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 | |
7af5af30 | 43 | /* |
276f2edc | 44 | * Transmitter History Routines |
7af5af30 | 45 | */ |
e9c8b24a | 46 | static struct kmem_cache *tfrc_tx_hist_slab; |
7af5af30 | 47 | |
df8f83fd GR |
48 | int __init tfrc_tx_packet_history_init(void) |
49 | { | |
50 | tfrc_tx_hist_slab = kmem_cache_create("tfrc_tx_hist", | |
51 | sizeof(struct tfrc_tx_hist_entry), | |
52 | 0, SLAB_HWCACHE_ALIGN, NULL); | |
53 | return tfrc_tx_hist_slab == NULL ? -ENOBUFS : 0; | |
54 | } | |
55 | ||
56 | void tfrc_tx_packet_history_exit(void) | |
57 | { | |
58 | if (tfrc_tx_hist_slab != NULL) { | |
59 | kmem_cache_destroy(tfrc_tx_hist_slab); | |
60 | tfrc_tx_hist_slab = NULL; | |
61 | } | |
62 | } | |
63 | ||
276f2edc | 64 | int tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno) |
7af5af30 | 65 | { |
e9c8b24a | 66 | struct tfrc_tx_hist_entry *entry = kmem_cache_alloc(tfrc_tx_hist_slab, gfp_any()); |
276f2edc ACM |
67 | |
68 | if (entry == NULL) | |
69 | return -ENOBUFS; | |
70 | entry->seqno = seqno; | |
71 | entry->stamp = ktime_get_real(); | |
72 | entry->next = *headp; | |
73 | *headp = entry; | |
74 | return 0; | |
7af5af30 | 75 | } |
276f2edc | 76 | EXPORT_SYMBOL_GPL(tfrc_tx_hist_add); |
7af5af30 | 77 | |
276f2edc | 78 | void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp) |
7af5af30 | 79 | { |
276f2edc | 80 | struct tfrc_tx_hist_entry *head = *headp; |
7af5af30 | 81 | |
276f2edc ACM |
82 | while (head != NULL) { |
83 | struct tfrc_tx_hist_entry *next = head->next; | |
7af5af30 | 84 | |
e9c8b24a | 85 | kmem_cache_free(tfrc_tx_hist_slab, head); |
276f2edc | 86 | head = next; |
7af5af30 | 87 | } |
7af5af30 | 88 | |
276f2edc ACM |
89 | *headp = NULL; |
90 | } | |
91 | EXPORT_SYMBOL_GPL(tfrc_tx_hist_purge); | |
7af5af30 | 92 | |
78282d2a GR |
93 | /* |
94 | * Receiver History Routines | |
95 | */ | |
96 | static struct kmem_cache *tfrc_rx_hist_slab; | |
97 | ||
df8f83fd GR |
98 | int __init tfrc_rx_packet_history_init(void) |
99 | { | |
100 | tfrc_rx_hist_slab = kmem_cache_create("tfrc_rxh_cache", | |
101 | sizeof(struct tfrc_rx_hist_entry), | |
102 | 0, SLAB_HWCACHE_ALIGN, NULL); | |
103 | return tfrc_rx_hist_slab == NULL ? -ENOBUFS : 0; | |
104 | } | |
105 | ||
106 | void tfrc_rx_packet_history_exit(void) | |
107 | { | |
108 | if (tfrc_rx_hist_slab != NULL) { | |
109 | kmem_cache_destroy(tfrc_rx_hist_slab); | |
110 | tfrc_rx_hist_slab = NULL; | |
111 | } | |
112 | } | |
113 | ||
8a9c7e92 GR |
114 | static inline void tfrc_rx_hist_entry_from_skb(struct tfrc_rx_hist_entry *entry, |
115 | const struct sk_buff *skb, | |
5b5d0e70 | 116 | const u64 ndp) |
8c60f3fa | 117 | { |
b84a2189 ACM |
118 | const struct dccp_hdr *dh = dccp_hdr(skb); |
119 | ||
120 | entry->tfrchrx_seqno = DCCP_SKB_CB(skb)->dccpd_seq; | |
121 | entry->tfrchrx_ccval = dh->dccph_ccval; | |
122 | entry->tfrchrx_type = dh->dccph_type; | |
123 | entry->tfrchrx_ndp = ndp; | |
124 | entry->tfrchrx_tstamp = ktime_get_real(); | |
8c60f3fa | 125 | } |
8a9c7e92 GR |
126 | |
127 | void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h, | |
128 | const struct sk_buff *skb, | |
5b5d0e70 | 129 | const u64 ndp) |
8a9c7e92 GR |
130 | { |
131 | struct tfrc_rx_hist_entry *entry = tfrc_rx_hist_last_rcv(h); | |
132 | ||
133 | tfrc_rx_hist_entry_from_skb(entry, skb, ndp); | |
134 | } | |
b84a2189 | 135 | EXPORT_SYMBOL_GPL(tfrc_rx_hist_add_packet); |
8c60f3fa | 136 | |
b84a2189 ACM |
137 | /* has the packet contained in skb been seen before? */ |
