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74ba9207 | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2a91aa39 | 2 | /* |
2a91aa39 AB |
3 | * Copyright (c) 2005, 2006 Andrea Bittau <a.bittau@cs.ucl.ac.uk> |
4 | * | |
5 | * Changes to meet Linux coding standards, and DCCP infrastructure fixes. | |
6 | * | |
7 | * Copyright (c) 2006 Arnaldo Carvalho de Melo <acme@conectiva.com.br> | |
2a91aa39 AB |
8 | */ |
9 | ||
10 | /* | |
0e64e94e | 11 | * This implementation should follow RFC 4341 |
2a91aa39 | 12 | */ |
5a0e3ad6 | 13 | #include <linux/slab.h> |
e8ef967a | 14 | #include "../feat.h" |
2a91aa39 AB |
15 | #include "ccid2.h" |
16 | ||
2a91aa39 | 17 | |
8d424f6c | 18 | #ifdef CONFIG_IP_DCCP_CCID2_DEBUG |
eb939922 | 19 | static bool ccid2_debug; |
84116716 | 20 | #define ccid2_pr_debug(format, a...) DCCP_PR_DEBUG(ccid2_debug, format, ##a) |
2a91aa39 | 21 | #else |
84116716 | 22 | #define ccid2_pr_debug(format, a...) |
2a91aa39 AB |
23 | #endif |
24 | ||
77d2dd93 | 25 | static int ccid2_hc_tx_alloc_seq(struct ccid2_hc_tx_sock *hc) |
07978aab AB |
26 | { |
27 | struct ccid2_seq *seqp; | |
28 | int i; | |
29 | ||
30 | /* check if we have space to preserve the pointer to the buffer */ | |
77d2dd93 GR |
31 | if (hc->tx_seqbufc >= (sizeof(hc->tx_seqbuf) / |
32 | sizeof(struct ccid2_seq *))) | |
07978aab AB |
33 | return -ENOMEM; |
34 | ||
35 | /* allocate buffer and initialize linked list */ | |
6da2ec56 KC |
36 | seqp = kmalloc_array(CCID2_SEQBUF_LEN, sizeof(struct ccid2_seq), |
37 | gfp_any()); | |
07978aab AB |
38 | if (seqp == NULL) |
39 | return -ENOMEM; | |
40 | ||
cd1f7d34 | 41 | for (i = 0; i < (CCID2_SEQBUF_LEN - 1); i++) { |
07978aab AB |
42 | seqp[i].ccid2s_next = &seqp[i + 1]; |
43 | seqp[i + 1].ccid2s_prev = &seqp[i]; | |
44 | } | |
cd1f7d34 GR |
45 | seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = seqp; |
46 | seqp->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1]; | |
07978aab AB |
47 | |
48 | /* This is the first allocation. Initiate the head and tail. */ | |
77d2dd93 GR |
49 | if (hc->tx_seqbufc == 0) |
50 | hc->tx_seqh = hc->tx_seqt = seqp; | |
07978aab AB |
51 | else { |
52 | /* link the existing list with the one we just created */ | |
77d2dd93 GR |
53 | hc->tx_seqh->ccid2s_next = seqp; |
54 | seqp->ccid2s_prev = hc->tx_seqh; | |
07978aab | 55 | |
77d2dd93 GR |
56 | hc->tx_seqt->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1]; |
57 | seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = hc->tx_seqt; | |
07978aab AB |
58 | } |
59 | ||
60 | /* store the original pointer to the buffer so we can free it */ | |
77d2dd93 GR |
61 | hc->tx_seqbuf[hc->tx_seqbufc] = seqp; |
62 | hc->tx_seqbufc++; | |
07978aab AB |
63 | |
64 | return 0; | |
65 | } | |
66 | ||
6b57c93d | 67 | static int ccid2_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) |
2a91aa39 | 68 | { |
1c0e0a05 GR |
69 | if (ccid2_cwnd_network_limited(ccid2_hc_tx_sk(sk))) |
70 | return CCID_PACKET_WILL_DEQUEUE_LATER; | |
71 | return CCID_PACKET_SEND_AT_ONCE; | |
2a91aa39 AB |
72 | } |
73 | ||
df054e1d | 74 | static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val) |
2a91aa39 | 75 | { |
b1c00fe3 | 76 | u32 max_ratio = DIV_ROUND_UP(ccid2_hc_tx_sk(sk)->tx_cwnd, 2); |
d50ad163 | 77 | |
2a91aa39 | 78 | /* |
d50ad163 GR |
79 | * Ensure that Ack Ratio does not exceed ceil(cwnd/2), which is (2) from |
80 | * RFC 4341, 6.1.2. We ignore the statement that Ack Ratio 2 is always | |
81 | * acceptable since this causes starvation/deadlock whenever cwnd < 2. | |
82 | * The same problem arises when Ack Ratio is 0 (ie. Ack Ratio disabled). | |
2a91aa39 | 83 | */ |
d50ad163 GR |
84 | if (val == 0 || val > max_ratio) { |
85 | DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio); | |
86 | val = max_ratio; | |
2a91aa39 | 87 | } |
d346d886 SJ |
88 | dccp_feat_signal_nn_change(sk, DCCPF_ACK_RATIO, |
89 | min_t(u32, val, DCCPF_ACK_RATIO_MAX)); | |
90 | } | |
d50ad163 | 91 | |
d96a9e8d SJ |
92 | static void ccid2_check_l_ack_ratio(struct sock *sk) |
93 | { | |
94 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); | |
95 | ||
96 | /* | |
