1 /* 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 /* 24 * This implementation should follow RFC 4341 25 */ 26 #include <linux/slab.h> 27 #include "../feat.h" 28 #include "ccid2.h" 29 30 31 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG 32 static bool ccid2_debug; 33 #define ccid2_pr_debug(format, a...) DCCP_PR_DEBUG(ccid2_debug, format, ##a) 34 #else 35 #define ccid2_pr_debug(format, a...) 36 #endif 37 38 static int ccid2_hc_tx_alloc_seq(struct ccid2_hc_tx_sock *hc) 39 { 40 struct ccid2_seq *seqp; 41 int i; 42 43 /* check if we have space to preserve the pointer to the buffer */ 44 if (hc->tx_seqbufc >= (sizeof(hc->tx_seqbuf) / 45 sizeof(struct ccid2_seq *))) 46 return -ENOMEM; 47 48 /* allocate buffer and initialize linked list */ 49 seqp = kmalloc_array(CCID2_SEQBUF_LEN, sizeof(struct ccid2_seq), 50 gfp_any()); 51 if (seqp == NULL) 52 return -ENOMEM; 53 54 for (i = 0; i < (CCID2_SEQBUF_LEN - 1); i++) { 55 seqp[i].ccid2s_next = &seqp[i + 1]; 56 seqp[i + 1].ccid2s_prev = &seqp[i]; 57 } 58 seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = seqp; 59 seqp->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1]; 60 61 /* This is the first allocation. Initiate the head and tail. */ 62 if (hc->tx_seqbufc == 0) 63 hc->tx_seqh = hc->tx_seqt = seqp; 64 else { 65 /* link the existing list with the one we just created */ 66 hc->tx_seqh->ccid2s_next = seqp; 67 seqp->ccid2s_prev = hc->tx_seqh; 68 69 hc->tx_seqt->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1]; 70 seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = hc->tx_seqt; 71 } 72 73 /* store the original pointer to the buffer so we can free it */ 74 hc->tx_seqbuf[hc->tx_seqbufc] = seqp; 75 hc->tx_seqbufc++; 76 77 return 0; 78 } 79 80 static int ccid2_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) 81 { 82 if (ccid2_cwnd_network_limited(ccid2_hc_tx_sk(sk))) 83 return CCID_PACKET_WILL_DEQUEUE_LATER; 84 return CCID_PACKET_SEND_AT_ONCE; 85 } 86 87 static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val) 88 { 89 u32 max_ratio = DIV_ROUND_UP(ccid2_hc_tx_sk(sk)->tx_cwnd, 2); 90 91 /* 92 * Ensure that Ack Ratio does not exceed ceil(cwnd/2), which is (2) from 93 * RFC 4341, 6.1.2. We ignore the statement that Ack Ratio 2 is always 94 * acceptable since this causes starvation/deadlock whenever cwnd < 2. 95 * The same problem arises when Ack Ratio is 0 (ie. Ack Ratio disabled). 96 */ 97 if (val == 0 || val > max_ratio) { 98 DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio); 99 val = max_ratio; 100 } 101 dccp_feat_signal_nn_change(sk, DCCPF_ACK_RATIO, 102 min_t(u32, val, DCCPF_ACK_RATIO_MAX)); 103 } 104 105 static void ccid2_check_l_ack_ratio(struct sock *sk) 106 { 107 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); 108 109 /* 110 * After a loss, idle period, application limited period, or RTO we 111 * need to check that the ack ratio is still less than the congestion 112 * window. Otherwise, we will send an entire congestion window of 113 * packets and got no response because we haven't sent ack ratio 114 * packets yet. 115 * If the ack ratio does need