Commit | Line | Data |
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8c60f3fa | 1 | /* |
f3166c07 | 2 | * net/dccp/packet_history.c |
8c60f3fa | 3 | * |
276f2edc ACM |
4 | * Copyright (c) 2007 The University of Aberdeen, Scotland, UK |
5 | * Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand. | |
8c60f3fa ACM |
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/ | |
e6bccd35 | 11 | * or e-mail Ian McDonald - ian.mcdonald@jandi.co.nz |
8c60f3fa ACM |
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 | ||
8c60f3fa | 38 | #include <linux/string.h> |
b84a2189 | 39 | #include <linux/slab.h> |
8c60f3fa | 40 | #include "packet_history.h" |
b84a2189 | 41 | #include "../../dccp.h" |
8c60f3fa | 42 | |
9108d5f4 ACM |
43 | /** |
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 | |
48 | */ | |
49 | struct tfrc_tx_hist_entry { | |
50 | struct tfrc_tx_hist_entry *next; | |
51 | u64 seqno; | |
52 | ktime_t stamp; | |
53 | }; | |
54 | ||
7af5af30 | 55 | /* |
276f2edc | 56 | * Transmitter History Routines |
7af5af30 | 57 | */ |
e9c8b24a | 58 | static struct kmem_cache *tfrc_tx_hist_slab; |
7af5af30 | 59 | |
df8f83fd GR |
60 | int __init tfrc_tx_packet_history_init(void) |
61 | { | |
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; | |
66 | } | |
67 | ||
68 | void tfrc_tx_packet_history_exit(void) | |
69 | { | |
70 | if (tfrc_tx_hist_slab != NULL) { | |
71 | kmem_cache_destroy(tfrc_tx_hist_slab); | |
72 | tfrc_tx_hist_slab = NULL; | |
73 | } | |
74 | } | |
75 | ||
9108d5f4 | 76 | static struct tfrc_tx_hist_entry * |
276f2edc | 77 | tfrc_tx_hist_find_entry(struct tfrc_tx_hist_entry *head, u64 seqno) |
7af5af30 | 78 | { |
276f2edc ACM |
79 | while (head != NULL && head->seqno != seqno) |
80 | head = head->next; | |
7af5af30 | 81 | |
276f2edc | 82 | return head; |
7af5af30 GR |
83 | } |
84 | ||
276f2edc | 85 | int tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno) |
7af5af30 | 86 | { |
e9c8b24a | 87 | struct tfrc_tx_hist_entry *entry = kmem_cache_alloc(tfrc_tx_hist_slab, gfp_any()); |
276f2edc ACM |
88 | |
89 | if (entry == NULL) | |
90 | return -ENOBUFS; | |
91 | entry->seqno = seqno; | |
92 | entry->stamp = ktime_get_real(); | |
93 | entry->next = *headp; | |
94 | *headp = entry; | |
95 | return 0; | |
7af5af30 | 96 | } |
276f2edc | 97 | EXPORT_SYMBOL_GPL(tfrc_tx_hist_add); |
7af5af30 | 98 | |
276f2edc | 99 | void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp) |
7af5af30 | 100 | { |
276f2edc | 101 | struct tfrc_tx_hist_entry *head = *headp; |
7af5af30 | 102 | |
276f2edc ACM |
103 | while (head != NULL) { |
104 | struct tfrc_tx_hist_entry *next = head->next; | |
7af5af30 | 105 | |
e9c8b24a | 106 | kmem_cache_free(tfrc_tx_hist_slab, head); |
276f2edc | 107 | head = next; |
7af5af30 | 108 | } |
7af5af30 | 109 | |
276f2edc ACM |
110 | *headp = NULL; |
111 | } | |
112 | EXPORT_SYMBOL_GPL(tfrc_tx_hist_purge); | |
7af5af30 | 113 | |
9108d5f4 ACM |
114 | u32 tfrc_tx_hist_rtt(struct tfrc_tx_hist_entry *head, const u64 seqno, |
115 | const ktime_t now) | |
116 | { | |
117 | u32 rtt = 0; | |
118 | struct tfrc_tx_hist_entry *packet = tfrc_tx_hist_find_entry(head, seqno); | |
119 | ||
120 | if (packet != NULL) { | |
121 | rtt = ktime_us_delta(now, packet->stamp); | |
122 | /* | |
123 | * Garbage-collect older (irrelevant) entries: | |
124 | */ | |
125 | tfrc_tx_hist_purge(&packet->next); | |
126 | } | |
127 | ||
128 | return rtt; | |
129 | } | |
130 | EXPORT_SYMBOL_GPL(tfrc_tx_hist_rtt); | |
131 | ||
b84a2189 | 132 | |
78282d2a GR |
133 | /* |
134 | * Receiver History Routines | |