97 | * After a loss, idle period, application limited period, or RTO we | |
98 | * need to check that the ack ratio is still less than the congestion | |
99 | * window. Otherwise, we will send an entire congestion window of | |
100 | * packets and got no response because we haven't sent ack ratio | |
101 | * packets yet. | |
102 | * If the ack ratio does need to be reduced, we reduce it to half of | |
103 | * the congestion window (or 1 if that's zero) instead of to the | |
104 | * congestion window. This prevents problems if one ack is lost. | |
105 | */ | |
106 | if (dccp_feat_nn_get(sk, DCCPF_ACK_RATIO) > hc->tx_cwnd) | |
107 | ccid2_change_l_ack_ratio(sk, hc->tx_cwnd/2 ? : 1U); | |
108 | } | |
109 | ||
d346d886 SJ |
110 | static void ccid2_change_l_seq_window(struct sock *sk, u64 val) |
111 | { | |
112 | dccp_feat_signal_nn_change(sk, DCCPF_SEQUENCE_WINDOW, | |
113 | clamp_val(val, DCCPF_SEQ_WMIN, | |
114 | DCCPF_SEQ_WMAX)); | |
2a91aa39 AB |
115 | } |
116 | ||
a8d7aa17 ED |
117 | static void dccp_tasklet_schedule(struct sock *sk) |
118 | { | |
119 | struct tasklet_struct *t = &dccp_sk(sk)->dccps_xmitlet; | |
120 | ||
121 | if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) { | |
122 | sock_hold(sk); | |
123 | __tasklet_schedule(t); | |
124 | } | |
125 | } | |
126 | ||
839a6094 | 127 | static void ccid2_hc_tx_rto_expire(struct timer_list *t) |
2a91aa39 | 128 | { |
839a6094 KC |
129 | struct ccid2_hc_tx_sock *hc = from_timer(hc, t, tx_rtotimer); |
130 | struct sock *sk = hc->sk; | |
1c0e0a05 | 131 | const bool sender_was_blocked = ccid2_cwnd_network_limited(hc); |
2a91aa39 | 132 | |
2a91aa39 AB |
133 | bh_lock_sock(sk); |
134 | if (sock_owned_by_user(sk)) { | |
77d2dd93 | 135 | sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + HZ / 5); |
2a91aa39 AB |
136 | goto out; |
137 | } | |
138 | ||
139 | ccid2_pr_debug("RTO_EXPIRE\n"); | |
140 | ||
dd5684ec AK |
141 | if (sk->sk_state == DCCP_CLOSED) |
142 | goto out; | |
143 | ||
2a91aa39 | 144 | /* back-off timer */ |
77d2dd93 | 145 | hc->tx_rto <<= 1; |
231cc2aa GR |
146 | if (hc->tx_rto > DCCP_RTO_MAX) |
147 | hc->tx_rto = DCCP_RTO_MAX; | |
410e27a4 | 148 | |
2a91aa39 | 149 | /* adjust pipe, cwnd etc */ |
77d2dd93 GR |
150 | hc->tx_ssthresh = hc->tx_cwnd / 2; |
151 | if (hc->tx_ssthresh < 2) | |
152 | hc->tx_ssthresh = 2; | |
67b67e36 GR |
153 | hc->tx_cwnd = 1; |
154 | hc->tx_pipe = 0; | |
2a91aa39 AB |
155 | |
156 | /* clear state about stuff we sent */ | |
77d2dd93 GR |
157 | hc->tx_seqt = hc->tx_seqh; |
158 | hc->tx_packets_acked = 0; | |
2a91aa39 AB |
159 | |
160 | /* clear ack ratio state. */ | |
77d2dd93 GR |
161 | hc->tx_rpseq = 0; |
162 | hc->tx_rpdupack = -1; | |
2a91aa39 | 163 | ccid2_change_l_ack_ratio(sk, 1); |
1c0e0a05 GR |
164 | |
165 | /* if we were blocked before, we may now send cwnd=1 packet */ | |
166 | if (sender_was_blocked) | |
a8d7aa17 | 167 | dccp_tasklet_schedule(sk); |
1c0e0a05 GR |
168 | /* restart backed-off timer */ |
169 | sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto); | |
2a91aa39 AB |
170 | out: |
171 | bh_unlock_sock(sk); | |
77ff72d5 | 172 | sock_put(sk); |
2a91aa39 AB |
173 | } |
174 | ||
113ced1f GR |
175 | /* |
176 | * Congestion window validation (RFC 2861). | |
177 | */ | |
eb939922 | 178 | static bool ccid2_do_cwv = true; |
113ced1f GR |
179 | module_param(ccid2_do_cwv, bool, 0644); |
180 | MODULE_PARM_DESC(ccid2_do_cwv, "Perform RFC2861 Congestion Window Validation"); | |
181 | ||
182 | /** | |
183 | * ccid2_update_used_window - Track how much of cwnd is actually used | |
184 | * This is done in addition to CWV. The sender needs to have an idea of how many | |
185 | * packets may be in flight, to set the local Sequence Window value accordingly | |
186 | * (RFC 4340, 7.5.2). The CWV mechanism is exploited to keep track of the | |
187 | * maximum-used window. We use an EWMA low-pass filter to filter out noise. | |
188 | */ | |
189 | static void ccid2_update_used_window(struct ccid2_hc_tx_sock *hc, u32 new_wnd) | |
190 | { | |
191 | hc->tx_expected_wnd = (3 * hc->tx_expected_wnd + new_wnd) / 4; | |
192 | } | |
193 | ||
194 | /* This borrows the code of tcp_cwnd_application_limited() */ | |
