]>
Commit | Line | Data |
---|---|---|
2a91aa39 | 1 | /* |
2a91aa39 AB |
2 | * Copyright (c) 2005, 2006 Andrea Bittau <a.bittau@cs.ucl.ac.uk> |
3 | * | |
4 | * Changes to meet Linux coding standards, and DCCP infrastructure fixes. | |
5 | * | |
6 | * Copyright (c) 2006 Arnaldo Carvalho de Melo <acme@conectiva.com.br> | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License as published by | |
10 | * the Free Software Foundation; either version 2 of the License, or | |
11 | * (at your option) any later version. | |
12 | * | |
13 | * This program is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | * GNU General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU General Public License | |
19 | * along with this program; if not, write to the Free Software | |
20 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
21 | */ | |
22 | ||
23 | /* | |
0e64e94e | 24 | * This implementation should follow RFC 4341 |
2a91aa39 | 25 | */ |
5a0e3ad6 | 26 | #include <linux/slab.h> |
e8ef967a | 27 | #include "../feat.h" |
2a91aa39 AB |
28 | #include "ccid2.h" |
29 | ||
2a91aa39 | 30 | |
8d424f6c | 31 | #ifdef CONFIG_IP_DCCP_CCID2_DEBUG |
eb939922 | 32 | static bool ccid2_debug; |
84116716 | 33 | #define ccid2_pr_debug(format, a...) DCCP_PR_DEBUG(ccid2_debug, format, ##a) |
2a91aa39 | 34 | #else |
84116716 | 35 | #define ccid2_pr_debug(format, a...) |
2a91aa39 AB |
36 | #endif |
37 | ||
77d2dd93 | 38 | static int ccid2_hc_tx_alloc_seq(struct ccid2_hc_tx_sock *hc) |
07978aab AB |
39 | { |
40 | struct ccid2_seq *seqp; | |
41 | int i; | |
42 | ||
43 | /* check if we have space to preserve the pointer to the buffer */ | |
77d2dd93 GR |
44 | if (hc->tx_seqbufc >= (sizeof(hc->tx_seqbuf) / |
45 | sizeof(struct ccid2_seq *))) | |
07978aab AB |
46 | return -ENOMEM; |
47 | ||
48 | /* allocate buffer and initialize linked list */ | |
cd1f7d34 | 49 | seqp = kmalloc(CCID2_SEQBUF_LEN * sizeof(struct ccid2_seq), gfp_any()); |
07978aab AB |
50 | if (seqp == NULL) |
51 | return -ENOMEM; | |
52 | ||
cd1f7d34 | 53 | for (i = 0; i < (CCID2_SEQBUF_LEN - 1); i++) { |
07978aab AB |
54 | seqp[i].ccid2s_next = &seqp[i + 1]; |
55 | seqp[i + 1].ccid2s_prev = &seqp[i]; | |
56 | } | |
cd1f7d34 GR |
57 | seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = seqp; |
58 | seqp->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1]; | |
07978aab AB |
59 | |
60 | /* This is the first allocation. Initiate the head and tail. */ | |
77d2dd93 GR |
61 | if (hc->tx_seqbufc == 0) |
62 | hc->tx_seqh = hc->tx_seqt = seqp; | |
07978aab AB |
63 | else { |
64 | /* link the existing list with the one we just created */ | |
77d2dd93 GR |
65 | hc->tx_seqh->ccid2s_next = seqp; |
66 | seqp->ccid2s_prev = hc->tx_seqh; | |
07978aab | 67 | |
77d2dd93 GR |
68 | hc->tx_seqt->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1]; |
69 | seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = hc->tx_seqt; | |
07978aab AB |
70 | } |
71 | ||
72 | /* store the original pointer to the buffer so we can free it */ | |
77d2dd93 GR |
73 | hc->tx_seqbuf[hc->tx_seqbufc] = seqp; |
74 | hc->tx_seqbufc++; | |
07978aab AB |
75 | |
76 | return 0; | |
77 | } | |
78 | ||
6b57c93d | 79 | static int ccid2_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) |
2a91aa39 | 80 | { |
1c0e0a05 GR |
81 | if (ccid2_cwnd_network_limited(ccid2_hc_tx_sk(sk))) |
82 | return CCID_PACKET_WILL_DEQUEUE_LATER; | |
83 | return CCID_PACKET_SEND_AT_ONCE; | |
2a91aa39 AB |
84 | } |
85 | ||
df054e1d | 86 | static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val) |
2a91aa39 | 87 | { |
b1c00fe3 | 88 | u32 max_ratio = DIV_ROUND_UP(ccid2_hc_tx_sk(sk)->tx_cwnd, 2); |
d50ad163 | 89 | |
2a91aa39 | 90 | /* |
d50ad163 GR |
91 | * Ensure that Ack Ratio does not exceed ceil(cwnd/2), which is (2) from |
92 | * RFC 4341, 6.1.2. We ignore the statement that Ack Ratio 2 is always | |
93 | * acceptable since this causes starvation/deadlock whenever cwnd < 2. | |
94 | * The same problem arises when Ack Ratio is 0 (ie. Ack Ratio disabled). | |
2a91aa39 | 95 | */ |
d50ad163 GR |
96 | if (val == 0 || val > max_ratio) { |
