1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
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> |
8 | */ |
9 | |
10 | /* |
11 | * This implementation should follow RFC 4341 |
12 | */ |
13 | #include <linux/slab.h> |
14 | #include "../feat.h" |
15 | #include "ccid2.h" |
16 | |
17 | |
18 | #ifdef CONFIG_IP_DCCP_CCID2_DEBUG |
19 | static bool ccid2_debug; |
20 | #define ccid2_pr_debug(format, a...) DCCP_PR_DEBUG(ccid2_debug, format, ##a) |
21 | #else |
22 | #define ccid2_pr_debug(format, a...) |
23 | #endif |
24 | |
25 | static int ccid2_hc_tx_alloc_seq(struct ccid2_hc_tx_sock *hc) |
26 | { |
27 | struct ccid2_seq *seqp; |
28 | int i; |
29 | |
30 | /* check if we have space to preserve the pointer to the buffer */ |
31 | if (hc->tx_seqbufc >= (sizeof(hc->tx_seqbuf) / |
32 | sizeof(struct ccid2_seq *))) |
33 | return -ENOMEM; |
34 | |
35 | /* allocate buffer and initialize linked list */ |
36 | seqp = kmalloc_array(CCID2_SEQBUF_LEN, size: sizeof(struct ccid2_seq), |
37 | flags: gfp_any()); |
38 | if (seqp == NULL) |
39 | return -ENOMEM; |
40 | |
41 | for (i = 0; i < (CCID2_SEQBUF_LEN - 1); i++) { |
42 | seqp[i].ccid2s_next = &seqp[i + 1]; |
43 | seqp[i + 1].ccid2s_prev = &seqp[i]; |
44 | } |
45 | seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = seqp; |
46 | seqp->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1]; |
47 | |
48 | /* This is the first allocation. Initiate the head and tail. */ |
49 | if (hc->tx_seqbufc == 0) |
50 | hc->tx_seqh = hc->tx_seqt = seqp; |
51 | else { |
52 | /* link the existing list with the one we just created */ |
53 | hc->tx_seqh->ccid2s_next = seqp; |
54 | seqp->ccid2s_prev = hc->tx_seqh; |
55 | |
56 | hc->tx_seqt->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1]; |
57 | seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = hc->tx_seqt; |
58 | } |
59 | |
60 | /* store the original pointer to the buffer so we can free it */ |
61 | hc->tx_seqbuf[hc->tx_seqbufc] = seqp; |
62 | hc->tx_seqbufc++; |
63 | |
64 | return 0; |
65 | } |
66 | |
67 | static int ccid2_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) |
68 | { |
69 | if (ccid2_cwnd_network_limited(hc: ccid2_hc_tx_sk(sk))) |
70 | return CCID_PACKET_WILL_DEQUEUE_LATER; |
71 | return CCID_PACKET_SEND_AT_ONCE; |
72 | } |
73 | |
74 | static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val) |
75 | { |
76 | u32 max_ratio = DIV_ROUND_UP(ccid2_hc_tx_sk(sk)->tx_cwnd, 2); |
77 | |
78 | /* |
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). |
83 | */ |
84 | if (val == 0 || val > max_ratio) { |
85 | DCCP_WARN("Limiting Ack Ratio (%u) to %u\n" , val, max_ratio); |
86 | val = max_ratio; |
87 | } |
88 | dccp_feat_signal_nn_change(sk, feat: DCCPF_ACK_RATIO, |
89 | min_t(u32, val, DCCPF_ACK_RATIO_MAX)); |
90 | } |
91 | |
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, feat: DCCPF_ACK_RATIO) > hc->tx_cwnd) |
107 | ccid2_change_l_ack_ratio(sk, val: hc->tx_cwnd/2 ? : 1U); |
108 | } |
109 | |
110 | static void ccid2_change_l_seq_window(struct sock *sk, u64 val) |
111 | { |
112 | dccp_feat_signal_nn_change(sk, feat: DCCPF_SEQUENCE_WINDOW, |
113 | clamp_val(val, DCCPF_SEQ_WMIN, |
114 | DCCPF_SEQ_WMAX)); |
115 | } |
116 | |
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(nr: TASKLET_STATE_SCHED, addr: &t->state)) { |
122 | sock_hold(sk); |
123 | __tasklet_schedule(t); |
124 | } |
125 | } |
126 | |