135 | */ | |
136 | static struct kmem_cache *tfrc_rx_hist_slab; | |
137 | ||
df8f83fd GR |
138 | int __init tfrc_rx_packet_history_init(void) |
139 | { | |
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; | |
144 | } | |
145 | ||
146 | void tfrc_rx_packet_history_exit(void) | |
147 | { | |
148 | if (tfrc_rx_hist_slab != NULL) { | |
149 | kmem_cache_destroy(tfrc_rx_hist_slab); | |
150 | tfrc_rx_hist_slab = NULL; | |
151 | } | |
152 | } | |
153 | ||
8a9c7e92 GR |
154 | static inline void tfrc_rx_hist_entry_from_skb(struct tfrc_rx_hist_entry *entry, |
155 | const struct sk_buff *skb, | |
156 | const u32 ndp) | |
8c60f3fa | 157 | { |
b84a2189 ACM |
158 | const struct dccp_hdr *dh = dccp_hdr(skb); |
159 | ||
160 | entry->tfrchrx_seqno = DCCP_SKB_CB(skb)->dccpd_seq; | |
161 | entry->tfrchrx_ccval = dh->dccph_ccval; | |
162 | entry->tfrchrx_type = dh->dccph_type; | |
163 | entry->tfrchrx_ndp = ndp; | |
164 | entry->tfrchrx_tstamp = ktime_get_real(); | |
8c60f3fa | 165 | } |
8a9c7e92 GR |
166 | |
167 | void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h, | |
168 | const struct sk_buff *skb, | |
169 | const u32 ndp) | |
170 | { | |
171 | struct tfrc_rx_hist_entry *entry = tfrc_rx_hist_last_rcv(h); | |
172 | ||
173 | tfrc_rx_hist_entry_from_skb(entry, skb, ndp); | |
174 | } | |
b84a2189 | 175 | EXPORT_SYMBOL_GPL(tfrc_rx_hist_add_packet); |
8c60f3fa | 176 | |
b84a2189 ACM |
177 | /* has the packet contained in skb been seen before? */ |
178 | int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb) | |
179 | { | |
180 | const u64 seq = DCCP_SKB_CB(skb)->dccpd_seq; | |
181 | int i; | |
182 | ||
183 | if (dccp_delta_seqno(tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, seq) <= 0) | |
184 | return 1; | |
8c60f3fa | 185 | |
b84a2189 ACM |
186 | for (i = 1; i <= h->loss_count; i++) |
187 | if (tfrc_rx_hist_entry(h, i)->tfrchrx_seqno == seq) | |
188 | return 1; | |
8c60f3fa | 189 | |
b84a2189 | 190 | return 0; |
7af5af30 | 191 | } |
b84a2189 | 192 | EXPORT_SYMBOL_GPL(tfrc_rx_hist_duplicate); |
7af5af30 | 193 | |
8a9c7e92 GR |
194 | static void tfrc_rx_hist_swap(struct tfrc_rx_hist *h, const u8 a, const u8 b) |
195 | { | |
196 | const u8 idx_a = tfrc_rx_hist_index(h, a), | |
197 | idx_b = tfrc_rx_hist_index(h, b); | |
198 | struct tfrc_rx_hist_entry *tmp = h->ring[idx_a]; | |
199 | ||
200 | h->ring[idx_a] = h->ring[idx_b]; | |
201 | h->ring[idx_b] = tmp; | |
202 | } | |
203 | ||
204 | /* | |
205 | * Private helper functions for loss detection. | |
206 | * | |
207 | * In the descriptions, `Si' refers to the sequence number of entry number i, | |
208 | * whose NDP count is `Ni' (lower case is used for variables). | |
209 | * Note: All __after_loss functions expect that a test against duplicates has | |
210 | * been performed already: the seqno of the skb must not be less than the | |
211 | * seqno of loss_prev; and it must not equal that of any valid hist_entry. | |
212 | */ | |
213 | static void __one_after_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u32 n2) | |
214 | { | |
215 | u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, | |
216 | s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno, | |
217 | s2 = DCCP_SKB_CB(skb)->dccpd_seq; | |
218 | int n1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_ndp, | |
219 | d12 = dccp_delta_seqno(s1, s2), d2; | |
220 | ||
221 | if (d12 > 0) { /* S1 < S2 */ | |
222 | h->loss_count = 2; | |
223 | tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 2), skb, n2); | |
224 | return; | |
225 | } | |
226 | ||
227 | /* S0 < S2 < S1 */ | |
