aboutsummaryrefslogtreecommitdiffstats
path: root/net/dccp/ccids/ccid3.c
blob: f4097ddf250402d10f5a9b391cc4409c5b829335 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
/*
 *  net/dccp/ccids/ccid3.c
 *
 *  Copyright (c) 2005 The University of Waikato, Hamilton, New Zealand.
 *  Copyright (c) 2005-6 Ian McDonald <ian.mcdonald@jandi.co.nz>
 *
 *  An implementation of the DCCP protocol
 *
 *  This code has been developed by the University of Waikato WAND
 *  research group. For further information please see http://www.wand.net.nz/
 *
 *  This code also uses code from Lulea University, rereleased as GPL by its
 *  authors:
 *  Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
 *
 *  Changes to meet Linux coding standards, to make it meet latest ccid3 draft
 *  and to make it work as a loadable module in the DCCP stack written by
 *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
 *
 *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
#include "../ccid.h"
#include "../dccp.h"
#include "lib/packet_history.h"
#include "lib/loss_interval.h"
#include "lib/tfrc.h"
#include "ccid3.h"

#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
static int ccid3_debug;
#define ccid3_pr_debug(format, a...)	DCCP_PR_DEBUG(ccid3_debug, format, ##a)
#else
#define ccid3_pr_debug(format, a...)
#endif

static struct dccp_tx_hist *ccid3_tx_hist;
static struct dccp_rx_hist *ccid3_rx_hist;
static struct dccp_li_hist *ccid3_li_hist;

/*
 *	Transmitter Half-Connection Routines
 */
#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
static const char *ccid3_tx_state_name(enum ccid3_hc_tx_states state)
{
	static char *ccid3_state_names[] = {
	[TFRC_SSTATE_NO_SENT]  = "NO_SENT",
	[TFRC_SSTATE_NO_FBACK] = "NO_FBACK",
	[TFRC_SSTATE_FBACK]    = "FBACK",
	[TFRC_SSTATE_TERM]     = "TERM",
	};

	return ccid3_state_names[state];
}
#endif

static void ccid3_hc_tx_set_state(struct sock *sk,
				  enum ccid3_hc_tx_states state)
{
	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
	enum ccid3_hc_tx_states oldstate = hctx->ccid3hctx_state;

	ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
		       dccp_role(sk), sk, ccid3_tx_state_name(oldstate),
		       ccid3_tx_state_name(state));
	WARN_ON(state == oldstate);
	hctx->ccid3hctx_state = state;
}

/*
 * Compute the initial sending rate X_init according to RFC 3390:
 *	w_init   =    min(4 * MSS, max(2 * MSS, 4380 bytes))
 *	X_init   =    w_init / RTT
 * For consistency with other parts of the code, X_init is scaled by 2^6.
 */
static inline u64 rfc3390_initial_rate(struct sock *sk)
{
	const struct dccp_sock *dp = dccp_sk(sk);
	const __u32 w_init = min(4 * dp->dccps_mss_cache,
				 max(2 * dp->dccps_mss_cache, 4380U));

	return scaled_div(w_init << 6, ccid3_hc_tx_sk(sk)->ccid3hctx_rtt);
}

/*
 * Recalculate t_ipi and delta (should be called whenever X changes)
 */
static inline void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hctx)
{
	/* Calculate new t_ipi = s / X_inst (X_inst is in 64 * bytes/second) */
	hctx->ccid3hctx_t_ipi = scaled_div(hctx->ccid3hctx_s,
					   hctx->ccid3hctx_x >> 6);

	/* Calculate new delta by delta = min(t_ipi / 2, t_gran / 2) */
	hctx->ccid3hctx_delta = min_t(u32, hctx->ccid3hctx_t_ipi / 2,
					   TFRC_OPSYS_HALF_TIME_GRAN);

	ccid3_pr_debug("t_ipi=%u, delta=%u, s=%u, X=%u\n",
		       hctx->ccid3hctx_t_ipi, hctx->ccid3hctx_delta,
		       hctx->ccid3hctx_s, (unsigned)(hctx->ccid3hctx_x >> 6));

}
/*
 * Update X by
 *    If (p > 0)
 *       X_calc = calcX(s, R, p);
 *       X = max(min(X_calc, 2 * X_recv), s / t_mbi);
 *    Else
 *       If (now - tld >= R)
 *          X = max(min(2 * X, 2 * X_recv), s / R);
 *          tld = now;
 *
 * Note: X and X_recv are both stored in units of 64 * bytes/second, to support
 *       fine-grained resolution of sending rates. This requires scaling by 2^6
 *       throughout the code. Only X_calc is unscaled (in bytes/second).
 *
 */
static void ccid3_hc_tx_update_x(struct sock *sk, struct timeval *now)

{
	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
	__u64 min_rate = 2 * hctx->ccid3hctx_x_recv;
	const  __u64 old_x = hctx->ccid3hctx_x;

	/*
	 * Handle IDLE periods: do not reduce below RFC3390 initial sending rate
	 * when idling [RFC 4342, 5.1]. See also draft-ietf-dccp-rfc3448bis.
	 * For consistency with X and X_recv, min_rate is also scaled by 2^6.
	 */
	if (unlikely(hctx->ccid3hctx_idle)) {
		min_rate = rfc3390_initial_rate(sk);
		min_rate = max(min_rate, 2 * hctx->ccid3hctx_x_recv);
	}

	if (hctx->ccid3hctx_p > 0) {

		hctx->ccid3hctx_x = min(((__u64)hctx->ccid3hctx_x_calc) << 6,
					min_rate);
		hctx->ccid3hctx_x = max(hctx->ccid3hctx_x,
					(((__u64)hctx->ccid3hctx_s) << 6) /
								TFRC_T_MBI);