127 | static void ccid2_hc_tx_rto_expire(struct timer_list *t) |
128 | { |
129 | struct ccid2_hc_tx_sock *hc = from_timer(hc, t, tx_rtotimer); |
130 | struct sock *sk = hc->sk; |
131 | const bool sender_was_blocked = ccid2_cwnd_network_limited(hc); |
132 | |
133 | bh_lock_sock(sk); |
134 | if (sock_owned_by_user(sk)) { |
135 | sk_reset_timer(sk, timer: &hc->tx_rtotimer, expires: jiffies + HZ / 5); |
136 | goto out; |
137 | } |
138 | |
139 | ccid2_pr_debug("RTO_EXPIRE\n" ); |
140 | |
141 | if (sk->sk_state == DCCP_CLOSED) |
142 | goto out; |
143 | |
144 | /* back-off timer */ |
145 | hc->tx_rto <<= 1; |
146 | if (hc->tx_rto > DCCP_RTO_MAX) |
147 | hc->tx_rto = DCCP_RTO_MAX; |
148 | |
149 | /* adjust pipe, cwnd etc */ |
150 | hc->tx_ssthresh = hc->tx_cwnd / 2; |
151 | if (hc->tx_ssthresh < 2) |
152 | hc->tx_ssthresh = 2; |
153 | hc->tx_cwnd = 1; |
154 | hc->tx_pipe = 0; |
155 | |
156 | /* clear state about stuff we sent */ |
157 | hc->tx_seqt = hc->tx_seqh; |
158 | hc->tx_packets_acked = 0; |
159 | |
160 | /* clear ack ratio state. */ |
161 | hc->tx_rpseq = 0; |
162 | hc->tx_rpdupack = -1; |
163 | ccid2_change_l_ack_ratio(sk, val: 1); |
164 | |
165 | /* if we were blocked before, we may now send cwnd=1 packet */ |
166 | if (sender_was_blocked) |
167 | dccp_tasklet_schedule(sk); |
168 | /* restart backed-off timer */ |
169 | sk_reset_timer(sk, timer: &hc->tx_rtotimer, expires: jiffies + hc->tx_rto); |
170 | out: |
171 | bh_unlock_sock(sk); |
172 | sock_put(sk); |
173 | } |
174 | |
175 | /* |
176 | * Congestion window validation (RFC 2861). |
177 | */ |
178 | static bool ccid2_do_cwv = true; |
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 | * @hc: socket to update window |
185 | * @new_wnd: new window values to add into the filter |
186 | * |
187 | * This is done in addition to CWV. The sender needs to have an idea of how many |
188 | * packets may be in flight, to set the local Sequence Window value accordingly |
189 | * (RFC 4340, 7.5.2). The CWV mechanism is exploited to keep track of the |
190 | * maximum-used window. We use an EWMA low-pass filter to filter out noise. |
191 | */ |
192 | static void ccid2_update_used_window(struct ccid2_hc_tx_sock *hc, u32 new_wnd) |
193 | { |
194 | hc->tx_expected_wnd = (3 * hc->tx_expected_wnd + new_wnd) / 4; |
195 | } |
196 | |
197 | /* This borrows the code of tcp_cwnd_application_limited() */ |
198 | static void ccid2_cwnd_application_limited(struct sock *sk, const u32 now) |
199 | { |
200 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
201 | /* don't reduce cwnd below the initial window (IW) */ |
202 | u32 init_win = rfc3390_bytes_to_packets(dccp_sk(sk)->dccps_mss_cache), |
203 | win_used = max(hc->tx_cwnd_used, init_win); |
204 | |
205 | if (win_used < hc->tx_cwnd) { |
206 | hc->tx_ssthresh = max(hc->tx_ssthresh, |
207 | (hc->tx_cwnd >> 1) + (hc->tx_cwnd >> 2)); |
208 | hc->tx_cwnd = (hc->tx_cwnd + win_used) >> 1; |
209 | } |
210 | hc->tx_cwnd_used = 0; |
211 | hc->tx_cwnd_stamp = now; |
212 | |
213 | ccid2_check_l_ack_ratio(sk); |
214 | } |
215 | |
216 | /* This borrows the code of tcp_cwnd_restart() */ |
217 | static void ccid2_cwnd_restart(struct sock *sk, const u32 now) |
218 | { |
219 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
220 | u32 cwnd = hc->tx_cwnd, restart_cwnd, |
221 | iwnd = rfc3390_bytes_to_packets(dccp_sk(sk)->dccps_mss_cache); |
222 | s32 delta = now - hc->tx_lsndtime; |
223 | |