97 | DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio); | |
98 | val = max_ratio; | |
2a91aa39 | 99 | } |
d346d886 SJ |
100 | dccp_feat_signal_nn_change(sk, DCCPF_ACK_RATIO, |
101 | min_t(u32, val, DCCPF_ACK_RATIO_MAX)); | |
102 | } | |
d50ad163 | 103 | |
d96a9e8d SJ |
104 | static void ccid2_check_l_ack_ratio(struct sock *sk) |
105 | { | |
106 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); | |
107 | ||
108 | /* | |
109 | * After a loss, idle period, application limited period, or RTO we | |
110 | * need to check that the ack ratio is still less than the congestion | |
111 | * window. Otherwise, we will send an entire congestion window of | |
112 | * packets and got no response because we haven't sent ack ratio | |
113 | * packets yet. | |
114 | * If the ack ratio does need to be reduced, we reduce it to half of | |
115 | * the congestion window (or 1 if that's zero) instead of to the | |
116 | * congestion window. This prevents problems if one ack is lost. | |
117 | */ | |
118 | if (dccp_feat_nn_get(sk, DCCPF_ACK_RATIO) > hc->tx_cwnd) | |
119 | ccid2_change_l_ack_ratio(sk, hc->tx_cwnd/2 ? : 1U); | |
120 | } | |
121 | ||
d346d886 SJ |
122 | static void ccid2_change_l_seq_window(struct sock *sk, u64 val) |
123 | { | |
124 | dccp_feat_signal_nn_change(sk, DCCPF_SEQUENCE_WINDOW, | |
125 | clamp_val(val, DCCPF_SEQ_WMIN, | |
126 | DCCPF_SEQ_WMAX)); | |
2a91aa39 AB |
127 | } |
128 | ||
2a91aa39 AB |
129 | static void ccid2_hc_tx_rto_expire(unsigned long data) |
130 | { | |
131 | struct sock *sk = (struct sock *)data; | |
77d2dd93 | 132 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
1c0e0a05 | 133 | const bool sender_was_blocked = ccid2_cwnd_network_limited(hc); |
2a91aa39 | 134 | |
2a91aa39 AB |
135 | bh_lock_sock(sk); |
136 | if (sock_owned_by_user(sk)) { | |
77d2dd93 | 137 | sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + HZ / 5); |
2a91aa39 AB |
138 | goto out; |
139 | } | |
140 | ||
141 | ccid2_pr_debug("RTO_EXPIRE\n"); | |
142 | ||
2a91aa39 | 143 | /* back-off timer */ |
77d2dd93 | 144 | hc->tx_rto <<= 1; |
231cc2aa GR |
145 | if (hc->tx_rto > DCCP_RTO_MAX) |
146 | hc->tx_rto = DCCP_RTO_MAX; | |
410e27a4 | 147 | |
2a91aa39 | 148 | /* adjust pipe, cwnd etc */ |
77d2dd93 GR |
149 | hc->tx_ssthresh = hc->tx_cwnd / 2; |
150 | if (hc->tx_ssthresh < 2) | |
151 | hc->tx_ssthresh = 2; | |
67b67e36 GR |
152 | hc->tx_cwnd = 1; |
153 | hc->tx_pipe = 0; | |
2a91aa39 AB |
154 | |
155 | /* clear state about stuff we sent */ | |
77d2dd93 GR |
156 | hc->tx_seqt = hc->tx_seqh; |
157 | hc->tx_packets_acked = 0; | |
2a91aa39 AB |
158 | |
159 | /* clear ack ratio state. */ | |
77d2dd93 GR |
160 | hc->tx_rpseq = 0; |
161 | hc->tx_rpdupack = -1; | |
2a91aa39 | 162 | ccid2_change_l_ack_ratio(sk, 1); |
1c0e0a05 GR |
163 | |
164 | /* if we were blocked before, we may now send cwnd=1 packet */ | |
165 | if (sender_was_blocked) | |
166 | tasklet_schedule(&dccp_sk(sk)->dccps_xmitlet); | |
167 | /* restart backed-off timer */ | |
168 | sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto); | |
2a91aa39 AB |
169 | out: |
170 | bh_unlock_sock(sk); | |
77ff72d5 | 171 | sock_put(sk); |
2a91aa39 AB |
172 | } |
173 | ||
113ced1f GR |
174 | /* |
175 | * Congestion window validation (RFC 2861). | |
176 | */ | |
eb939922 | 177 | static bool ccid2_do_cwv = true; |
113ced1f GR |
178 | module_param(ccid2_do_cwv, bool, 0644); |
179 | MODULE_PARM_DESC(ccid2_do_cwv, "Perform RFC2861 Congestion Window Validation"); | |
180 | ||
181 | /** | |
182 | * ccid2_update_used_window - Track how much of cwnd is actually used | |
183 | * This is done in addition to CWV. The sender needs to have an idea of how many | |
184 | * packets may be in flight, to set the local Sequence Window value accordingly | |
185 | * (RFC 4340, 7.5.2). The CWV mechanism is exploited to keep track of the | |
186 | * maximum-used window. We use an EWMA low-pass filter to filter out noise. | |
187 | */ | |
188 | static void ccid2_update_used_window(struct ccid2_hc_tx_sock *hc, u32 new_wnd) | |
189 | { | |
190 | hc->tx_expected_wnd = (3 * hc->tx_expected_wnd + new_wnd) / 4; | |
191 | } | |
