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(CCID2_SEQBUF_LEN * sizeof(struct ccid2_seq), gfp_any()); 50 if (seqp == NULL) 51 return -ENOMEM; 52 53 for (i = 0; i < (CCID2_SEQBUF_LEN - 1); i++) { 54 seqp[i].ccid2s_next = &seqp[i + 1]; 55 seqp[i + 1].ccid2s_prev = &seqp[i]; 56 } 57 seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = seqp; 58 seqp->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1]; 59 60 /* This is the first allocation. Initiate the head and tail. */ 61 if (hc->tx_seqbufc == 0) 62 hc->tx_seqh = hc->tx_seqt = seqp; 63 else { 64 /* link the existing list with the one we just created */ 65 hc->tx_seqh->ccid2s_next = seqp; 66 seqp->ccid2s_prev = hc->tx_seqh; 67 68 hc->tx_seqt->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1]; 69 seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = hc->tx_seqt; 70 } 71 72 /* store the original pointer to the buffer so we can free it */ 73 hc->tx_seqbuf[hc->tx_seqbufc] = seqp; 74 hc->tx_seqbufc++; 75 76 return 0; 77 } 78 79 static int ccid2_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) 80 { 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; 84 } 85 86 static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val) 87 { 88 u32 max_ratio = DIV_ROUND_UP(ccid2_hc_tx_sk(sk)->tx_cwnd, 2); 89 90 /* 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). 95 */ 96 if (val == 0 || val > max_ratio) { 97 DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio); 98 val = max_ratio; 99 } 100 dccp_feat_signal_nn_change(sk, DCCPF_ACK_RATIO, 101 min_t(u32, val, DCCPF_ACK_RATIO_MAX)); 102 } 103 104 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 } 121 122 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)); 127 } 128 129 static void ccid2_hc_tx_rto_expire(unsigned long data) 130 { 131 struct sock *sk = (struct sock *)data; 132 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); 133 const bool sender_was_blocked = ccid2_cwnd_network_limited(hc); 134 135 bh_lock_sock(sk); 136 if (sock_owned_by_user(sk)) { 137 sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + HZ / 5); 138 goto out; 139 } 140 141 ccid2_pr_debug("RTO_EXPIRE\n"); 142 143 /* back-off timer */ 144 hc->tx_rto <<= 1; 145 if (hc->tx_rto > DCCP_RTO_MAX) 146 hc->tx_rto = DCCP_RTO_MAX; 147 148 /* adjust pipe, cwnd etc */ 149 hc->tx_ssthresh = hc->tx_cwnd / 2; 150 if (hc->tx_ssthresh < 2) 151 hc->tx_ssthresh = 2; 152 hc->tx_cwnd = 1; 153 hc->tx_pipe = 0; 154 155 /* clear state about stuff we sent */ 156 hc->tx_seqt = hc->tx_seqh; 157 hc->tx_packets_acked = 0; 158 159 /* clear ack ratio state. */ 160 hc->tx_rpseq = 0; 161 hc->tx_rpdupack = -1; 162 ccid2_change_l_ack_ratio(sk, 1); 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); 169 out: 170 bh_unlock_sock(sk); 171 sock_put(sk); 172 } 173 174 /* 175 * Congestion window validation (RFC 2861). 176 */ 177 static bool ccid2_do_cwv = true; 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; 208 209 ccid2_check_l_ack_ratio(sk); 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; 228 229 ccid2_check_l_ack_ratio(sk); 230 } 231 232 static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len) 233 { 234 struct dccp_sock *dp = dccp_sk(sk); 235 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); 236 const u32 now = ccid2_time_stamp; 237 struct ccid2_seq *next; 238 239 /* 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 } 261 262 hc->tx_seqh->ccid2s_seq = dp->dccps_gss; 263 hc->tx_seqh->ccid2s_acked = 0; 264 hc->tx_seqh->ccid2s_sent = now; 265 266 next = hc->tx_seqh->ccid2s_next; 267 /* check if we need to alloc more space */ 268 if (next == hc->tx_seqt) { 269 if (ccid2_hc_tx_alloc_seq(hc)) { 270 DCCP_CRIT("packet history - out of memory!"); 271 /* FIXME: find a more graceful way to bail out */ 272 return; 273 } 274 next = hc->tx_seqh->ccid2s_next; 275 BUG_ON(next == hc->tx_seqt); 276 } 277 hc->tx_seqh = next; 278 279 ccid2_pr_debug("cwnd=%d pipe=%d\n", hc->tx_cwnd, hc->tx_pipe); 280 281 /* 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 0 301 /* Ack Ratio. Need to maintain a concept of how many windows we sent */ 302 hc->tx_arsent++; 303 /* We had an ack loss in this window... */ 304 if (hc->tx_ackloss) { 305 if (hc->tx_arsent >= hc->tx_cwnd) { 306 hc->tx_arsent = 0; 307 hc->tx_ackloss = 0; 