[TFRC]: Provide central source file and debug facility
[linux-2.6.git] / net / dccp / ccids / lib / packet_history.c
1 /*
2  *  net/dccp/packet_history.c
3  *
4  *  Copyright (c) 2007   The University of Aberdeen, Scotland, UK
5  *  Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
6  *
7  *  An implementation of the DCCP protocol
8  *
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
12  *
13  *  This code also uses code from Lulea University, rereleased as GPL by its
14  *  authors:
15  *  Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
16  *
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>.
20  *
21  *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
22  *
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.
27  *
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.
32  *
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.
36  */
37
38 #include <linux/string.h>
39 #include "packet_history.h"
40
41 /**
42  *  tfrc_tx_hist_entry  -  Simple singly-linked TX history list
43  *  @next:  next oldest entry (LIFO order)
44  *  @seqno: sequence number of this entry
45  *  @stamp: send time of packet with sequence number @seqno
46  */
47 struct tfrc_tx_hist_entry {
48         struct tfrc_tx_hist_entry *next;
49         u64                       seqno;
50         ktime_t                   stamp;
51 };
52
53 /*
54  * Transmitter History Routines
55  */
56 static struct kmem_cache *tfrc_tx_hist;
57
58 static struct tfrc_tx_hist_entry *
59         tfrc_tx_hist_find_entry(struct tfrc_tx_hist_entry *head, u64 seqno)
60 {
61         while (head != NULL && head->seqno != seqno)
62                 head = head->next;
63
64         return head;
65 }
66
67 int tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno)
68 {
69         struct tfrc_tx_hist_entry *entry = kmem_cache_alloc(tfrc_tx_hist, gfp_any());
70
71         if (entry == NULL)
72                 return -ENOBUFS;
73         entry->seqno = seqno;
74         entry->stamp = ktime_get_real();
75         entry->next  = *headp;
76         *headp       = entry;
77         return 0;
78 }
79 EXPORT_SYMBOL_GPL(tfrc_tx_hist_add);
80
81 void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp)
82 {
83         struct tfrc_tx_hist_entry *head = *headp;
84
85         while (head != NULL) {
86                 struct tfrc_tx_hist_entry *next = head->next;
87
88                 kmem_cache_free(tfrc_tx_hist, head);
89                 head = next;
90         }
91
92         *headp = NULL;
93 }
94 EXPORT_SYMBOL_GPL(tfrc_tx_hist_purge);
95
96 u32 tfrc_tx_hist_rtt(struct tfrc_tx_hist_entry *head, const u64 seqno,
97                      const ktime_t now)
98 {
99         u32 rtt = 0;
100         struct tfrc_tx_hist_entry *packet = tfrc_tx_hist_find_entry(head, seqno);
101
102         if (packet != NULL) {
103                 rtt = ktime_us_delta(now, packet->stamp);
104                 /*
105                  * Garbage-collect older (irrelevant) entries:
106                  */
107                 tfrc_tx_hist_purge(&packet->next);
108         }
109
110         return rtt;
111 }
112 EXPORT_SYMBOL_GPL(tfrc_tx_hist_rtt);
113
114 /*
115  *      Receiver History Routines
116  */
117 struct dccp_rx_hist *dccp_rx_hist_new(const char *name)
118 {
119         struct dccp_rx_hist *hist = kmalloc(sizeof(*hist), GFP_ATOMIC);
120         static const char dccp_rx_hist_mask[] = "rx_hist_%s";
121         char *slab_name;
122
123         if (hist == NULL)
124                 goto out;
125
126         slab_name = kmalloc(strlen(name) + sizeof(dccp_rx_hist_mask) - 1,
127                             GFP_ATOMIC);
128         if (slab_name == NULL)
129                 goto out_free_hist;
130
131         sprintf(slab_name, dccp_rx_hist_mask, name);
132         hist->dccprxh_slab = kmem_cache_create(slab_name,
133                                              sizeof(struct dccp_rx_hist_entry),
134                                              0, SLAB_HWCACHE_ALIGN, NULL);
135         if (hist->dccprxh_slab == NULL)
136                 goto out_free_slab_name;
137 out:
138         return hist;
139 out_free_slab_name:
140         kfree(slab_name);
141 out_free_hist:
142         kfree(hist);
143         hist = NULL;
144         goto out;
145 }
146
147 EXPORT_SYMBOL_GPL(dccp_rx_hist_new);
148
149 void dccp_rx_hist_delete(struct dccp_rx_hist *hist)
150 {
151         const char* name = kmem_cache_name(hist->dccprxh_slab);
152
153         kmem_cache_destroy(hist->dccprxh_slab);
154         kfree(name);
155         kfree(hist);
156 }
157
158 EXPORT_SYMBOL_GPL(dccp_rx_hist_delete);
159
160 int dccp_rx_hist_find_entry(const struct list_head *list, const u64 seq,
161                             u8 *ccval)
162 {
163         struct dccp_rx_hist_entry *packet = NULL, *entry;
164
165         list_for_each_entry(entry, list, dccphrx_node)
166                 if (entry->dccphrx_seqno == seq) {
167                         packet = entry;
168                         break;
169                 }
170
171         if (packet)
172                 *ccval = packet->dccphrx_ccval;
173
174         return packet != NULL;
175 }
176
177 EXPORT_SYMBOL_GPL(dccp_rx_hist_find_entry);
178 struct dccp_rx_hist_entry *