to be reduced, we reduce it to half of 116 * the congestion window (or 1 if that's zero) instead of to the 117 * congestion window. This prevents problems if one ack is lost. 118 */ 119 if (dccp_feat_nn_get(sk, DCCPF_ACK_RATIO) > hc->tx_cwnd) 120 ccid2_change_l_ack_ratio(sk, hc->tx_cwnd/2 ? : 1U); 121 } 122 123 static void ccid2_change_l_seq_window(struct sock *sk, u64 val) 124 { 125 dccp_feat_signal_nn_change(sk, DCCPF_SEQUENCE_WINDOW, 126 clamp_val(val, DCCPF_SEQ_WMIN, 127 DCCPF_SEQ_WMAX)); 128 } 129 130 static void dccp_tasklet_schedule(struct sock *sk) 131 { 132 struct tasklet_struct *t = &dccp_sk(sk)->dccps_xmitlet; 133 134 if (!test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) { 135 sock_hold(sk); 136 __tasklet_schedule(t); 137 } 138 } 139 140 static void ccid2_hc_tx_rto_expire(struct timer_list *t) 141 { 142 struct ccid2_hc_tx_sock *hc = from_timer(hc, t, tx_rtotimer); 143 struct sock *sk = hc->sk; 144 const bool sender_was_blocked = ccid2_cwnd_network_limited(hc); 145 146 bh_lock_sock(sk); 147 if (sock_owned_by_user(sk)) { 148 sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + HZ / 5); 149 goto out; 150 } 151 152 ccid2_pr_debug("RTO_EXPIRE\n"); 153 154 if (sk->sk_state == DCCP_CLOSED) 155 goto out; 156 157 /* back-off timer */ 158 hc->tx_rto <<= 1; 159 if (hc->tx_rto > DCCP_RTO_MAX) 160 hc->tx_rto = DCCP_RTO_MAX; 161 162 /* adjust pipe, cwnd etc */ 163 hc->tx_ssthresh = hc->tx_cwnd / 2; 164 if (hc->tx_ssthresh < 2) 165 hc->tx_ssthresh = 2; 166 hc->tx_cwnd = 1; 167 hc->tx_pipe = 0; 168 169 /* clear state about stuff we sent */ 170 hc->tx_seqt = hc->tx_seqh; 171 hc->tx_packets_acked = 0; 172 173 /* clear ack ratio state. */ 174 hc->tx_rpseq = 0; 175 hc->tx_rpdupack = -1; 176 ccid2_change_l_ack_ratio(sk, 1); 177 178 /* if we were blocked before, we may now send cwnd=1 packet */ 179 if (sender_was_blocked) 180 dccp_tasklet_schedule(sk); 181 /* restart backed-off timer */ 182 sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto); 183 out: 184 bh_unlock_sock(sk); 185 sock_put(sk); 186 } 187 188 /* 189 * Congestion window validation (RFC 2861). 190 */ 191 static bool ccid2_do_cwv = true; 192 module_param(ccid2_do_cwv, bool, 0644); 193 MODULE_PARM_DESC(ccid2_do_cwv, "Perform RFC2861 Congestion Window Validation"); 194 195 /** 196 * ccid2_update_used_window - Track how much of cwnd is actually used 197 * This is done in addition to CWV. The sender needs to have an idea of how many 198 * packets may be in flight, to set the local Sequence Window value accordingly 199 * (RFC 4340, 7.5.2). The CWV mechanism is exploited to keep track of the 200 * maximum-used window. We use an EWMA low-pass filter to filter out noise. 