308 } 309 } else { 310 /* No acks lost up to now... */ 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 */ 314 int denom = dp->dccps_l_ack_ratio * dp->dccps_l_ack_ratio - 315 dp->dccps_l_ack_ratio; 316 317 denom = hc->tx_cwnd * hc->tx_cwnd / denom; 318 319 if (hc->tx_arsent >= denom) { 320 ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio - 1); 321 hc->tx_arsent = 0; 322 } 323 } else { 324 /* we can't increase ack ratio further [1] */ 325 hc->tx_arsent = 0; /* or maybe set it to cwnd*/ 326 } 327 } 328 #endif 329 330 sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto); 331 332 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG 333 do { 334 struct ccid2_seq *seqp = hc->tx_seqt; 335 336 while (seqp != hc->tx_seqh) { 337 ccid2_pr_debug("out seq=%llu acked=%d time=%u\n", 338 (unsigned long long)seqp->ccid2s_seq, 339 seqp->ccid2s_acked, seqp->ccid2s_sent); 340 seqp = seqp->ccid2s_next; 341 } 342 } while (0); 343 ccid2_pr_debug("=========\n"); 344 #endif 345 } 346 347 /** 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; 365 366 hc->tx_mdev_max = max(hc->tx_mdev, tcp_rto_min(sk)); 367 hc->tx_rttvar = hc->tx_mdev_max; 368 369 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; 409 hc->tx_mdev_max = tcp_rto_min(sk); 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) 428 { 429 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); 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) { 436 if (*maxincr > 0 && ++hc->tx_packets_acked >= 2) { 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) { 442 hc->tx_cwnd += 1; 443 hc->tx_packets_acked = 0; 444 } 445 } 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); 460 461 /* 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 */ 469 ccid2_rtt_estimator(sk, ccid2_time_stamp - seqp->ccid2s_sent); 470 } 471 472 static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp) 473 { 474 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); 475 476 if ((s32)(seqp->ccid2s_sent - hc->tx_last_cong) < 0) { 477 ccid2_pr_debug("Multiple losses in an RTT---treating as one\n"); 478 return; 479 } 480 481 hc->tx_last_cong = ccid2_time_stamp; 482 483 hc->tx_cwnd = hc->tx_cwnd / 2 ? : 1U; 484 hc->tx_ssthresh = max(hc->tx_cwnd, 2U); 485 486 ccid2_check_l_ack_ratio(sk); 487 } 488 489 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 } 502 503 static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) 504 { 505 struct dccp_sock *dp = dccp_sk(sk); 506 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); 507 const bool sender_was_blocked = ccid2_cwnd_network_limited(hc); 508 struct dccp_ackvec_parsed *avp; 509 u64 ackno, seqno; 510 struct ccid2_seq *seqp; 511 int done = 0; 512 unsigned int maxincr = 0; 513 514 /* 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 */ 522 if (hc->tx_rpdupack == -1) { 523 hc->tx_rpdupack = 0; 524 hc->tx_rpseq = seqno; 525 } else { 526 /* check if packet is consecutive */ 527 if (dccp_delta_seqno(hc->tx_rpseq, seqno) == 1) 528 hc->tx_rpseq = seqno; 529 /* it's a later packet */ 530 else if (after48(seqno, hc->tx_rpseq)) { 531 hc->tx_rpdupack++; 532 533 /* check if we got enough dupacks */ 534 if (hc->tx_rpdupack >= NUMDUPACK) { 535 hc->tx_rpdupack = -1; /* XXX lame */ 536 hc->tx_rpseq = 0; 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 */ 545 ccid2_change_l_ack_ratio(sk, 2 * dp->dccps_l_ack_ratio); 546 #endif 547 } 548 } 549 } 550 551 /* check forward path congestion */ 552 if (dccp_packet_without_ack(skb)) 553 return; 554 555 /* still didn't send out new data packets */ 556 if (hc->tx_seqh == hc->tx_seqt) 557 goto done; 558 559 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq; 560 if (after48(ackno, hc->tx_high_ack)) 561 hc->tx_high_ack = ackno; 562 563 seqp = hc->tx_seqt; 564 while (before48(seqp->ccid2s_seq, ackno)) { 565 seqp = seqp->ccid2s_next; 566 if (seqp == hc->tx_seqh) { 567 seqp = hc->tx_seqh->ccid2s_prev; 568 break; 569 } 570 } 571 572 /* 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. 