195 | static void ccid2_cwnd_application_limited(struct sock *sk, const u32 now) | |
196 | { | |
197 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); | |
198 | /* don't reduce cwnd below the initial window (IW) */ | |
199 | u32 init_win = rfc3390_bytes_to_packets(dccp_sk(sk)->dccps_mss_cache), | |
200 | win_used = max(hc->tx_cwnd_used, init_win); | |
201 | ||
202 | if (win_used < hc->tx_cwnd) { | |
203 | hc->tx_ssthresh = max(hc->tx_ssthresh, | |
204 | (hc->tx_cwnd >> 1) + (hc->tx_cwnd >> 2)); | |
205 | hc->tx_cwnd = (hc->tx_cwnd + win_used) >> 1; | |
206 | } | |
207 | hc->tx_cwnd_used = 0; | |
208 | hc->tx_cwnd_stamp = now; | |
d96a9e8d SJ |
209 | |
210 | ccid2_check_l_ack_ratio(sk); | |
113ced1f GR |
211 | } |
212 | ||
213 | /* This borrows the code of tcp_cwnd_restart() */ | |
214 | static void ccid2_cwnd_restart(struct sock *sk, const u32 now) | |
215 | { | |
216 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); | |
217 | u32 cwnd = hc->tx_cwnd, restart_cwnd, | |
218 | iwnd = rfc3390_bytes_to_packets(dccp_sk(sk)->dccps_mss_cache); | |
61ef4b07 | 219 | s32 delta = now - hc->tx_lsndtime; |
113ced1f GR |
220 | |
221 | hc->tx_ssthresh = max(hc->tx_ssthresh, (cwnd >> 1) + (cwnd >> 2)); | |
222 | ||
223 | /* don't reduce cwnd below the initial window (IW) */ | |
224 | restart_cwnd = min(cwnd, iwnd); | |
113ced1f | 225 | |
61ef4b07 AK |
226 | while ((delta -= hc->tx_rto) >= 0 && cwnd > restart_cwnd) |
227 | cwnd >>= 1; | |
228 | hc->tx_cwnd = max(cwnd, restart_cwnd); | |
113ced1f GR |
229 | hc->tx_cwnd_stamp = now; |
230 | hc->tx_cwnd_used = 0; | |
d96a9e8d SJ |
231 | |
232 | ccid2_check_l_ack_ratio(sk); | |
113ced1f GR |
233 | } |
234 | ||
baf9e782 | 235 | static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len) |
2a91aa39 AB |
236 | { |
237 | struct dccp_sock *dp = dccp_sk(sk); | |
77d2dd93 | 238 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
d011b9a4 | 239 | const u32 now = ccid2_jiffies32; |
07978aab | 240 | struct ccid2_seq *next; |
2a91aa39 | 241 | |
113ced1f GR |
242 | /* slow-start after idle periods (RFC 2581, RFC 2861) */ |
243 | if (ccid2_do_cwv && !hc->tx_pipe && | |
244 | (s32)(now - hc->tx_lsndtime) >= hc->tx_rto) | |
245 | ccid2_cwnd_restart(sk, now); | |
246 | ||
247 | hc->tx_lsndtime = now; | |
248 | hc->tx_pipe += 1; | |
249 | ||
250 | /* see whether cwnd was fully used (RFC 2861), update expected window */ | |
251 | if (ccid2_cwnd_network_limited(hc)) { | |
252 | ccid2_update_used_window(hc, hc->tx_cwnd); | |
253 | hc->tx_cwnd_used = 0; | |
254 | hc->tx_cwnd_stamp = now; | |
255 | } else { | |
256 | if (hc->tx_pipe > hc->tx_cwnd_used) | |
257 | hc->tx_cwnd_used = hc->tx_pipe; | |
258 | ||
259 | ccid2_update_used_window(hc, hc->tx_cwnd_used); | |
260 | ||
261 | if (ccid2_do_cwv && (s32)(now - hc->tx_cwnd_stamp) >= hc->tx_rto) | |
262 | ccid2_cwnd_application_limited(sk, now); | |
263 | } | |
2a91aa39 | 264 | |
77d2dd93 GR |
265 | hc->tx_seqh->ccid2s_seq = dp->dccps_gss; |
266 | hc->tx_seqh->ccid2s_acked = 0; | |
113ced1f | 267 | hc->tx_seqh->ccid2s_sent = now; |
2a91aa39 | 268 | |
77d2dd93 | 269 | next = hc->tx_seqh->ccid2s_next; |
07978aab | 270 | /* check if we need to alloc more space */ |
77d2dd93 GR |
271 | if (next == hc->tx_seqt) { |
272 | if (ccid2_hc_tx_alloc_seq(hc)) { | |
7d9e8931 GR |
273 | DCCP_CRIT("packet history - out of memory!"); |
274 | /* FIXME: find a more graceful way to bail out */ | |
275 | return; | |
276 | } | |
77d2dd93 GR |
277 | next = hc->tx_seqh->ccid2s_next; |
278 | BUG_ON(next == hc->tx_seqt); | |
2a91aa39 | 279 | } |
77d2dd93 | 280 | hc->tx_seqh = next; |
07978aab | 281 | |
77d2dd93 | 282 | ccid2_pr_debug("cwnd=%d pipe=%d\n", hc->tx_cwnd, hc->tx_pipe); |
2a91aa39 | 283 | |
900bfed4 GR |
284 | /* |
285 | * FIXME: The code below is broken and the variables have been removed | |
286 | * from the socket struct. The `ackloss' variable was always set to 0, | |
287 | * and with arsent there are several problems: | |
288 | * (i) it doesn't just count the number of Acks, but all sent packets; | |
289 | * (ii) it is expressed in # of packets, not # of windows, so the | |