224 | hc->tx_ssthresh = max(hc->tx_ssthresh, (cwnd >> 1) + (cwnd >> 2)); |
225 | |
226 | /* don't reduce cwnd below the initial window (IW) */ |
227 | restart_cwnd = min(cwnd, iwnd); |
228 | |
229 | while ((delta -= hc->tx_rto) >= 0 && cwnd > restart_cwnd) |
230 | cwnd >>= 1; |
231 | hc->tx_cwnd = max(cwnd, restart_cwnd); |
232 | hc->tx_cwnd_stamp = now; |
233 | hc->tx_cwnd_used = 0; |
234 | |
235 | ccid2_check_l_ack_ratio(sk); |
236 | } |
237 | |
238 | static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len) |
239 | { |
240 | struct dccp_sock *dp = dccp_sk(sk); |
241 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
242 | const u32 now = ccid2_jiffies32; |
243 | struct ccid2_seq *next; |
244 | |
245 | /* slow-start after idle periods (RFC 2581, RFC 2861) */ |
246 | if (ccid2_do_cwv && !hc->tx_pipe && |
247 | (s32)(now - hc->tx_lsndtime) >= hc->tx_rto) |
248 | ccid2_cwnd_restart(sk, now); |
249 | |
250 | hc->tx_lsndtime = now; |
251 | hc->tx_pipe += 1; |
252 | |
253 | /* see whether cwnd was fully used (RFC 2861), update expected window */ |
254 | if (ccid2_cwnd_network_limited(hc)) { |
255 | ccid2_update_used_window(hc, new_wnd: hc->tx_cwnd); |
256 | hc->tx_cwnd_used = 0; |
257 | hc->tx_cwnd_stamp = now; |
258 | } else { |
259 | if (hc->tx_pipe > hc->tx_cwnd_used) |
260 | hc->tx_cwnd_used = hc->tx_pipe; |
261 | |
262 | ccid2_update_used_window(hc, new_wnd: hc->tx_cwnd_used); |
263 | |
264 | if (ccid2_do_cwv && (s32)(now - hc->tx_cwnd_stamp) >= hc->tx_rto) |
265 | ccid2_cwnd_application_limited(sk, now); |
266 | } |
267 | |
268 | hc->tx_seqh->ccid2s_seq = dp->dccps_gss; |
269 | hc->tx_seqh->ccid2s_acked = 0; |
270 | hc->tx_seqh->ccid2s_sent = now; |
271 | |
272 | next = hc->tx_seqh->ccid2s_next; |
273 | /* check if we need to alloc more space */ |
274 | if (next == hc->tx_seqt) { |
275 | if (ccid2_hc_tx_alloc_seq(hc)) { |
276 | DCCP_CRIT("packet history - out of memory!" ); |
277 | /* FIXME: find a more graceful way to bail out */ |
278 | return; |
279 | } |
280 | next = hc->tx_seqh->ccid2s_next; |
281 | BUG_ON(next == hc->tx_seqt); |
282 | } |
283 | hc->tx_seqh = next; |
284 | |
285 | ccid2_pr_debug("cwnd=%d pipe=%d\n" , hc->tx_cwnd, hc->tx_pipe); |
286 | |
287 | /* |
288 | * FIXME: The code below is broken and the variables have been removed |
289 | * from the socket struct. The `ackloss' variable was always set to 0, |
290 | * and with arsent there are several problems: |
291 | * (i) it doesn't just count the number of Acks, but all sent packets; |
292 | * (ii) it is expressed in # of packets, not # of windows, so the |
293 | * comparison below uses the wrong formula: Appendix A of RFC 4341 |
294 | * comes up with the number K = cwnd / (R^2 - R) of consecutive windows |
295 | * of data with no lost or marked Ack packets. If arsent were the # of |
296 | * consecutive Acks received without loss, then Ack Ratio needs to be |
297 | * decreased by 1 when |
298 | * arsent >= K * cwnd / R = cwnd^2 / (R^3 - R^2) |
299 | * where cwnd / R is the number of Acks received per window of data |
300 | * (cf. RFC 4341, App. A). The problems are that |
301 | * - arsent counts other packets as well; |
302 | * - the comparison uses a formula different from RFC 4341; |
303 | * - computing a cubic/quadratic equation each time is too complicated. |
304 | * Hence a different algorithm is needed. |
305 | */ |
306 | #if 0 |