576 */ 577 if (hc->tx_cwnd < hc->tx_ssthresh) 578 maxincr = DIV_ROUND_UP(dp->dccps_l_ack_ratio, 2); 579 580 /* go through all ack vectors */ 581 list_for_each_entry(avp, &hc->tx_av_chunks, node) { 582 /* go through this ack vector */ 583 for (; avp->len--; avp->vec++) { 584 u64 ackno_end_rl = SUB48(ackno, 585 dccp_ackvec_runlen(avp->vec)); 586 587 ccid2_pr_debug("ackvec %llu |%u,%u|\n", 588 (unsigned long long)ackno, 589 dccp_ackvec_state(avp->vec) >> 6, 590 dccp_ackvec_runlen(avp->vec)); 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)) { 596 if (seqp == hc->tx_seqt) { 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)) { 609 const u8 state = dccp_ackvec_state(avp->vec); 610 611 /* new packet received or marked */ 612 if (state != DCCPAV_NOT_RECEIVED && 613 !seqp->ccid2s_acked) { 614 if (state == DCCPAV_ECN_MARKED) 615 ccid2_congestion_event(sk, 616 seqp); 617 else 618 ccid2_new_ack(sk, seqp, 619 &maxincr); 620 621 seqp->ccid2s_acked = 1; 622 ccid2_pr_debug("Got ack for %llu\n", 623 (unsigned long long)seqp->ccid2s_seq); 624 hc->tx_pipe--; 625 } 626 if (seqp == hc->tx_seqt) { 627 done = 1; 628 break; 629 } 630 seqp = seqp->ccid2s_prev; 631 } 632 if (done) 633 break; 634 635 ackno = SUB48(ackno_end_rl, 1); 636 } 637 if (done) 638 break; 639 } 640 641 /* The state about what is acked should be correct now 642 * Check for NUMDUPACK 643 */ 644 seqp = hc->tx_seqt; 645 while (before48(seqp->ccid2s_seq, hc->tx_high_ack)) { 646 seqp = seqp->ccid2s_next; 647 if (seqp == hc->tx_seqh) { 648 seqp = hc->tx_seqh->ccid2s_prev; 649 break; 650 } 651 } 652 done = 0; 653 while (1) { 654 if (seqp->ccid2s_acked) { 655 done++; 656 if (done == NUMDUPACK) 657 break; 658 } 659 if (seqp == hc->tx_seqt) 660 break; 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 */ 667 if (done == NUMDUPACK) { 668 struct ccid2_seq *last_acked = seqp; 669 670 /* check for lost packets */ 671 while (1) { 672 if (!seqp->ccid2s_acked) { 673 ccid2_pr_debug("Packet lost: %llu\n", 674 (unsigned long long)seqp->ccid2s_seq); 675 /* XXX need to traverse from tail -> head in 676 * order to detect multiple congestion events in 677 * one ack vector. 678 */ 679 ccid2_congestion_event(sk, seqp); 680 hc->tx_pipe--; 681 } 682 if (seqp == hc->tx_seqt) 683 break; 684 seqp = seqp->ccid2s_prev; 685 } 686 687 hc->tx_seqt = last_acked; 688 } 689 690 /* trim acked packets in tail */ 691 while (hc->tx_seqt != hc->tx_seqh) { 692 if (!hc->tx_seqt->ccid2s_acked) 693 break; 694 695 hc->tx_seqt = hc->tx_seqt->ccid2s_next; 696 } 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); 703 done: 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); 707 dccp_ackvec_parsed_cleanup(&hc->tx_av_chunks); 708 } 709 710 static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk) 711 { 712 struct ccid2_hc_tx_sock *hc = ccid_priv(ccid); 713 struct dccp_sock *dp = dccp_sk(sk); 714 u32 max_ratio; 715 716 /* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */ 717 hc->tx_ssthresh = ~0U; 718 719 /* Use larger initial windows (RFC 4341, section 5). */ 720 hc->tx_cwnd = rfc3390_bytes_to_packets(dp->dccps_mss_cache); 721 hc->tx_expected_wnd = hc->tx_cwnd; 722 723 /* Make sure that Ack Ratio is enabled and within bounds. */ 724 max_ratio = DIV_ROUND_UP(hc->tx_cwnd, 2); 725 if (dp->dccps_l_ack_ratio == 0 || dp->dccps_l_ack_ratio > max_ratio) 726 dp->dccps_l_ack_ratio = max_ratio; 727 728 /* XXX init ~ to window size... */ 729 if (ccid2_hc_tx_alloc_seq(hc)) 730 return -ENOMEM; 731 732 hc->tx_rto = DCCP_TIMEOUT_INIT; 733 hc->tx_rpdupack = -1; 734 hc->tx_last_cong = hc->tx_lsndtime = hc->tx_cwnd_stamp = ccid2_time_stamp; 735 hc->tx_cwnd_used = 0; 736 setup_timer(&hc->tx_rtotimer, ccid2_hc_tx_rto_expire, 737 (unsigned long)sk); 738 INIT_LIST_HEAD(&hc->tx_av_chunks); 739 return 0; 740 } 741 742 static void ccid2_hc_tx_exit(struct sock *sk) 743 { 744 struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); 745 int i; 746 747 sk_stop_timer(sk, &hc->tx_rtotimer); 748 749 for (i = 0; i < hc->tx_seqbufc; i++) 750 kfree(hc->tx_seqbuf[i]); 751 hc->tx_seqbufc = 0; 752 } 753 754 static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb) 755 { 756 struct ccid2_hc_rx_sock *hc = ccid2_hc_rx_sk(sk); 757 758 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; 764 } 765 } 766 767 struct ccid_operations ccid2_ops = { 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, 779 }; 780 781 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG 782 module_param(ccid2_debug, bool, 0644); 783 MODULE_PARM_DESC(ccid2_debug, "Enable CCID-2 debug messages"); 784 #endif 785