * the new min & 3rd choice the new 2nd. So forth and so on.
+ */
+ m[0] = m[1];
+ m[1] = m[2];
+ m[2] = rttm;
+ if (now - m[0].ts > wlen) {
+ m[0] = m[1];
+ m[1] = rttm;
+ if (now - m[0].ts > wlen)
+ m[0] = rttm;
+ }
+ } else if (m[1].ts == m[0].ts && elapsed > wlen / 4) {
+ /* Passed a quarter of the window without a new min so
+ * take 2nd choice from the 2nd quarter of the window.
+ */
+ m[2] = m[1] = rttm;
+ } else if (m[2].ts == m[1].ts && elapsed > wlen / 2) {
+ /* Passed half the window without a new min so take the 3rd
+ * choice from the last half of the window.
+ */
+ m[2] = rttm;
+ }
+}
+
static inline bool tcp_ack_update_rtt(struct sock *sk, const int flag,
- long seq_rtt_us, long sack_rtt_us)
+ long seq_rtt_us, long sack_rtt_us,
+ long ca_rtt_us)
{
const struct tcp_sock *tp = tcp_sk(sk);
@@ -2928,9 +2950,6 @@ static inline bool tcp_ack_update_rtt(struct sock *sk, const int flag,
* Karn's algorithm forbids taking RTT if some retransmitted data
* is acked (RFC6298).
*/
- if (flag & FLAG_RETRANS_DATA_ACKED)
- seq_rtt_us = -1L;
-
if (seq_rtt_us < 0)
seq_rtt_us = sack_rtt_us;
@@ -2942,11 +2961,16 @@ static inline bool tcp_ack_update_rtt(struct sock *sk, const int flag,
*/
if (seq_rtt_us < 0 && tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr &&
flag & FLAG_ACKED)
- seq_rtt_us = jiffies_to_usecs(tcp_time_stamp - tp->rx_opt.rcv_tsecr);
-
+ seq_rtt_us = ca_rtt_us = jiffies_to_usecs(tcp_time_stamp -
+ tp->rx_opt.rcv_tsecr);
if (seq_rtt_us < 0)
return false;
+ /* ca_rtt_us >= 0 is counting on the invariant that ca_rtt_us is
+ * always taken together with ACK, SACK, or TS-opts. Any negative
+ * values will be skipped with the seq_rtt_us < 0 check above.
+ */
+ tcp_update_rtt_min(sk, ca_rtt_us);
tcp_rtt_estimator(sk, seq_rtt_us);
tcp_set_rto(sk);
@@ -2956,21 +2980,21 @@ static inline bool tcp_ack_update_rtt(struct sock *sk, const int flag,
}
/* Compute time elapsed between (last) SYNACK and the ACK completing 3WHS. */
-static void tcp_synack_rtt_meas(struct sock *sk, const u32 synack_stamp)
+void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req)
{
- struct tcp_sock *tp = tcp_sk(sk);
- long seq_rtt_us = -1L;
+ long rtt_us = -1L;
- if (synack_stamp && !tp->total_retrans)
- seq_rtt_us = jiffies_to_usecs(tcp_time_stamp - synack_stamp);
+ if (req && !req->num_retrans && tcp_rsk(req)->snt_synack.v64) {
+ struct skb_mstamp now;
- /* If the ACK acks both the SYNACK and the (Fast Open'd) data packets
- * sent in SYN_RECV, SYNACK RTT is the smooth RTT computed in tcp_ack()
- */
- if (!tp->srtt_us)
- tcp_ack_update_rtt(sk, FLAG_SYN_ACKED, seq_rtt_us, -1L);
+ skb_mstamp_get(&now);
+ rtt_us = skb_mstamp_us_delta(&now, &tcp_rsk(req)->snt_synack);
+ }
+
+ tcp_ack_update_rtt(sk, FLAG_SYN_ACKED, rtt_us, -1L, rtt_us);
}
+
static void tcp_cong_avoid(struct sock *sk, u32 ack, u32 acked)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
@@ -3134,6 +3158,8 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
if (sacked & TCPCB_SACKED_ACKED)
tp->sacked_out -= acked_pcount;
+ else if (tcp_is_sack(tp) && !tcp_skb_spurious_retrans(tp, skb))
+ tcp_rack_advance(tp, &skb->skb_mstamp, sacked);
if (sacked & TCPCB_LOST)
tp->lost_out -= acked_pcount;
@@ -3172,7 +3198,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