192 | ||
193 | /* This borrows the code of tcp_cwnd_application_limited() */ | |
194 | static void ccid2_cwnd_application_limited(struct sock *sk, const u32 now) | |
195 | { | |
196 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); | |
197 | /* don't reduce cwnd below the initial window (IW) */ | |
198 | u32 init_win = rfc3390_bytes_to_packets(dccp_sk(sk)->dccps_mss_cache), | |
199 | win_used = max(hc->tx_cwnd_used, init_win); | |
200 | ||
201 | if (win_used < hc->tx_cwnd) { | |
202 | hc->tx_ssthresh = max(hc->tx_ssthresh, | |
203 | (hc->tx_cwnd >> 1) + (hc->tx_cwnd >> 2)); | |
204 | hc->tx_cwnd = (hc->tx_cwnd + win_used) >> 1; | |
205 | } | |
206 | hc->tx_cwnd_used = 0; | |
207 | hc->tx_cwnd_stamp = now; | |
d96a9e8d SJ |
208 | |
209 | ccid2_check_l_ack_ratio(sk); | |
113ced1f GR |
210 | } |
211 | ||
212 | /* This borrows the code of tcp_cwnd_restart() */ | |
213 | static void ccid2_cwnd_restart(struct sock *sk, const u32 now) | |
214 | { | |
215 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); | |
216 | u32 cwnd = hc->tx_cwnd, restart_cwnd, | |
217 | iwnd = rfc3390_bytes_to_packets(dccp_sk(sk)->dccps_mss_cache); | |
218 | ||
219 | hc->tx_ssthresh = max(hc->tx_ssthresh, (cwnd >> 1) + (cwnd >> 2)); | |
220 | ||
221 | /* don't reduce cwnd below the initial window (IW) */ | |
222 | restart_cwnd = min(cwnd, iwnd); | |
223 | cwnd >>= (now - hc->tx_lsndtime) / hc->tx_rto; | |
224 | hc->tx_cwnd = max(cwnd, restart_cwnd); | |
225 | ||
226 | hc->tx_cwnd_stamp = now; | |
227 | hc->tx_cwnd_used = 0; | |
d96a9e8d SJ |
228 | |
229 | ccid2_check_l_ack_ratio(sk); | |
113ced1f GR |
230 | } |
231 | ||
baf9e782 | 232 | static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len) |
2a91aa39 AB |
233 | { |
234 | struct dccp_sock *dp = dccp_sk(sk); | |
77d2dd93 | 235 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
113ced1f | 236 | const u32 now = ccid2_time_stamp; |
07978aab | 237 | struct ccid2_seq *next; |
2a91aa39 | 238 | |
113ced1f GR |
239 | /* slow-start after idle periods (RFC 2581, RFC 2861) */ |
240 | if (ccid2_do_cwv && !hc->tx_pipe && | |
241 | (s32)(now - hc->tx_lsndtime) >= hc->tx_rto) | |
242 | ccid2_cwnd_restart(sk, now); | |
243 | ||
244 | hc->tx_lsndtime = now; | |
245 | hc->tx_pipe += 1; | |
246 | ||
247 | /* see whether cwnd was fully used (RFC 2861), update expected window */ | |
248 | if (ccid2_cwnd_network_limited(hc)) { | |
249 | ccid2_update_used_window(hc, hc->tx_cwnd); | |
250 | hc->tx_cwnd_used = 0; | |
251 | hc->tx_cwnd_stamp = now; | |
252 | } else { | |
253 | if (hc->tx_pipe > hc->tx_cwnd_used) | |
254 | hc->tx_cwnd_used = hc->tx_pipe; | |
255 | ||
256 | ccid2_update_used_window(hc, hc->tx_cwnd_used); | |
257 | ||
258 | if (ccid2_do_cwv && (s32)(now - hc->tx_cwnd_stamp) >= hc->tx_rto) | |
259 | ccid2_cwnd_application_limited(sk, now); | |
260 | } | |
2a91aa39 | 261 | |
77d2dd93 GR |
262 | hc->tx_seqh->ccid2s_seq = dp->dccps_gss; |
263 | hc->tx_seqh->ccid2s_acked = 0; | |
113ced1f | 264 | hc->tx_seqh->ccid2s_sent = now; |
2a91aa39 | 265 | |
77d2dd93 | 266 | next = hc->tx_seqh->ccid2s_next; |
07978aab | 267 | /* check if we need to alloc more space */ |
77d2dd93 GR |
268 | if (next == hc->tx_seqt) { |
269 | if (ccid2_hc_tx_alloc_seq(hc)) { | |
7d9e8931 GR |
270 | DCCP_CRIT("packet history - out of memory!"); |
271 | /* FIXME: find a more graceful way to bail out */ | |
272 | return; | |
273 | } | |
77d2dd93 GR |
274 | next = hc->tx_seqh->ccid2s_next; |
275 | BUG_ON(next == hc->tx_seqt); | |
2a91aa39 | 276 | } |
77d2dd93 | 277 | hc->tx_seqh = next; |
07978aab | 278 | |
77d2dd93 | 279 | ccid2_pr_debug("cwnd=%d pipe=%d\n", hc->tx_cwnd, hc->tx_pipe); |
2a91aa39 | 280 | |
900bfed4 GR |
281 | /* |
282 | * FIXME: The code below is broken and the variables have been removed | |
283 | * from the socket struct. The `ackloss' variable was always set to 0, | |
284 | * and with arsent there are several problems: | |
285 | * (i) it doesn't just count the number of Acks, but all sent packets; | |
286 | * (ii) it is expressed in # of packets, not # of windows, so the | |
287 | * comparison below uses the wrong formula: Appendix A of RFC 4341 | |
