2 * net/dccp/packet_history.c
4 * Copyright (c) 2007 The University of Aberdeen, Scotland, UK
5 * Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
7 * An implementation of the DCCP protocol
9 * This code has been developed by the University of Waikato WAND
10 * research group. For further information please see http://www.wand.net.nz/
11 * or e-mail Ian McDonald - ian.mcdonald@jandi.co.nz
13 * This code also uses code from Lulea University, rereleased as GPL by its
15 * Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
17 * Changes to meet Linux coding standards, to make it meet latest ccid3 draft
18 * and to make it work as a loadable module in the DCCP stack written by
19 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
21 * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
23 * This program is free software; you can redistribute it and/or modify
24 * it under the terms of the GNU General Public License as published by
25 * the Free Software Foundation; either version 2 of the License, or
26 * (at your option) any later version.
28 * This program is distributed in the hope that it will be useful,
29 * but WITHOUT ANY WARRANTY; without even the implied warranty of
30 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
31 * GNU General Public License for more details.
33 * You should have received a copy of the GNU General Public License
34 * along with this program; if not, write to the Free Software
35 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
38 #include <linux/string.h>
39 #include <linux/slab.h>
40 #include "packet_history.h"
41 #include "../../dccp.h"
44 * tfrc_tx_hist_entry - Simple singly-linked TX history list
45 * @next: next oldest entry (LIFO order)
46 * @seqno: sequence number of this entry
47 * @stamp: send time of packet with sequence number @seqno
49 struct tfrc_tx_hist_entry {
50 struct tfrc_tx_hist_entry *next;
56 * Transmitter History Routines
58 static struct kmem_cache *tfrc_tx_hist_slab;
60 int __init tfrc_tx_packet_history_init(void)
62 tfrc_tx_hist_slab = kmem_cache_create("tfrc_tx_hist",
63 sizeof(struct tfrc_tx_hist_entry),
64 0, SLAB_HWCACHE_ALIGN, NULL);
65 return tfrc_tx_hist_slab == NULL ? -ENOBUFS : 0;
68 void tfrc_tx_packet_history_exit(void)
70 if (tfrc_tx_hist_slab != NULL) {
71 kmem_cache_destroy(tfrc_tx_hist_slab);
72 tfrc_tx_hist_slab = NULL;
76 static struct tfrc_tx_hist_entry *
77 tfrc_tx_hist_find_entry(struct tfrc_tx_hist_entry *head, u64 seqno)
79 while (head != NULL && head->seqno != seqno)
85 int tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno)
87 struct tfrc_tx_hist_entry *entry = kmem_cache_alloc(tfrc_tx_hist_slab, gfp_any());
92 entry->stamp = ktime_get_real();
97 EXPORT_SYMBOL_GPL(tfrc_tx_hist_add);
99 void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp)
101 struct tfrc_tx_hist_entry *head = *headp;
103 while (head != NULL) {
104 struct tfrc_tx_hist_entry *next = head->next;
106 kmem_cache_free(tfrc_tx_hist_slab, head);
112 EXPORT_SYMBOL_GPL(tfrc_tx_hist_purge);
114 u32 tfrc_tx_hist_rtt(struct tfrc_tx_hist_entry *head, const u64 seqno,
118 struct tfrc_tx_hist_entry *packet = tfrc_tx_hist_find_entry(head, seqno);
120 if (packet != NULL) {
121 rtt = ktime_us_delta(now, packet->stamp);
123 * Garbage-collect older (irrelevant) entries:
125 tfrc_tx_hist_purge(&packet->next);
130 EXPORT_SYMBOL_GPL(tfrc_tx_hist_rtt);
134 * Receiver History Routines
136 static struct kmem_cache *tfrc_rx_hist_slab;
138 int __init tfrc_rx_packet_history_init(void)
140 tfrc_rx_hist_slab = kmem_cache_create("tfrc_rxh_cache",
141 sizeof(struct tfrc_rx_hist_entry),
142 0, SLAB_HWCACHE_ALIGN, NULL);
143 return tfrc_rx_hist_slab == NULL ? -ENOBUFS : 0;
146 void tfrc_rx_packet_history_exit(void)
148 if (tfrc_rx_hist_slab != NULL) {
149 kmem_cache_destroy(tfrc_rx_hist_slab);
150 tfrc_rx_hist_slab = NULL;
155 * tfrc_rx_hist_index - index to reach n-th entry after loss_start
157 static inline u8 tfrc_rx_hist_index(const struct tfrc_rx_hist *h, const u8 n)
159 return (h->loss_start + n) & TFRC_NDUPACK;
163 * tfrc_rx_hist_last_rcv - entry with highest-received-seqno so far
165 static inline struct tfrc_rx_hist_entry *
166 tfrc_rx_hist_last_rcv(const struct tfrc_rx_hist *h)
168 return h->ring[tfrc_rx_hist_index(h, h->loss_count)];
171 void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h,
172 const struct sk_buff *skb,
175 struct tfrc_rx_hist_entry *entry = tfrc_rx_hist_last_rcv(h);
176 const struct dccp_hdr *dh = dccp_hdr(skb);
178 entry->tfrchrx_seqno = DCCP_SKB_CB(skb)->dccpd_seq;
179 entry->tfrchrx_ccval = dh->dccph_ccval;
180 entry->tfrchrx_type = dh->dccph_type;