	} else if (timeval_delta(now, &hctx->ccid3hctx_t_ld) -
			(suseconds_t)hctx->ccid3hctx_rtt >= 0) {

		hctx->ccid3hctx_x =
			max(min(2 * hctx->ccid3hctx_x, min_rate),
			    scaled_div(((__u64)hctx->ccid3hctx_s) << 6,
				       hctx->ccid3hctx_rtt));
		hctx->ccid3hctx_t_ld = *now;
	}

	if (hctx->ccid3hctx_x != old_x) {
		ccid3_pr_debug("X_prev=%u, X_now=%u, X_calc=%u, "
			       "X_recv=%u\n", (unsigned)(old_x >> 6),
			       (unsigned)(hctx->ccid3hctx_x >> 6),
			       hctx->ccid3hctx_x_calc,
			       (unsigned)(hctx->ccid3hctx_x_recv >> 6));

		ccid3_update_send_interval(hctx);
	}
}

/*
 *	Track the mean packet size `s' (cf. RFC 4342, 5.3 and  RFC 3448, 4.1)
 *	@len: DCCP packet payload size in bytes
 */
static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hctx, int len)
{
	const u16 old_s = hctx->ccid3hctx_s;

	hctx->ccid3hctx_s = old_s == 0 ? len : (9 * old_s + len) / 10;

	if (hctx->ccid3hctx_s != old_s)
		ccid3_update_send_interval(hctx);
}

/*
 *	Update Window Counter using the algorithm from [RFC 4342, 8.1].
 *	The algorithm is not applicable if RTT < 4 microseconds.
 */
static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hctx,
						struct timeval *now)
{
	suseconds_t delta;
	u32 quarter_rtts;

	if (unlikely(hctx->ccid3hctx_rtt < 4))	/* avoid divide-by-zero */
		return;

	delta = timeval_delta(now, &hctx->ccid3hctx_t_last_win_count);
	DCCP_BUG_ON(delta < 0);

	quarter_rtts = (u32)delta / (hctx->ccid3hctx_rtt / 4);

	if (quarter_rtts > 0) {
		hctx->ccid3hctx_t_last_win_count = *now;
		hctx->ccid3hctx_last_win_count	+= min_t(u32, quarter_rtts, 5);
		hctx->ccid3hctx_last_win_count	&= 0xF;		/* mod 16 */

		ccid3_pr_debug("now at %#X\n", hctx->ccid3hctx_last_win_count);
	}
}

static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
{
	struct sock *sk = (struct sock *)data;
	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
	struct timeval now;
	unsigned long t_nfb = USEC_PER_SEC / 5;

	bh_lock_sock(sk);
	if (sock_owned_by_user(sk)) {
		/* Try again later. */
		/* XXX: set some sensible MIB */
		goto restart_timer;
	}

	ccid3_pr_debug("%s(%p, state=%s) - entry \n", dccp_role(sk), sk,
		       ccid3_tx_state_name(hctx->ccid3hctx_state));

	hctx->ccid3hctx_idle = 1;

	switch (hctx->ccid3hctx_state) {
	case TFRC_SSTATE_NO_FBACK:
		/* RFC 3448, 4.4: Halve send rate directly */
		hctx->ccid3hctx_x = max(hctx->ccid3hctx_x / 2,
					(((__u64)hctx->ccid3hctx_s) << 6) /
								    TFRC_T_MBI);

		ccid3_pr_debug("%s(%p, state=%s), updated tx rate to %u "
			       "bytes/s\n", dccp_role(sk), sk,
			       ccid3_tx_state_name(hctx->ccid3hctx_state),
			       (unsigned)(hctx->ccid3hctx_x >> 6));
		/* The value of R is still undefined and so we can not recompute
		 * the timout value. Keep initial value as per [RFC 4342, 5]. */
		t_nfb = TFRC_INITIAL_TIMEOUT;
		ccid3_update_send_interval(hctx);
		break;
	case TFRC_SSTATE_FBACK:
		/*
		 *  Modify the cached value of X_recv [RFC 3448, 4.4]
		 *
		 *  If (p == 0 || X_calc > 2 * X_recv)
		 *    X_recv = max(X_recv / 2, s / (2 * t_mbi));
		 *  Else
		 *    X_recv = X_calc / 4;
		 *
		 *  Note that X_recv is scaled by 2^6 while X_calc is not
		 */
		BUG_ON(hctx->ccid3hctx_p && !hctx->ccid3hctx_x_calc);

		if (hctx->ccid3hctx_p == 0 ||
		    (hctx->ccid3hctx_x_calc > (hctx->ccid3hctx_x_recv >> 5))) {

			hctx->ccid3hctx_x_recv =
				max(hctx->ccid3hctx_x_recv / 2,
				    (((__u64)hctx->ccid3hctx_s) << 6) /
							      (2 * TFRC_T_MBI));

			if (hctx->ccid3hctx_p == 0)
				dccp_timestamp(sk, &now);
		} else {
			hctx->ccid3hctx_x_recv = hctx->ccid3hctx_x_calc;
			hctx->ccid3hctx_x_recv <<= 4;
		}
		/* Now recalculate X [RFC 3448, 4.3, step (4)] */
		ccid3_hc_tx_update_x(sk, &now);
		/*
		 * Schedule no feedback timer to expire in
		 * max(t_RTO, 2 * s/X)  =  max(t_RTO, 2 * t_ipi)
		 * See comments in packet_recv() regarding the value of t_RTO.
		 */
		t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi);
		break;
	case TFRC_SSTATE_NO_SENT:
		DCCP_BUG("%s(%p) - Illegal state NO_SENT", dccp_role(sk), sk);
		/* fall through */
	case TFRC_SSTATE_TERM:
		goto out;
	}

restart_timer:
	sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
			   jiffies + usecs_to_jiffies(t_nfb));
out:
	bh_unlock_sock(sk);
	sock_put(sk);
}

/*
 * returns
 *   > 0: delay (in msecs) that should pass before actually sending
 *   = 0: can send immediately
 *   < 0: error condition; do not send packet
 */
static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
{
	struct dccp_sock *dp = dccp_sk(sk);
	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
	struct timeval now;
	suseconds_t delay;

	BUG_ON(hctx == NULL);

