2 * net/dccp/ccids/ccid2.c
4 * Copyright (c) 2005, 2006 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
6 * Changes to meet Linux coding standards, and DCCP infrastructure fixes.
8 * Copyright (c) 2006 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
26 * This implementation should follow RFC 4341
34 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
35 static int ccid2_debug
;
36 #define ccid2_pr_debug(format, a...) DCCP_PR_DEBUG(ccid2_debug, format, ##a)
38 #define ccid2_pr_debug(format, a...)
41 static int ccid2_hc_tx_alloc_seq(struct ccid2_hc_tx_sock
*hctx
)
43 struct ccid2_seq
*seqp
;
46 /* check if we have space to preserve the pointer to the buffer */
47 if (hctx
->seqbufc
>= sizeof(hctx
->seqbuf
) / sizeof(struct ccid2_seq
*))
50 /* allocate buffer and initialize linked list */
51 seqp
= kmalloc(CCID2_SEQBUF_LEN
* sizeof(struct ccid2_seq
), gfp_any());
55 for (i
= 0; i
< (CCID2_SEQBUF_LEN
- 1); i
++) {
56 seqp
[i
].ccid2s_next
= &seqp
[i
+ 1];
57 seqp
[i
+ 1].ccid2s_prev
= &seqp
[i
];
59 seqp
[CCID2_SEQBUF_LEN
- 1].ccid2s_next
= seqp
;
60 seqp
->ccid2s_prev
= &seqp
[CCID2_SEQBUF_LEN
- 1];
62 /* This is the first allocation. Initiate the head and tail. */
63 if (hctx
->seqbufc
== 0)
64 hctx
->seqh
= hctx
->seqt
= seqp
;
66 /* link the existing list with the one we just created */
67 hctx
->seqh
->ccid2s_next
= seqp
;
68 seqp
->ccid2s_prev
= hctx
->seqh
;
70 hctx
->seqt
->ccid2s_prev
= &seqp
[CCID2_SEQBUF_LEN
- 1];
71 seqp
[CCID2_SEQBUF_LEN
- 1].ccid2s_next
= hctx
->seqt
;
74 /* store the original pointer to the buffer so we can free it */
75 hctx
->seqbuf
[hctx
->seqbufc
] = seqp
;
81 static int ccid2_hc_tx_send_packet(struct sock
*sk
, struct sk_buff
*skb
)
83 if (ccid2_cwnd_network_limited(ccid2_hc_tx_sk(sk
)))
84 return CCID_PACKET_WILL_DEQUEUE_LATER
;
85 return CCID_PACKET_SEND_AT_ONCE
;
88 static void ccid2_change_l_ack_ratio(struct sock
*sk
, u32 val
)
90 struct dccp_sock
*dp
= dccp_sk(sk
);
91 u32 max_ratio
= DIV_ROUND_UP(ccid2_hc_tx_sk(sk
)->cwnd
, 2);
94 * Ensure that Ack Ratio does not exceed ceil(cwnd/2), which is (2) from
95 * RFC 4341, 6.1.2. We ignore the statement that Ack Ratio 2 is always
96 * acceptable since this causes starvation/deadlock whenever cwnd < 2.
97 * The same problem arises when Ack Ratio is 0 (ie. Ack Ratio disabled).