201 */ 202 static void ccid2_update_used_window(struct ccid2_hc_tx_sock *hc, u32 new_wnd) 203 { 204 hc->tx_expected_wnd = (3 * hc->tx_expected_wnd + new_wnd) / 4; 205 } 206 207 /* This borrows the code of tcp_cwnd_application_limited() */ 208 static void ccid2_cwnd_application_limited(struct sock *sk, const u32 now) 209 { 210 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); 211 /* don't reduce cwnd below the initial window (IW) */ 212 u32 init_win = rfc3390_bytes_to_packets(dccp_sk(sk)->dccps_mss_cache), 213 win_used = max(hc->tx_cwnd_used, init_win); 214 215 if (win_used < hc->tx_cwnd) { 216 hc->tx_ssthresh = max(hc->tx_ssthresh, 217 (hc->tx_cwnd >> 1) + (hc->tx_cwnd >> 2)); 218 hc->tx_cwnd = (hc->tx_cwnd + win_used) >> 1; 219 } 220 hc->tx_cwnd_used = 0; 221 hc->tx_cwnd_stamp = now; 222 223 ccid2_check_l_ack_ratio(sk); 224 } 225 226 /* This borrows the code of tcp_cwnd_restart() */ 227 static void ccid2_cwnd_restart(struct sock *sk, const u32 now) 228 { 229 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); 230 u32 cwnd = hc->tx_cwnd, restart_cwnd, 231 iwnd = rfc3390_bytes_to_packets(dccp_sk(sk)->dccps_mss_cache); 232 233 hc->tx_ssthresh = max(hc->tx_ssthresh, (cwnd >> 1) + (cwnd >> 2)); 234 235 /* don't reduce cwnd below the initial window (IW) */ 236 restart_cwnd = min(cwnd, iwnd); 237 cwnd >>= (now - hc->tx_lsndtime) / hc->tx_rto; 238 hc->tx_cwnd = max(cwnd, restart_cwnd); 239 240 hc->tx_cwnd_stamp = now; 241 hc->tx_cwnd_used = 0; 242 243 ccid2_check_l_ack_ratio(sk); 244 } 245 246 static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len) 247 { 248 struct dccp_sock *dp = dccp_sk(sk); 249 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); 250 const u32 now = ccid2_jiffies32; 251 struct ccid2_seq *next; 252 253 /* slow-start after idle periods (RFC 2581, RFC 2861) */ 254 if (ccid2_do_cwv && !hc->tx_pipe && 255 (s32)(now - hc->tx_lsndtime) >= hc->tx_rto) 256 ccid2_cwnd_restart(sk, now); 257 258 hc->tx_lsndtime = now; 259 hc->tx_pipe += 1; 260 261 /* see whether cwnd was fully used (RFC 2861), update expected window */ 262 if (ccid2_cwnd_network_limited(hc)) { 263 ccid2_update_used_window(hc, hc->tx_cwnd); 264 hc->tx_cwnd_used = 0; 265 hc->tx_cwnd_stamp = now; 266 } else { 267 if (hc->tx_pipe > hc->tx_cwnd_used) 268 hc->tx_cwnd_used = hc->tx_pipe; 269 270 ccid2_update_used_window(hc, hc->tx_cwnd_used); 271 272 if (ccid2_do_cwv && (s32)(now - hc->tx_cwnd_stamp) >= hc->tx_rto) 273 ccid2_cwnd_application_limited(sk, now); 274 } 275 276 hc->tx_seqh->ccid2s_seq = dp->dccps_gss; 277 hc->tx_seqh->ccid2s_acked = 0; 278 hc->tx_seqh->ccid2s_sent = now; 279 280 next = hc->tx_seqh->ccid2s_next; 281 /* check if we need to alloc more space */ 282 if (next == hc->tx_seqt) { 283 if (ccid2_hc_tx_alloc_seq(hc)) { 284 DCCP_CRIT("packet history - out of memory!"); 285 /* FIXME: find a more graceful way to bail out */ 286 return; 287 } 288 next = hc->tx_seqh->ccid2s_next; 289 BUG_ON(next == hc->tx_seqt); 290 } 291 hc->tx_seqh = next; 292 293 ccid2_pr_debug("cwnd=%d pipe=%d\n", hc->tx_cwnd, hc->tx_pipe); 294 295 /* 296 * FIXME: The code below is broken and the variables have been removed 297 * from the socket struct. The `ackloss' variable was always set to 0, 298 * and with arsent there are several problems: 299 * (i) it doesn't just count the number of Acks, but all sent packets; 300 * (ii) it is expressed in # of packets, not # of windows, so the 301 * comparison below uses the wrong formula: Appendix A of RFC 4341 302 * comes up with the number K = cwnd / (R^2 - R) of consecutive windows 303 * of data with no lost or marked Ack packets. If arsent were the # of 304 * consecutive Acks received without loss, then Ack Ratio needs to be 305 * decreased by 1 when 306 * arsent >= K * cwnd / R = cwnd^2 / (R^3 - R^2) 307 * where cwnd / R is the number of Acks received per window of data 308 * (cf. RFC 4341, App. A). The problems are that 309 * - arsent counts other packets as well; 310 * - the comparison uses a formula different from RFC 4341; 311 * - computing a cubic/quadratic equation each time is too complicated. 312 * Hence a different algorithm is needed. 313 */ 314 #if 0 315 /* Ack Ratio. Need to maintain a concept of how many windows we sent */ 316 hc->tx_arsent++; 317 /* We had an ack loss in this window... */ 318 if (hc->tx_ackloss) { 319 if (hc->tx_arsent >= hc->tx_cwnd) { 320 hc->tx_arsent = 0; 321 hc->tx_ackloss = 0; 322 } 323 } else { 324 /* No acks lost up to now... */ 325 /* decrease ack ratio if enough packets were sent */ 326 if (dp->dccps_l_ack_ratio > 1) { 327 /* XXX don't calculate denominator each time */ 328 int denom = dp->dccps_l_ack_ratio * dp->dccps_l_ack_ratio - 329 dp->dccps_l_ack_ratio; 330 331 denom = hc->tx_cwnd * hc->tx_cwnd / denom; 332 333 if (hc->tx_arsent >= denom) { 334 ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio - 1); 335 hc->tx_arsent = 0; 336 } 337 } else { 338 /* we can't increase ack ratio further [1] */ 339 hc->tx_arsent = 0; /* or maybe set it to cwnd*/ 340 } 341 } 342 #endif 343 344 sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto); 345 346 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG 347 do { 348 struct ccid2_seq *seqp = hc->tx_seqt; 349 350 while (seqp != hc->tx_seqh) { 351 ccid2_pr_debug("out seq=%llu acked=%d time=%u\n", 352 (unsigned long long)seqp->ccid2s_seq, 353 seqp->ccid2s_acked, seqp->ccid2s_sent); 354 seqp = seqp->ccid2s_next; 355 } 356 } while (0); 357 ccid2_pr_debug("=========\n"); 358 #endif 359 } 360 361 /** 362 * ccid2_rtt_estimator - Sample RTT and compute RTO using RFC2988 algorithm 363 * This code is almost identical with TCP's tcp_rtt_estimator(), since 364 * - it has a higher sampling frequency (recommended by RFC 1323), 365 * - the RTO does not collapse into RTT due to RTTVAR going towards zero, 366 * - it is simple (cf. more complex proposals such as Eifel timer or research 367 * which suggests that the gain should be set according to window size), 368 * - in tests it was found to work well with CCID2 [gerrit]. 369 */ 370 static void ccid2_rtt_estimator(struct sock *sk, const long mrtt) 371 { 372 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); 373 long m = mrtt ? : 1; 374 375 if (hc->tx_srtt == 0) { 376 /* First measurement m */ 377 hc->tx_srtt = m << 3; 378 hc->tx_mdev = m << 1; 379 380 hc->tx_mdev_max = max(hc->tx_mdev, tcp_rto_min(sk)); 381 hc->tx_rttvar = hc->tx_mdev_max; 382 383 hc->tx_rtt_seq = dccp_sk(sk)->dccps_gss; 384 } else { 385 /* Update scaled SRTT as SRTT += 1/8 * (m - SRTT) */ 386 m -= (hc->tx_srtt >> 3); 387 hc->tx_srtt += m; 388 389 /* Similarly, update scaled mdev with regard to |m| */ 390 if (m < 0) { 391 m = -m; 392 m -= (hc->tx_mdev >> 2); 393 /* 394 * This neutralises RTO increase when RTT < SRTT - mdev 395 * (see P. Sarolahti, A. Kuznetsov,"Congestion Control 396 * in Linux TCP", USENIX 2002, pp. 49-62). 