4805de9965684bcf74c8ed45a98283e7bf50717a
[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/module.h>
39 #include <linux/string.h>
40 #include "packet_history.h"
41
42 /**
43  *  tfrc_tx_hist_entry  -  Simple singly-linked TX history list
44  *  @next:  next oldest entry (LIFO order)
45  *  @seqno: sequence number of this entry
46  *  @stamp: send time of packet with sequence number @seqno
47  */
48 struct tfrc_tx_hist_entry {
49         struct tfrc_tx_hist_entry *next;
50         u64                       seqno;
51         ktime_t                   stamp;
52 };
53
54 /*
55  * Transmitter History Routines
56  */
57 static struct kmem_cache *tfrc_tx_hist;
58
59 static struct tfrc_tx_hist_entry *
60         tfrc_tx_hist_find_entry(struct tfrc_tx_hist_entry *head, u64 seqno)
61 {
62         while (head != NULL && head->seqno != seqno)
63                 head = head->next;
64
65         return head;
66 }
67
68 int tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno)
69 {
70         struct tfrc_tx_hist_entry *entry = kmem_cache_alloc(tfrc_tx_hist, gfp_any());
71
72         if (entry == NULL)
73                 return -ENOBUFS;
74         entry->seqno = seqno;
75         entry->stamp = ktime_get_real();
76         entry->next  = *headp;
77         *headp       = entry;
78         return 0;
79 }
80 EXPORT_SYMBOL_GPL(tfrc_tx_hist_add);
81
82 void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp)
83 {
84         struct tfrc_tx_hist_entry *head = *headp;
85
86         while (head != NULL) {
87                 struct tfrc_tx_hist_entry *next = head->next;
88
89                 kmem_cache_free(tfrc_tx_hist, head);
90                 head = next;
91         }
92
93         *headp = NULL;
94 }
95 EXPORT_SYMBOL_GPL(tfrc_tx_hist_purge);
96
97 u32 tfrc_tx_hist_rtt(struct tfrc_tx_hist_entry *head, const u64 seqno,
98                      const ktime_t now)
99 {
100         u32 rtt = 0;
101         struct tfrc_tx_hist_entry *packet = tfrc_tx_hist_find_entry(head, seqno);
102
103         if (packet != NULL) {
104                 rtt = ktime_us_delta(now, packet->stamp);
105                 /*
106                  * Garbage-collect older (irrelevant) entries:
107                  */
108                 tfrc_tx_hist_purge(&packet->next);
109         }
110
111         return rtt;
112 }
113 EXPORT_SYMBOL_GPL(tfrc_tx_hist_rtt);
114
115 /*
116  *      Receiver History Routines
117  */
118 struct dccp_rx_hist *dccp_rx_hist_new(const char *name)
119 {
120         struct dccp_rx_hist *hist = kmalloc(sizeof(*hist), GFP_ATOMIC);
121         static const char dccp_rx_hist_mask[] = "rx_hist_%s";
122         char *slab_name;
123
124         if (hist == NULL)
125                 goto out;
126
127         slab_name = kmalloc(strlen(name) + sizeof(dccp_rx_hist_mask) - 1,
128                             GFP_ATOMIC);
129         if (slab_name == NULL)
130                 goto out_free_hist;
131
132         sprintf(slab_name, dccp_rx_hist_mask, name);
133         hist->dccprxh_slab = kmem_cache_create(slab_name,
134                                              sizeof(struct dccp_rx_hist_entry),
135                                              0, SLAB_HWCACHE_ALIGN, NULL);
136         if (hist->dccprxh_slab == NULL)
137                 goto out_free_slab_name;
138 out:
139         return hist;
140 out_free_slab_name:
141         kfree(slab_name);
142 out_free_hist:
143         kfree(hist);
144         hist = NULL;
145         goto out;
146 }
147
148 EXPORT_SYMBOL_GPL(dccp_rx_hist_new);
149
150 void dccp_rx_hist_delete(struct dccp_rx_hist *hist)
151 {
152         const char* name = kmem_cache_name(hist->dccprxh_slab);
153
154         kmem_cache_destroy(hist->dccprxh_slab);
155         kfree(name);
156         kfree(hist);
157 }
158
159 EXPORT_SYMBOL_GPL(dccp_rx_hist_delete);
160
161 int dccp_rx_hist_find_entry(const struct list_head *list, const u64 seq,
162                             u8 *ccval)
163 {
164         struct dccp_rx_hist_entry *packet = NULL, *entry;
165
166         list_for_each_entry(entry, list, dccphrx_node)
167                 if (entry->dccphrx_seqno == seq) {
168                         packet = entry;
169                         break;
170                 }
171
172         if (packet)
173                 *ccval = packet->dccphrx_ccval;
174
175         return packet != NULL;
176 }
177
178 EXPORT_SYMBOL_GPL(dccp_rx_hist_find_entry);
179 struct dccp_rx_hist_entry *
180                 dccp_rx_hist_find_data_packet(const struct list_head *list)
181 {
182         struct dccp_rx_hist_entry *entry, *packet = NULL;
183
184         list_for_each_entry(entry, list, dccphrx_node)
185                 if (entry->dccphrx_type == DCCP_PKT_DATA ||
186                     entry->dccphrx_type == DCCP_PKT_DATAACK) {
187                         packet = entry;
188                         break;
189                 }
190
191         return packet;
192 }
193
194 EXPORT_SYMBOL_GPL(dccp_rx_hist_find_data_packet);
195
196 void dccp_rx_hist_add_packet(struct dccp_rx_hist *hist,
197                             struct list_head *rx_list,
198                             struct list_head *li_list,