	/*
	 * This function is called only for Data and DataAck packets. Sending
	 * zero-sized Data(Ack)s is theoretically possible, but for congestion
	 * control this case is pathological - ignore it.
	 */
	if (unlikely(skb->len == 0))
		return -EBADMSG;

	dccp_timestamp(sk, &now);

	switch (hctx->ccid3hctx_state) {
	case TFRC_SSTATE_NO_SENT:
		sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
			       (jiffies +
				usecs_to_jiffies(TFRC_INITIAL_TIMEOUT)));
		hctx->ccid3hctx_last_win_count	 = 0;
		hctx->ccid3hctx_t_last_win_count = now;
		ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);

		/* Set initial sending rate X/s to 1pps (X is scaled by 2^6) */
		hctx->ccid3hctx_x = hctx->ccid3hctx_s = skb->len;
		hctx->ccid3hctx_x <<= 6;

		/* First timeout, according to [RFC 3448, 4.2], is 1 second */
		hctx->ccid3hctx_t_ipi = USEC_PER_SEC;
		/* Initial delta: minimum of 0.5 sec and t_gran/2 */
		hctx->ccid3hctx_delta = TFRC_OPSYS_HALF_TIME_GRAN;

		/* Set t_0 for initial packet */
		hctx->ccid3hctx_t_nom = now;
		break;
	case TFRC_SSTATE_NO_FBACK:
	case TFRC_SSTATE_FBACK:
		delay = timeval_delta(&hctx->ccid3hctx_t_nom, &now);
		ccid3_pr_debug("delay=%ld\n", (long)delay);
		/*
		 *	Scheduling of packet transmissions [RFC 3448, 4.6]
		 *
		 * if (t_now > t_nom - delta)
		 *       // send the packet now
		 * else
		 *       // send the packet in (t_nom - t_now) milliseconds.
		 */
		if (delay - (suseconds_t)hctx->ccid3hctx_delta >= 0)
			return delay / 1000L;

		ccid3_hc_tx_update_win_count(hctx, &now);
		break;
	case TFRC_SSTATE_TERM:
		DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk), sk);
		return -EINVAL;
	}

	/* prepare to send now (add options etc.) */
	dp->dccps_hc_tx_insert_options = 1;
	DCCP_SKB_CB(skb)->dccpd_ccval = hctx->ccid3hctx_last_win_count;
	hctx->ccid3hctx_idle = 0;

	/* set the nominal send time for the next following packet */
	timeval_add_usecs(&hctx->ccid3hctx_t_nom, hctx->ccid3hctx_t_ipi);

	return 0;
}

static void ccid3_hc_tx_packet_sent(struct sock *sk, int more,
				    unsigned int len)
{
	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
	struct timeval now;
	struct dccp_tx_hist_entry *packet;

	BUG_ON(hctx == NULL);

	ccid3_hc_tx_update_s(hctx, len);

	packet = dccp_tx_hist_entry_new(ccid3_tx_hist, GFP_ATOMIC);
	if (unlikely(packet == NULL)) {
		DCCP_CRIT("packet history - out of memory!");
		return;
	}
	dccp_tx_hist_add_entry(&hctx->ccid3hctx_hist, packet);

	dccp_timestamp(sk, &now);
	packet->dccphtx_tstamp = now;
	packet->dccphtx_seqno  = dccp_sk(sk)->dccps_gss;
	packet->dccphtx_rtt    = hctx->ccid3hctx_rtt;
	packet->dccphtx_sent   = 1;
}

static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
{
	const struct dccp_sock *dp = dccp_sk(sk);
	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
	struct ccid3_options_received *opt_recv;
	struct dccp_tx_hist_entry *packet;
	struct timeval now;
	unsigned long t_nfb;
	u32 pinv, r_sample;

	BUG_ON(hctx == NULL);

	/* we are only interested in ACKs */
	if (!(DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK ||
	      DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_DATAACK))
		return;

	opt_recv = &hctx->ccid3hctx_options_received;

	switch (hctx->ccid3hctx_state) {
	case TFRC_SSTATE_NO_FBACK:
	case TFRC_SSTATE_FBACK:
		/* get packet from history to look up t_recvdata */
		packet = dccp_tx_hist_find_entry(&hctx->ccid3hctx_hist,
					      DCCP_SKB_CB(skb)->dccpd_ack_seq);
		if (unlikely(packet == NULL)) {
			DCCP_WARN("%s(%p), seqno %llu(%s) doesn't exist "
				  "in history!\n",  dccp_role(sk), sk,
			    (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
				dccp_packet_name(DCCP_SKB_CB(skb)->dccpd_type));
			return;
		}

		/* Update receive rate in units of 64 * bytes/second */
		hctx->ccid3hctx_x_recv = opt_recv->ccid3or_receive_rate;
		hctx->ccid3hctx_x_recv <<= 6;

		/* Update loss event rate */
		pinv = opt_recv->ccid3or_loss_event_rate;
		if (pinv == ~0U || pinv == 0)	       /* see RFC 4342, 8.5   */
			hctx->ccid3hctx_p = 0;
		else				       /* can not exceed 100% */
			hctx->ccid3hctx_p = 1000000 / pinv;

		dccp_timestamp(sk, &now);

		/*
		 * Calculate new round trip sample as per [RFC 3448, 4.3] by
		 *	R_sample  =  (now - t_recvdata) - t_elapsed
		 */
		r_sample = dccp_sample_rtt(sk, &now, &packet->dccphtx_tstamp);

		/*
		 * Update RTT estimate by
		 * If (No feedback recv)
		 *    R = R_sample;
		 * Else
		 *    R = q * R + (1 - q) * R_sample;
		 *
		 * q is a constant, RFC 3448 recomments 0.9
		 */
		if (hctx->ccid3hctx_state == TFRC_SSTATE_NO_FBACK) {
			/*
			 * Larger Initial Windows [RFC 4342, sec. 5]
			 */
			hctx->ccid3hctx_rtt  = r_sample;
			hctx->ccid3hctx_x    = rfc3390_initial_rate(sk);
			hctx->ccid3hctx_t_ld = now;

			ccid3_update_send_interval(hctx);

			ccid3_pr_debug("%s(%p), s=%u, MSS=%u, "
				       "R_sample=%uus, X=%u\n", dccp_role(sk),
				       sk, hctx->ccid3hctx_s,
				       dp->dccps_mss_cache, r_sample,
				       (unsigned)(hctx->ccid3hctx_x >> 6));

			ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
		} else {
			hctx->ccid3hctx_rtt = (9 * hctx->ccid3hctx_rtt +
						   r_sample) / 10;

			/* Update sending rate (step 4 of [RFC 3448, 4.3]) */
			if (hctx->ccid3hctx_p > 0)
				hctx->ccid3hctx_x_calc =
					tfrc_calc_x(hctx->ccid3hctx_s,
						    hctx->ccid3hctx_rtt,
						    hctx->ccid3hctx_p);
			ccid3_hc_tx_update_x(sk, &now);

			ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, "
				       "p=%u, X_calc=%u, X_recv=%u, X=%u\n",
				       dccp_role(sk),
				       sk, hctx->ccid3hctx_rtt, r_sample,
				       hctx->ccid3hctx_s, hctx->ccid3hctx_p,
				       hctx->ccid3hctx_x_calc,
				       (unsigned)(hctx->ccid3hctx_x_recv >> 6),
				       (unsigned)(hctx->ccid3hctx_x >> 6));
		}

		/* unschedule no feedback timer */
		sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);

		/* remove all packets older than the one acked from history */
		dccp_tx_hist_purge_older(ccid3_tx_hist,
					 &hctx->ccid3hctx_hist, packet);
		/*
		 * As we have calculated new ipi, delta, t_nom it is possible
		 * that we now can send a packet, so wake up dccp_wait_for_ccid
		 */
		sk->sk_write_space(sk);

		/*
		 * Update timeout interval for the nofeedback timer.
		 * We use a configuration option to increase the lower bound.
		 * This can help avoid triggering the nofeedback timer too
		 * often ('spinning') on LANs with small RTTs.
		 */
		hctx->ccid3hctx_t_rto = max_t(u32, 4 * hctx->ccid3hctx_rtt,
						   CONFIG_IP_DCCP_CCID3_RTO *
						   (USEC_PER_SEC/1000));
		/*
		 * Schedule no feedback timer to expire in
		 * max(t_RTO, 2 * s/X)  =  max(t_RTO, 2 * t_ipi)
		 */
		t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi);

		ccid3_pr_debug("%s(%p), Scheduled no feedback timer to "
			       "expire in %lu jiffies (%luus)\n",
			       dccp_role(sk),
			       sk, usecs_to_jiffies(t_nfb), t_nfb);

		sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
				   jiffies + usecs_to_jiffies(t_nfb));

		/* set idle flag */
		hctx->ccid3hctx_idle = 1;
		break;
	case TFRC_SSTATE_NO_SENT:	/* fall through */
	case TFRC_SSTATE_TERM:		/* ignore feedback when closing */
		break;
	}
}

static int ccid3_hc_tx_parse_options(struct sock *sk, unsigned char option,
				     unsigned char len, u16 idx,
				     unsigned char *value)
{
	int rc = 0;
	const struct dccp_sock *dp = dccp_sk(sk);
	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
	struct ccid3_options_received *opt_recv;

	BUG_ON(hctx == NULL);

	opt_recv = &hctx->ccid3hctx_options_received;

	if (opt_recv->ccid3or_seqno != dp->dccps_gsr) {
		opt_recv->ccid3or_seqno		     = dp->dccps_gsr;
		opt_recv->ccid3or_loss_event_rate    = ~0;
		opt_recv->ccid3or_loss_intervals_idx = 0;
		opt_recv->ccid3or_loss_intervals_len = 0;
		opt_recv->ccid3or_receive_rate	     = 0;
	}

	switch (option) {
	case TFRC_OPT_LOSS_EVENT_RATE:
		if (unlikely(len != 4)) {
			DCCP_WARN("%s(%p), invalid len %d "
				  "for TFRC_OPT_LOSS_EVENT_RATE\n",
				  dccp_role(sk), sk, len);
			rc = -EINVAL;
		} else {
			opt_recv->ccid3or_loss_event_rate =
						ntohl(*(__be32 *)value);
			ccid3_pr_debug("%s(%p), LOSS_EVENT_RATE=%u\n",
				       dccp_role(sk), sk,
				       opt_recv->ccid3or_loss_event_rate);
		}
		break;
	case TFRC_OPT_LOSS_INTERVALS:
		opt_recv->ccid3or_loss_intervals_idx = idx;
		opt_recv->ccid3or_loss_intervals_len = len;
		ccid3_pr_debug("%s(%p), LOSS_INTERVALS=(%u, %u)\n",
			       dccp_role(sk), sk,
			       opt_recv->ccid3or_loss_intervals_idx,
			       opt_recv->ccid3or_loss_intervals_len);
		break;
	case TFRC_OPT_RECEIVE_RATE:
		if (unlikely(len != 4)) {
			DCCP_WARN("%s(%p), invalid len %d "
				  "for TFRC_OPT_RECEIVE_RATE\n",
				  dccp_role(sk), sk, len);
			rc = -EINVAL;
		} else {
			opt_recv->ccid3or_receive_rate =
						ntohl(*(__be32 *)value);
			ccid3_pr_debug("%s(%p), RECEIVE_RATE=%u\n",
				       dccp_role(sk), sk,
				       opt_recv->ccid3or_receive_rate);
		}
		break;
	}

	return rc;
}

static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk)
{
	struct ccid3_hc_tx_sock *hctx = ccid_priv(ccid);

	hctx->ccid3hctx_s     = 0;
	hctx->ccid3hctx_rtt   = 0;
	hctx->ccid3hctx_state = TFRC_SSTATE_NO_SENT;
	INIT_LIST_HEAD(&hctx->ccid3hctx_hist);

	hctx->ccid3hctx_no_feedback_timer.function =
				ccid3_hc_tx_no_feedback_timer;
	hctx->ccid3hctx_no_feedback_timer.data     = (unsigned long)sk;
	init_timer(&hctx->ccid3hctx_no_feedback_timer);

	return 0;
}

static void ccid3_hc_tx_exit(struct sock *sk)
{
	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);