290 | * comparison below uses the wrong formula: Appendix A of RFC 4341 | |
291 | * comes up with the number K = cwnd / (R^2 - R) of consecutive windows | |
292 | * of data with no lost or marked Ack packets. If arsent were the # of | |
293 | * consecutive Acks received without loss, then Ack Ratio needs to be | |
294 | * decreased by 1 when | |
295 | * arsent >= K * cwnd / R = cwnd^2 / (R^3 - R^2) | |
296 | * where cwnd / R is the number of Acks received per window of data | |
297 | * (cf. RFC 4341, App. A). The problems are that | |
298 | * - arsent counts other packets as well; | |
299 | * - the comparison uses a formula different from RFC 4341; | |
300 | * - computing a cubic/quadratic equation each time is too complicated. | |
301 | * Hence a different algorithm is needed. | |
302 | */ | |
303 | #if 0 | |
2a91aa39 | 304 | /* Ack Ratio. Need to maintain a concept of how many windows we sent */ |
77d2dd93 | 305 | hc->tx_arsent++; |
2a91aa39 | 306 | /* We had an ack loss in this window... */ |
77d2dd93 GR |
307 | if (hc->tx_ackloss) { |
308 | if (hc->tx_arsent >= hc->tx_cwnd) { | |
309 | hc->tx_arsent = 0; | |
310 | hc->tx_ackloss = 0; | |
2a91aa39 | 311 | } |
c0c736db ACM |
312 | } else { |
313 | /* No acks lost up to now... */ | |
2a91aa39 AB |
314 | /* decrease ack ratio if enough packets were sent */ |
315 | if (dp->dccps_l_ack_ratio > 1) { | |
316 | /* XXX don't calculate denominator each time */ | |
c0c736db ACM |
317 | int denom = dp->dccps_l_ack_ratio * dp->dccps_l_ack_ratio - |
318 | dp->dccps_l_ack_ratio; | |
2a91aa39 | 319 | |
77d2dd93 | 320 | denom = hc->tx_cwnd * hc->tx_cwnd / denom; |
2a91aa39 | 321 | |
77d2dd93 | 322 | if (hc->tx_arsent >= denom) { |
2a91aa39 | 323 | ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio - 1); |
77d2dd93 | 324 | hc->tx_arsent = 0; |
2a91aa39 | 325 | } |
c0c736db ACM |
326 | } else { |
327 | /* we can't increase ack ratio further [1] */ | |
77d2dd93 | 328 | hc->tx_arsent = 0; /* or maybe set it to cwnd*/ |
2a91aa39 AB |
329 | } |
330 | } | |
900bfed4 | 331 | #endif |
2a91aa39 | 332 | |
d26eeb07 | 333 | sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto); |
c0c736db | 334 | |
8d424f6c | 335 | #ifdef CONFIG_IP_DCCP_CCID2_DEBUG |
2a91aa39 | 336 | do { |
77d2dd93 | 337 | struct ccid2_seq *seqp = hc->tx_seqt; |
2a91aa39 | 338 | |
77d2dd93 | 339 | while (seqp != hc->tx_seqh) { |
d82b6f85 | 340 | ccid2_pr_debug("out seq=%llu acked=%d time=%u\n", |
8109b02b | 341 | (unsigned long long)seqp->ccid2s_seq, |
234af484 | 342 | seqp->ccid2s_acked, seqp->ccid2s_sent); |
2a91aa39 AB |
343 | seqp = seqp->ccid2s_next; |
344 | } | |
c0c736db | 345 | } while (0); |
2a91aa39 | 346 | ccid2_pr_debug("=========\n"); |
2a91aa39 AB |
347 | #endif |
348 | } | |
349 | ||
231cc2aa GR |
350 | /** |
351 | * ccid2_rtt_estimator - Sample RTT and compute RTO using RFC2988 algorithm | |
352 | * This code is almost identical with TCP's tcp_rtt_estimator(), since | |
353 | * - it has a higher sampling frequency (recommended by RFC 1323), | |
354 | * - the RTO does not collapse into RTT due to RTTVAR going towards zero, | |
355 | * - it is simple (cf. more complex proposals such as Eifel timer or research | |
356 | * which suggests that the gain should be set according to window size), | |
357 | * - in tests it was found to work well with CCID2 [gerrit]. | |
358 | */ | |
359 | static void ccid2_rtt_estimator(struct sock *sk, const long mrtt) | |
360 | { | |
361 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); | |
362 | long m = mrtt ? : 1; | |
363 | ||
364 | if (hc->tx_srtt == 0) { | |
365 | /* First measurement m */ | |
366 | hc->tx_srtt = m << 3; | |
367 | hc->tx_mdev = m << 1; | |
368 | ||
4886fcad | 369 | hc->tx_mdev_max = max(hc->tx_mdev, tcp_rto_min(sk)); |
231cc2aa | 370 | hc->tx_rttvar = hc->tx_mdev_max; |
4886fcad | 371 | |
231cc2aa GR |
372 | hc->tx_rtt_seq = dccp_sk(sk)->dccps_gss; |
373 | } else { | |
374 | /* Update scaled SRTT as SRTT += 1/8 * (m - SRTT) */ | |
375 | m -= (hc->tx_srtt >> 3); | |
376 | hc->tx_srtt += m; | |
377 | ||
378 | /* Similarly, update scaled mdev with regard to |m| */ | |