flag |= FLAG_SACK_RENEGING;
skb_mstamp_get(&now);
- if (likely(first_ackt.v64)) {
+ if (likely(first_ackt.v64) && !(flag & FLAG_RETRANS_DATA_ACKED)) {
seq_rtt_us = skb_mstamp_us_delta(&now, &first_ackt);
ca_rtt_us = skb_mstamp_us_delta(&now, &last_ackt);
}
@@ -3181,7 +3207,8 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
ca_rtt_us = skb_mstamp_us_delta(&now, &sack->last_sackt);
}
- rtt_update = tcp_ack_update_rtt(sk, flag, seq_rtt_us, sack_rtt_us);
+ rtt_update = tcp_ack_update_rtt(sk, flag, seq_rtt_us, sack_rtt_us,
+ ca_rtt_us);
if (flag & FLAG_ACKED) {
tcp_rearm_rto(sk);
@@ -5574,7 +5601,7 @@ static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synack,
}
static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
- const struct tcphdr *th, unsigned int len)
+ const struct tcphdr *th)
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
@@ -5801,15 +5828,14 @@ reset_and_undo:
* address independent.
*/
-int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
- const struct tcphdr *th, unsigned int len)
+int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
{
struct tcp_sock *tp = tcp_sk(sk);
struct inet_connection_sock *icsk = inet_csk(sk);
+ const struct tcphdr *th = tcp_hdr(skb);
struct request_sock *req;
int queued = 0;
bool acceptable;
- u32 synack_stamp;
tp->rx_opt.saw_tstamp = 0;
@@ -5853,7 +5879,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
goto discard;
case TCP_SYN_SENT:
- queued = tcp_rcv_synsent_state_process(sk, skb, th, len);
+ queued = tcp_rcv_synsent_state_process(sk, skb, th);
if (queued >= 0)
return queued;
@@ -5888,15 +5914,16 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
if (!acceptable)
return 1;
+ if (!tp->srtt_us)
+ tcp_synack_rtt_meas(sk, req);
+
/* Once we leave TCP_SYN_RECV, we no longer need req
* so release it.
*/
if (req) {
- synack_stamp = tcp_rsk(req)->snt_synack;
tp->total_retrans = req->num_retrans;
reqsk_fastopen_remove(sk, req, false);
} else {
- synack_stamp = tp->lsndtime;
/* Make sure socket is routed, for correct metrics. */
icsk->icsk_af_ops->rebuild_header(sk);
tcp_init_congestion_control(sk);
@@ -5919,7 +5946,6 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
tp->snd_una = TCP_SKB_CB(skb)->ack_seq;
tp->snd_wnd = ntohs(th->window) << tp->rx_opt.snd_wscale;
tcp_init_wl(tp, TCP_SKB_CB(skb)->seq);
- tcp_synack_rtt_meas(sk, synack_stamp);
if (tp->rx_opt.tstamp_ok)
tp->advmss -= TCPOLEN_TSTAMP_ALIGNED;
@@ -6126,11 +6152,11 @@ static void tcp_openreq_init(struct request_sock *req,
{
struct inet_request_sock *ireq = inet_rsk(req);
- req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
+ req->rsk_rcv_wnd = 0; /* So that tcp_send_synack() knows! */
req->cookie_ts = 0;
tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
- tcp_rsk(req)->snt_synack = tcp_time_stamp;
+ skb_mstamp_get(&tcp_rsk(req)->snt_synack);
tcp_rsk(req)->last_oow_ack_time = 0;
req->mss = rx_opt->mss_clamp;
req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
@@ -6146,9 +6172,11 @@ static void tcp_openreq_init(struct request_sock *req,
}
struct request_sock *inet_reqsk_alloc(const struct request_sock_ops *ops,
- struct sock *sk_listener)
+ struct sock *sk_listener,
+ bool attach_listener)
{
- struct request_sock *req = reqsk_alloc(ops, sk_listener);