99 if (val
== 0 || val
> max_ratio
) {
100 DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val
, max_ratio
);
103 if (val
> DCCPF_ACK_RATIO_MAX
)
104 val
= DCCPF_ACK_RATIO_MAX
;
106 if (val
== dp
->dccps_l_ack_ratio
)
109 ccid2_pr_debug("changing local ack ratio to %u\n", val
);
110 dp
->dccps_l_ack_ratio
= val
;
113 static void ccid2_hc_tx_rto_expire(unsigned long data
)
115 struct sock
*sk
= (struct sock
*)data
;
116 struct ccid2_hc_tx_sock
*hctx
= ccid2_hc_tx_sk(sk
);
117 const bool sender_was_blocked
= ccid2_cwnd_network_limited(hctx
);
120 if (sock_owned_by_user(sk
)) {
121 sk_reset_timer(sk
, &hctx
->rtotimer
, jiffies
+ HZ
/ 5);
125 ccid2_pr_debug("RTO_EXPIRE\n");
129 if (hctx
->rto
> DCCP_RTO_MAX
)
130 hctx
->rto
= DCCP_RTO_MAX
;
132 /* adjust pipe, cwnd etc */
133 hctx
->ssthresh
= hctx
->cwnd
/ 2;
134 if (hctx
->ssthresh
< 2)
139 /* clear state about stuff we sent */
140 hctx
->seqt
= hctx
->seqh
;
141 hctx
->packets_acked
= 0;
143 /* clear ack ratio state. */
146 ccid2_change_l_ack_ratio(sk
, 1);
148 /* if we were blocked before, we may now send cwnd=1 packet */
149 if (sender_was_blocked
)
150 tasklet_schedule(&dccp_sk(sk
)->dccps_xmitlet
);
151 /* restart backed-off timer */
152 sk_reset_timer(sk
, &hctx
->rtotimer
, jiffies
+ hctx
->rto
);
158 static void ccid2_hc_tx_packet_sent(struct sock
*sk
, unsigned int len
)
160 struct dccp_sock
*dp
= dccp_sk(sk
);
161 struct ccid2_hc_tx_sock
*hctx
= ccid2_hc_tx_sk(sk
);
162 struct ccid2_seq
*next
;
166 hctx
->seqh
->ccid2s_seq
= dp
->dccps_gss
;
167 hctx
->seqh
->ccid2s_acked
= 0;
168 hctx
->seqh
->ccid2s_sent
= jiffies
;
170 next
= hctx
->seqh
->ccid2s_next
;
171 /* check if we need to alloc more space */
172 if (next
== hctx
->seqt
) {
173 if (ccid2_hc_tx_alloc_seq(hctx
)) {
174 DCCP_CRIT("packet history - out of memory!");
175 /* FIXME: find a more graceful way to bail out */
178 next
= hctx
->seqh
->ccid2s_next
;
179 BUG_ON(next
== hctx
->seqt
);
183 ccid2_pr_debug("cwnd=%d pipe=%d\n", hctx
->cwnd
, hctx
->pipe
);
186 * FIXME: The code below is broken and the variables have been removed
187 * from the socket struct. The `ackloss' variable was always set to 0,
188 * and with arsent there are several problems:
189 * (i) it doesn't just count the number of Acks, but all sent packets;
190 * (ii) it is expressed in # of packets, not # of windows, so the
191 * comparison below uses the wrong formula: Appendix A of RFC 4341
192 * comes up with the number K = cwnd / (R^2 - R) of consecutive windows
193 * of data with no lost or marked Ack packets. If arsent were the # of
194 * consecutive Acks received without loss, then Ack Ratio needs to be
195 * decreased by 1 when
196 * arsent >= K * cwnd / R = cwnd^2 / (R^3 - R^2)
197 * where cwnd / R is the number of Acks received per window of data
198 * (cf. RFC 4341, App. A). The problems are that
199 * - arsent counts other packets as well;
200 * - the comparison uses a formula different from RFC 4341;
201 * - computing a cubic/quadratic equation each time is too complicated.
202 * Hence a different algorithm is needed.
205 /* Ack Ratio. Need to maintain a concept of how many windows we sent */
207 /* We had an ack loss in this window... */
209 if (hctx
->arsent
>= hctx
->cwnd
) {
214 /* No acks lost up to now... */
215 /* decrease ack ratio if enough packets were sent */
216 if (dp
->dccps_l_ack_ratio
> 1) {
217 /* XXX don't calculate denominator each time */
218 int denom
= dp
->dccps_l_ack_ratio
* dp
->dccps_l_ack_ratio
-
219 dp
->dccps_l_ack_ratio
;
221 denom
= hctx
->cwnd
* hctx
->cwnd
/ denom
;
223 if (hctx
->arsent
>= denom
) {
224 ccid2_change_l_ack_ratio(sk
, dp
->dccps_l_ack_ratio
- 1);
228 /* we can't increase ack ratio further [1] */
229 hctx
->arsent
= 0; /* or maybe set it to cwnd*/
234 /* setup RTO timer */
235 if (!timer_pending(&hctx
->rtotimer
))
236 sk_reset_timer(sk
, &hctx
->rtotimer
, jiffies
+ hctx
->rto
);
238 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
240 struct ccid2_seq
*seqp
= hctx
->seqt
;
242 while (seqp
!= hctx
->seqh
) {
243 ccid2_pr_debug("out seq=%llu acked=%d time=%lu\n",
244 (unsigned long long)seqp
->ccid2s_seq
,
245 seqp
->ccid2s_acked
, seqp
->ccid2s_sent
);
246 seqp
= seqp
->ccid2s_next
;
249 ccid2_pr_debug("=========\n");
254 * ccid2_rtt_estimator - Sample RTT and compute RTO using RFC2988 algorithm
255 * This code is almost identical with TCP's tcp_rtt_estimator(), since
256 * - it has a higher sampling frequency (recommended by RFC 1323),
257 * - the RTO does not collapse into RTT due to RTTVAR going towards zero,
258 * - it is simple (cf. more complex proposals such as Eifel timer or research
259 * which suggests that the gain should be set according to window size),
260 * - in tests it was found to work well with CCID2 [gerrit].