379 | if (m < 0) { | |
380 | m = -m; | |
381 | m -= (hc->tx_mdev >> 2); | |
382 | /* | |
383 | * This neutralises RTO increase when RTT < SRTT - mdev | |
384 | * (see P. Sarolahti, A. Kuznetsov,"Congestion Control | |
385 | * in Linux TCP", USENIX 2002, pp. 49-62). | |
386 | */ | |
387 | if (m > 0) | |
388 | m >>= 3; | |
389 | } else { | |
390 | m -= (hc->tx_mdev >> 2); | |
391 | } | |
392 | hc->tx_mdev += m; | |
393 | ||
394 | if (hc->tx_mdev > hc->tx_mdev_max) { | |
395 | hc->tx_mdev_max = hc->tx_mdev; | |
396 | if (hc->tx_mdev_max > hc->tx_rttvar) | |
397 | hc->tx_rttvar = hc->tx_mdev_max; | |
398 | } | |
399 | ||
400 | /* | |
401 | * Decay RTTVAR at most once per flight, exploiting that | |
402 | * 1) pipe <= cwnd <= Sequence_Window = W (RFC 4340, 7.5.2) | |
403 | * 2) AWL = GSS-W+1 <= GAR <= GSS (RFC 4340, 7.5.1) | |
404 | * GAR is a useful bound for FlightSize = pipe. | |
405 | * AWL is probably too low here, as it over-estimates pipe. | |
406 | */ | |
407 | if (after48(dccp_sk(sk)->dccps_gar, hc->tx_rtt_seq)) { | |
408 | if (hc->tx_mdev_max < hc->tx_rttvar) | |
409 | hc->tx_rttvar -= (hc->tx_rttvar - | |
410 | hc->tx_mdev_max) >> 2; | |
411 | hc->tx_rtt_seq = dccp_sk(sk)->dccps_gss; | |
4886fcad | 412 | hc->tx_mdev_max = tcp_rto_min(sk); |
231cc2aa GR |
413 | } |
414 | } | |
415 | ||
416 | /* | |
417 | * Set RTO from SRTT and RTTVAR | |
418 | * As in TCP, 4 * RTTVAR >= TCP_RTO_MIN, giving a minimum RTO of 200 ms. | |
419 | * This agrees with RFC 4341, 5: | |
420 | * "Because DCCP does not retransmit data, DCCP does not require | |
421 | * TCP's recommended minimum timeout of one second". | |
422 | */ | |
423 | hc->tx_rto = (hc->tx_srtt >> 3) + hc->tx_rttvar; | |
424 | ||
425 | if (hc->tx_rto > DCCP_RTO_MAX) | |
426 | hc->tx_rto = DCCP_RTO_MAX; | |
427 | } | |
428 | ||
429 | static void ccid2_new_ack(struct sock *sk, struct ccid2_seq *seqp, | |
430 | unsigned int *maxincr) | |
374bcf32 | 431 | { |
77d2dd93 | 432 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
d346d886 SJ |
433 | struct dccp_sock *dp = dccp_sk(sk); |
434 | int r_seq_used = hc->tx_cwnd / dp->dccps_l_ack_ratio; | |
435 | ||
436 | if (hc->tx_cwnd < dp->dccps_l_seq_win && | |
437 | r_seq_used < dp->dccps_r_seq_win) { | |
438 | if (hc->tx_cwnd < hc->tx_ssthresh) { | |
0ce95dc7 | 439 | if (*maxincr > 0 && ++hc->tx_packets_acked >= 2) { |
d346d886 SJ |
440 | hc->tx_cwnd += 1; |
441 | *maxincr -= 1; | |
442 | hc->tx_packets_acked = 0; | |
443 | } | |
444 | } else if (++hc->tx_packets_acked >= hc->tx_cwnd) { | |
77d2dd93 | 445 | hc->tx_cwnd += 1; |
77d2dd93 | 446 | hc->tx_packets_acked = 0; |
410e27a4 | 447 | } |
374bcf32 | 448 | } |
d346d886 SJ |
449 | |
450 | /* | |
451 | * Adjust the local sequence window and the ack ratio to allow about | |
452 | * 5 times the number of packets in the network (RFC 4340 7.5.2) | |
453 | */ | |
454 | if (r_seq_used * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_r_seq_win) | |
455 | ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio * 2); | |
456 | else if (r_seq_used * CCID2_WIN_CHANGE_FACTOR < dp->dccps_r_seq_win/2) | |
457 | ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio / 2 ? : 1U); | |
458 | ||
459 | if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_l_seq_win) | |
460 | ccid2_change_l_seq_window(sk, dp->dccps_l_seq_win * 2); | |
461 | else if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR < dp->dccps_l_seq_win/2) | |
462 | ccid2_change_l_seq_window(sk, dp->dccps_l_seq_win / 2); | |
463 | ||
231cc2aa GR |
464 | /* |
465 | * FIXME: RTT is sampled several times per acknowledgment (for each | |
466 | * entry in the Ack Vector), instead of once per Ack (as in TCP SACK). | |
467 | * This causes the RTT to be over-estimated, since the older entries | |
468 | * in the Ack Vector have earlier sending times. | |
469 | * The cleanest solution is to not use the ccid2s_sent field at all | |
470 | * and instead use DCCP timestamps: requires changes in other places. | |
471 | */ | |
d011b9a4 | 472 | ccid2_rtt_estimator(sk, ccid2_jiffies32 - seqp->ccid2s_sent); |
410e27a4 GR |
473 | } |
474 | ||