138 | int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb) | |
139 | { | |
140 | const u64 seq = DCCP_SKB_CB(skb)->dccpd_seq; | |
141 | int i; | |
142 | ||
143 | if (dccp_delta_seqno(tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, seq) <= 0) | |
144 | return 1; | |
8c60f3fa | 145 | |
b84a2189 ACM |
146 | for (i = 1; i <= h->loss_count; i++) |
147 | if (tfrc_rx_hist_entry(h, i)->tfrchrx_seqno == seq) | |
148 | return 1; | |
8c60f3fa | 149 | |
b84a2189 | 150 | return 0; |
7af5af30 | 151 | } |
b84a2189 | 152 | EXPORT_SYMBOL_GPL(tfrc_rx_hist_duplicate); |
7af5af30 | 153 | |
8a9c7e92 GR |
154 | static void tfrc_rx_hist_swap(struct tfrc_rx_hist *h, const u8 a, const u8 b) |
155 | { | |
156 | const u8 idx_a = tfrc_rx_hist_index(h, a), | |
157 | idx_b = tfrc_rx_hist_index(h, b); | |
158 | struct tfrc_rx_hist_entry *tmp = h->ring[idx_a]; | |
159 | ||
160 | h->ring[idx_a] = h->ring[idx_b]; | |
161 | h->ring[idx_b] = tmp; | |
162 | } | |
163 | ||
164 | /* | |
165 | * Private helper functions for loss detection. | |
166 | * | |
167 | * In the descriptions, `Si' refers to the sequence number of entry number i, | |
168 | * whose NDP count is `Ni' (lower case is used for variables). | |
b552c623 GR |
169 | * Note: All __xxx_loss functions expect that a test against duplicates has been |
170 | * performed already: the seqno of the skb must not be less than the seqno | |
171 | * of loss_prev; and it must not equal that of any valid history entry. | |
8a9c7e92 | 172 | */ |
b552c623 GR |
173 | static void __do_track_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u64 n1) |
174 | { | |
175 | u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, | |
176 | s1 = DCCP_SKB_CB(skb)->dccpd_seq; | |
177 | ||
178 | if (!dccp_loss_free(s0, s1, n1)) { /* gap between S0 and S1 */ | |
179 | h->loss_count = 1; | |
180 | tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n1); | |
181 | } | |
182 | } | |
183 | ||
8a9c7e92 GR |
184 | static void __one_after_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u32 n2) |
185 | { | |
186 | u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, | |
187 | s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno, | |
188 | s2 = DCCP_SKB_CB(skb)->dccpd_seq; | |
8a9c7e92 | 189 | |
2013c7e3 | 190 | if (likely(dccp_delta_seqno(s1, s2) > 0)) { /* S1 < S2 */ |
8a9c7e92 GR |
191 | h->loss_count = 2; |
192 | tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 2), skb, n2); | |
193 | return; | |
194 | } | |
195 | ||
196 | /* S0 < S2 < S1 */ | |
8a9c7e92 | 197 | |
2013c7e3 GR |
198 | if (dccp_loss_free(s0, s2, n2)) { |
199 | u64 n1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_ndp; | |
8a9c7e92 | 200 | |
2013c7e3 | 201 | if (dccp_loss_free(s2, s1, n1)) { |
8a9c7e92 GR |
202 | /* hole is filled: S0, S2, and S1 are consecutive */ |
203 | h->loss_count = 0; | |
204 | h->loss_start = tfrc_rx_hist_index(h, 1); | |
205 | } else | |
206 | /* gap between S2 and S1: just update loss_prev */ | |
207 | tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_loss_prev(h), skb, n2); | |
208 | ||
2013c7e3 | 209 | } else { /* gap between S0 and S2 */ |
8a9c7e92 | 210 | /* |
2013c7e3 | 211 | * Reorder history to insert S2 between S0 and S1 |
8a9c7e92 GR |
212 | */ |
213 | tfrc_rx_hist_swap(h, 0, 3); | |
214 | h->loss_start = tfrc_rx_hist_index(h, 3); | |
215 | tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n2); | |
216 | h->loss_count = 2; | |
217 | } | |
218 | } | |
219 | ||