397 */ 398 if (m > 0) 399 m >>= 3; 400 } else { 401 m -= (hc->tx_mdev >> 2); 402 } 403 hc->tx_mdev += m; 404 405 if (hc->tx_mdev > hc->tx_mdev_max) { 406 hc->tx_mdev_max = hc->tx_mdev; 407 if (hc->tx_mdev_max > hc->tx_rttvar) 408 hc->tx_rttvar = hc->tx_mdev_max; 409 } 410 411 /* 412 * Decay RTTVAR at most once per flight, exploiting that 413 * 1) pipe <= cwnd <= Sequence_Window = W (RFC 4340, 7.5.2) 414 * 2) AWL = GSS-W+1 <= GAR <= GSS (RFC 4340, 7.5.1) 415 * GAR is a useful bound for FlightSize = pipe. 416 * AWL is probably too low here, as it over-estimates pipe. 417 */ 418 if (after48(dccp_sk(sk)->dccps_gar, hc->tx_rtt_seq)) { 419 if (hc->tx_mdev_max < hc->tx_rttvar) 420 hc->tx_rttvar -= (hc->tx_rttvar - 421 hc->tx_mdev_max) >> 2; 422 hc->tx_rtt_seq = dccp_sk(sk)->dccps_gss; 423 hc->tx_mdev_max = tcp_rto_min(sk); 424 } 425 } 426 427 /* 428 * Set RTO from SRTT and RTTVAR 429 * As in TCP, 4 * RTTVAR >= TCP_RTO_MIN, giving a minimum RTO of 200 ms. 430 * This agrees with RFC 4341, 5: 431 * "Because DCCP does not retransmit data, DCCP does not require 432 * TCP's recommended minimum timeout of one second". 433 */ 434 hc->tx_rto = (hc->tx_srtt >> 3) + hc->tx_rttvar; 435 436 if (hc->tx_rto > DCCP_RTO_MAX) 437 hc->tx_rto = DCCP_RTO_MAX; 438 } 439 440 static void ccid2_new_ack(struct sock *sk, struct ccid2_seq *seqp, 441 unsigned int *maxincr) 442 { 443 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); 444 struct dccp_sock *dp = dccp_sk(sk); 445 int r_seq_used = hc->tx_cwnd / dp->dccps_l_ack_ratio; 446 447 if (hc->tx_cwnd < dp->dccps_l_seq_win && 448 r_seq_used < dp->dccps_r_seq_win) { 449 if (hc->tx_cwnd < hc->tx_ssthresh) { 450 if (*maxincr > 0 && ++hc->tx_packets_acked >= 2) { 451 hc->tx_cwnd += 1; 452 *maxincr -= 1; 453 hc->tx_packets_acked = 0; 454 } 455 } else if (++hc->tx_packets_acked >= hc->tx_cwnd) { 456 hc->tx_cwnd += 1; 457 hc->tx_packets_acked = 0; 458 } 459 } 460 461 /* 462 * Adjust the local sequence window and the ack ratio to allow about 463 * 5 times the number of packets in the network (RFC 4340 7.5.2) 464 */ 465 if (r_seq_used * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_r_seq_win) 466 ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio * 2); 467 else if (r_seq_used * CCID2_WIN_CHANGE_FACTOR < dp->dccps_r_seq_win/2) 468 ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio / 2 ? : 1U); 469 470 if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_l_seq_win) 471 ccid2_change_l_seq_window(sk, dp->dccps_l_seq_win * 2); 472 else if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR < dp->dccps_l_seq_win/2) 473 ccid2_change_l_seq_window(sk, dp->dccps_l_seq_win / 2); 474 475 /* 476 * FIXME: RTT is sampled several times per acknowledgment (for each 477 * entry in the Ack Vector), instead of once per Ack (as in TCP SACK). 478 * This causes the RTT to be over-estimated, since the older entries 479 * in the Ack Vector have earlier sending times. 