262 static void ccid2_rtt_estimator(struct sock
*sk
, const long mrtt
)
264 struct ccid2_hc_tx_sock
*hctx
= ccid2_hc_tx_sk(sk
);
267 if (hctx
->srtt
== 0) {
268 /* First measurement m */
272 hctx
->mdev_max
= max(TCP_RTO_MIN
, hctx
->mdev
);
273 hctx
->rttvar
= hctx
->mdev_max
;
274 hctx
->rtt_seq
= dccp_sk(sk
)->dccps_gss
;
276 /* Update scaled SRTT as SRTT += 1/8 * (m - SRTT) */
277 m
-= (hctx
->srtt
>> 3);
280 /* Similarly, update scaled mdev with regard to |m| */
283 m
-= (hctx
->mdev
>> 2);
285 * This neutralises RTO increase when RTT < SRTT - mdev
286 * (see P. Sarolahti, A. Kuznetsov,"Congestion Control
287 * in Linux TCP", USENIX 2002, pp. 49-62).
292 m
-= (hctx
->mdev
>> 2);
296 if (hctx
->mdev
> hctx
->mdev_max
) {
297 hctx
->mdev_max
= hctx
->mdev
;
298 if (hctx
->mdev_max
> hctx
->rttvar
)
299 hctx
->rttvar
= hctx
->mdev_max
;
303 * Decay RTTVAR at most once per flight, exploiting that
304 * 1) pipe <= cwnd <= Sequence_Window = W (RFC 4340, 7.5.2)
305 * 2) AWL = GSS-W+1 <= GAR <= GSS (RFC 4340, 7.5.1)
306 * GAR is a useful bound for FlightSize = pipe, AWL is probably
307 * too low as it over-estimates pipe.
309 if (after48(dccp_sk(sk
)->dccps_gar
, hctx
->rtt_seq
)) {
310 if (hctx
->mdev_max
< hctx
->rttvar
)
311 hctx
->rttvar
-= (hctx
->rttvar
-
312 hctx
->mdev_max
) >> 2;
313 hctx
->rtt_seq
= dccp_sk(sk
)->dccps_gss
;
314 hctx
->mdev_max
= TCP_RTO_MIN
;
319 * Set RTO from SRTT and RTTVAR
320 * Clock granularity is ignored since the minimum error for RTTVAR is
321 * clamped to 50msec (corresponding to HZ=20). This leads to a minimum
322 * RTO of 200msec. This agrees with TCP and RFC 4341, 5.: "Because DCCP
323 * does not retransmit data, DCCP does not require TCP's recommended
324 * minimum timeout of one second".
326 hctx
->rto
= (hctx
->srtt
>> 3) + hctx
->rttvar
;
328 if (hctx
->rto
> DCCP_RTO_MAX
)
329 hctx
->rto
= DCCP_RTO_MAX
;
332 static void ccid2_new_ack(struct sock
*sk
, struct ccid2_seq
*seqp
,
333 unsigned int *maxincr
)
335 struct ccid2_hc_tx_sock
*hctx
= ccid2_hc_tx_sk(sk
);
337 if (hctx
->cwnd
< hctx
->ssthresh
) {
338 if (*maxincr
> 0 && ++hctx
->packets_acked
== 2) {
341 hctx
->packets_acked
= 0;
343 } else if (++hctx
->packets_acked
>= hctx
->cwnd
) {
345 hctx
->packets_acked
= 0;
348 * FIXME: RTT is sampled several times per acknowledgment (for each
349 * entry in the Ack Vector), instead of once per Ack (as in TCP SACK).