307 | /* Ack Ratio. Need to maintain a concept of how many windows we sent */ |
308 | hc->tx_arsent++; |
309 | /* We had an ack loss in this window... */ |
310 | if (hc->tx_ackloss) { |
311 | if (hc->tx_arsent >= hc->tx_cwnd) { |
312 | hc->tx_arsent = 0; |
313 | hc->tx_ackloss = 0; |
314 | } |
315 | } else { |
316 | /* No acks lost up to now... */ |
317 | /* decrease ack ratio if enough packets were sent */ |
318 | if (dp->dccps_l_ack_ratio > 1) { |
319 | /* XXX don't calculate denominator each time */ |
320 | int denom = dp->dccps_l_ack_ratio * dp->dccps_l_ack_ratio - |
321 | dp->dccps_l_ack_ratio; |
322 | |
323 | denom = hc->tx_cwnd * hc->tx_cwnd / denom; |
324 | |
325 | if (hc->tx_arsent >= denom) { |
326 | ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio - 1); |
327 | hc->tx_arsent = 0; |
328 | } |
329 | } else { |
330 | /* we can't increase ack ratio further [1] */ |
331 | hc->tx_arsent = 0; /* or maybe set it to cwnd*/ |
332 | } |
333 | } |
334 | #endif |
335 | |
336 | sk_reset_timer(sk, timer: &hc->tx_rtotimer, expires: jiffies + hc->tx_rto); |
337 | |
338 | #ifdef CONFIG_IP_DCCP_CCID2_DEBUG |
339 | do { |
340 | struct ccid2_seq *seqp = hc->tx_seqt; |
341 | |
342 | while (seqp != hc->tx_seqh) { |
343 | ccid2_pr_debug("out seq=%llu acked=%d time=%u\n" , |
344 | (unsigned long long)seqp->ccid2s_seq, |
345 | seqp->ccid2s_acked, seqp->ccid2s_sent); |
346 | seqp = seqp->ccid2s_next; |
347 | } |
348 | } while (0); |
349 | ccid2_pr_debug("=========\n" ); |
350 | #endif |
351 | } |
352 | |
353 | /** |
354 | * ccid2_rtt_estimator - Sample RTT and compute RTO using RFC2988 algorithm |
355 | * @sk: socket to perform estimator on |
356 | * |
357 | * This code is almost identical with TCP's tcp_rtt_estimator(), since |
358 | * - it has a higher sampling frequency (recommended by RFC 1323), |
359 | * - the RTO does not collapse into RTT due to RTTVAR going towards zero, |
360 | * - it is simple (cf. more complex proposals such as Eifel timer or research |
361 | * which suggests that the gain should be set according to window size), |
362 | * - in tests it was found to work well with CCID2 [gerrit]. |
363 | */ |
364 | static void ccid2_rtt_estimator(struct sock *sk, const long mrtt) |
365 | { |
366 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
367 | long m = mrtt ? : 1; |
368 | |
369 | if (hc->tx_srtt == 0) { |
370 | /* First measurement m */ |
371 | hc->tx_srtt = m << 3; |
372 | hc->tx_mdev = m << 1; |
373 | |
374 | hc->tx_mdev_max = max(hc->tx_mdev, tcp_rto_min(sk)); |
375 | hc->tx_rttvar = hc->tx_mdev_max; |
376 | |
377 | hc->tx_rtt_seq = dccp_sk(sk)->dccps_gss; |
378 | } else { |
379 | /* Update scaled SRTT as SRTT += 1/8 * (m - SRTT) */ |
380 | m -= (hc->tx_srtt >> 3); |
381 | hc->tx_srtt += m; |
382 | |
383 | /* Similarly, update scaled mdev with regard to |m| */ |
384 | if (m < 0) { |
385 | m = -m; |
386 | m -= (hc->tx_mdev >> 2); |
387 | /* |
388 | * This neutralises RTO increase when RTT < SRTT - mdev |
389 | * (see P. Sarolahti, A. Kuznetsov,"Congestion Control |
390 | * in Linux TCP", USENIX 2002, pp. 49-62). |
391 | */ |
392 | if (m > 0) |
393 | m >>= 3; |
394 | } else { |
395 | m -= (hc->tx_mdev >> 2); |
396 | } |
397 | hc->tx_mdev += m; |
398 | |
399 | if (hc->tx_mdev > hc->tx_mdev_max) { |
400 | hc->tx_mdev_max = hc->tx_mdev; |
401 | if (hc->tx_mdev_max > hc->tx_rttvar) |
402 | hc->tx_rttvar = hc->tx_mdev_max; |
403 | } |
404 | |
405 | /* |