181 entry->tfrchrx_ndp = ndp;
182 entry->tfrchrx_tstamp = ktime_get_real();
184 EXPORT_SYMBOL_GPL(tfrc_rx_hist_add_packet);
187 * tfrc_rx_hist_entry - return the n-th history entry after loss_start
189 static inline struct tfrc_rx_hist_entry *
190 tfrc_rx_hist_entry(const struct tfrc_rx_hist *h, const u8 n)
192 return h->ring[tfrc_rx_hist_index(h, n)];
196 * tfrc_rx_hist_loss_prev - entry with highest-received-seqno before loss was detected
198 static inline struct tfrc_rx_hist_entry *
199 tfrc_rx_hist_loss_prev(const struct tfrc_rx_hist *h)
201 return h->ring[h->loss_start];
204 /* has the packet contained in skb been seen before? */
205 int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb)
207 const u64 seq = DCCP_SKB_CB(skb)->dccpd_seq;
210 if (dccp_delta_seqno(tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, seq) <= 0)
213 for (i = 1; i <= h->loss_count; i++)
214 if (tfrc_rx_hist_entry(h, i)->tfrchrx_seqno == seq)
219 EXPORT_SYMBOL_GPL(tfrc_rx_hist_duplicate);
221 /* initialise loss detection and disable RTT sampling */
222 static inline void tfrc_rx_hist_loss_indicated(struct tfrc_rx_hist *h)
227 /* indicate whether previously a packet was detected missing */
228 static inline int tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h)
230 return h->loss_count;
233 /* any data packets missing between last reception and skb ? */
234 int tfrc_rx_hist_new_loss_indicated(struct tfrc_rx_hist *h,
235 const struct sk_buff *skb, u32 ndp)
237 int delta = dccp_delta_seqno(tfrc_rx_hist_last_rcv(h)->tfrchrx_seqno,
238 DCCP_SKB_CB(skb)->dccpd_seq);
240 if (delta > 1 && ndp < delta)
241 tfrc_rx_hist_loss_indicated(h);
243 return tfrc_rx_hist_loss_pending(h);
245 EXPORT_SYMBOL_GPL(tfrc_rx_hist_new_loss_indicated);
247 int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h)
251 for (i = 0; i <= TFRC_NDUPACK; i++) {
252 h->ring[i] = kmem_cache_alloc(tfrc_rx_hist_slab, GFP_ATOMIC);
253 if (h->ring[i] == NULL)
257 h->loss_count = h->loss_start = 0;
262 kmem_cache_free(tfrc_rx_hist_slab, h->ring[i]);
267 EXPORT_SYMBOL_GPL(tfrc_rx_hist_alloc);
269 void tfrc_rx_hist_purge(struct tfrc_rx_hist *h)
273 for (i = 0; i <= TFRC_NDUPACK; ++i)
274 if (h->ring[i] != NULL) {
275 kmem_cache_free(tfrc_rx_hist_slab, h->ring[i]);
279 EXPORT_SYMBOL_GPL(tfrc_rx_hist_purge);
282 * tfrc_rx_hist_rtt_last_s - reference entry to compute RTT samples against
284 static inline struct tfrc_rx_hist_entry *
285 tfrc_rx_hist_rtt_last_s(const struct tfrc_rx_hist *h)
291 * tfrc_rx_hist_rtt_prev_s: previously suitable (wrt rtt_last_s) RTT-sampling entry
293 static inline struct tfrc_rx_hist_entry *
294 tfrc_rx_hist_rtt_prev_s(const struct tfrc_rx_hist *h)
296 return h->ring[h->rtt_sample_prev];
300 * tfrc_rx_hist_sample_rtt - Sample RTT from timestamp / CCVal
301 * Based on ideas presented in RFC 4342, 8.1. Returns 0 if it was not able
302 * to compute a sample with given data - calling function should check this.
304 u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h, const struct sk_buff *skb)
307 delta_v = SUB16(dccp_hdr(skb)->dccph_ccval,
308 tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval);
310 if (delta_v < 1 || delta_v > 4) { /* unsuitable CCVal delta */
311 if (h->rtt_sample_prev == 2) { /* previous candidate stored */
312 sample = SUB16(tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_ccval,
313 tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval);
315 sample = 4 / sample *
316 ktime_us_delta(tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_tstamp,
317 tfrc_rx_hist_rtt_last_s(h)->tfrchrx_tstamp);
319 * FIXME: This condition is in principle not
320 * possible but occurs when CCID is used for
321 * two-way data traffic. I have tried to trace
322 * it, but the cause does not seem to be here.
324 DCCP_BUG("please report to dccp@vger.kernel.org"
325 " => prev = %u, last = %u",
326 tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_ccval,
327 tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval);
328 } else if (delta_v < 1) {
329 h->rtt_sample_prev = 1;
330 goto keep_ref_for_next_time;
333 } else if (delta_v == 4) /* optimal match */
334 sample = ktime_to_us(net_timedelta(tfrc_rx_hist_rtt_last_s(h)->tfrchrx_tstamp));
335 else { /* suboptimal match */
336 h->rtt_sample_prev = 2;
337 goto keep_ref_for_next_time;
340 if (unlikely(sample > DCCP_SANE_RTT_MAX)) {
341 DCCP_WARN("RTT sample %u too large, using max\n", sample);
342 sample = DCCP_SANE_RTT_MAX;
345 h->rtt_sample_prev = 0; /* use current entry as next reference */
346 keep_ref_for_next_time:
350 EXPORT_SYMBOL_GPL(tfrc_rx_hist_sample_rtt);