480 * The cleanest solution is to not use the ccid2s_sent field at all 481 * and instead use DCCP timestamps: requires changes in other places. 482 */ 483 ccid2_rtt_estimator(sk, ccid2_jiffies32 - seqp->ccid2s_sent); 484 } 485 486 static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp) 487 { 488 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); 489 490 if ((s32)(seqp->ccid2s_sent - hc->tx_last_cong) < 0) { 491 ccid2_pr_debug("Multiple losses in an RTT---treating as one\n"); 492 return; 493 } 494 495 hc->tx_last_cong = ccid2_jiffies32; 496 497 hc->tx_cwnd = hc->tx_cwnd / 2 ? : 1U; 498 hc->tx_ssthresh = max(hc->tx_cwnd, 2U); 499 500 ccid2_check_l_ack_ratio(sk); 501 } 502 503 static int ccid2_hc_tx_parse_options(struct sock *sk, u8 packet_type, 504 u8 option, u8 *optval, u8 optlen) 505 { 506 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); 507 508 switch (option) { 509 case DCCPO_ACK_VECTOR_0: 510 case DCCPO_ACK_VECTOR_1: 511 return dccp_ackvec_parsed_add(&hc->tx_av_chunks, optval, optlen, 512 option - DCCPO_ACK_VECTOR_0); 513 } 514 return 0; 515 } 516 517 static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) 518 { 519 struct dccp_sock *dp = dccp_sk(sk); 520 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); 521 const bool sender_was_blocked = ccid2_cwnd_network_limited(hc); 522 struct dccp_ackvec_parsed *avp; 523 u64 ackno, seqno; 524 struct ccid2_seq *seqp; 525 int done = 0; 526 unsigned int maxincr = 0; 527 528 /* check reverse path congestion */ 529 seqno = DCCP_SKB_CB(skb)->dccpd_seq; 530 531 /* XXX this whole "algorithm" is broken. Need to fix it to keep track 532 * of the seqnos of the dupacks so that rpseq and rpdupack are correct 533 * -sorbo. 534 */ 535 /* need to bootstrap */ 536 if (hc->tx_rpdupack == -1) { 537 hc->tx_rpdupack = 0; 538 hc->tx_rpseq = seqno; 539 } else { 540 /* check if packet is consecutive */ 541 if (dccp_delta_seqno(hc->tx_rpseq, seqno) == 1) 542 hc->tx_rpseq = seqno; 543 /* it's a later packet */ 544 else if (after48(seqno, hc->tx_rpseq)) { 545 hc->tx_rpdupack++; 546 547 /* check if we got enough dupacks */ 548 if (hc->tx_rpdupack >= NUMDUPACK) { 549 hc->tx_rpdupack = -1; /* XXX lame */ 550 hc->tx_rpseq = 0; 551 #ifdef __CCID2_COPES_GRACEFULLY_WITH_ACK_CONGESTION_CONTROL__ 552 /* 553 * FIXME: Ack Congestion Control is broken; in 554 * the current state instabilities occurred with 555 * Ack Ratios greater than 1; causing hang-ups 556 * and long RTO timeouts. This needs to be fixed 557 * before opening up dynamic changes. -- gerrit 558 */ 559 ccid2_change_l_ack_ratio(sk, 2 * dp->dccps_l_ack_ratio); 560 #endif 561 } 562 } 563 } 564 565 /* check forward path congestion */ 566 if (dccp_packet_without_ack(skb)) 567 return; 568 569 /* still didn't send out new data packets */ 570 if (hc->tx_seqh == hc->tx_seqt) 571 goto done; 572 573 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq; 574 if (after48(ackno, hc->tx_high_ack)) 575 hc->tx_high_ack = ackno; 576 577 seqp = hc->tx_seqt; 578 while (before48(seqp->ccid2s_seq, ackno)) { 579 seqp = seqp->ccid2s_next; 580 if (seqp == hc->tx_seqh) { 581 seqp = hc->tx_seqh->ccid2s_prev; 582 break; 583 } 584 } 585 586 /* 587 * In slow-start, cwnd can increase up to a maximum of Ack Ratio/2 588 * packets per acknowledgement. Rounding up avoids that cwnd is not 589 * advanced when Ack Ratio is 1 and gives a slight edge otherwise. 