406 | * Decay RTTVAR at most once per flight, exploiting that |
407 | * 1) pipe <= cwnd <= Sequence_Window = W (RFC 4340, 7.5.2) |
408 | * 2) AWL = GSS-W+1 <= GAR <= GSS (RFC 4340, 7.5.1) |
409 | * GAR is a useful bound for FlightSize = pipe. |
410 | * AWL is probably too low here, as it over-estimates pipe. |
411 | */ |
412 | if (after48(dccp_sk(sk)->dccps_gar, hc->tx_rtt_seq)) { |
413 | if (hc->tx_mdev_max < hc->tx_rttvar) |
414 | hc->tx_rttvar -= (hc->tx_rttvar - |
415 | hc->tx_mdev_max) >> 2; |
416 | hc->tx_rtt_seq = dccp_sk(sk)->dccps_gss; |
417 | hc->tx_mdev_max = tcp_rto_min(sk); |
418 | } |
419 | } |
420 | |
421 | /* |
422 | * Set RTO from SRTT and RTTVAR |
423 | * As in TCP, 4 * RTTVAR >= TCP_RTO_MIN, giving a minimum RTO of 200 ms. |
424 | * This agrees with RFC 4341, 5: |
425 | * "Because DCCP does not retransmit data, DCCP does not require |
426 | * TCP's recommended minimum timeout of one second". |
427 | */ |
428 | hc->tx_rto = (hc->tx_srtt >> 3) + hc->tx_rttvar; |
429 | |
430 | if (hc->tx_rto > DCCP_RTO_MAX) |
431 | hc->tx_rto = DCCP_RTO_MAX; |
432 | } |
433 | |
434 | static void ccid2_new_ack(struct sock *sk, struct ccid2_seq *seqp, |
435 | unsigned int *maxincr) |
436 | { |
437 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
438 | struct dccp_sock *dp = dccp_sk(sk); |
439 | int r_seq_used = hc->tx_cwnd / dp->dccps_l_ack_ratio; |
440 | |
441 | if (hc->tx_cwnd < dp->dccps_l_seq_win && |
442 | r_seq_used < dp->dccps_r_seq_win) { |
443 | if (hc->tx_cwnd < hc->tx_ssthresh) { |
444 | if (*maxincr > 0 && ++hc->tx_packets_acked >= 2) { |
445 | hc->tx_cwnd += 1; |
446 | *maxincr -= 1; |
447 | hc->tx_packets_acked = 0; |
448 | } |
449 | } else if (++hc->tx_packets_acked >= hc->tx_cwnd) { |
450 | hc->tx_cwnd += 1; |
451 | hc->tx_packets_acked = 0; |
452 | } |
453 | } |
454 | |
455 | /* |
456 | * Adjust the local sequence window and the ack ratio to allow about |
457 | * 5 times the number of packets in the network (RFC 4340 7.5.2) |
458 | */ |
459 | if (r_seq_used * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_r_seq_win) |
460 | ccid2_change_l_ack_ratio(sk, val: dp->dccps_l_ack_ratio * 2); |
461 | else if (r_seq_used * CCID2_WIN_CHANGE_FACTOR < dp->dccps_r_seq_win/2) |
462 | ccid2_change_l_ack_ratio(sk, val: dp->dccps_l_ack_ratio / 2 ? : 1U); |
463 | |
464 | if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_l_seq_win) |
465 | ccid2_change_l_seq_window(sk, val: dp->dccps_l_seq_win * 2); |
466 | else if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR < dp->dccps_l_seq_win/2) |
467 | ccid2_change_l_seq_window(sk, val: dp->dccps_l_seq_win / 2); |
468 | |
469 | /* |
470 | * FIXME: RTT is sampled several times per acknowledgment (for each |
471 | * entry in the Ack Vector), instead of once per Ack (as in TCP SACK). |
472 | * This causes the RTT to be over-estimated, since the older entries |
473 | * in the Ack Vector have earlier sending times. |
474 | * The cleanest solution is to not use the ccid2s_sent field at all |
475 | * and instead use DCCP timestamps: requires changes in other places. |
476 | */ |
477 | ccid2_rtt_estimator(sk, ccid2_jiffies32 - seqp->ccid2s_sent); |
478 | } |
479 | |
480 | static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp) |
481 | { |
482 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
483 | |
484 | if ((s32)(seqp->ccid2s_sent - hc->tx_last_cong) < 0) { |