475 | static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp) | |
476 | { | |
77d2dd93 | 477 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
410e27a4 | 478 | |
d82b6f85 | 479 | if ((s32)(seqp->ccid2s_sent - hc->tx_last_cong) < 0) { |
410e27a4 GR |
480 | ccid2_pr_debug("Multiple losses in an RTT---treating as one\n"); |
481 | return; | |
c8bf462b | 482 | } |
410e27a4 | 483 | |
d011b9a4 | 484 | hc->tx_last_cong = ccid2_jiffies32; |
410e27a4 | 485 | |
77d2dd93 GR |
486 | hc->tx_cwnd = hc->tx_cwnd / 2 ? : 1U; |
487 | hc->tx_ssthresh = max(hc->tx_cwnd, 2U); | |
410e27a4 | 488 | |
d96a9e8d | 489 | ccid2_check_l_ack_ratio(sk); |
c8bf462b GR |
490 | } |
491 | ||
7e87fe84 GR |
492 | static int ccid2_hc_tx_parse_options(struct sock *sk, u8 packet_type, |
493 | u8 option, u8 *optval, u8 optlen) | |
494 | { | |
495 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); | |
496 | ||
497 | switch (option) { | |
498 | case DCCPO_ACK_VECTOR_0: | |
499 | case DCCPO_ACK_VECTOR_1: | |
500 | return dccp_ackvec_parsed_add(&hc->tx_av_chunks, optval, optlen, | |
501 | option - DCCPO_ACK_VECTOR_0); | |
502 | } | |
503 | return 0; | |
504 | } | |
505 | ||
2a91aa39 AB |
506 | static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) |
507 | { | |
508 | struct dccp_sock *dp = dccp_sk(sk); | |
77d2dd93 | 509 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
1c0e0a05 | 510 | const bool sender_was_blocked = ccid2_cwnd_network_limited(hc); |
7e87fe84 | 511 | struct dccp_ackvec_parsed *avp; |
2a91aa39 AB |
512 | u64 ackno, seqno; |
513 | struct ccid2_seq *seqp; | |
2a91aa39 | 514 | int done = 0; |
2a91aa39 AB |
515 | unsigned int maxincr = 0; |
516 | ||
2a91aa39 AB |
517 | /* check reverse path congestion */ |
518 | seqno = DCCP_SKB_CB(skb)->dccpd_seq; | |
519 | ||
520 | /* XXX this whole "algorithm" is broken. Need to fix it to keep track | |
521 | * of the seqnos of the dupacks so that rpseq and rpdupack are correct | |
522 | * -sorbo. | |
523 | */ | |
524 | /* need to bootstrap */ | |
77d2dd93 GR |
525 | if (hc->tx_rpdupack == -1) { |
526 | hc->tx_rpdupack = 0; | |
527 | hc->tx_rpseq = seqno; | |
c0c736db | 528 | } else { |
2a91aa39 | 529 | /* check if packet is consecutive */ |
77d2dd93 GR |
530 | if (dccp_delta_seqno(hc->tx_rpseq, seqno) == 1) |
531 | hc->tx_rpseq = seqno; | |
2a91aa39 | 532 | /* it's a later packet */ |
77d2dd93 GR |
533 | else if (after48(seqno, hc->tx_rpseq)) { |
534 | hc->tx_rpdupack++; | |
2a91aa39 AB |
535 | |
536 | /* check if we got enough dupacks */ | |
77d2dd93 GR |
537 | if (hc->tx_rpdupack >= NUMDUPACK) { |
538 | hc->tx_rpdupack = -1; /* XXX lame */ | |
539 | hc->tx_rpseq = 0; | |
31daf039 GR |
540 | #ifdef __CCID2_COPES_GRACEFULLY_WITH_ACK_CONGESTION_CONTROL__ |
541 | /* | |
542 | * FIXME: Ack Congestion Control is broken; in | |
543 | * the current state instabilities occurred with | |
544 | * Ack Ratios greater than 1; causing hang-ups | |
545 | * and long RTO timeouts. This needs to be fixed | |
546 | * before opening up dynamic changes. -- gerrit | |
547 | */ | |
df054e1d | 548 | ccid2_change_l_ack_ratio(sk, 2 * dp->dccps_l_ack_ratio); |
31daf039 | 549 | #endif |
2a91aa39 AB |
550 | } |
551 | } | |
552 | } | |
553 | ||
554 | /* check forward path congestion */ | |
7e87fe84 | 555 | if (dccp_packet_without_ack(skb)) |
2a91aa39 AB |
556 | return; |
557 | ||
7e87fe84 GR |
558 | /* still didn't send out new data packets */ |
559 | if (hc->tx_seqh == hc->tx_seqt) | |
560 | goto done; | |
2a91aa39 AB |
561 | |
562 | ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq; | |
77d2dd93 GR |
563 | if (after48(ackno, hc->tx_high_ack)) |
564 | hc->tx_high_ack = ackno; | |
32aac18d | 565 | |
77d2dd93 | 566 | seqp = hc->tx_seqt; |
32aac18d AB |
567 | while (before48(seqp->ccid2s_seq, ackno)) { |
568 | seqp = seqp->ccid2s_next; | |
77d2dd93 GR |
569 | if (seqp == hc->tx_seqh) { |
570 | seqp = hc->tx_seqh->ccid2s_prev; | |
32aac18d AB |
571 | break; |
572 | } | |
573 | } | |
2a91aa39 | 574 | |
a3020025 GR |
575 | /* |
576 | * In slow-start, cwnd can increase up to a maximum of Ack Ratio/2 | |
577 | * packets per acknowledgement. Rounding up avoids that cwnd is not | |