228 | d2 = dccp_delta_seqno(s0, s2); | |
229 | ||
230 | if (d2 == 1 || n2 >= d2) { /* S2 is direct successor of S0 */ | |
231 | int d21 = -d12; | |
232 | ||
233 | if (d21 == 1 || n1 >= d21) { | |
234 | /* hole is filled: S0, S2, and S1 are consecutive */ | |
235 | h->loss_count = 0; | |
236 | h->loss_start = tfrc_rx_hist_index(h, 1); | |
237 | } else | |
238 | /* gap between S2 and S1: just update loss_prev */ | |
239 | tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_loss_prev(h), skb, n2); | |
240 | ||
241 | } else { /* hole between S0 and S2 */ | |
242 | /* | |
243 | * Reorder history to insert S2 between S0 and s1 | |
244 | */ | |
245 | tfrc_rx_hist_swap(h, 0, 3); | |
246 | h->loss_start = tfrc_rx_hist_index(h, 3); | |
247 | tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n2); | |
248 | h->loss_count = 2; | |
249 | } | |
250 | } | |
251 | ||
252 | /* return 1 if a new loss event has been identified */ | |
253 | static int __two_after_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u32 n3) | |
254 | { | |
255 | u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, | |
256 | s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno, | |
257 | s2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_seqno, | |
258 | s3 = DCCP_SKB_CB(skb)->dccpd_seq; | |
259 | int n1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_ndp, | |
260 | d23 = dccp_delta_seqno(s2, s3), d13, d3, d31; | |
261 | ||
262 | if (d23 > 0) { /* S2 < S3 */ | |
263 | h->loss_count = 3; | |
264 | tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 3), skb, n3); | |
265 | return 1; | |
266 | } | |
267 | ||
268 | /* S3 < S2 */ | |
269 | d13 = dccp_delta_seqno(s1, s3); | |
270 | ||
271 | if (d13 > 0) { | |
272 | /* | |
273 | * The sequence number order is S1, S3, S2 | |
274 | * Reorder history to insert entry between S1 and S2 | |
275 | */ | |
276 | tfrc_rx_hist_swap(h, 2, 3); | |
277 | tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 2), skb, n3); | |
278 | h->loss_count = 3; | |
279 | return 1; | |
280 | } | |
281 | ||
282 | /* S0 < S3 < S1 */ | |
283 | d31 = -d13; | |
284 | d3 = dccp_delta_seqno(s0, s3); | |
285 | ||
286 | if (d3 == 1 || n3 >= d3) { /* S3 is a successor of S0 */ | |
287 | ||
288 | if (d31 == 1 || n1 >= d31) { | |
289 | /* hole between S0 and S1 filled by S3 */ | |
290 | int d2 = dccp_delta_seqno(s1, s2), | |
291 | n2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_ndp; | |
292 | ||
293 | if (d2 == 1 || n2 >= d2) { | |
294 | /* entire hole filled by S0, S3, S1, S2 */ | |
295 | h->loss_start = tfrc_rx_hist_index(h, 2); | |
296 | h->loss_count = 0; | |
297 | } else { | |
298 | /* gap remains between S1 and S2 */ | |
299 | h->loss_start = tfrc_rx_hist_index(h, 1); | |
300 | h->loss_count = 1; | |
301 | } | |
302 | ||
303 | } else /* gap exists between S3 and S1, loss_count stays at 2 */ | |
304 | tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_loss_prev(h), skb, n3); | |
305 | ||
306 | return 0; | |
307 | } | |
308 | ||
309 | /* | |
310 | * The remaining case: S3 is not a successor of S0. | |
311 | * Sequence order is S0, S3, S1, S2; reorder to insert between S0 and S1 | |
312 | */ | |
313 | tfrc_rx_hist_swap(h, 0, 3); | |
314 | h->loss_start = tfrc_rx_hist_index(h, 3); | |
315 | tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n3); | |
316 | h->loss_count = 3; | |
317 | ||
318 | return 1; | |
319 | } | |
320 | ||
321 | /* return the signed modulo-2^48 sequence number distance from entry e1 to e2 */ | |
322 | static s64 tfrc_rx_hist_delta_seqno(struct tfrc_rx_hist *h, u8 e1, u8 e2) | |