485 | ccid2_pr_debug("Multiple losses in an RTT---treating as one\n" ); |
486 | return; |
487 | } |
488 | |
489 | hc->tx_last_cong = ccid2_jiffies32; |
490 | |
491 | hc->tx_cwnd = hc->tx_cwnd / 2 ? : 1U; |
492 | hc->tx_ssthresh = max(hc->tx_cwnd, 2U); |
493 | |
494 | ccid2_check_l_ack_ratio(sk); |
495 | } |
496 | |
497 | static int ccid2_hc_tx_parse_options(struct sock *sk, u8 packet_type, |
498 | u8 option, u8 *optval, u8 optlen) |
499 | { |
500 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
501 | |
502 | switch (option) { |
503 | case DCCPO_ACK_VECTOR_0: |
504 | case DCCPO_ACK_VECTOR_1: |
505 | return dccp_ackvec_parsed_add(head: &hc->tx_av_chunks, vec: optval, len: optlen, |
506 | nonce: option - DCCPO_ACK_VECTOR_0); |
507 | } |
508 | return 0; |
509 | } |
510 | |
511 | static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) |
512 | { |
513 | struct dccp_sock *dp = dccp_sk(sk); |
514 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
515 | const bool sender_was_blocked = ccid2_cwnd_network_limited(hc); |
516 | struct dccp_ackvec_parsed *avp; |
517 | u64 ackno, seqno; |
518 | struct ccid2_seq *seqp; |
519 | int done = 0; |
520 | unsigned int maxincr = 0; |
521 | |
522 | /* check reverse path congestion */ |
523 | seqno = DCCP_SKB_CB(skb)->dccpd_seq; |
524 | |
525 | /* XXX this whole "algorithm" is broken. Need to fix it to keep track |
526 | * of the seqnos of the dupacks so that rpseq and rpdupack are correct |
527 | * -sorbo. |
528 | */ |
529 | /* need to bootstrap */ |
530 | if (hc->tx_rpdupack == -1) { |
531 | hc->tx_rpdupack = 0; |
532 | hc->tx_rpseq = seqno; |
533 | } else { |
534 | /* check if packet is consecutive */ |
535 | if (dccp_delta_seqno(seqno1: hc->tx_rpseq, seqno2: seqno) == 1) |
536 | hc->tx_rpseq = seqno; |
537 | /* it's a later packet */ |
538 | else if (after48(seqno, hc->tx_rpseq)) { |
539 | hc->tx_rpdupack++; |
540 | |
541 | /* check if we got enough dupacks */ |
542 | if (hc->tx_rpdupack >= NUMDUPACK) { |
543 | hc->tx_rpdupack = -1; /* XXX lame */ |
544 | hc->tx_rpseq = 0; |
545 | #ifdef __CCID2_COPES_GRACEFULLY_WITH_ACK_CONGESTION_CONTROL__ |
546 | /* |
547 | * FIXME: Ack Congestion Control is broken; in |
548 | * the current state instabilities occurred with |
549 | * Ack Ratios greater than 1; causing hang-ups |
550 | * and long RTO timeouts. This needs to be fixed |
551 | * before opening up dynamic changes. -- gerrit |
552 | */ |
553 | ccid2_change_l_ack_ratio(sk, 2 * dp->dccps_l_ack_ratio); |
554 | #endif |
555 | } |
556 | } |
557 | } |
558 | |
559 | /* check forward path congestion */ |
560 | if (dccp_packet_without_ack(skb)) |
561 | return; |
562 | |
563 | /* still didn't send out new data packets */ |
564 | if (hc->tx_seqh == hc->tx_seqt) |
565 | goto done; |
566 | |
567 | ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq; |
568 | if (after48(ackno, hc->tx_high_ack)) |
569 | hc->tx_high_ack = ackno; |
570 | |
571 | seqp = hc->tx_seqt; |
572 | while (before48(seq1: seqp->ccid2s_seq, seq2: ackno)) { |
573 | seqp = seqp->ccid2s_next; |
574 | if (seqp == hc->tx_seqh) { |
575 | seqp = hc->tx_seqh->ccid2s_prev; |
576 | break; |
577 | } |
578 | } |
579 | |
580 | /* |
581 | * In slow-start, cwnd can increase up to a maximum of Ack Ratio/2 |
582 | * packets per acknowledgement. Rounding up avoids that cwnd is not |
583 | * advanced when Ack Ratio is 1 and gives a slight edge otherwise. |
584 | */ |