350 * This causes the RTT to be over-estimated, since the older entries
351 * in the Ack Vector have earlier sending times.
352 * The cleanest solution is to not use the ccid2s_sent field at all
353 * and instead use DCCP timestamps - need to be resolved at some time.
355 ccid2_rtt_estimator(sk
, jiffies
- seqp
->ccid2s_sent
);
358 static void ccid2_congestion_event(struct sock
*sk
, struct ccid2_seq
*seqp
)
360 struct ccid2_hc_tx_sock
*hctx
= ccid2_hc_tx_sk(sk
);
362 if (time_before(seqp
->ccid2s_sent
, hctx
->last_cong
)) {
363 ccid2_pr_debug("Multiple losses in an RTT---treating as one\n");
367 hctx
->last_cong
= jiffies
;
369 hctx
->cwnd
= hctx
->cwnd
/ 2 ? : 1U;
370 hctx
->ssthresh
= max(hctx
->cwnd
, 2U);
372 /* Avoid spurious timeouts resulting from Ack Ratio > cwnd */
373 if (dccp_sk(sk
)->dccps_l_ack_ratio
> hctx
->cwnd
)
374 ccid2_change_l_ack_ratio(sk
, hctx
->cwnd
);
377 static int ccid2_hc_tx_parse_options(struct sock
*sk
, u8 packet_type
,
378 u8 option
, u8
*optval
, u8 optlen
)
380 struct ccid2_hc_tx_sock
*hctx
= ccid2_hc_tx_sk(sk
);
383 case DCCPO_ACK_VECTOR_0
:
384 case DCCPO_ACK_VECTOR_1
:
385 return dccp_ackvec_parsed_add(&hctx
->av_chunks
, optval
, optlen
,
386 option
- DCCPO_ACK_VECTOR_0
);
391 static void ccid2_hc_tx_packet_recv(struct sock
*sk
, struct sk_buff
*skb
)
393 struct dccp_sock
*dp
= dccp_sk(sk
);
394 struct ccid2_hc_tx_sock
*hctx
= ccid2_hc_tx_sk(sk
);
395 const bool sender_was_blocked
= ccid2_cwnd_network_limited(hctx
);
396 struct dccp_ackvec_parsed
*avp
;
398 struct ccid2_seq
*seqp
;
400 unsigned int maxincr
= 0;
402 /* check reverse path congestion */
403 seqno
= DCCP_SKB_CB(skb
)->dccpd_seq
;
405 /* XXX this whole "algorithm" is broken. Need to fix it to keep track
406 * of the seqnos of the dupacks so that rpseq and rpdupack are correct
409 /* need to bootstrap */
410 if (hctx
->rpdupack
== -1) {
414 /* check if packet is consecutive */
415 if (dccp_delta_seqno(hctx
->rpseq
, seqno
) == 1)
417 /* it's a later packet */
418 else if (after48(seqno
, hctx
->rpseq
)) {
421 /* check if we got enough dupacks */
422 if (hctx
->rpdupack
>= NUMDUPACK
) {
423 hctx
->rpdupack
= -1; /* XXX lame */
426 ccid2_change_l_ack_ratio(sk
, 2 * dp
->dccps_l_ack_ratio
);
431 /* check forward path congestion */
432 if (dccp_packet_without_ack(skb
))
435 /* still didn't send out new data packets */
436 if (hctx
->seqh
== hctx
->seqt
)
439 ackno
= DCCP_SKB_CB(skb
)->dccpd_ack_seq
;
440 if (after48(ackno
, hctx
->high_ack
))
441 hctx
->high_ack
= ackno
;
444 while (before48(seqp
->ccid2s_seq
, ackno
)) {
445 seqp
= seqp
->ccid2s_next
;
446 if (seqp
== hctx
->seqh
) {
447 seqp
= hctx
->seqh
->ccid2s_prev
;
453 * In slow-start, cwnd can increase up to a maximum of Ack Ratio/2
454 * packets per acknowledgement. Rounding up avoids that cwnd is not
455 * advanced when Ack Ratio is 1 and gives a slight edge otherwise.