	BUG_ON(hctx == NULL);

	ccid3_hc_tx_set_state(sk, TFRC_SSTATE_TERM);
	sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);

	/* Empty packet history */
	dccp_tx_hist_purge(ccid3_tx_hist, &hctx->ccid3hctx_hist);
}

static void ccid3_hc_tx_get_info(struct sock *sk, struct tcp_info *info)
{
	const struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);

	/* Listen socks doesn't have a private CCID block */
	if (sk->sk_state == DCCP_LISTEN)
		return;

	BUG_ON(hctx == NULL);

	info->tcpi_rto = hctx->ccid3hctx_t_rto;
	info->tcpi_rtt = hctx->ccid3hctx_rtt;
}

static int ccid3_hc_tx_getsockopt(struct sock *sk, const int optname, int len,
				  u32 __user *optval, int __user *optlen)
{
	const struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
	const void *val;

	/* Listen socks doesn't have a private CCID block */
	if (sk->sk_state == DCCP_LISTEN)
		return -EINVAL;

	switch (optname) {
	case DCCP_SOCKOPT_CCID_TX_INFO:
		if (len < sizeof(hctx->ccid3hctx_tfrc))
			return -EINVAL;
		len = sizeof(hctx->ccid3hctx_tfrc);
		val = &hctx->ccid3hctx_tfrc;
		break;
	default:
		return -ENOPROTOOPT;
	}

	if (put_user(len, optlen) || copy_to_user(optval, val, len))
		return -EFAULT;

	return 0;
}

/*
 *	Receiver Half-Connection Routines
 */
#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
static const char *ccid3_rx_state_name(enum ccid3_hc_rx_states state)
{
	static char *ccid3_rx_state_names[] = {
	[TFRC_RSTATE_NO_DATA] = "NO_DATA",
	[TFRC_RSTATE_DATA]    = "DATA",
	[TFRC_RSTATE_TERM]    = "TERM",
	};

	return ccid3_rx_state_names[state];
}
#endif

static void ccid3_hc_rx_set_state(struct sock *sk,
				  enum ccid3_hc_rx_states state)
{
	struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
	enum ccid3_hc_rx_states oldstate = hcrx->ccid3hcrx_state;

	ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
		       dccp_role(sk), sk, ccid3_rx_state_name(oldstate),
		       ccid3_rx_state_name(state));
	WARN_ON(state == oldstate);
	hcrx->ccid3hcrx_state = state;
}

static inline void ccid3_hc_rx_update_s(struct ccid3_hc_rx_sock *hcrx, int len)
{
	if (unlikely(len == 0))	/* don't update on empty packets (e.g. ACKs) */
		ccid3_pr_debug("Packet payload length is 0 - not updating\n");
	else
		hcrx->ccid3hcrx_s = hcrx->ccid3hcrx_s == 0 ? len :
				    (9 * hcrx->ccid3hcrx_s + len) / 10;
}

static void ccid3_hc_rx_send_feedback(struct sock *sk)
{
	struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
	struct dccp_sock *dp = dccp_sk(sk);
	struct dccp_rx_hist_entry *packet;
	struct timeval now;
	suseconds_t delta;

	ccid3_pr_debug("%s(%p) - entry \n", dccp_role(sk), sk);

	dccp_timestamp(sk, &now);

	switch (hcrx->ccid3hcrx_state) {
	case TFRC_RSTATE_NO_DATA:
		hcrx->ccid3hcrx_x_recv = 0;
		break;
	case TFRC_RSTATE_DATA:
		delta = timeval_delta(&now,
				      &hcrx->ccid3hcrx_tstamp_last_feedback);
		DCCP_BUG_ON(delta < 0);
		hcrx->ccid3hcrx_x_recv =
			scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta);
		break;
	case TFRC_RSTATE_TERM:
		DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk), sk);
		return;
	}

	packet = dccp_rx_hist_find_data_packet(&hcrx->ccid3hcrx_hist);
	if (unlikely(packet == NULL)) {
		DCCP_WARN("%s(%p), no data packet in history!\n",
			  dccp_role(sk), sk);
		return;
	}

	hcrx->ccid3hcrx_tstamp_last_feedback = now;
	hcrx->ccid3hcrx_ccval_last_counter   = packet->dccphrx_ccval;
	hcrx->ccid3hcrx_bytes_recv	     = 0;

	/* Elapsed time information [RFC 4340, 13.2] in units of 10 * usecs */
	delta = timeval_delta(&now, &packet->dccphrx_tstamp);
	DCCP_BUG_ON(delta < 0);
	hcrx->ccid3hcrx_elapsed_time = delta / 10;

	if (hcrx->ccid3hcrx_p == 0)
		hcrx->ccid3hcrx_pinv = ~0U;	/* see RFC 4342, 8.5 */
	else if (hcrx->ccid3hcrx_p > 1000000) {
		DCCP_WARN("p (%u) > 100%%\n", hcrx->ccid3hcrx_p);
		hcrx->ccid3hcrx_pinv = 1;	/* use 100% in this case */
	} else
		hcrx->ccid3hcrx_pinv = 1000000 / hcrx->ccid3hcrx_p;

	dp->dccps_hc_rx_insert_options = 1;
	dccp_send_ack(sk);
}

static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb)
{
	const struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
	__be32 x_recv, pinv;

	BUG_ON(hcrx == NULL);

	if (!(sk->sk_state == DCCP_OPEN || sk->sk_state == DCCP_PARTOPEN))
		return 0;