585 | if (hc->tx_cwnd < hc->tx_ssthresh) |
586 | maxincr = DIV_ROUND_UP(dp->dccps_l_ack_ratio, 2); |
587 | |
588 | /* go through all ack vectors */ |
589 | list_for_each_entry(avp, &hc->tx_av_chunks, node) { |
590 | /* go through this ack vector */ |
591 | for (; avp->len--; avp->vec++) { |
592 | u64 ackno_end_rl = SUB48(ackno, |
593 | dccp_ackvec_runlen(avp->vec)); |
594 | |
595 | ccid2_pr_debug("ackvec %llu |%u,%u|\n" , |
596 | (unsigned long long)ackno, |
597 | dccp_ackvec_state(avp->vec) >> 6, |
598 | dccp_ackvec_runlen(avp->vec)); |
599 | /* if the seqno we are analyzing is larger than the |
600 | * current ackno, then move towards the tail of our |
601 | * seqnos. |
602 | */ |
603 | while (after48(seqp->ccid2s_seq, ackno)) { |
604 | if (seqp == hc->tx_seqt) { |
605 | done = 1; |
606 | break; |
607 | } |
608 | seqp = seqp->ccid2s_prev; |
609 | } |
610 | if (done) |
611 | break; |
612 | |
613 | /* check all seqnos in the range of the vector |
614 | * run length |
615 | */ |
616 | while (between48(seq1: seqp->ccid2s_seq,seq2: ackno_end_rl,seq3: ackno)) { |
617 | const u8 state = dccp_ackvec_state(cell: avp->vec); |
618 | |
619 | /* new packet received or marked */ |
620 | if (state != DCCPAV_NOT_RECEIVED && |
621 | !seqp->ccid2s_acked) { |
622 | if (state == DCCPAV_ECN_MARKED) |
623 | ccid2_congestion_event(sk, |
624 | seqp); |
625 | else |
626 | ccid2_new_ack(sk, seqp, |
627 | maxincr: &maxincr); |
628 | |
629 | seqp->ccid2s_acked = 1; |
630 | ccid2_pr_debug("Got ack for %llu\n" , |
631 | (unsigned long long)seqp->ccid2s_seq); |
632 | hc->tx_pipe--; |
633 | } |
634 | if (seqp == hc->tx_seqt) { |
635 | done = 1; |
636 | break; |
637 | } |
638 | seqp = seqp->ccid2s_prev; |
639 | } |
640 | if (done) |
641 | break; |
642 | |
643 | ackno = SUB48(ackno_end_rl, 1); |
644 | } |
645 | if (done) |
646 | break; |
647 | } |
648 | |
649 | /* The state about what is acked should be correct now |
650 | * Check for NUMDUPACK |
651 | */ |
652 | seqp = hc->tx_seqt; |
653 | while (before48(seq1: seqp->ccid2s_seq, seq2: hc->tx_high_ack)) { |
654 | seqp = seqp->ccid2s_next; |
655 | if (seqp == hc->tx_seqh) { |
656 | seqp = hc->tx_seqh->ccid2s_prev; |
657 | break; |
658 | } |
659 | } |
660 | done = 0; |
661 | while (1) { |
662 | if (seqp->ccid2s_acked) { |
663 | done++; |
664 | if (done == NUMDUPACK) |
665 | break; |
666 | } |
667 | if (seqp == hc->tx_seqt) |
668 | break; |
669 | seqp = seqp->ccid2s_prev; |
670 | } |
671 | |
672 | /* If there are at least 3 acknowledgements, anything unacknowledged |
673 | * below the last sequence number is considered lost |
674 | */ |
675 | if (done == NUMDUPACK) { |
676 | struct ccid2_seq *last_acked = seqp; |
677 | |
678 | /* check for lost packets */ |
679 | while (1) { |
680 | if (!seqp->ccid2s_acked) { |
681 | ccid2_pr_debug("Packet lost: %llu\n" , |
682 | (unsigned long long)seqp->ccid2s_seq); |
683 | /* XXX need to traverse from tail -> head in |
684 | * order to detect multiple congestion events in |
685 | * one ack vector. |
686 | */ |
687 | ccid2_congestion_event(sk, seqp); |
688 | hc->tx_pipe--; |
689 | } |
690 | if (seqp == hc->tx_seqt) |
691 | break; |
692 | seqp = seqp->ccid2s_prev; |
693 | } |
694 | |
695 | hc->tx_seqt = last_acked; |
696 | } |
697 | |
698 | /* trim acked packets in tail */ |
699 | while (hc->tx_seqt != hc->tx_seqh) { |
700 | if (!hc->tx_seqt->ccid2s_acked) |
701 | break; |
702 | |
703 | hc->tx_seqt = hc->tx_seqt->ccid2s_next; |