323 | { | |
324 | DCCP_BUG_ON(e1 > h->loss_count || e2 > h->loss_count); | |
325 | ||
326 | return dccp_delta_seqno(tfrc_rx_hist_entry(h, e1)->tfrchrx_seqno, | |
327 | tfrc_rx_hist_entry(h, e2)->tfrchrx_seqno); | |
328 | } | |
329 | ||
330 | /* recycle RX history records to continue loss detection if necessary */ | |
331 | static void __three_after_loss(struct tfrc_rx_hist *h) | |
332 | { | |
333 | /* | |
334 | * The distance between S0 and S1 is always greater than 1 and the NDP | |
335 | * count of S1 is smaller than this distance. Otherwise there would | |
336 | * have been no loss. Hence it is only necessary to see whether there | |
337 | * are further missing data packets between S1/S2 and S2/S3. | |
338 | */ | |
339 | int d2 = tfrc_rx_hist_delta_seqno(h, 1, 2), | |
340 | d3 = tfrc_rx_hist_delta_seqno(h, 2, 3), | |
341 | n2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_ndp, | |
342 | n3 = tfrc_rx_hist_entry(h, 3)->tfrchrx_ndp; | |
343 | ||
344 | if (d2 == 1 || n2 >= d2) { /* S2 is successor to S1 */ | |
345 | ||
346 | if (d3 == 1 || n3 >= d3) { | |
347 | /* S3 is successor of S2: entire hole is filled */ | |
348 | h->loss_start = tfrc_rx_hist_index(h, 3); | |
349 | h->loss_count = 0; | |
350 | } else { | |
351 | /* gap between S2 and S3 */ | |
352 | h->loss_start = tfrc_rx_hist_index(h, 2); | |
353 | h->loss_count = 1; | |
354 | } | |
355 | ||
356 | } else { /* gap between S1 and S2 */ | |
357 | h->loss_start = tfrc_rx_hist_index(h, 1); | |
358 | h->loss_count = 2; | |
359 | } | |
360 | } | |
361 | ||
362 | /** | |
363 | * tfrc_rx_handle_loss - Loss detection and further processing | |
364 | * @h: The non-empty RX history object | |
365 | * @lh: Loss Intervals database to update | |
366 | * @skb: Currently received packet | |
367 | * @ndp: The NDP count belonging to @skb | |
368 | * @calc_first_li: Caller-dependent computation of first loss interval in @lh | |
369 | * @sk: Used by @calc_first_li (see tfrc_lh_interval_add) | |
370 | * Chooses action according to pending loss, updates LI database when a new | |
371 | * loss was detected, and does required post-processing. Returns 1 when caller | |
372 | * should send feedback, 0 otherwise. | |
373 | */ | |
374 | int tfrc_rx_handle_loss(struct tfrc_rx_hist *h, | |
375 | struct tfrc_loss_hist *lh, | |
376 | struct sk_buff *skb, u32 ndp, | |
377 | u32 (*calc_first_li)(struct sock *), struct sock *sk) | |
378 | { | |
379 | int is_new_loss = 0; | |
380 | ||
381 | if (h->loss_count == 1) { | |
382 | __one_after_loss(h, skb, ndp); | |
383 | } else if (h->loss_count != 2) { | |
384 | DCCP_BUG("invalid loss_count %d", h->loss_count); | |
385 | } else if (__two_after_loss(h, skb, ndp)) { | |
386 | /* | |
387 | * Update Loss Interval database and recycle RX records | |
388 | */ | |
389 | is_new_loss = tfrc_lh_interval_add(lh, h, calc_first_li, sk); | |
390 | __three_after_loss(h); | |
391 | } | |
392 | return is_new_loss; | |
393 | } | |
394 | EXPORT_SYMBOL_GPL(tfrc_rx_handle_loss); | |
395 | ||
b84a2189 ACM |
396 | int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h) |
397 | { | |
398 | int i; | |
399 | ||
400 | for (i = 0; i <= TFRC_NDUPACK; i++) { | |
401 | h->ring[i] = kmem_cache_alloc(tfrc_rx_hist_slab, GFP_ATOMIC); | |
402 | if (h->ring[i] == NULL) | |
403 | goto out_free; | |
404 | } | |
405 | ||
406 | h->loss_count = h->loss_start = 0; | |
407 | return 0; | |
408 | ||
409 | out_free: | |
410 | while (i-- != 0) { | |
411 | kmem_cache_free(tfrc_rx_hist_slab, h->ring[i]); | |
412 | h->ring[i] = NULL; | |
413 | } | |
414 | return -ENOBUFS; | |
415 | } | |
416 | EXPORT_SYMBOL_GPL(tfrc_rx_hist_alloc); | |
8c60f3fa | 417 | |
b84a2189 | 418 | void tfrc_rx_hist_purge(struct tfrc_rx_hist *h) |
072ab6c6 | 419 | { |
b84a2189 ACM |
420 | int i; |
421 | ||
422 | for (i = 0; i <= TFRC_NDUPACK; ++i) | |
423 | if (h->ring[i] != NULL) { | |
424 | kmem_cache_free(tfrc_rx_hist_slab, h->ring[i]); | |
425 | h->ring[i] = NULL; | |
072ab6c6 | 426 | } |
072ab6c6 | 427 | } |
b84a2189 | 428 | EXPORT_SYMBOL_GPL(tfrc_rx_hist_purge); |
072ab6c6 | 429 | |
b84a2189 ACM |
430 | /** |
431 | * tfrc_rx_hist_rtt_last_s - reference entry to compute RTT samples against | |
432 | */ | |
433 | static inline struct tfrc_rx_hist_entry * | |
434 | tfrc_rx_hist_rtt_last_s(const struct tfrc_rx_hist *h) | |
435 | { | |
436 | return h->ring[0]; | |
437 | } | |
072ab6c6 | 438 | |
b84a2189 ACM |
439 | /** |
440 | * tfrc_rx_hist_rtt_prev_s: previously suitable (wrt rtt_last_s) RTT-sampling entry | |
441 | */ | |
442 | static inline struct tfrc_rx_hist_entry * | |
443 | tfrc_rx_hist_rtt_prev_s(const struct tfrc_rx_hist *h) | |
8c60f3fa | 444 | { |
b84a2189 ACM |
445 | return h->ring[h->rtt_sample_prev]; |
446 | } | |
8c60f3fa | 447 | |
b84a2189 ACM |
448 | /** |
449 | * tfrc_rx_hist_sample_rtt - Sample RTT from timestamp / CCVal | |
450 | * Based on ideas presented in RFC 4342, 8.1. Returns 0 if it was not able | |
451 | * to compute a sample with given data - calling function should check this. | |
452 | */ | |
453 | u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h, const struct sk_buff *skb) | |
454 | { | |
455 | u32 sample = 0, | |
456 | delta_v = SUB16(dccp_hdr(skb)->dccph_ccval, | |
457 | tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval); | |
458 | ||
459 | if (delta_v < 1 || delta_v > 4) { /* unsuitable CCVal delta */ | |
460 | if (h->rtt_sample_prev == 2) { /* previous candidate stored */ | |
461 | sample = SUB16(tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_ccval, | |
462 | tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval); | |
463 | if (sample) | |
464 | sample = 4 / sample * | |
465 | ktime_us_delta(tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_tstamp, | |
466 | tfrc_rx_hist_rtt_last_s(h)->tfrchrx_tstamp); | |
467 | else /* | |
468 | * FIXME: This condition is in principle not | |
469 | * possible but occurs when CCID is used for | |
470 | * two-way data traffic. I have tried to trace | |
471 | * it, but the cause does not seem to be here. | |
472 | */ | |
473 | DCCP_BUG("please report to dccp@vger.kernel.org" | |
474 | " => prev = %u, last = %u", | |
475 | tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_ccval, | |
476 | tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval); | |
477 | } else if (delta_v < 1) { | |
478 | h->rtt_sample_prev = 1; | |
479 | goto keep_ref_for_next_time; | |
480 | } | |
481 | ||
482 | } else if (delta_v == 4) /* optimal match */ | |
483 | sample = ktime_to_us(net_timedelta(tfrc_rx_hist_rtt_last_s(h)->tfrchrx_tstamp)); | |
484 | else { /* suboptimal match */ | |
485 | h->rtt_sample_prev = 2; | |
486 | goto keep_ref_for_next_time; | |
8c60f3fa | 487 | } |
8c60f3fa | 488 | |
b84a2189 ACM |
489 | if (unlikely(sample > DCCP_SANE_RTT_MAX)) { |
490 | DCCP_WARN("RTT sample %u too large, using max\n", sample); | |
491 | sample = DCCP_SANE_RTT_MAX; | |
492 | } | |
493 | ||
494 | h->rtt_sample_prev = 0; /* use current entry as next reference */ | |
495 | keep_ref_for_next_time: | |
496 | ||
497 | return sample; | |
498 | } | |
499 | EXPORT_SYMBOL_GPL(tfrc_rx_hist_sample_rtt); |