	DCCP_SKB_CB(skb)->dccpd_ccval = hcrx->ccid3hcrx_ccval_last_counter;

	if (dccp_packet_without_ack(skb))
		return 0;

	x_recv = htonl(hcrx->ccid3hcrx_x_recv);
	pinv   = htonl(hcrx->ccid3hcrx_pinv);

	if ((hcrx->ccid3hcrx_elapsed_time != 0 &&
	     dccp_insert_option_elapsed_time(sk, skb,
					     hcrx->ccid3hcrx_elapsed_time)) ||
	    dccp_insert_option_timestamp(sk, skb) ||
	    dccp_insert_option(sk, skb, TFRC_OPT_LOSS_EVENT_RATE,
			       &pinv, sizeof(pinv)) ||
	    dccp_insert_option(sk, skb, TFRC_OPT_RECEIVE_RATE,
			       &x_recv, sizeof(x_recv)))
		return -1;

	return 0;
}

/* calculate first loss interval
 *
 * returns estimated loss interval in usecs */

static u32 ccid3_hc_rx_calc_first_li(struct sock *sk)
{
	struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
	struct dccp_rx_hist_entry *entry, *next, *tail = NULL;
	u32 x_recv, p;
	suseconds_t rtt, delta;
	struct timeval tstamp = { 0, };
	int interval = 0;
	int win_count = 0;
	int step = 0;
	u64 fval;

	list_for_each_entry_safe(entry, next, &hcrx->ccid3hcrx_hist,
				 dccphrx_node) {
		if (dccp_rx_hist_entry_data_packet(entry)) {
			tail = entry;

			switch (step) {
			case 0:
				tstamp	  = entry->dccphrx_tstamp;
				win_count = entry->dccphrx_ccval;
				step = 1;
				break;
			case 1:
				interval = win_count - entry->dccphrx_ccval;
				if (interval < 0)
					interval += TFRC_WIN_COUNT_LIMIT;
				if (interval > 4)
					goto found;
				break;
			}
		}
	}

	if (unlikely(step == 0)) {
		DCCP_WARN("%s(%p), packet history has no data packets!\n",
			  dccp_role(sk), sk);
		return ~0;
	}

	if (unlikely(interval == 0)) {
		DCCP_WARN("%s(%p), Could not find a win_count interval > 0."
			  "Defaulting to 1\n", dccp_role(sk), sk);
		interval = 1;
	}
found:
	if (!tail) {
		DCCP_CRIT("tail is null\n");
		return ~0;
	}

	delta = timeval_delta(&tstamp, &tail->dccphrx_tstamp);
	DCCP_BUG_ON(delta < 0);

	rtt = delta * 4 / interval;
	ccid3_pr_debug("%s(%p), approximated RTT to %dus\n",
		       dccp_role(sk), sk, (int)rtt);

	/*
	 * Determine the length of the first loss interval via inverse lookup.
	 * Assume that X_recv can be computed by the throughput equation
	 *		    s
	 *	X_recv = --------
	 *		 R * fval
	 * Find some p such that f(p) = fval; return 1/p [RFC 3448, 6.3.1].
	 */
	if (rtt == 0) {			/* would result in divide-by-zero */
		DCCP_WARN("RTT==0\n");
		return ~0;
	}

	dccp_timestamp(sk, &tstamp);
	delta = timeval_delta(&tstamp, &hcrx->ccid3hcrx_tstamp_last_feedback);
	DCCP_BUG_ON(delta <= 0);

	x_recv = scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta);
	if (x_recv == 0) {		/* would also trigger divide-by-zero */
		DCCP_WARN("X_recv==0\n");
		if ((x_recv = hcrx->ccid3hcrx_x_recv) == 0) {
			DCCP_BUG("stored value of X_recv is zero");
			return ~0;
		}
	}

	fval = scaled_div(hcrx->ccid3hcrx_s, rtt);
	fval = scaled_div32(fval, x_recv);
	p = tfrc_calc_x_reverse_lookup(fval);

	ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
		       "loss rate=%u\n", dccp_role(sk), sk, x_recv, p);

	if (p == 0)
		return ~0;
	else
		return 1000000 / p;
}

static void ccid3_hc_rx_update_li(struct sock *sk, u64 seq_loss, u8 win_loss)
{
	struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
	struct dccp_li_hist_entry *head;
	u64 seq_temp;

	if (list_empty(&hcrx->ccid3hcrx_li_hist)) {
		if (!dccp_li_hist_interval_new(ccid3_li_hist,
		   &hcrx->ccid3hcrx_li_hist, seq_loss, win_loss))
			return;

		head = list_entry(hcrx->ccid3hcrx_li_hist.next,
		   struct dccp_li_hist_entry, dccplih_node);
		head->dccplih_interval = ccid3_hc_rx_calc_first_li(sk);
	} else {
		struct dccp_li_hist_entry *entry;
		struct list_head *tail;

		head = list_entry(hcrx->ccid3hcrx_li_hist.next,
		   struct dccp_li_hist_entry, dccplih_node);
		/* FIXME win count check removed as was wrong */
		/* should make this check with receive history */
		/* and compare there as per section 10.2 of RFC4342 */

		/* new loss event detected */
		/* calculate last interval length */
		seq_temp = dccp_delta_seqno(head->dccplih_seqno, seq_loss);
		entry = dccp_li_hist_entry_new(ccid3_li_hist, GFP_ATOMIC);

		if (entry == NULL) {
			DCCP_BUG("out of memory - can not allocate entry");
			return;
		}

		list_add(&entry->dccplih_node, &hcrx->ccid3hcrx_li_hist);

		tail = hcrx->ccid3hcrx_li_hist.prev;
		list_del(tail);
		kmem_cache_free(ccid3_li_hist->dccplih_slab, tail);