704 | } |
705 | |
706 | /* restart RTO timer if not all outstanding data has been acked */ |
707 | if (hc->tx_pipe == 0) |
708 | sk_stop_timer(sk, timer: &hc->tx_rtotimer); |
709 | else |
710 | sk_reset_timer(sk, timer: &hc->tx_rtotimer, expires: jiffies + hc->tx_rto); |
711 | done: |
712 | /* check if incoming Acks allow pending packets to be sent */ |
713 | if (sender_was_blocked && !ccid2_cwnd_network_limited(hc)) |
714 | dccp_tasklet_schedule(sk); |
715 | dccp_ackvec_parsed_cleanup(parsed_chunks: &hc->tx_av_chunks); |
716 | } |
717 | |
718 | static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk) |
719 | { |
720 | struct ccid2_hc_tx_sock *hc = ccid_priv(ccid); |
721 | struct dccp_sock *dp = dccp_sk(sk); |
722 | u32 max_ratio; |
723 | |
724 | /* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */ |
725 | hc->tx_ssthresh = ~0U; |
726 | |
727 | /* Use larger initial windows (RFC 4341, section 5). */ |
728 | hc->tx_cwnd = rfc3390_bytes_to_packets(smss: dp->dccps_mss_cache); |
729 | hc->tx_expected_wnd = hc->tx_cwnd; |
730 | |
731 | /* Make sure that Ack Ratio is enabled and within bounds. */ |
732 | max_ratio = DIV_ROUND_UP(hc->tx_cwnd, 2); |
733 | if (dp->dccps_l_ack_ratio == 0 || dp->dccps_l_ack_ratio > max_ratio) |
734 | dp->dccps_l_ack_ratio = max_ratio; |
735 | |
736 | /* XXX init ~ to window size... */ |
737 | if (ccid2_hc_tx_alloc_seq(hc)) |
738 | return -ENOMEM; |
739 | |
740 | hc->tx_rto = DCCP_TIMEOUT_INIT; |
741 | hc->tx_rpdupack = -1; |
742 | hc->tx_last_cong = hc->tx_lsndtime = hc->tx_cwnd_stamp = ccid2_jiffies32; |
743 | hc->tx_cwnd_used = 0; |
744 | hc->sk = sk; |
745 | timer_setup(&hc->tx_rtotimer, ccid2_hc_tx_rto_expire, 0); |
746 | INIT_LIST_HEAD(list: &hc->tx_av_chunks); |
747 | return 0; |
748 | } |
749 | |
750 | static void ccid2_hc_tx_exit(struct sock *sk) |
751 | { |
752 | struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); |
753 | int i; |
754 | |
755 | sk_stop_timer(sk, timer: &hc->tx_rtotimer); |
756 | |
757 | for (i = 0; i < hc->tx_seqbufc; i++) |
758 | kfree(objp: hc->tx_seqbuf[i]); |
759 | hc->tx_seqbufc = 0; |
760 | dccp_ackvec_parsed_cleanup(parsed_chunks: &hc->tx_av_chunks); |
761 | } |
762 | |
763 | static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb) |
764 | { |
765 | struct ccid2_hc_rx_sock *hc = ccid2_hc_rx_sk(sk); |
766 | |
767 | if (!dccp_data_packet(skb)) |
768 | return; |
769 | |
770 | if (++hc->rx_num_data_pkts >= dccp_sk(sk)->dccps_r_ack_ratio) { |
771 | dccp_send_ack(sk); |
772 | hc->rx_num_data_pkts = 0; |
773 | } |
774 | } |
775 | |
776 | struct ccid_operations ccid2_ops = { |
777 | .ccid_id = DCCPC_CCID2, |
778 | .ccid_name = "TCP-like" , |
779 | .ccid_hc_tx_obj_size = sizeof(struct ccid2_hc_tx_sock), |
780 | .ccid_hc_tx_init = ccid2_hc_tx_init, |
781 | .ccid_hc_tx_exit = ccid2_hc_tx_exit, |
782 | .ccid_hc_tx_send_packet = ccid2_hc_tx_send_packet, |
783 | .ccid_hc_tx_packet_sent = ccid2_hc_tx_packet_sent, |
784 | .ccid_hc_tx_parse_options = ccid2_hc_tx_parse_options, |
785 | .ccid_hc_tx_packet_recv = ccid2_hc_tx_packet_recv, |
786 | .ccid_hc_rx_obj_size = sizeof(struct ccid2_hc_rx_sock), |
787 | .ccid_hc_rx_packet_recv = ccid2_hc_rx_packet_recv, |
788 | }; |
789 | |
790 | #ifdef CONFIG_IP_DCCP_CCID2_DEBUG |
791 | module_param(ccid2_debug, bool, 0644); |
792 | MODULE_PARM_DESC(ccid2_debug, "Enable CCID-2 debug messages" ); |
793 | #endif |
794 | |