578 | * advanced when Ack Ratio is 1 and gives a slight edge otherwise. | |
2a91aa39 | 579 | */ |
77d2dd93 | 580 | if (hc->tx_cwnd < hc->tx_ssthresh) |
a3020025 | 581 | maxincr = DIV_ROUND_UP(dp->dccps_l_ack_ratio, 2); |
2a91aa39 AB |
582 | |
583 | /* go through all ack vectors */ | |
7e87fe84 | 584 | list_for_each_entry(avp, &hc->tx_av_chunks, node) { |
2a91aa39 | 585 | /* go through this ack vector */ |
7e87fe84 GR |
586 | for (; avp->len--; avp->vec++) { |
587 | u64 ackno_end_rl = SUB48(ackno, | |
588 | dccp_ackvec_runlen(avp->vec)); | |
2a91aa39 | 589 | |
7e87fe84 | 590 | ccid2_pr_debug("ackvec %llu |%u,%u|\n", |
234af484 | 591 | (unsigned long long)ackno, |
7e87fe84 GR |
592 | dccp_ackvec_state(avp->vec) >> 6, |
593 | dccp_ackvec_runlen(avp->vec)); | |
2a91aa39 AB |
594 | /* if the seqno we are analyzing is larger than the |
595 | * current ackno, then move towards the tail of our | |
596 | * seqnos. | |
597 | */ | |
598 | while (after48(seqp->ccid2s_seq, ackno)) { | |
77d2dd93 | 599 | if (seqp == hc->tx_seqt) { |
2a91aa39 AB |
600 | done = 1; |
601 | break; | |
602 | } | |
603 | seqp = seqp->ccid2s_prev; | |
604 | } | |
605 | if (done) | |
606 | break; | |
607 | ||
608 | /* check all seqnos in the range of the vector | |
609 | * run length | |
610 | */ | |
611 | while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) { | |
7e87fe84 | 612 | const u8 state = dccp_ackvec_state(avp->vec); |
2a91aa39 AB |
613 | |
614 | /* new packet received or marked */ | |
f17a37c9 | 615 | if (state != DCCPAV_NOT_RECEIVED && |
2a91aa39 | 616 | !seqp->ccid2s_acked) { |
f17a37c9 | 617 | if (state == DCCPAV_ECN_MARKED) |
d50ad163 | 618 | ccid2_congestion_event(sk, |
374bcf32 | 619 | seqp); |
f17a37c9 | 620 | else |
2a91aa39 AB |
621 | ccid2_new_ack(sk, seqp, |
622 | &maxincr); | |
2a91aa39 AB |
623 | |
624 | seqp->ccid2s_acked = 1; | |
625 | ccid2_pr_debug("Got ack for %llu\n", | |
234af484 | 626 | (unsigned long long)seqp->ccid2s_seq); |
c38c92a8 | 627 | hc->tx_pipe--; |
2a91aa39 | 628 | } |
77d2dd93 | 629 | if (seqp == hc->tx_seqt) { |
2a91aa39 AB |
630 | done = 1; |
631 | break; | |
632 | } | |
3de5489f | 633 | seqp = seqp->ccid2s_prev; |
2a91aa39 AB |
634 | } |
635 | if (done) | |
636 | break; | |
637 | ||
cfbbeabc | 638 | ackno = SUB48(ackno_end_rl, 1); |
2a91aa39 AB |
639 | } |
640 | if (done) | |
641 | break; | |
642 | } | |
643 | ||
644 | /* The state about what is acked should be correct now | |
645 | * Check for NUMDUPACK | |
646 | */ | |
77d2dd93 GR |
647 | seqp = hc->tx_seqt; |
648 | while (before48(seqp->ccid2s_seq, hc->tx_high_ack)) { | |
32aac18d | 649 | seqp = seqp->ccid2s_next; |
77d2dd93 GR |
650 | if (seqp == hc->tx_seqh) { |
651 | seqp = hc->tx_seqh->ccid2s_prev; | |
32aac18d AB |
652 | break; |
653 | } | |
654 | } | |
2a91aa39 AB |
655 | done = 0; |
656 | while (1) { | |
657 | if (seqp->ccid2s_acked) { | |
658 | done++; | |
63df18ad | 659 | if (done == NUMDUPACK) |
2a91aa39 | 660 | break; |
2a91aa39 | 661 | } |
77d2dd93 | 662 | if (seqp == hc->tx_seqt) |
2a91aa39 | 663 | break; |
2a91aa39 AB |
664 | seqp = seqp->ccid2s_prev; |
665 | } | |
666 | ||
667 | /* If there are at least 3 acknowledgements, anything unacknowledged | |
668 | * below the last sequence number is considered lost | |
669 | */ | |
63df18ad | 670 | if (done == NUMDUPACK) { |
2a91aa39 AB |
671 | struct ccid2_seq *last_acked = seqp; |
672 | ||
673 | /* check for lost packets */ | |
674 | while (1) { | |
675 | if (!seqp->ccid2s_acked) { | |
374bcf32 | 676 | ccid2_pr_debug("Packet lost: %llu\n", |
234af484 | 677 | (unsigned long long)seqp->ccid2s_seq); |
374bcf32 AB |
678 | /* XXX need to traverse from tail -> head in |
679 | * order to detect multiple congestion events in | |
680 | * one ack vector. | |
681 | */ | |
d50ad163 | 682 | ccid2_congestion_event(sk, seqp); |
c38c92a8 | 683 | hc->tx_pipe--; |
2a91aa39 | 684 | } |
77d2dd93 | 685 | if (seqp == hc->tx_seqt) |
2a91aa39 AB |
686 | break; |
687 | seqp = seqp->ccid2s_prev; | |
688 | } | |
689 | ||
77d2dd93 | 690 | hc->tx_seqt = last_acked; |
2a91aa39 AB |
691 | } |
692 | ||
693 | /* trim acked packets in tail */ | |
77d2dd93 GR |
694 | while (hc->tx_seqt != hc->tx_seqh) { |
695 | if (!hc->tx_seqt->ccid2s_acked) | |
2a91aa39 AB |
696 | break; |
697 | ||
77d2dd93 | 698 | hc->tx_seqt = hc->tx_seqt->ccid2s_next; |
2a91aa39 | 699 | } |
c38c92a8 GR |
700 | |
701 | /* restart RTO timer if not all outstanding data has been acked */ | |
702 | if (hc->tx_pipe == 0) | |
703 | sk_stop_timer(sk, &hc->tx_rtotimer); | |
704 | else | |
705 | sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto); | |
7e87fe84 | 706 | done: |
1c0e0a05 GR |
707 | /* check if incoming Acks allow pending packets to be sent */ |
708 | if (sender_was_blocked && !ccid2_cwnd_network_limited(hc)) | |
a8d7aa17 | 709 | dccp_tasklet_schedule(sk); |
7e87fe84 | 710 | dccp_ackvec_parsed_cleanup(&hc->tx_av_chunks); |
2a91aa39 AB |
711 | } |
712 | ||
91f0ebf7 | 713 | static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk) |
2a91aa39 | 714 | { |
77d2dd93 | 715 | struct ccid2_hc_tx_sock *hc = ccid_priv(ccid); |
b00d2bbc GR |
716 | struct dccp_sock *dp = dccp_sk(sk); |
717 | u32 max_ratio; | |
2a91aa39 | 718 | |
b00d2bbc | 719 | /* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */ |
77d2dd93 | 720 | hc->tx_ssthresh = ~0U; |
2a91aa39 | 721 | |
22b71c8f GR |
722 | /* Use larger initial windows (RFC 4341, section 5). */ |
723 | hc->tx_cwnd = rfc3390_bytes_to_packets(dp->dccps_mss_cache); | |
113ced1f | 724 | hc->tx_expected_wnd = hc->tx_cwnd; |
b00d2bbc GR |
725 | |
726 | /* Make sure that Ack Ratio is enabled and within bounds. */ | |
77d2dd93 | 727 | max_ratio = DIV_ROUND_UP(hc->tx_cwnd, 2); |
b00d2bbc GR |
728 | if (dp->dccps_l_ack_ratio == 0 || dp->dccps_l_ack_ratio > max_ratio) |
729 | dp->dccps_l_ack_ratio = max_ratio; | |
730 | ||
2a91aa39 | 731 | /* XXX init ~ to window size... */ |
77d2dd93 | 732 | if (ccid2_hc_tx_alloc_seq(hc)) |
2a91aa39 | 733 | return -ENOMEM; |
91f0ebf7 | 734 | |
231cc2aa | 735 | hc->tx_rto = DCCP_TIMEOUT_INIT; |
77d2dd93 | 736 | hc->tx_rpdupack = -1; |
d011b9a4 | 737 | hc->tx_last_cong = hc->tx_lsndtime = hc->tx_cwnd_stamp = ccid2_jiffies32; |
113ced1f | 738 | hc->tx_cwnd_used = 0; |
839a6094 KC |
739 | hc->sk = sk; |
740 | timer_setup(&hc->tx_rtotimer, ccid2_hc_tx_rto_expire, 0); | |
7e87fe84 | 741 | INIT_LIST_HEAD(&hc->tx_av_chunks); |
2a91aa39 AB |
742 | return 0; |
743 | } | |
744 | ||
745 | static void ccid2_hc_tx_exit(struct sock *sk) | |
746 | { | |
77d2dd93 | 747 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
07978aab | 748 | int i; |
2a91aa39 | 749 | |
d26eeb07 | 750 | sk_stop_timer(sk, &hc->tx_rtotimer); |
07978aab | 751 | |
77d2dd93 GR |
752 | for (i = 0; i < hc->tx_seqbufc; i++) |
753 | kfree(hc->tx_seqbuf[i]); | |
754 | hc->tx_seqbufc = 0; | |
72ef9c41 | 755 | dccp_ackvec_parsed_cleanup(&hc->tx_av_chunks); |
2a91aa39 AB |
756 | } |
757 | ||
758 | static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb) | |
759 | { | |
77d2dd93 | 760 | struct ccid2_hc_rx_sock *hc = ccid2_hc_rx_sk(sk); |
2a91aa39 | 761 | |
58fdea0f GR |
762 | if (!dccp_data_packet(skb)) |
763 | return; | |
764 | ||
765 | if (++hc->rx_num_data_pkts >= dccp_sk(sk)->dccps_r_ack_ratio) { | |
766 | dccp_send_ack(sk); | |
767 | hc->rx_num_data_pkts = 0; | |
2a91aa39 AB |
768 | } |
769 | } | |
770 | ||
ddebc973 | 771 | struct ccid_operations ccid2_ops = { |
7e87fe84 GR |
772 | .ccid_id = DCCPC_CCID2, |
773 | .ccid_name = "TCP-like", | |
774 | .ccid_hc_tx_obj_size = sizeof(struct ccid2_hc_tx_sock), | |
775 | .ccid_hc_tx_init = ccid2_hc_tx_init, | |
776 | .ccid_hc_tx_exit = ccid2_hc_tx_exit, | |
777 | .ccid_hc_tx_send_packet = ccid2_hc_tx_send_packet, | |
778 | .ccid_hc_tx_packet_sent = ccid2_hc_tx_packet_sent, | |
779 | .ccid_hc_tx_parse_options = ccid2_hc_tx_parse_options, | |
780 | .ccid_hc_tx_packet_recv = ccid2_hc_tx_packet_recv, | |
781 | .ccid_hc_rx_obj_size = sizeof(struct ccid2_hc_rx_sock), | |
782 | .ccid_hc_rx_packet_recv = ccid2_hc_rx_packet_recv, | |
2a91aa39 AB |
783 | }; |
784 | ||
84116716 | 785 | #ifdef CONFIG_IP_DCCP_CCID2_DEBUG |
43264991 | 786 | module_param(ccid2_debug, bool, 0644); |
ddebc973 | 787 | MODULE_PARM_DESC(ccid2_debug, "Enable CCID-2 debug messages"); |
84116716 | 788 | #endif |