		/* Create the newest interval */
		entry->dccplih_seqno = seq_loss;
		entry->dccplih_interval = seq_temp;
		entry->dccplih_win_count = win_loss;
	}
}

static int ccid3_hc_rx_detect_loss(struct sock *sk,
				    struct dccp_rx_hist_entry *packet)
{
	struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
	struct dccp_rx_hist_entry *rx_hist =
				dccp_rx_hist_head(&hcrx->ccid3hcrx_hist);
	u64 seqno = packet->dccphrx_seqno;
	u64 tmp_seqno;
	int loss = 0;
	u8 ccval;


	tmp_seqno = hcrx->ccid3hcrx_seqno_nonloss;

	if (!rx_hist ||
	   follows48(packet->dccphrx_seqno, hcrx->ccid3hcrx_seqno_nonloss)) {
		hcrx->ccid3hcrx_seqno_nonloss = seqno;
		hcrx->ccid3hcrx_ccval_nonloss = packet->dccphrx_ccval;
		goto detect_out;
	}


	while (dccp_delta_seqno(hcrx->ccid3hcrx_seqno_nonloss, seqno)
	   > TFRC_RECV_NUM_LATE_LOSS) {
		loss = 1;
		ccid3_hc_rx_update_li(sk, hcrx->ccid3hcrx_seqno_nonloss,
		   hcrx->ccid3hcrx_ccval_nonloss);
		tmp_seqno = hcrx->ccid3hcrx_seqno_nonloss;
		dccp_inc_seqno(&tmp_seqno);
		hcrx->ccid3hcrx_seqno_nonloss = tmp_seqno;
		dccp_inc_seqno(&tmp_seqno);
		while (dccp_rx_hist_find_entry(&hcrx->ccid3hcrx_hist,
		   tmp_seqno, &ccval)) {
			hcrx->ccid3hcrx_seqno_nonloss = tmp_seqno;
			hcrx->ccid3hcrx_ccval_nonloss = ccval;
			dccp_inc_seqno(&tmp_seqno);
		}
	}

	/* FIXME - this code could be simplified with above while */
	/* but works at moment */
	if (follows48(packet->dccphrx_seqno, hcrx->ccid3hcrx_seqno_nonloss)) {
		hcrx->ccid3hcrx_seqno_nonloss = seqno;
		hcrx->ccid3hcrx_ccval_nonloss = packet->dccphrx_ccval;
	}

detect_out:
	dccp_rx_hist_add_packet(ccid3_rx_hist, &hcrx->ccid3hcrx_hist,
		   &hcrx->ccid3hcrx_li_hist, packet,
		   hcrx->ccid3hcrx_seqno_nonloss);
	return loss;
}

static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
{
	struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
	const struct dccp_options_received *opt_recv;
	struct dccp_rx_hist_entry *packet;
	struct timeval now;
	u32 p_prev, r_sample, rtt_prev;
	int loss, payload_size;

	BUG_ON(hcrx == NULL);

	opt_recv = &dccp_sk(sk)->dccps_options_received;

	switch (DCCP_SKB_CB(skb)->dccpd_type) {
	case DCCP_PKT_ACK:
		if (hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA)
			return;
	case DCCP_PKT_DATAACK:
		if (opt_recv->dccpor_timestamp_echo == 0)
			break;
		rtt_prev = hcrx->ccid3hcrx_rtt;
		dccp_timestamp(sk, &now);
		r_sample = dccp_sample_rtt(sk, &now, NULL);

		if (hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA)
			hcrx->ccid3hcrx_rtt = r_sample;
		else
			hcrx->ccid3hcrx_rtt = (hcrx->ccid3hcrx_rtt * 9) / 10 +
					      r_sample / 10;

		if (rtt_prev != hcrx->ccid3hcrx_rtt)
			ccid3_pr_debug("%s(%p), New RTT=%uus, elapsed time=%u\n",
				       dccp_role(sk), sk, hcrx->ccid3hcrx_rtt,
				       opt_recv->dccpor_elapsed_time);
		break;
	case DCCP_PKT_DATA:
		break;
	default: /* We're not interested in other packet types, move along */
		return;
	}

	packet = dccp_rx_hist_entry_new(ccid3_rx_hist, sk, opt_recv->dccpor_ndp,
					skb, GFP_ATOMIC);
	if (unlikely(packet == NULL)) {
		DCCP_WARN("%s(%p), Not enough mem to add rx packet "
			  "to history, consider it lost!\n", dccp_role(sk), sk);
		return;
	}

	loss = ccid3_hc_rx_detect_loss(sk, packet);

	if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK)
		return;

	payload_size = skb->len - dccp_hdr(skb)->dccph_doff * 4;
	ccid3_hc_rx_update_s(hcrx, payload_size);

	switch (hcrx->ccid3hcrx_state) {
	case TFRC_RSTATE_NO_DATA:
		ccid3_pr_debug("%s(%p, state=%s), skb=%p, sending initial "
			       "feedback\n", dccp_role(sk), sk,
			       dccp_state_name(sk->sk_state), skb);
		ccid3_hc_rx_send_feedback(sk);
		ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA);
		return;
	case TFRC_RSTATE_DATA:
		hcrx->ccid3hcrx_bytes_recv += payload_size;
		if (loss)
			break;

		dccp_timestamp(sk, &now);
		if ((timeval_delta(&now, &hcrx->ccid3hcrx_tstamp_last_ack) -
		     (suseconds_t)hcrx->ccid3hcrx_rtt) >= 0) {
			hcrx->ccid3hcrx_tstamp_last_ack = now;
			ccid3_hc_rx_send_feedback(sk);
		}
		return;
	case TFRC_RSTATE_TERM:
		DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk), sk);
		return;
	}

	/* Dealing with packet loss */
	ccid3_pr_debug("%s(%p, state=%s), data loss! Reacting...\n",
		       dccp_role(sk), sk, dccp_state_name(sk->sk_state));

	p_prev = hcrx->ccid3hcrx_p;

	/* Calculate loss event rate */
	if (!list_empty(&hcrx->ccid3hcrx_li_hist)) {
		u32 i_mean = dccp_li_hist_calc_i_mean(&hcrx->ccid3hcrx_li_hist);