199                             struct dccp_rx_hist_entry *packet,
200                             u64 nonloss_seqno)
201 {
202         struct dccp_rx_hist_entry *entry, *next;
203         u8 num_later = 0;
204
205         list_add(&packet->dccphrx_node, rx_list);
206
207         num_later = TFRC_RECV_NUM_LATE_LOSS + 1;
208
209         if (!list_empty(li_list)) {
210                 list_for_each_entry_safe(entry, next, rx_list, dccphrx_node) {
211                         if (num_later == 0) {
212                                 if (after48(nonloss_seqno,
213                                    entry->dccphrx_seqno)) {
214                                         list_del_init(&entry->dccphrx_node);
215                                         dccp_rx_hist_entry_delete(hist, entry);
216                                 }
217                         } else if (dccp_rx_hist_entry_data_packet(entry))
218                                 --num_later;
219                 }
220         } else {
221                 int step = 0;
222                 u8 win_count = 0; /* Not needed, but lets shut up gcc */
223                 int tmp;
224                 /*
225                  * We have no loss interval history so we need at least one
226                  * rtt:s of data packets to approximate rtt.
227                  */
228                 list_for_each_entry_safe(entry, next, rx_list, dccphrx_node) {
229                         if (num_later == 0) {
230                                 switch (step) {
231                                 case 0:
232                                         step = 1;
233                                         /* OK, find next data packet */
234                                         num_later = 1;
235                                         break;
236                                 case 1:
237                                         step = 2;
238                                         /* OK, find next data packet */
239                                         num_later = 1;
240                                         win_count = entry->dccphrx_ccval;
241                                         break;
242                                 case 2:
243                                         tmp = win_count - entry->dccphrx_ccval;
244                                         if (tmp < 0)
245                                                 tmp += TFRC_WIN_COUNT_LIMIT;
246                                         if (tmp > TFRC_WIN_COUNT_PER_RTT + 1) {
247                                                 /*
248                                                  * We have found a packet older
249                                                  * than one rtt remove the rest
250                                                  */
251                                                 step = 3;
252                                         } else /* OK, find next data packet */
253                                                 num_later = 1;
254                                         break;
255                                 case 3:
256                                         list_del_init(&entry->dccphrx_node);
257                                         dccp_rx_hist_entry_delete(hist, entry);
258                                         break;
259                                 }
260                         } else if (dccp_rx_hist_entry_data_packet(entry))
261                                 --num_later;
262                 }
263         }
264 }
265
266 EXPORT_SYMBOL_GPL(dccp_rx_hist_add_packet);
267
268 void dccp_rx_hist_purge(struct dccp_rx_hist *hist, struct list_head *list)
269 {
270         struct dccp_rx_hist_entry *entry, *next;
271
272         list_for_each_entry_safe(entry, next, list, dccphrx_node) {
273                 list_del_init(&entry->dccphrx_node);
274                 kmem_cache_free(hist->dccprxh_slab, entry);
275         }
276 }
277
278 EXPORT_SYMBOL_GPL(dccp_rx_hist_purge);
279
280 extern int __init dccp_li_init(void);
281 extern void dccp_li_exit(void);
282
283 static __init int packet_history_init(void)
284 {
285         if (dccp_li_init() != 0)
286                 goto out;
287
288         tfrc_tx_hist = kmem_cache_create("tfrc_tx_hist",
289                                          sizeof(struct tfrc_tx_hist_entry), 0,
290                                          SLAB_HWCACHE_ALIGN, NULL);
291         if (tfrc_tx_hist == NULL)
292                 goto out_li_exit;
293
294         return 0;
295 out_li_exit:
296         dccp_li_exit();
297 out:
298         return -ENOBUFS;
299 }
300 module_init(packet_history_init);
301
302 static __exit void packet_history_exit(void)
303 {
304         if (tfrc_tx_hist != NULL) {
305                 kmem_cache_destroy(tfrc_tx_hist);
306                 tfrc_tx_hist = NULL;
307         }
308         dccp_li_exit();
309 }
310 module_exit(packet_history_exit);
311
312 MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>, "
313               "Arnaldo Carvalho de Melo <acme@ghostprotocols.net>");
314 MODULE_DESCRIPTION("DCCP TFRC library");
315 MODULE_LICENSE("GPL");