457 if (hctx
->cwnd
< hctx
->ssthresh
)
458 maxincr
= DIV_ROUND_UP(dp
->dccps_l_ack_ratio
, 2);
460 /* go through all ack vectors */
461 list_for_each_entry(avp
, &hctx
->av_chunks
, node
) {
462 /* go through this ack vector */
463 for (; avp
->len
--; avp
->vec
++) {
464 u64 ackno_end_rl
= SUB48(ackno
,
465 dccp_ackvec_runlen(avp
->vec
));
467 ccid2_pr_debug("ackvec %llu |%u,%u|\n",
468 (unsigned long long)ackno
,
469 dccp_ackvec_state(avp
->vec
) >> 6,
470 dccp_ackvec_runlen(avp
->vec
));
471 /* if the seqno we are analyzing is larger than the
472 * current ackno, then move towards the tail of our
475 while (after48(seqp
->ccid2s_seq
, ackno
)) {
476 if (seqp
== hctx
->seqt
) {
480 seqp
= seqp
->ccid2s_prev
;
485 /* check all seqnos in the range of the vector
488 while (between48(seqp
->ccid2s_seq
,ackno_end_rl
,ackno
)) {
489 const u8 state
= dccp_ackvec_state(avp
->vec
);
491 /* new packet received or marked */
492 if (state
!= DCCPAV_NOT_RECEIVED
&&
493 !seqp
->ccid2s_acked
) {
494 if (state
== DCCPAV_ECN_MARKED
)
495 ccid2_congestion_event(sk
,
498 ccid2_new_ack(sk
, seqp
,
501 seqp
->ccid2s_acked
= 1;
502 ccid2_pr_debug("Got ack for %llu\n",
503 (unsigned long long)seqp
->ccid2s_seq
);
506 if (seqp
== hctx
->seqt
) {
510 seqp
= seqp
->ccid2s_prev
;
515 ackno
= SUB48(ackno_end_rl
, 1);
521 /* The state about what is acked should be correct now
522 * Check for NUMDUPACK
525 while (before48(seqp
->ccid2s_seq
, hctx
->high_ack
)) {
526 seqp
= seqp
->ccid2s_next
;
527 if (seqp
== hctx
->seqh
) {
528 seqp
= hctx
->seqh
->ccid2s_prev
;
534 if (seqp
->ccid2s_acked
) {
536 if (done
== NUMDUPACK
)
539 if (seqp
== hctx
->seqt
)
541 seqp
= seqp
->ccid2s_prev
;
544 /* If there are at least 3 acknowledgements, anything unacknowledged
545 * below the last sequence number is considered lost
547 if (done
== NUMDUPACK
) {
548 struct ccid2_seq
*last_acked
= seqp
;
550 /* check for lost packets */
552 if (!seqp
->ccid2s_acked
) {
553 ccid2_pr_debug("Packet lost: %llu\n",
554 (unsigned long long)seqp
->ccid2s_seq
);
555 /* XXX need to traverse from tail -> head in
556 * order to detect multiple congestion events in
559 ccid2_congestion_event(sk
, seqp
);
562 if (seqp
== hctx
->seqt
)
564 seqp
= seqp
->ccid2s_prev
;
567 hctx
->seqt
= last_acked
;
570 /* trim acked packets in tail */
571 while (hctx
->seqt
!= hctx
->seqh
) {
572 if (!hctx
->seqt
->ccid2s_acked
)
575 hctx
->seqt
= hctx
->seqt
->ccid2s_next
;
578 /* restart RTO timer if not all outstanding data has been acked */
580 sk_stop_timer(sk
, &hctx
->rtotimer
);
582 sk_reset_timer(sk
, &hctx
->rtotimer
, jiffies
+ hctx
->rto
);
584 /* check if incoming Acks allow pending packets to be sent */
585 if (sender_was_blocked
&& !ccid2_cwnd_network_limited(hctx
))
586 tasklet_schedule(&dccp_sk(sk
)->dccps_xmitlet
);
587 dccp_ackvec_parsed_cleanup(&hctx
->av_chunks
);
590 static int ccid2_hc_tx_init(struct ccid
*ccid
, struct sock
*sk
)
592 struct ccid2_hc_tx_sock
*hctx
= ccid_priv(ccid
);
593 struct dccp_sock
*dp
= dccp_sk(sk
);
596 /* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */
597 hctx
->ssthresh
= ~0U;
600 * RFC 4341, 5: "The cwnd parameter is initialized to at most four
601 * packets for new connections, following the rules from [RFC3390]".