288 | * comes up with the number K = cwnd / (R^2 - R) of consecutive windows | |
289 | * of data with no lost or marked Ack packets. If arsent were the # of | |
290 | * consecutive Acks received without loss, then Ack Ratio needs to be | |
291 | * decreased by 1 when | |
292 | * arsent >= K * cwnd / R = cwnd^2 / (R^3 - R^2) | |
293 | * where cwnd / R is the number of Acks received per window of data | |
294 | * (cf. RFC 4341, App. A). The problems are that | |
295 | * - arsent counts other packets as well; | |
296 | * - the comparison uses a formula different from RFC 4341; | |
297 | * - computing a cubic/quadratic equation each time is too complicated. | |
298 | * Hence a different algorithm is needed. | |
299 | */ | |
300 | #if 0 | |
2a91aa39 | 301 | /* Ack Ratio. Need to maintain a concept of how many windows we sent */ |
77d2dd93 | 302 | hc->tx_arsent++; |
2a91aa39 | 303 | /* We had an ack loss in this window... */ |
77d2dd93 GR |
304 | if (hc->tx_ackloss) { |
305 | if (hc->tx_arsent >= hc->tx_cwnd) { | |
306 | hc->tx_arsent = 0; | |
307 | hc->tx_ackloss = 0; | |
2a91aa39 | 308 | } |
c0c736db ACM |
309 | } else { |
310 | /* No acks lost up to now... */ | |
2a91aa39 AB |
311 | /* decrease ack ratio if enough packets were sent */ |
312 | if (dp->dccps_l_ack_ratio > 1) { | |
313 | /* XXX don't calculate denominator each time */ | |
c0c736db ACM |
314 | int denom = dp->dccps_l_ack_ratio * dp->dccps_l_ack_ratio - |
315 | dp->dccps_l_ack_ratio; | |
2a91aa39 | 316 | |
77d2dd93 | 317 | denom = hc->tx_cwnd * hc->tx_cwnd / denom; |
2a91aa39 | 318 | |
77d2dd93 | 319 | if (hc->tx_arsent >= denom) { |
2a91aa39 | 320 | ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio - 1); |
77d2dd93 | 321 | hc->tx_arsent = 0; |
2a91aa39 | 322 | } |
c0c736db ACM |
323 | } else { |
324 | /* we can't increase ack ratio further [1] */ | |
77d2dd93 | 325 | hc->tx_arsent = 0; /* or maybe set it to cwnd*/ |
2a91aa39 AB |
326 | } |
327 | } | |
900bfed4 | 328 | #endif |
2a91aa39 | 329 | |
d26eeb07 | 330 | sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto); |
c0c736db | 331 | |
8d424f6c | 332 | #ifdef CONFIG_IP_DCCP_CCID2_DEBUG |
2a91aa39 | 333 | do { |
77d2dd93 | 334 | struct ccid2_seq *seqp = hc->tx_seqt; |
2a91aa39 | 335 | |
77d2dd93 | 336 | while (seqp != hc->tx_seqh) { |
d82b6f85 | 337 | ccid2_pr_debug("out seq=%llu acked=%d time=%u\n", |
8109b02b | 338 | (unsigned long long)seqp->ccid2s_seq, |
234af484 | 339 | seqp->ccid2s_acked, seqp->ccid2s_sent); |
2a91aa39 AB |
340 | seqp = seqp->ccid2s_next; |
341 | } | |
c0c736db | 342 | } while (0); |
2a91aa39 | 343 | ccid2_pr_debug("=========\n"); |
2a91aa39 AB |
344 | #endif |
345 | } | |
346 | ||
231cc2aa GR |
347 | /** |
348 | * ccid2_rtt_estimator - Sample RTT and compute RTO using RFC2988 algorithm | |
349 | * This code is almost identical with TCP's tcp_rtt_estimator(), since | |
350 | * - it has a higher sampling frequency (recommended by RFC 1323), | |
351 | * - the RTO does not collapse into RTT due to RTTVAR going towards zero, | |
352 | * - it is simple (cf. more complex proposals such as Eifel timer or research | |
353 | * which suggests that the gain should be set according to window size), | |
354 | * - in tests it was found to work well with CCID2 [gerrit]. | |
355 | */ | |
356 | static void ccid2_rtt_estimator(struct sock *sk, const long mrtt) | |
357 | { | |
358 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); | |
359 | long m = mrtt ? : 1; | |
360 | ||
361 | if (hc->tx_srtt == 0) { | |
362 | /* First measurement m */ | |
363 | hc->tx_srtt = m << 3; | |
364 | hc->tx_mdev = m << 1; | |
365 | ||
4886fcad | 366 | hc->tx_mdev_max = max(hc->tx_mdev, tcp_rto_min(sk)); |
231cc2aa | 367 | hc->tx_rttvar = hc->tx_mdev_max; |
4886fcad | 368 | |
231cc2aa GR |
369 | hc->tx_rtt_seq = dccp_sk(sk)->dccps_gss; |
370 | } else { | |
371 | /* Update scaled SRTT as SRTT += 1/8 * (m - SRTT) */ | |
372 | m -= (hc->tx_srtt >> 3); | |
373 | hc->tx_srtt += m; | |
374 | ||
375 | /* Similarly, update scaled mdev with regard to |m| */ | |
376 | if (m < 0) { | |
377 | m = -m; | |
378 | m -= (hc->tx_mdev >> 2); | |
379 | /* | |
380 | * This neutralises RTO increase when RTT < SRTT - mdev | |
381 | * (see P. Sarolahti, A. Kuznetsov,"Congestion Control | |
382 | * in Linux TCP", USENIX 2002, pp. 49-62). | |
383 | */ | |
384 | if (m > 0) | |
385 | m >>= 3; | |
386 | } else { | |
387 | m -= (hc->tx_mdev >> 2); | |
388 | } | |
389 | hc->tx_mdev += m; | |
390 | ||
391 | if (hc->tx_mdev > hc->tx_mdev_max) { | |
392 | hc->tx_mdev_max = hc->tx_mdev; | |
393 | if (hc->tx_mdev_max > hc->tx_rttvar) | |
394 | hc->tx_rttvar = hc->tx_mdev_max; | |
395 | } | |
396 | ||
397 | /* | |
398 | * Decay RTTVAR at most once per flight, exploiting that | |
399 | * 1) pipe <= cwnd <= Sequence_Window = W (RFC 4340, 7.5.2) | |
400 | * 2) AWL = GSS-W+1 <= GAR <= GSS (RFC 4340, 7.5.1) | |
401 | * GAR is a useful bound for FlightSize = pipe. | |
402 | * AWL is probably too low here, as it over-estimates pipe. | |
403 | */ | |
404 | if (after48(dccp_sk(sk)->dccps_gar, hc->tx_rtt_seq)) { | |
405 | if (hc->tx_mdev_max < hc->tx_rttvar) | |
406 | hc->tx_rttvar -= (hc->tx_rttvar - | |
407 | hc->tx_mdev_max) >> 2; | |
408 | hc->tx_rtt_seq = dccp_sk(sk)->dccps_gss; | |
4886fcad | 409 | hc->tx_mdev_max = tcp_rto_min(sk); |
231cc2aa GR |
410 | } |
411 | } | |
412 | ||
413 | /* | |
414 | * Set RTO from SRTT and RTTVAR | |
415 | * As in TCP, 4 * RTTVAR >= TCP_RTO_MIN, giving a minimum RTO of 200 ms. | |
416 | * This agrees with RFC 4341, 5: | |
417 | * "Because DCCP does not retransmit data, DCCP does not require | |
418 | * TCP's recommended minimum timeout of one second". | |
419 | */ | |
420 | hc->tx_rto = (hc->tx_srtt >> 3) + hc->tx_rttvar; | |
421 | ||
422 | if (hc->tx_rto > DCCP_RTO_MAX) | |
423 | hc->tx_rto = DCCP_RTO_MAX; | |
424 | } | |
425 | ||
426 | static void ccid2_new_ack(struct sock *sk, struct ccid2_seq *seqp, | |
427 | unsigned int *maxincr) | |
374bcf32 | 428 | { |
77d2dd93 | 429 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
d346d886 SJ |
430 | struct dccp_sock *dp = dccp_sk(sk); |
431 | int r_seq_used = hc->tx_cwnd / dp->dccps_l_ack_ratio; | |
432 | ||
433 | if (hc->tx_cwnd < dp->dccps_l_seq_win && | |
434 | r_seq_used < dp->dccps_r_seq_win) { | |
435 | if (hc->tx_cwnd < hc->tx_ssthresh) { | |
0ce95dc7 | 436 | if (*maxincr > 0 && ++hc->tx_packets_acked >= 2) { |
d346d886 SJ |
437 | hc->tx_cwnd += 1; |
438 | *maxincr -= 1; | |
439 | hc->tx_packets_acked = 0; | |
440 | } | |
441 | } else if (++hc->tx_packets_acked >= hc->tx_cwnd) { | |
77d2dd93 | 442 | hc->tx_cwnd += 1; |
77d2dd93 | 443 | hc->tx_packets_acked = 0; |
410e27a4 | 444 | } |
374bcf32 | 445 | } |
d346d886 SJ |
446 | |
447 | /* | |
448 | * Adjust the local sequence window and the ack ratio to allow about | |
449 | * 5 times the number of packets in the network (RFC 4340 7.5.2) | |
450 | */ | |
451 | if (r_seq_used * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_r_seq_win) | |
452 | ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio * 2); | |
453 | else if (r_seq_used * CCID2_WIN_CHANGE_FACTOR < dp->dccps_r_seq_win/2) | |
454 | ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio / 2 ? : 1U); | |
455 | ||
456 | if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_l_seq_win) | |
457 | ccid2_change_l_seq_window(sk, dp->dccps_l_seq_win * 2); | |
458 | else if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR < dp->dccps_l_seq_win/2) | |
459 | ccid2_change_l_seq_window(sk, dp->dccps_l_seq_win / 2); | |
460 | ||
231cc2aa GR |
461 | /* |
462 | * FIXME: RTT is sampled several times per acknowledgment (for each | |
463 | * entry in the Ack Vector), instead of once per Ack (as in TCP SACK). | |
464 | * This causes the RTT to be over-estimated, since the older entries | |
465 | * in the Ack Vector have earlier sending times. | |
466 | * The cleanest solution is to not use the ccid2s_sent field at all | |
467 | * and instead use DCCP timestamps: requires changes in other places. | |
468 | */ | |
d82b6f85 | 469 | ccid2_rtt_estimator(sk, ccid2_time_stamp - seqp->ccid2s_sent); |
410e27a4 GR |
470 | } |
471 | ||
472 | static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp) | |
473 | { | |
77d2dd93 | 474 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
410e27a4 | 475 | |
d82b6f85 | 476 | if ((s32)(seqp->ccid2s_sent - hc->tx_last_cong) < 0) { |
410e27a4 GR |
477 | ccid2_pr_debug("Multiple losses in an RTT---treating as one\n"); |
478 | return; | |
c8bf462b | 479 | } |
410e27a4 | 480 | |
d82b6f85 | 481 | hc->tx_last_cong = ccid2_time_stamp; |
410e27a4 | 482 | |
77d2dd93 GR |
483 | hc->tx_cwnd = hc->tx_cwnd / 2 ? : 1U; |
484 | hc->tx_ssthresh = max(hc->tx_cwnd, 2U); | |
410e27a4 | 485 | |
d96a9e8d | 486 | ccid2_check_l_ack_ratio(sk); |
c8bf462b GR |
487 | } |
488 | ||
7e87fe84 GR |
489 | static int ccid2_hc_tx_parse_options(struct sock *sk, u8 packet_type, |
490 | u8 option, u8 *optval, u8 optlen) | |
491 | { | |
492 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); | |
493 | ||
494 | switch (option) { | |
495 | case DCCPO_ACK_VECTOR_0: | |
496 | case DCCPO_ACK_VECTOR_1: | |
497 | return dccp_ackvec_parsed_add(&hc->tx_av_chunks, optval, optlen, | |
498 | option - DCCPO_ACK_VECTOR_0); | |
499 | } | |
500 | return 0; | |
501 | } | |
502 | ||
2a91aa39 AB |
503 | static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) |
504 | { | |
505 | struct dccp_sock *dp = dccp_sk(sk); | |
77d2dd93 | 506 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
1c0e0a05 | 507 | const bool sender_was_blocked = ccid2_cwnd_network_limited(hc); |
7e87fe84 | 508 | struct dccp_ackvec_parsed *avp; |
2a91aa39 AB |
509 | u64 ackno, seqno; |
510 | struct ccid2_seq *seqp; | |
2a91aa39 | 511 | int done = 0; |
2a91aa39 AB |
512 | unsigned int maxincr = 0; |
513 | ||
2a91aa39 AB |
514 | /* check reverse path congestion */ |
515 | seqno = DCCP_SKB_CB(skb)->dccpd_seq; | |
516 | ||
517 | /* XXX this whole "algorithm" is broken. Need to fix it to keep track | |
518 | * of the seqnos of the dupacks so that rpseq and rpdupack are correct | |
519 | * -sorbo. | |
520 | */ | |
521 | /* need to bootstrap */ | |
77d2dd93 GR |
522 | if (hc->tx_rpdupack == -1) { |
523 | hc->tx_rpdupack = 0; | |
524 | hc->tx_rpseq = seqno; | |
c0c736db | 525 | } else { |
2a91aa39 | 526 | /* check if packet is consecutive */ |
77d2dd93 GR |
527 | if (dccp_delta_seqno(hc->tx_rpseq, seqno) == 1) |
528 | hc->tx_rpseq = seqno; | |
2a91aa39 | 529 | /* it's a later packet */ |
77d2dd93 GR |
530 | else if (after48(seqno, hc->tx_rpseq)) { |
531 | hc->tx_rpdupack++; | |
2a91aa39 AB |
532 | |
533 | /* check if we got enough dupacks */ | |
77d2dd93 GR |
534 | if (hc->tx_rpdupack >= NUMDUPACK) { |
535 | hc->tx_rpdupack = -1; /* XXX lame */ | |
536 | hc->tx_rpseq = 0; | |
31daf039 GR |
537 | #ifdef __CCID2_COPES_GRACEFULLY_WITH_ACK_CONGESTION_CONTROL__ |
538 | /* | |
539 | * FIXME: Ack Congestion Control is broken; in | |
540 | * the current state instabilities occurred with | |
541 | * Ack Ratios greater than 1; causing hang-ups | |
542 | * and long RTO timeouts. This needs to be fixed | |
543 | * before opening up dynamic changes. -- gerrit | |
544 | */ | |
df054e1d | 545 | ccid2_change_l_ack_ratio(sk, 2 * dp->dccps_l_ack_ratio); |
31daf039 | 546 | #endif |
2a91aa39 AB |
547 | } |
548 | } | |
549 | } | |
550 | ||
551 | /* check forward path congestion */ | |
7e87fe84 | 552 | if (dccp_packet_without_ack(skb)) |
2a91aa39 AB |
553 | return; |
554 | ||
7e87fe84 GR |
555 | /* still didn't send out new data packets */ |
556 | if (hc->tx_seqh == hc->tx_seqt) | |
557 | goto done; | |
2a91aa39 AB |
558 | |
559 | ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq; | |
77d2dd93 GR |
560 | if (after48(ackno, hc->tx_high_ack)) |
561 | hc->tx_high_ack = ackno; | |
32aac18d | 562 | |
77d2dd93 | 563 | seqp = hc->tx_seqt; |
32aac18d AB |
564 | while (before48(seqp->ccid2s_seq, ackno)) { |
565 | seqp = seqp->ccid2s_next; | |
77d2dd93 GR |
566 | if (seqp == hc->tx_seqh) { |
567 | seqp = hc->tx_seqh->ccid2s_prev; | |
32aac18d AB |
568 | break; |
569 | } | |
570 | } | |
2a91aa39 | 571 | |
a3020025 GR |
572 | /* |
573 | * In slow-start, cwnd can increase up to a maximum of Ack Ratio/2 | |
574 | * packets per acknowledgement. Rounding up avoids that cwnd is not | |
575 | * advanced when Ack Ratio is 1 and gives a slight edge otherwise. | |
2a91aa39 | 576 | */ |
77d2dd93 | 577 | if (hc->tx_cwnd < hc->tx_ssthresh) |
a3020025 | 578 | maxincr = DIV_ROUND_UP(dp->dccps_l_ack_ratio, 2); |
2a91aa39 AB |
579 | |
580 | /* go through all ack vectors */ | |
7e87fe84 | 581 | list_for_each_entry(avp, &hc->tx_av_chunks, node) { |
2a91aa39 | 582 | /* go through this ack vector */ |
7e87fe84 GR |
583 | for (; avp->len--; avp->vec++) { |
584 | u64 ackno_end_rl = SUB48(ackno, | |
585 | dccp_ackvec_runlen(avp->vec)); | |
2a91aa39 | 586 | |
7e87fe84 | 587 | ccid2_pr_debug("ackvec %llu |%u,%u|\n", |
234af484 | 588 | (unsigned long long)ackno, |
7e87fe84 GR |
589 | dccp_ackvec_state(avp->vec) >> 6, |
590 | dccp_ackvec_runlen(avp->vec)); | |
2a91aa39 AB |
591 | /* if the seqno we are analyzing is larger than the |
592 | * current ackno, then move towards the tail of our | |
593 | * seqnos. | |
594 | */ | |
595 | while (after48(seqp->ccid2s_seq, ackno)) { | |
77d2dd93 | 596 | if (seqp == hc->tx_seqt) { |
2a91aa39 AB |
597 | done = 1; |
598 | break; | |
599 | } | |
600 | seqp = seqp->ccid2s_prev; | |
601 | } | |
602 | if (done) | |
603 | break; | |
604 | ||
605 | /* check all seqnos in the range of the vector | |
606 | * run length | |
607 | */ | |
608 | while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) { | |
7e87fe84 | 609 | const u8 state = dccp_ackvec_state(avp->vec); |
2a91aa39 AB |
610 | |
611 | /* new packet received or marked */ | |
f17a37c9 | 612 | if (state != DCCPAV_NOT_RECEIVED && |
2a91aa39 | 613 | !seqp->ccid2s_acked) { |
f17a37c9 | 614 | if (state == DCCPAV_ECN_MARKED) |
d50ad163 | 615 | ccid2_congestion_event(sk, |
374bcf32 | 616 | seqp); |
f17a37c9 | 617 | else |
2a91aa39 AB |
618 | ccid2_new_ack(sk, seqp, |
619 | &maxincr); | |
2a91aa39 AB |
620 | |
621 | seqp->ccid2s_acked = 1; | |
622 | ccid2_pr_debug("Got ack for %llu\n", | |
234af484 | 623 | (unsigned long long)seqp->ccid2s_seq); |
c38c92a8 | 624 | hc->tx_pipe--; |
2a91aa39 | 625 | } |
77d2dd93 | 626 | if (seqp == hc->tx_seqt) { |
2a91aa39 AB |
627 | done = 1; |
628 | break; | |
629 | } | |
3de5489f | 630 | seqp = seqp->ccid2s_prev; |
2a91aa39 AB |
631 | } |
632 | if (done) | |
633 | break; | |
634 | ||
cfbbeabc | 635 | ackno = SUB48(ackno_end_rl, 1); |
2a91aa39 AB |
636 | } |
637 | if (done) | |
638 | break; | |
639 | } | |
640 | ||
641 | /* The state about what is acked should be correct now | |
642 | * Check for NUMDUPACK | |
643 | */ | |
77d2dd93 GR |
644 | seqp = hc->tx_seqt; |
645 | while (before48(seqp->ccid2s_seq, hc->tx_high_ack)) { | |
32aac18d | 646 | seqp = seqp->ccid2s_next; |
77d2dd93 GR |
647 | if (seqp == hc->tx_seqh) { |
648 | seqp = hc->tx_seqh->ccid2s_prev; | |
32aac18d AB |
649 | break; |
650 | } | |
651 | } | |
2a91aa39 AB |
652 | done = 0; |
653 | while (1) { | |
654 | if (seqp->ccid2s_acked) { | |
655 | done++; | |
63df18ad | 656 | if (done == NUMDUPACK) |
2a91aa39 | 657 | break; |
2a91aa39 | 658 | } |
77d2dd93 | 659 | if (seqp == hc->tx_seqt) |
2a91aa39 | 660 | break; |
2a91aa39 AB |
661 | seqp = seqp->ccid2s_prev; |
662 | } | |
663 | ||
664 | /* If there are at least 3 acknowledgements, anything unacknowledged | |
665 | * below the last sequence number is considered lost | |
666 | */ | |
63df18ad | 667 | if (done == NUMDUPACK) { |
2a91aa39 AB |
668 | struct ccid2_seq *last_acked = seqp; |
669 | ||
670 | /* check for lost packets */ | |
671 | while (1) { | |
672 | if (!seqp->ccid2s_acked) { | |
374bcf32 | 673 | ccid2_pr_debug("Packet lost: %llu\n", |
234af484 | 674 | (unsigned long long)seqp->ccid2s_seq); |
374bcf32 AB |
675 | /* XXX need to traverse from tail -> head in |
676 | * order to detect multiple congestion events in | |
677 | * one ack vector. | |
678 | */ | |
d50ad163 | 679 | ccid2_congestion_event(sk, seqp); |
c38c92a8 | 680 | hc->tx_pipe--; |
2a91aa39 | 681 | } |
77d2dd93 | 682 | if (seqp == hc->tx_seqt) |
2a91aa39 AB |
683 | break; |
684 | seqp = seqp->ccid2s_prev; | |
685 | } | |
686 | ||
77d2dd93 | 687 | hc->tx_seqt = last_acked; |
2a91aa39 AB |
688 | } |
689 | ||
690 | /* trim acked packets in tail */ | |
77d2dd93 GR |
691 | while (hc->tx_seqt != hc->tx_seqh) { |
692 | if (!hc->tx_seqt->ccid2s_acked) | |
2a91aa39 AB |
693 | break; |
694 | ||
77d2dd93 | 695 | hc->tx_seqt = hc->tx_seqt->ccid2s_next; |
2a91aa39 | 696 | } |
c38c92a8 GR |
697 | |
698 | /* restart RTO timer if not all outstanding data has been acked */ | |
699 | if (hc->tx_pipe == 0) | |
700 | sk_stop_timer(sk, &hc->tx_rtotimer); | |
701 | else | |
702 | sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto); | |
7e87fe84 | 703 | done: |
1c0e0a05 GR |
704 | /* check if incoming Acks allow pending packets to be sent */ |
705 | if (sender_was_blocked && !ccid2_cwnd_network_limited(hc)) | |
706 | tasklet_schedule(&dccp_sk(sk)->dccps_xmitlet); | |
7e87fe84 | 707 | dccp_ackvec_parsed_cleanup(&hc->tx_av_chunks); |
2a91aa39 AB |
708 | } |
709 | ||
91f0ebf7 | 710 | static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk) |
2a91aa39 | 711 | { |
77d2dd93 | 712 | struct ccid2_hc_tx_sock *hc = ccid_priv(ccid); |
b00d2bbc GR |
713 | struct dccp_sock *dp = dccp_sk(sk); |
714 | u32 max_ratio; | |
2a91aa39 | 715 | |
b00d2bbc | 716 | /* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */ |
77d2dd93 | 717 | hc->tx_ssthresh = ~0U; |
2a91aa39 | 718 | |
22b71c8f GR |
719 | /* Use larger initial windows (RFC 4341, section 5). */ |
720 | hc->tx_cwnd = rfc3390_bytes_to_packets(dp->dccps_mss_cache); | |
113ced1f | 721 | hc->tx_expected_wnd = hc->tx_cwnd; |
b00d2bbc GR |
722 | |
723 | /* Make sure that Ack Ratio is enabled and within bounds. */ | |
77d2dd93 | 724 | max_ratio = DIV_ROUND_UP(hc->tx_cwnd, 2); |
b00d2bbc GR |
725 | if (dp->dccps_l_ack_ratio == 0 || dp->dccps_l_ack_ratio > max_ratio) |
726 | dp->dccps_l_ack_ratio = max_ratio; | |
727 | ||
2a91aa39 | 728 | /* XXX init ~ to window size... */ |
77d2dd93 | 729 | if (ccid2_hc_tx_alloc_seq(hc)) |
2a91aa39 | 730 | return -ENOMEM; |
91f0ebf7 | 731 | |
231cc2aa | 732 | hc->tx_rto = DCCP_TIMEOUT_INIT; |
77d2dd93 | 733 | hc->tx_rpdupack = -1; |
113ced1f GR |
734 | hc->tx_last_cong = hc->tx_lsndtime = hc->tx_cwnd_stamp = ccid2_time_stamp; |
735 | hc->tx_cwnd_used = 0; | |
77d2dd93 | 736 | setup_timer(&hc->tx_rtotimer, ccid2_hc_tx_rto_expire, |
410e27a4 | 737 | (unsigned long)sk); |
7e87fe84 | 738 | INIT_LIST_HEAD(&hc->tx_av_chunks); |
2a91aa39 AB |
739 | return 0; |
740 | } | |
741 | ||
742 | static void ccid2_hc_tx_exit(struct sock *sk) | |
743 | { | |
77d2dd93 | 744 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
07978aab | 745 | int i; |
2a91aa39 | 746 | |
d26eeb07 | 747 | sk_stop_timer(sk, &hc->tx_rtotimer); |
07978aab | 748 | |
77d2dd93 GR |
749 | for (i = 0; i < hc->tx_seqbufc; i++) |
750 | kfree(hc->tx_seqbuf[i]); | |
751 | hc->tx_seqbufc = 0; | |
2a91aa39 AB |
752 | } |
753 | ||
754 | static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb) | |
755 | { | |
77d2dd93 | 756 | struct ccid2_hc_rx_sock *hc = ccid2_hc_rx_sk(sk); |
2a91aa39 | 757 | |
58fdea0f GR |
758 | if (!dccp_data_packet(skb)) |
759 | return; | |
760 | ||
761 | if (++hc->rx_num_data_pkts >= dccp_sk(sk)->dccps_r_ack_ratio) { | |
762 | dccp_send_ack(sk); | |
763 | hc->rx_num_data_pkts = 0; | |
2a91aa39 AB |
764 | } |
765 | } | |
766 | ||
ddebc973 | 767 | struct ccid_operations ccid2_ops = { |
7e87fe84 GR |
768 | .ccid_id = DCCPC_CCID2, |
769 | .ccid_name = "TCP-like", | |
770 | .ccid_hc_tx_obj_size = sizeof(struct ccid2_hc_tx_sock), | |
771 | .ccid_hc_tx_init = ccid2_hc_tx_init, | |
772 | .ccid_hc_tx_exit = ccid2_hc_tx_exit, | |
773 | .ccid_hc_tx_send_packet = ccid2_hc_tx_send_packet, | |
774 | .ccid_hc_tx_packet_sent = ccid2_hc_tx_packet_sent, | |
775 | .ccid_hc_tx_parse_options = ccid2_hc_tx_parse_options, | |
776 | .ccid_hc_tx_packet_recv = ccid2_hc_tx_packet_recv, | |
777 | .ccid_hc_rx_obj_size = sizeof(struct ccid2_hc_rx_sock), | |
778 | .ccid_hc_rx_packet_recv = ccid2_hc_rx_packet_recv, | |
2a91aa39 AB |
779 | }; |
780 | ||
84116716 | 781 | #ifdef CONFIG_IP_DCCP_CCID2_DEBUG |
43264991 | 782 | module_param(ccid2_debug, bool, 0644); |
ddebc973 | 783 | MODULE_PARM_DESC(ccid2_debug, "Enable CCID-2 debug messages"); |
84116716 | 784 | #endif |