220 | /* return 1 if a new loss event has been identified */ | |
221 | static int __two_after_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u32 n3) | |
222 | { | |
223 | u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, | |
224 | s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno, | |
225 | s2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_seqno, | |
226 | s3 = DCCP_SKB_CB(skb)->dccpd_seq; | |
8a9c7e92 | 227 | |
2013c7e3 | 228 | if (likely(dccp_delta_seqno(s2, s3) > 0)) { /* S2 < S3 */ |
8a9c7e92 GR |
229 | h->loss_count = 3; |
230 | tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 3), skb, n3); | |
231 | return 1; | |
232 | } | |
233 | ||
234 | /* S3 < S2 */ | |
8a9c7e92 | 235 | |
2013c7e3 | 236 | if (dccp_delta_seqno(s1, s3) > 0) { /* S1 < S3 < S2 */ |
8a9c7e92 | 237 | /* |
2013c7e3 | 238 | * Reorder history to insert S3 between S1 and S2 |
8a9c7e92 GR |
239 | */ |
240 | tfrc_rx_hist_swap(h, 2, 3); | |
241 | tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 2), skb, n3); | |
242 | h->loss_count = 3; | |
243 | return 1; | |
244 | } | |
245 | ||
246 | /* S0 < S3 < S1 */ | |
8a9c7e92 | 247 | |
2013c7e3 GR |
248 | if (dccp_loss_free(s0, s3, n3)) { |
249 | u64 n1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_ndp; | |
8a9c7e92 | 250 | |
2013c7e3 | 251 | if (dccp_loss_free(s3, s1, n1)) { |
8a9c7e92 | 252 | /* hole between S0 and S1 filled by S3 */ |
2013c7e3 | 253 | u64 n2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_ndp; |
8a9c7e92 | 254 | |
2013c7e3 | 255 | if (dccp_loss_free(s1, s2, n2)) { |
8a9c7e92 GR |
256 | /* entire hole filled by S0, S3, S1, S2 */ |
257 | h->loss_start = tfrc_rx_hist_index(h, 2); | |
258 | h->loss_count = 0; | |
259 | } else { | |
260 | /* gap remains between S1 and S2 */ | |
261 | h->loss_start = tfrc_rx_hist_index(h, 1); | |
262 | h->loss_count = 1; | |
263 | } | |
264 | ||
265 | } else /* gap exists between S3 and S1, loss_count stays at 2 */ | |
266 | tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_loss_prev(h), skb, n3); | |
267 | ||
268 | return 0; | |
269 | } | |
270 | ||
271 | /* | |
2013c7e3 GR |
272 | * The remaining case: S0 < S3 < S1 < S2; gap between S0 and S3 |
273 | * Reorder history to insert S3 between S0 and S1. | |
8a9c7e92 GR |
274 | */ |
275 | tfrc_rx_hist_swap(h, 0, 3); | |
276 | h->loss_start = tfrc_rx_hist_index(h, 3); | |
277 | tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n3); | |
278 | h->loss_count = 3; | |
279 | ||
280 | return 1; | |
281 | } | |
282 | ||
8a9c7e92 GR |
283 | /* recycle RX history records to continue loss detection if necessary */ |
284 | static void __three_after_loss(struct tfrc_rx_hist *h) | |
285 | { | |
286 | /* | |
2013c7e3 GR |
287 | * At this stage we know already that there is a gap between S0 and S1 |
288 | * (since S0 was the highest sequence number received before detecting | |
289 | * the loss). To recycle the loss record, it is thus only necessary to | |
290 | * check for other possible gaps between S1/S2 and between S2/S3. | |
8a9c7e92 | 291 | */ |
2013c7e3 GR |
292 | u64 s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno, |
293 | s2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_seqno, | |
294 | s3 = tfrc_rx_hist_entry(h, 3)->tfrchrx_seqno; | |
295 | u64 n2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_ndp, | |
8a9c7e92 GR |
296 | n3 = tfrc_rx_hist_entry(h, 3)->tfrchrx_ndp; |
297 | ||
2013c7e3 | 298 | if (dccp_loss_free(s1, s2, n2)) { |
8a9c7e92 | 299 | |
2013c7e3 GR |