590 */ 591 if (hc->tx_cwnd < hc->tx_ssthresh) 592 maxincr = DIV_ROUND_UP(dp->dccps_l_ack_ratio, 2); 593 594 /* go through all ack vectors */ 595 list_for_each_entry(avp, &hc->tx_av_chunks, node) { 596 /* go through this ack vector */ 597 for (; avp->len--; avp->vec++) { 598 u64 ackno_end_rl = SUB48(ackno, 599 dccp_ackvec_runlen(avp->vec)); 600 601 ccid2_pr_debug("ackvec %llu |%u,%u|\n", 602 (unsigned long long)ackno, 603 dccp_ackvec_state(avp->vec) >> 6, 604 dccp_ackvec_runlen(avp->vec)); 605 /* if the seqno we are analyzing is larger than the 606 * current ackno, then move towards the tail of our 607 * seqnos. 608 */ 609 while (after48(seqp->ccid2s_seq, ackno)) { 610 if (seqp == hc->tx_seqt) { 611 done = 1; 612 break; 613 } 614 seqp = seqp->ccid2s_prev; 615 } 616 if (done) 617 break; 618 619 /* check all seqnos in the range of the vector 620 * run length 621 */ 622 while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) { 623 const u8 state = dccp_ackvec_state(avp->vec); 624 625 /* new packet received or marked */ 626 if (state != DCCPAV_NOT_RECEIVED && 627 !seqp->ccid2s_acked) { 628 if (state == DCCPAV_ECN_MARKED) 629 ccid2_congestion_event(sk, 630 seqp); 631 else 632 ccid2_new_ack(sk, seqp, 633 &maxincr); 634 635 seqp->ccid2s_acked = 1; 636 ccid2_pr_debug("Got ack for %llu\n", 637 (unsigned long long)seqp->ccid2s_seq); 638 hc->tx_pipe--; 639 } 640 if (seqp == hc->tx_seqt) { 641 done = 1; 642 break; 643 } 644 seqp = seqp->ccid2s_prev; 645 } 646 if (done) 647 break; 648 649 ackno = SUB48(ackno_end_rl, 1); 650 } 651 if (done) 652 break; 653 } 654 655 /* The state about what is acked should be correct now 656 * Check for NUMDUPACK 657 */ 658 seqp = hc->tx_seqt; 659 while (before48(seqp->ccid2s_seq, hc->tx_high_ack)) { 660 seqp = seqp->ccid2s_next; 661 if (seqp == hc->tx_seqh) { 662 seqp = hc->tx_seqh->ccid2s_prev; 663 break; 664 } 665 } 666 done = 0; 667 while (1) { 668 if (seqp->ccid2s_acked) { 669 done++; 670 if (done == NUMDUPACK) 671 break; 672 } 673 if (seqp == hc->tx_seqt) 674 break; 675 seqp = seqp->ccid2s_prev; 676 } 677 678 /* If there are at least 3 acknowledgements, anything unacknowledged 679 * below the last sequence number is considered lost 680 */ 681 if (done == NUMDUPACK) { 682 struct ccid2_seq *last_acked = seqp; 683 684 /* check for lost packets */ 685 while (1) { 686 if (!seqp->ccid2s_acked) { 687 ccid2_pr_debug("Packet lost: %llu\n", 688 (unsigned long long)seqp->ccid2s_seq); 689 /* XXX need to traverse from tail -> head in 690 * order to detect multiple congestion events in 691 * one ack vector. 