		/* Scaling up by 1000000 as fixed decimal */
		if (i_mean != 0)
			hcrx->ccid3hcrx_p = 1000000 / i_mean;
	} else
		DCCP_BUG("empty loss history");

	if (hcrx->ccid3hcrx_p > p_prev) {
		ccid3_hc_rx_send_feedback(sk);
		return;
	}
}

static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk)
{
	struct ccid3_hc_rx_sock *hcrx = ccid_priv(ccid);

	ccid3_pr_debug("entry\n");

	hcrx->ccid3hcrx_state = TFRC_RSTATE_NO_DATA;
	INIT_LIST_HEAD(&hcrx->ccid3hcrx_hist);
	INIT_LIST_HEAD(&hcrx->ccid3hcrx_li_hist);
	dccp_timestamp(sk, &hcrx->ccid3hcrx_tstamp_last_ack);
	hcrx->ccid3hcrx_tstamp_last_feedback = hcrx->ccid3hcrx_tstamp_last_ack;
	hcrx->ccid3hcrx_s   = 0;
	hcrx->ccid3hcrx_rtt = 0;
	return 0;
}

static void ccid3_hc_rx_exit(struct sock *sk)
{
	struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);

	BUG_ON(hcrx == NULL);

	ccid3_hc_rx_set_state(sk, TFRC_RSTATE_TERM);

	/* Empty packet history */
	dccp_rx_hist_purge(ccid3_rx_hist, &hcrx->ccid3hcrx_hist);

	/* Empty loss interval history */
	dccp_li_hist_purge(ccid3_li_hist, &hcrx->ccid3hcrx_li_hist);
}

static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info)
{
	const struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);

	/* Listen socks doesn't have a private CCID block */
	if (sk->sk_state == DCCP_LISTEN)
		return;

	BUG_ON(hcrx == NULL);

	info->tcpi_ca_state = hcrx->ccid3hcrx_state;
	info->tcpi_options  |= TCPI_OPT_TIMESTAMPS;
	info->tcpi_rcv_rtt  = hcrx->ccid3hcrx_rtt;
}

static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len,
				  u32 __user *optval, int __user *optlen)
{
	const struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
	const void *val;

	/* Listen socks doesn't have a private CCID block */
	if (sk->sk_state == DCCP_LISTEN)
		return -EINVAL;

	switch (optname) {
	case DCCP_SOCKOPT_CCID_RX_INFO:
		if (len < sizeof(hcrx->ccid3hcrx_tfrc))
			return -EINVAL;
		len = sizeof(hcrx->ccid3hcrx_tfrc);
		val = &hcrx->ccid3hcrx_tfrc;
		break;
	default:
		return -ENOPROTOOPT;
	}

	if (put_user(len, optlen) || copy_to_user(optval, val, len))
		return -EFAULT;

	return 0;
}

static struct ccid_operations ccid3 = {
	.ccid_id		   = DCCPC_CCID3,
	.ccid_name		   = "ccid3",
	.ccid_owner		   = THIS_MODULE,
	.ccid_hc_tx_obj_size	   = sizeof(struct ccid3_hc_tx_sock),
	.ccid_hc_tx_init	   = ccid3_hc_tx_init,
	.ccid_hc_tx_exit	   = ccid3_hc_tx_exit,
	.ccid_hc_tx_send_packet	   = ccid3_hc_tx_send_packet,
	.ccid_hc_tx_packet_sent	   = ccid3_hc_tx_packet_sent,
	.ccid_hc_tx_packet_recv	   = ccid3_hc_tx_packet_recv,
	.ccid_hc_tx_parse_options  = ccid3_hc_tx_parse_options,
	.ccid_hc_rx_obj_size	   = sizeof(struct ccid3_hc_rx_sock),
	.ccid_hc_rx_init	   = ccid3_hc_rx_init,
	.ccid_hc_rx_exit	   = ccid3_hc_rx_exit,
	.ccid_hc_rx_insert_options = ccid3_hc_rx_insert_options,
	.ccid_hc_rx_packet_recv	   = ccid3_hc_rx_packet_recv,
	.ccid_hc_rx_get_info	   = ccid3_hc_rx_get_info,
	.ccid_hc_tx_get_info	   = ccid3_hc_tx_get_info,
	.ccid_hc_rx_getsockopt	   = ccid3_hc_rx_getsockopt,
	.ccid_hc_tx_getsockopt	   = ccid3_hc_tx_getsockopt,
};

#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
module_param(ccid3_debug, int, 0444);
MODULE_PARM_DESC(ccid3_debug, "Enable debug messages");
#endif

static __init int ccid3_module_init(void)
{
	int rc = -ENOBUFS;

	ccid3_rx_hist = dccp_rx_hist_new("ccid3");
	if (ccid3_rx_hist == NULL)
		goto out;

	ccid3_tx_hist = dccp_tx_hist_new("ccid3");
	if (ccid3_tx_hist == NULL)
		goto out_free_rx;

	ccid3_li_hist = dccp_li_hist_new("ccid3");
	if (ccid3_li_hist == NULL)
		goto out_free_tx;

	rc = ccid_register(&ccid3);
	if (rc != 0)
		goto out_free_loss_interval_history;
out:
	return rc;

out_free_loss_interval_history:
	dccp_li_hist_delete(ccid3_li_hist);
	ccid3_li_hist = NULL;
out_free_tx:
	dccp_tx_hist_delete(ccid3_tx_hist);
	ccid3_tx_hist = NULL;
out_free_rx:
	dccp_rx_hist_delete(ccid3_rx_hist);
	ccid3_rx_hist = NULL;
	goto out;
}
module_init(ccid3_module_init);

static __exit void ccid3_module_exit(void)
{
	ccid_unregister(&ccid3);

	if (ccid3_tx_hist != NULL) {
		dccp_tx_hist_delete(ccid3_tx_hist);
		ccid3_tx_hist = NULL;
	}
	if (ccid3_rx_hist != NULL) {
		dccp_rx_hist_delete(ccid3_rx_hist);
		ccid3_rx_hist = NULL;
	}
	if (ccid3_li_hist != NULL) {
		dccp_li_hist_delete(ccid3_li_hist);
		ccid3_li_hist = NULL;
	}
}
module_exit(ccid3_module_exit);

MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>, "
	      "Arnaldo Carvalho de Melo <acme@ghostprotocols.net>");
MODULE_DESCRIPTION("DCCP TFRC CCID3 CCID");
MODULE_LICENSE("GPL");
MODULE_ALIAS("net-dccp-ccid-3");