179                 dccp_rx_hist_find_data_packet(const struct list_head *list)
180 {
181         struct dccp_rx_hist_entry *entry, *packet = NULL;
182
183         list_for_each_entry(entry, list, dccphrx_node)
184                 if (entry->dccphrx_type == DCCP_PKT_DATA ||
185                     entry->dccphrx_type == DCCP_PKT_DATAACK) {
186                         packet = entry;
187                         break;
188                 }
189
190         return packet;
191 }
192
193 EXPORT_SYMBOL_GPL(dccp_rx_hist_find_data_packet);
194
195 void dccp_rx_hist_add_packet(struct dccp_rx_hist *hist,
196                             struct list_head *rx_list,
197                             struct list_head *li_list,
198                             struct dccp_rx_hist_entry *packet,
199                             u64 nonloss_seqno)
200 {
201         struct dccp_rx_hist_entry *entry, *next;
202         u8 num_later = 0;
203
204         list_add(&packet->dccphrx_node, rx_list);
205
206         num_later = TFRC_RECV_NUM_LATE_LOSS + 1;
207
208         if (!list_empty(li_list)) {
209                 list_for_each_entry_safe(entry, next, rx_list, dccphrx_node) {
210                         if (num_later == 0) {
211                                 if (after48(nonloss_seqno,
212                                    entry->dccphrx_seqno)) {
213                                         list_del_init(&entry->dccphrx_node);
214                                         dccp_rx_hist_entry_delete(hist, entry);
215                                 }
216                         } else if (dccp_rx_hist_entry_data_packet(entry))
217                                 --num_later;
218                 }
219         } else {
220                 int step = 0;
221                 u8 win_count = 0; /* Not needed, but lets shut up gcc */
222                 int tmp;
223                 /*
224                  * We have no loss interval history so we need at least one
225                  * rtt:s of data packets to approximate rtt.
226                  */
227                 list_for_each_entry_safe(entry, next, rx_list, dccphrx_node) {
228                         if (num_later == 0) {
229                                 switch (step) {
230                                 case 0:
231                                         step = 1;
232                                         /* OK, find next data packet */
233                                         num_later = 1;
234                                         break;
235                                 case 1:
236                                         step = 2;
237                                         /* OK, find next data packet */
238                                         num_later = 1;
239                                         win_count = entry->dccphrx_ccval;
240                                         break;
241                                 case 2:
242                                         tmp = win_count - entry->dccphrx_ccval;
243                                         if (tmp < 0)
244                                                 tmp += TFRC_WIN_COUNT_LIMIT;
245                                         if (tmp > TFRC_WIN_COUNT_PER_RTT + 1) {
246                                                 /*
247                                                  * We have found a packet older
248                                                  * than one rtt remove the rest
249                                                  */
250                                                 step = 3;
251                                         } else /* OK, find next data packet */
252                                                 num_later = 1;
253                                         break;
254                                 case 3:
255                                         list_del_init(&entry->dccphrx_node);
256                                         dccp_rx_hist_entry_delete(hist, entry);
257                                         break;
258                                 }
259                         } else if (dccp_rx_hist_entry_data_packet(entry))
260                                 --num_later;
261                 }
262         }
263 }
264
265 EXPORT_SYMBOL_GPL(dccp_rx_hist_add_packet);
266
267 void dccp_rx_hist_purge(struct dccp_rx_hist *hist, struct list_head *list)
268 {
269         struct dccp_rx_hist_entry *entry, *next;
270
271         list_for_each_entry_safe(entry, next, list, dccphrx_node) {
272                 list_del_init(&entry->dccphrx_node);
273                 kmem_cache_free(hist->dccprxh_slab, entry);
274         }
275 }
276
277 EXPORT_SYMBOL_GPL(dccp_rx_hist_purge);
278
279 __init int packet_history_init(void)
280 {
281         tfrc_tx_hist = kmem_cache_create("tfrc_tx_hist",
282                                          sizeof(struct tfrc_tx_hist_entry), 0,
283                                          SLAB_HWCACHE_ALIGN, NULL);
284
285         return tfrc_tx_hist == NULL ? -ENOBUFS : 0;
286 }
287
288 void packet_history_exit(void)
289 {
290         if (tfrc_tx_hist != NULL) {
291                 kmem_cache_destroy(tfrc_tx_hist);
292                 tfrc_tx_hist = NULL;
293         }
294 }