300 | if (dccp_loss_free(s2, s3, n3)) { |
301 | /* no gap between S2 and S3: entire hole is filled */ | |
8a9c7e92 GR |
302 | h->loss_start = tfrc_rx_hist_index(h, 3); |
303 | h->loss_count = 0; | |
304 | } else { | |
305 | /* gap between S2 and S3 */ | |
306 | h->loss_start = tfrc_rx_hist_index(h, 2); | |
307 | h->loss_count = 1; | |
308 | } | |
309 | ||
2013c7e3 | 310 | } else { /* gap between S1 and S2 */ |
8a9c7e92 GR |
311 | h->loss_start = tfrc_rx_hist_index(h, 1); |
312 | h->loss_count = 2; | |
313 | } | |
314 | } | |
315 | ||
316 | /** | |
317 | * tfrc_rx_handle_loss - Loss detection and further processing | |
318 | * @h: The non-empty RX history object | |
319 | * @lh: Loss Intervals database to update | |
320 | * @skb: Currently received packet | |
321 | * @ndp: The NDP count belonging to @skb | |
322 | * @calc_first_li: Caller-dependent computation of first loss interval in @lh | |
323 | * @sk: Used by @calc_first_li (see tfrc_lh_interval_add) | |
324 | * Chooses action according to pending loss, updates LI database when a new | |
325 | * loss was detected, and does required post-processing. Returns 1 when caller | |
326 | * should send feedback, 0 otherwise. | |
b552c623 GR |
327 | * Since it also takes care of reordering during loss detection and updates the |
328 | * records accordingly, the caller should not perform any more RX history | |
329 | * operations when loss_count is greater than 0 after calling this function. | |
8a9c7e92 GR |
330 | */ |
331 | int tfrc_rx_handle_loss(struct tfrc_rx_hist *h, | |
332 | struct tfrc_loss_hist *lh, | |
5b5d0e70 | 333 | struct sk_buff *skb, const u64 ndp, |
8a9c7e92 GR |
334 | u32 (*calc_first_li)(struct sock *), struct sock *sk) |
335 | { | |
336 | int is_new_loss = 0; | |
337 | ||
d20ed95f GR |
338 | if (tfrc_rx_hist_duplicate(h, skb)) |
339 | return 0; | |
340 | ||
b552c623 GR |
341 | if (h->loss_count == 0) { |
342 | __do_track_loss(h, skb, ndp); | |
343 | } else if (h->loss_count == 1) { | |
8a9c7e92 GR |
344 | __one_after_loss(h, skb, ndp); |
345 | } else if (h->loss_count != 2) { | |
346 | DCCP_BUG("invalid loss_count %d", h->loss_count); | |
347 | } else if (__two_after_loss(h, skb, ndp)) { | |
348 | /* | |
349 | * Update Loss Interval database and recycle RX records | |
350 | */ | |
351 | is_new_loss = tfrc_lh_interval_add(lh, h, calc_first_li, sk); | |
352 | __three_after_loss(h); | |
353 | } | |
354 | return is_new_loss; | |
355 | } | |
356 | EXPORT_SYMBOL_GPL(tfrc_rx_handle_loss); | |
357 | ||
b84a2189 | 358 | void tfrc_rx_hist_purge(struct tfrc_rx_hist *h) |
072ab6c6 | 359 | { |
b84a2189 ACM |
360 | int i; |
361 | ||
362 | for (i = 0; i <= TFRC_NDUPACK; ++i) | |
363 | if (h->ring[i] != NULL) { | |
364 | kmem_cache_free(tfrc_rx_hist_slab, h->ring[i]); | |
365 | h->ring[i] = NULL; | |
072ab6c6 | 366 | } |
072ab6c6 | 367 | } |
b84a2189 | 368 | EXPORT_SYMBOL_GPL(tfrc_rx_hist_purge); |
072ab6c6 | 369 | |
24b8d343 GR |
370 | static int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h) |
371 | { | |
372 | int i; | |
373 | ||
374 | memset(h, 0, sizeof(*h)); | |
375 | ||
376 | for (i = 0; i <= TFRC_NDUPACK; i++) { | |
377 | h->ring[i] = kmem_cache_alloc(tfrc_rx_hist_slab, GFP_ATOMIC); | |
378 | if (h->ring[i] == NULL) { | |
379 | tfrc_rx_hist_purge(h); | |
380 | return -ENOBUFS; | |
381 | } | |
382 | } | |
383 | return 0; | |
384 | } | |
385 | ||
386 | int tfrc_rx_hist_init(struct tfrc_rx_hist *h, struct sock *sk) | |
387 | { | |
388 | if (tfrc_rx_hist_alloc(h)) | |
389 | return -ENOBUFS; | |