+ struct request_sock *req = reqsk_alloc(ops, sk_listener,
+ attach_listener);
if (req) {
struct inet_request_sock *ireq = inet_rsk(req);
@@ -6168,13 +6196,13 @@ EXPORT_SYMBOL(inet_reqsk_alloc);
/*
* Return true if a syncookie should be sent
*/
-static bool tcp_syn_flood_action(struct sock *sk,
+static bool tcp_syn_flood_action(const struct sock *sk,
const struct sk_buff *skb,
const char *proto)
{
+ struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
const char *msg = "Dropping request";
bool want_cookie = false;
- struct listen_sock *lopt;
#ifdef CONFIG_SYN_COOKIES
if (sysctl_tcp_syncookies) {
@@ -6185,12 +6213,12 @@ static bool tcp_syn_flood_action(struct sock *sk,
#endif
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPREQQFULLDROP);
- lopt = inet_csk(sk)->icsk_accept_queue.listen_opt;
- if (!lopt->synflood_warned && sysctl_tcp_syncookies != 2) {
- lopt->synflood_warned = 1;
+ if (!queue->synflood_warned &&
+ sysctl_tcp_syncookies != 2 &&
+ xchg(&queue->synflood_warned, 1) == 0)
pr_info("%s: Possible SYN flooding on port %d. %s. Check SNMP counters.\n",
proto, ntohs(tcp_hdr(skb)->dest), msg);
- }
+
return want_cookie;
}
@@ -6215,16 +6243,15 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
const struct tcp_request_sock_ops *af_ops,
struct sock *sk, struct sk_buff *skb)
{
+ struct tcp_fastopen_cookie foc = { .len = -1 };
+ __u32 isn = TCP_SKB_CB(skb)->tcp_tw_isn;
struct tcp_options_received tmp_opt;
- struct request_sock *req;
struct tcp_sock *tp = tcp_sk(sk);
+ struct sock *fastopen_sk = NULL;
struct dst_entry *dst = NULL;
- __u32 isn = TCP_SKB_CB(skb)->tcp_tw_isn;
- bool want_cookie = false, fastopen;
+ struct request_sock *req;
+ bool want_cookie = false;
struct flowi fl;
- struct tcp_fastopen_cookie foc = { .len = -1 };
- int err;
-
/* TW buckets are converted to open requests without
* limitations, they conserve resources and peer is
@@ -6248,7 +6275,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
goto drop;
}
- req = inet_reqsk_alloc(rsk_ops, sk);
+ req = inet_reqsk_alloc(rsk_ops, sk, !want_cookie);
if (!req)
goto drop;
@@ -6331,20 +6358,30 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
}
tcp_rsk(req)->snt_isn = isn;
+ tcp_rsk(req)->txhash = net_tx_rndhash();
tcp_openreq_init_rwin(req, sk, dst);
- fastopen = !want_cookie &&
- tcp_try_fastopen(sk, skb, req, &foc, dst);
- err = af_ops->send_synack(sk, dst, &fl, req,
- skb_get_queue_mapping(skb), &foc);
- if (!fastopen) {
- if (err || want_cookie)
- goto drop_and_free;
-
+ if (!want_cookie) {
+ tcp_reqsk_record_syn(sk, req, skb);
+ fastopen_sk = tcp_try_fastopen(sk, skb, req, &foc, dst);
+ }
+ if (fastopen_sk) {
+ af_ops->send_synack(fastopen_sk, dst, &fl, req,
+ &foc, false);
+ /* Add the child socket directly into the accept queue */
+ inet_csk_reqsk_queue_add(sk, req, fastopen_sk);
+ sk->sk_data_ready(sk);
+ bh_unlock_sock(fastopen_sk);
+ sock_put(fastopen_sk);
+ } else {
tcp_rsk(req)->tfo_listener = false;
- af_ops->queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
+ if (!want_cookie)
+ inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
+ af_ops->send_synack(sk, dst, &fl, req,
+ &foc, !want_cookie);
+ if (want_cookie)
+ goto drop_and_free;
}
- tcp_reqsk_record_syn(sk, req, skb);
-
+ reqsk_put(req);
return 0;
drop_and_release: