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1/*
2 * net/dccp/timer.c
3 *
4 * An implementation of the DCCP protocol
5 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
11 */
12
13#include <linux/dccp.h>
14#include <linux/skbuff.h>
15
16#include "dccp.h"
17
18/* sysctl variables governing numbers of retransmission attempts */
19int sysctl_dccp_request_retries __read_mostly = TCP_SYN_RETRIES;
20int sysctl_dccp_retries1 __read_mostly = TCP_RETR1;
21int sysctl_dccp_retries2 __read_mostly = TCP_RETR2;
22
23static void dccp_write_err(struct sock *sk)
24{
25 sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT;
26 sk->sk_error_report(sk);
27
28 dccp_send_reset(sk, DCCP_RESET_CODE_ABORTED);
29 dccp_done(sk);
30 DCCP_INC_STATS_BH(DCCP_MIB_ABORTONTIMEOUT);
31}
32
33/* A write timeout has occurred. Process the after effects. */
34static int dccp_write_timeout(struct sock *sk)
35{
36 const struct inet_connection_sock *icsk = inet_csk(sk);
37 int retry_until;
38
39 if (sk->sk_state == DCCP_REQUESTING || sk->sk_state == DCCP_PARTOPEN) {
40 if (icsk->icsk_retransmits != 0)
41 dst_negative_advice(sk);
42 retry_until = icsk->icsk_syn_retries ?
43 : sysctl_dccp_request_retries;
44 } else {
45 if (icsk->icsk_retransmits >= sysctl_dccp_retries1) {
46 /* NOTE. draft-ietf-tcpimpl-pmtud-01.txt requires pmtu
47 black hole detection. :-(
48
49 It is place to make it. It is not made. I do not want
50 to make it. It is disguisting. It does not work in any
51 case. Let me to cite the same draft, which requires for
52 us to implement this:
53
54 "The one security concern raised by this memo is that ICMP black holes
55 are often caused by over-zealous security administrators who block
56 all ICMP messages. It is vitally important that those who design and
57 deploy security systems understand the impact of strict filtering on
58 upper-layer protocols. The safest web site in the world is worthless
59 if most TCP implementations cannot transfer data from it. It would
60 be far nicer to have all of the black holes fixed rather than fixing
61 all of the TCP implementations."
62
63 Golden words :-).
64 */
65
66 dst_negative_advice(sk);
67 }
68
69 retry_until = sysctl_dccp_retries2;
70 /*
71 * FIXME: see tcp_write_timout and tcp_out_of_resources
72 */
73 }
74
75 if (icsk->icsk_retransmits >= retry_until) {
76 /* Has it gone just too far? */
77 dccp_write_err(sk);
78 return 1;
79 }
80 return 0;
81}
82
83/*
84 * The DCCP retransmit timer.
85 */
86static void dccp_retransmit_timer(struct sock *sk)
87{
88 struct inet_connection_sock *icsk = inet_csk(sk);
89
90 /*
91 * More than than 4MSL (8 minutes) has passed, a RESET(aborted) was
92 * sent, no need to retransmit, this sock is dead.
93 */
94 if (dccp_write_timeout(sk))
95 return;
96
97 /*
98 * We want to know the number of packets retransmitted, not the
99 * total number of retransmissions of clones of original packets.
100 */
101 if (icsk->icsk_retransmits == 0)
102 DCCP_INC_STATS_BH(DCCP_MIB_TIMEOUTS);
103
104 if (dccp_retransmit_skb(sk) != 0) {
105 /*
106 * Retransmission failed because of local congestion,
107 * do not backoff.
108 */
109 if (--icsk->icsk_retransmits == 0)
110 icsk->icsk_retransmits = 1;
111 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
112 min(icsk->icsk_rto,
113 TCP_RESOURCE_PROBE_INTERVAL),
114 DCCP_RTO_MAX);
115 return;
116 }
117
118 icsk->icsk_backoff++;
119
120 icsk->icsk_rto = min(icsk->icsk_rto << 1, DCCP_RTO_MAX);
121 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto,
122 DCCP_RTO_MAX);
123 if (icsk->icsk_retransmits > sysctl_dccp_retries1)
124 __sk_dst_reset(sk);
125}
126
127static void dccp_write_timer(unsigned long data)
128{
129 struct sock *sk = (struct sock *)data;
130 struct inet_connection_sock *icsk = inet_csk(sk);
131 int event = 0;
132
133 bh_lock_sock(sk);
134 if (sock_owned_by_user(sk)) {
135 /* Try again later */
136 sk_reset_timer(sk, &icsk->icsk_retransmit_timer,
137 jiffies + (HZ / 20));
138 goto out;
139 }
140
141 if (sk->sk_state == DCCP_CLOSED || !icsk->icsk_pending)
142 goto out;
143
144 if (time_after(icsk->icsk_timeout, jiffies)) {
145 sk_reset_timer(sk, &icsk->icsk_retransmit_timer,
146 icsk->icsk_timeout);
147 goto out;
148 }
149
150 event = icsk->icsk_pending;
151 icsk->icsk_pending = 0;
152
153 switch (event) {
154 case ICSK_TIME_RETRANS:
155 dccp_retransmit_timer(sk);
156 break;
157 }
158out:
159 bh_unlock_sock(sk);
160 sock_put(sk);
161}
162
163/*
164 * Timer for listening sockets
165 */
166static void dccp_response_timer(struct sock *sk)
167{
168 inet_csk_reqsk_queue_prune(sk, TCP_SYNQ_INTERVAL, DCCP_TIMEOUT_INIT,
169 DCCP_RTO_MAX);
170}
171
172static void dccp_keepalive_timer(unsigned long data)
173{
174 struct sock *sk = (struct sock *)data;
175
176 /* Only process if socket is not in use. */
177 bh_lock_sock(sk);
178 if (sock_owned_by_user(sk)) {
179 /* Try again later. */
180 inet_csk_reset_keepalive_timer(sk, HZ / 20);
181 goto out;
182 }
183
184 if (sk->sk_state == DCCP_LISTEN) {
185 dccp_response_timer(sk);
186 goto out;
187 }
188out:
189 bh_unlock_sock(sk);
190 sock_put(sk);
191}
192
193/* This is the same as tcp_delack_timer, sans prequeue & mem_reclaim stuff */
194static void dccp_delack_timer(unsigned long data)
195{
196 struct sock *sk = (struct sock *)data;
197 struct inet_connection_sock *icsk = inet_csk(sk);
198
199 bh_lock_sock(sk);
200 if (sock_owned_by_user(sk)) {
201 /* Try again later. */
202 icsk->icsk_ack.blocked = 1;
203 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);
204 sk_reset_timer(sk, &icsk->icsk_delack_timer,
205 jiffies + TCP_DELACK_MIN);
206 goto out;
207 }
208
209 if (sk->sk_state == DCCP_CLOSED ||
210 !(icsk->icsk_ack.pending & ICSK_ACK_TIMER))
211 goto out;
212 if (time_after(icsk->icsk_ack.timeout, jiffies)) {
213 sk_reset_timer(sk, &icsk->icsk_delack_timer,
214 icsk->icsk_ack.timeout);
215 goto out;
216 }
217
218 icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER;
219
220 if (inet_csk_ack_scheduled(sk)) {
221 if (!icsk->icsk_ack.pingpong) {
222 /* Delayed ACK missed: inflate ATO. */
223 icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1,
224 icsk->icsk_rto);
225 } else {
226 /* Delayed ACK missed: leave pingpong mode and
227 * deflate ATO.
228 */
229 icsk->icsk_ack.pingpong = 0;
230 icsk->icsk_ack.ato = TCP_ATO_MIN;
231 }
232 dccp_send_ack(sk);
233 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKS);
234 }
235out:
236 bh_unlock_sock(sk);
237 sock_put(sk);
238}
239
240/**
241 * dccp_write_xmitlet - Workhorse for CCID packet dequeueing interface
242 * See the comments above %ccid_dequeueing_decision for supported modes.
243 */
244static void dccp_write_xmitlet(unsigned long data)
245{
246 struct sock *sk = (struct sock *)data;
247
248 bh_lock_sock(sk);
249 if (sock_owned_by_user(sk))
250 sk_reset_timer(sk, &dccp_sk(sk)->dccps_xmit_timer, jiffies + 1);
251 else
252 dccp_write_xmit(sk);
253 bh_unlock_sock(sk);
254}
255
256static void dccp_write_xmit_timer(unsigned long data)
257{
258 dccp_write_xmitlet(data);
259 sock_put((struct sock *)data);
260}
261
262void dccp_init_xmit_timers(struct sock *sk)
263{
264 struct dccp_sock *dp = dccp_sk(sk);
265
266 tasklet_init(&dp->dccps_xmitlet, dccp_write_xmitlet, (unsigned long)sk);
267 setup_timer(&dp->dccps_xmit_timer, dccp_write_xmit_timer,
268 (unsigned long)sk);
269 inet_csk_init_xmit_timers(sk, &dccp_write_timer, &dccp_delack_timer,
270 &dccp_keepalive_timer);
271}
272
273static ktime_t dccp_timestamp_seed;
274/**
275 * dccp_timestamp - 10s of microseconds time source
276 * Returns the number of 10s of microseconds since loading DCCP. This is native
277 * DCCP time difference format (RFC 4340, sec. 13).
278 * Please note: This will wrap around about circa every 11.9 hours.
279 */
280u32 dccp_timestamp(void)
281{
282 s64 delta = ktime_us_delta(ktime_get_real(), dccp_timestamp_seed);
283
284 do_div(delta, 10);
285 return delta;
286}
287EXPORT_SYMBOL_GPL(dccp_timestamp);
288
289void __init dccp_timestamping_init(void)
290{
291 dccp_timestamp_seed = ktime_get_real();
292}
1/*
2 * net/dccp/timer.c
3 *
4 * An implementation of the DCCP protocol
5 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
11 */
12
13#include <linux/dccp.h>
14#include <linux/skbuff.h>
15#include <linux/export.h>
16
17#include "dccp.h"
18
19/* sysctl variables governing numbers of retransmission attempts */
20int sysctl_dccp_request_retries __read_mostly = TCP_SYN_RETRIES;
21int sysctl_dccp_retries1 __read_mostly = TCP_RETR1;
22int sysctl_dccp_retries2 __read_mostly = TCP_RETR2;
23
24static void dccp_write_err(struct sock *sk)
25{
26 sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT;
27 sk->sk_error_report(sk);
28
29 dccp_send_reset(sk, DCCP_RESET_CODE_ABORTED);
30 dccp_done(sk);
31 DCCP_INC_STATS_BH(DCCP_MIB_ABORTONTIMEOUT);
32}
33
34/* A write timeout has occurred. Process the after effects. */
35static int dccp_write_timeout(struct sock *sk)
36{
37 const struct inet_connection_sock *icsk = inet_csk(sk);
38 int retry_until;
39
40 if (sk->sk_state == DCCP_REQUESTING || sk->sk_state == DCCP_PARTOPEN) {
41 if (icsk->icsk_retransmits != 0)
42 dst_negative_advice(sk);
43 retry_until = icsk->icsk_syn_retries ?
44 : sysctl_dccp_request_retries;
45 } else {
46 if (icsk->icsk_retransmits >= sysctl_dccp_retries1) {
47 /* NOTE. draft-ietf-tcpimpl-pmtud-01.txt requires pmtu
48 black hole detection. :-(
49
50 It is place to make it. It is not made. I do not want
51 to make it. It is disguisting. It does not work in any
52 case. Let me to cite the same draft, which requires for
53 us to implement this:
54
55 "The one security concern raised by this memo is that ICMP black holes
56 are often caused by over-zealous security administrators who block
57 all ICMP messages. It is vitally important that those who design and
58 deploy security systems understand the impact of strict filtering on
59 upper-layer protocols. The safest web site in the world is worthless
60 if most TCP implementations cannot transfer data from it. It would
61 be far nicer to have all of the black holes fixed rather than fixing
62 all of the TCP implementations."
63
64 Golden words :-).
65 */
66
67 dst_negative_advice(sk);
68 }
69
70 retry_until = sysctl_dccp_retries2;
71 /*
72 * FIXME: see tcp_write_timout and tcp_out_of_resources
73 */
74 }
75
76 if (icsk->icsk_retransmits >= retry_until) {
77 /* Has it gone just too far? */
78 dccp_write_err(sk);
79 return 1;
80 }
81 return 0;
82}
83
84/*
85 * The DCCP retransmit timer.
86 */
87static void dccp_retransmit_timer(struct sock *sk)
88{
89 struct inet_connection_sock *icsk = inet_csk(sk);
90
91 /*
92 * More than than 4MSL (8 minutes) has passed, a RESET(aborted) was
93 * sent, no need to retransmit, this sock is dead.
94 */
95 if (dccp_write_timeout(sk))
96 return;
97
98 /*
99 * We want to know the number of packets retransmitted, not the
100 * total number of retransmissions of clones of original packets.
101 */
102 if (icsk->icsk_retransmits == 0)
103 DCCP_INC_STATS_BH(DCCP_MIB_TIMEOUTS);
104
105 if (dccp_retransmit_skb(sk) != 0) {
106 /*
107 * Retransmission failed because of local congestion,
108 * do not backoff.
109 */
110 if (--icsk->icsk_retransmits == 0)
111 icsk->icsk_retransmits = 1;
112 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
113 min(icsk->icsk_rto,
114 TCP_RESOURCE_PROBE_INTERVAL),
115 DCCP_RTO_MAX);
116 return;
117 }
118
119 icsk->icsk_backoff++;
120
121 icsk->icsk_rto = min(icsk->icsk_rto << 1, DCCP_RTO_MAX);
122 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto,
123 DCCP_RTO_MAX);
124 if (icsk->icsk_retransmits > sysctl_dccp_retries1)
125 __sk_dst_reset(sk);
126}
127
128static void dccp_write_timer(unsigned long data)
129{
130 struct sock *sk = (struct sock *)data;
131 struct inet_connection_sock *icsk = inet_csk(sk);
132 int event = 0;
133
134 bh_lock_sock(sk);
135 if (sock_owned_by_user(sk)) {
136 /* Try again later */
137 sk_reset_timer(sk, &icsk->icsk_retransmit_timer,
138 jiffies + (HZ / 20));
139 goto out;
140 }
141
142 if (sk->sk_state == DCCP_CLOSED || !icsk->icsk_pending)
143 goto out;
144
145 if (time_after(icsk->icsk_timeout, jiffies)) {
146 sk_reset_timer(sk, &icsk->icsk_retransmit_timer,
147 icsk->icsk_timeout);
148 goto out;
149 }
150
151 event = icsk->icsk_pending;
152 icsk->icsk_pending = 0;
153
154 switch (event) {
155 case ICSK_TIME_RETRANS:
156 dccp_retransmit_timer(sk);
157 break;
158 }
159out:
160 bh_unlock_sock(sk);
161 sock_put(sk);
162}
163
164static void dccp_keepalive_timer(unsigned long data)
165{
166 struct sock *sk = (struct sock *)data;
167
168 pr_err("dccp should not use a keepalive timer !\n");
169 sock_put(sk);
170}
171
172/* This is the same as tcp_delack_timer, sans prequeue & mem_reclaim stuff */
173static void dccp_delack_timer(unsigned long data)
174{
175 struct sock *sk = (struct sock *)data;
176 struct inet_connection_sock *icsk = inet_csk(sk);
177
178 bh_lock_sock(sk);
179 if (sock_owned_by_user(sk)) {
180 /* Try again later. */
181 icsk->icsk_ack.blocked = 1;
182 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);
183 sk_reset_timer(sk, &icsk->icsk_delack_timer,
184 jiffies + TCP_DELACK_MIN);
185 goto out;
186 }
187
188 if (sk->sk_state == DCCP_CLOSED ||
189 !(icsk->icsk_ack.pending & ICSK_ACK_TIMER))
190 goto out;
191 if (time_after(icsk->icsk_ack.timeout, jiffies)) {
192 sk_reset_timer(sk, &icsk->icsk_delack_timer,
193 icsk->icsk_ack.timeout);
194 goto out;
195 }
196
197 icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER;
198
199 if (inet_csk_ack_scheduled(sk)) {
200 if (!icsk->icsk_ack.pingpong) {
201 /* Delayed ACK missed: inflate ATO. */
202 icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1,
203 icsk->icsk_rto);
204 } else {
205 /* Delayed ACK missed: leave pingpong mode and
206 * deflate ATO.
207 */
208 icsk->icsk_ack.pingpong = 0;
209 icsk->icsk_ack.ato = TCP_ATO_MIN;
210 }
211 dccp_send_ack(sk);
212 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKS);
213 }
214out:
215 bh_unlock_sock(sk);
216 sock_put(sk);
217}
218
219/**
220 * dccp_write_xmitlet - Workhorse for CCID packet dequeueing interface
221 * See the comments above %ccid_dequeueing_decision for supported modes.
222 */
223static void dccp_write_xmitlet(unsigned long data)
224{
225 struct sock *sk = (struct sock *)data;
226
227 bh_lock_sock(sk);
228 if (sock_owned_by_user(sk))
229 sk_reset_timer(sk, &dccp_sk(sk)->dccps_xmit_timer, jiffies + 1);
230 else
231 dccp_write_xmit(sk);
232 bh_unlock_sock(sk);
233}
234
235static void dccp_write_xmit_timer(unsigned long data)
236{
237 dccp_write_xmitlet(data);
238 sock_put((struct sock *)data);
239}
240
241void dccp_init_xmit_timers(struct sock *sk)
242{
243 struct dccp_sock *dp = dccp_sk(sk);
244
245 tasklet_init(&dp->dccps_xmitlet, dccp_write_xmitlet, (unsigned long)sk);
246 setup_timer(&dp->dccps_xmit_timer, dccp_write_xmit_timer,
247 (unsigned long)sk);
248 inet_csk_init_xmit_timers(sk, &dccp_write_timer, &dccp_delack_timer,
249 &dccp_keepalive_timer);
250}
251
252static ktime_t dccp_timestamp_seed;
253/**
254 * dccp_timestamp - 10s of microseconds time source
255 * Returns the number of 10s of microseconds since loading DCCP. This is native
256 * DCCP time difference format (RFC 4340, sec. 13).
257 * Please note: This will wrap around about circa every 11.9 hours.
258 */
259u32 dccp_timestamp(void)
260{
261 u64 delta = (u64)ktime_us_delta(ktime_get_real(), dccp_timestamp_seed);
262
263 do_div(delta, 10);
264 return delta;
265}
266EXPORT_SYMBOL_GPL(dccp_timestamp);
267
268void __init dccp_timestamping_init(void)
269{
270 dccp_timestamp_seed = ktime_get_real();
271}