602 * We need to convert the bytes of RFC3390 into the packets of RFC 4341.
604 hctx
->cwnd
= clamp(4380U / dp
->dccps_mss_cache
, 2U, 4U);
606 /* Make sure that Ack Ratio is enabled and within bounds. */
607 max_ratio
= DIV_ROUND_UP(hctx
->cwnd
, 2);
608 if (dp
->dccps_l_ack_ratio
== 0 || dp
->dccps_l_ack_ratio
> max_ratio
)
609 dp
->dccps_l_ack_ratio
= max_ratio
;
611 /* XXX init ~ to window size... */
612 if (ccid2_hc_tx_alloc_seq(hctx
))
615 hctx
->rto
= DCCP_TIMEOUT_INIT
;
617 hctx
->last_cong
= jiffies
;
618 setup_timer(&hctx
->rtotimer
, ccid2_hc_tx_rto_expire
, (unsigned long)sk
);
619 INIT_LIST_HEAD(&hctx
->av_chunks
);
623 static void ccid2_hc_tx_exit(struct sock
*sk
)
625 struct ccid2_hc_tx_sock
*hctx
= ccid2_hc_tx_sk(sk
);
628 sk_stop_timer(sk
, &hctx
->rtotimer
);
630 for (i
= 0; i
< hctx
->seqbufc
; i
++)
631 kfree(hctx
->seqbuf
[i
]);
635 static void ccid2_hc_rx_packet_recv(struct sock
*sk
, struct sk_buff
*skb
)
637 const struct dccp_sock
*dp
= dccp_sk(sk
);
638 struct ccid2_hc_rx_sock
*hcrx
= ccid2_hc_rx_sk(sk
);
640 switch (DCCP_SKB_CB(skb
)->dccpd_type
) {
642 case DCCP_PKT_DATAACK
:
644 if (hcrx
->data
>= dp
->dccps_r_ack_ratio
) {
652 static struct ccid_operations ccid2
= {
653 .ccid_id
= DCCPC_CCID2
,
654 .ccid_name
= "TCP-like",
655 .ccid_owner
= THIS_MODULE
,
656 .ccid_hc_tx_obj_size
= sizeof(struct ccid2_hc_tx_sock
),
657 .ccid_hc_tx_init
= ccid2_hc_tx_init
,
658 .ccid_hc_tx_exit
= ccid2_hc_tx_exit
,
659 .ccid_hc_tx_send_packet
= ccid2_hc_tx_send_packet
,
660 .ccid_hc_tx_packet_sent
= ccid2_hc_tx_packet_sent
,
661 .ccid_hc_tx_parse_options
= ccid2_hc_tx_parse_options
,
662 .ccid_hc_tx_packet_recv
= ccid2_hc_tx_packet_recv
,
663 .ccid_hc_rx_obj_size
= sizeof(struct ccid2_hc_rx_sock
),
664 .ccid_hc_rx_packet_recv
= ccid2_hc_rx_packet_recv
,
667 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
668 module_param(ccid2_debug
, bool, 0644);
669 MODULE_PARM_DESC(ccid2_debug
, "Enable debug messages");
672 static __init
int ccid2_module_init(void)
674 return ccid_register(&ccid2
);
676 module_init(ccid2_module_init
);
678 static __exit
void ccid2_module_exit(void)
680 ccid_unregister(&ccid2
);
682 module_exit(ccid2_module_exit
);
684 MODULE_AUTHOR("Andrea Bittau <a.bittau@cs.ucl.ac.uk>");
685 MODULE_DESCRIPTION("DCCP TCP-Like (CCID2) CCID");
686 MODULE_LICENSE("GPL");
687 MODULE_ALIAS("net-dccp-ccid-2");