390 | /* | |
391 | * Initialise first entry with GSR to start loss detection as early as | |
392 | * possible. Code using this must not use any other fields. The entry | |
393 | * will be overwritten once the CCID updates its received packets. | |
394 | */ | |
395 | tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno = dccp_sk(sk)->dccps_gsr; | |
396 | return 0; | |
397 | } | |
398 | EXPORT_SYMBOL_GPL(tfrc_rx_hist_init); | |
399 | ||
b84a2189 ACM |
400 | /** |
401 | * tfrc_rx_hist_rtt_last_s - reference entry to compute RTT samples against | |
402 | */ | |
403 | static inline struct tfrc_rx_hist_entry * | |
404 | tfrc_rx_hist_rtt_last_s(const struct tfrc_rx_hist *h) | |
405 | { | |
406 | return h->ring[0]; | |
407 | } | |
072ab6c6 | 408 | |
b84a2189 ACM |
409 | /** |
410 | * tfrc_rx_hist_rtt_prev_s: previously suitable (wrt rtt_last_s) RTT-sampling entry | |
411 | */ | |
412 | static inline struct tfrc_rx_hist_entry * | |
413 | tfrc_rx_hist_rtt_prev_s(const struct tfrc_rx_hist *h) | |
8c60f3fa | 414 | { |
b84a2189 ACM |
415 | return h->ring[h->rtt_sample_prev]; |
416 | } | |
8c60f3fa | 417 | |
b84a2189 ACM |
418 | /** |
419 | * tfrc_rx_hist_sample_rtt - Sample RTT from timestamp / CCVal | |
420 | * Based on ideas presented in RFC 4342, 8.1. Returns 0 if it was not able | |
421 | * to compute a sample with given data - calling function should check this. | |
422 | */ | |
423 | u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h, const struct sk_buff *skb) | |
424 | { | |
425 | u32 sample = 0, | |
426 | delta_v = SUB16(dccp_hdr(skb)->dccph_ccval, | |
427 | tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval); | |
428 | ||
429 | if (delta_v < 1 || delta_v > 4) { /* unsuitable CCVal delta */ | |
430 | if (h->rtt_sample_prev == 2) { /* previous candidate stored */ | |
431 | sample = SUB16(tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_ccval, | |
432 | tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval); | |
433 | if (sample) | |
434 | sample = 4 / sample * | |
435 | ktime_us_delta(tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_tstamp, | |
436 | tfrc_rx_hist_rtt_last_s(h)->tfrchrx_tstamp); | |
437 | else /* | |
438 | * FIXME: This condition is in principle not | |
439 | * possible but occurs when CCID is used for | |
440 | * two-way data traffic. I have tried to trace | |
441 | * it, but the cause does not seem to be here. | |
442 | */ | |
443 | DCCP_BUG("please report to dccp@vger.kernel.org" | |
444 | " => prev = %u, last = %u", | |
445 | tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_ccval, | |
446 | tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval); | |
447 | } else if (delta_v < 1) { | |
448 | h->rtt_sample_prev = 1; | |
449 | goto keep_ref_for_next_time; | |
450 | } | |
451 | ||
452 | } else if (delta_v == 4) /* optimal match */ | |
453 | sample = ktime_to_us(net_timedelta(tfrc_rx_hist_rtt_last_s(h)->tfrchrx_tstamp)); | |
454 | else { /* suboptimal match */ | |
455 | h->rtt_sample_prev = 2; | |
456 | goto keep_ref_for_next_time; | |
8c60f3fa | 457 | } |
8c60f3fa | 458 | |
b84a2189 ACM |
459 | if (unlikely(sample > DCCP_SANE_RTT_MAX)) { |
460 | DCCP_WARN("RTT sample %u too large, using max\n", sample); | |
461 | sample = DCCP_SANE_RTT_MAX; | |
462 | } | |
463 | ||
464 | h->rtt_sample_prev = 0; /* use current entry as next reference */ | |
465 | keep_ref_for_next_time: | |
466 | ||
467 | return sample; | |
468 | } | |
469 | EXPORT_SYMBOL_GPL(tfrc_rx_hist_sample_rtt); |