692 */ 693 ccid2_congestion_event(sk, seqp); 694 hc->tx_pipe--; 695 } 696 if (seqp == hc->tx_seqt) 697 break; 698 seqp = seqp->ccid2s_prev; 699 } 700 701 hc->tx_seqt = last_acked; 702 } 703 704 /* trim acked packets in tail */ 705 while (hc->tx_seqt != hc->tx_seqh) { 706 if (!hc->tx_seqt->ccid2s_acked) 707 break; 708 709 hc->tx_seqt = hc->tx_seqt->ccid2s_next; 710 } 711 712 /* restart RTO timer if not all outstanding data has been acked */ 713 if (hc->tx_pipe == 0) 714 sk_stop_timer(sk, &hc->tx_rtotimer); 715 else 716 sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto); 717 done: 718 /* check if incoming Acks allow pending packets to be sent */ 719 if (sender_was_blocked && !ccid2_cwnd_network_limited(hc)) 720 dccp_tasklet_schedule(sk); 721 dccp_ackvec_parsed_cleanup(&hc->tx_av_chunks); 722 } 723 724 static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk) 725 { 726 struct ccid2_hc_tx_sock *hc = ccid_priv(ccid); 727 struct dccp_sock *dp = dccp_sk(sk); 728 u32 max_ratio; 729 730 /* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */ 731 hc->tx_ssthresh = ~0U; 732 733 /* Use larger initial windows (RFC 4341, section 5). */ 734 hc->tx_cwnd = rfc3390_bytes_to_packets(dp->dccps_mss_cache); 735 hc->tx_expected_wnd = hc->tx_cwnd; 736 737 /* Make sure that Ack Ratio is enabled and within bounds. */ 738 max_ratio = DIV_ROUND_UP(hc->tx_cwnd, 2); 739 if (dp->dccps_l_ack_ratio == 0 || dp->dccps_l_ack_ratio > max_ratio) 740 dp->dccps_l_ack_ratio = max_ratio; 741 742 /* XXX init ~ to window size... */ 743 if (ccid2_hc_tx_alloc_seq(hc)) 744 return -ENOMEM; 745 746 hc->tx_rto = DCCP_TIMEOUT_INIT; 747 hc->tx_rpdupack = -1; 748 hc->tx_last_cong = hc->tx_lsndtime = hc->tx_cwnd_stamp = ccid2_jiffies32; 749 hc->tx_cwnd_used = 0; 750 hc->sk = sk; 751 timer_setup(&hc->tx_rtotimer, ccid2_hc_tx_rto_expire, 0); 752 INIT_LIST_HEAD(&hc->tx_av_chunks); 753 return 0; 754 } 755 756 static void ccid2_hc_tx_exit(struct sock *sk) 757 { 758 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); 759 int i; 760 761 sk_stop_timer(sk, &hc->tx_rtotimer); 762 763 for (i = 0; i < hc->tx_seqbufc; i++) 764 kfree(hc->tx_seqbuf[i]); 765 hc->tx_seqbufc = 0; 766 dccp_ackvec_parsed_cleanup(&hc->tx_av_chunks); 767 } 768 769 static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb) 770 { 771 struct ccid2_hc_rx_sock *hc = ccid2_hc_rx_sk(sk); 772 773 if (!dccp_data_packet(skb)) 774 return; 775 776 if (++hc->rx_num_data_pkts >= dccp_sk(sk)->dccps_r_ack_ratio) { 777 dccp_send_ack(sk); 778 hc->rx_num_data_pkts = 0; 779 } 780 } 781 782 struct ccid_operations ccid2_ops = { 783 .ccid_id = DCCPC_CCID2, 784 .ccid_name = "TCP-like", 785 .ccid_hc_tx_obj_size = sizeof(struct ccid2_hc_tx_sock), 786 .ccid_hc_tx_init = ccid2_hc_tx_init, 787 .ccid_hc_tx_exit = ccid2_hc_tx_exit, 788 .ccid_hc_tx_send_packet = ccid2_hc_tx_send_packet, 789 .ccid_hc_tx_packet_sent = ccid2_hc_tx_packet_sent, 790 .ccid_hc_tx_parse_options = ccid2_hc_tx_parse_options, 791 .ccid_hc_tx_packet_recv = ccid2_hc_tx_packet_recv, 792 .ccid_hc_rx_obj_size = sizeof(struct ccid2_hc_rx_sock), 793 .ccid_hc_rx_packet_recv = ccid2_hc_rx_packet_recv, 794 }; 795 796 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG 797 module_param(ccid2_debug, bool, 0644); 798 MODULE_PARM_DESC(ccid2_debug, "Enable CCID-2 debug messages"); 799 #endif 800