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 * Transmitter History Routines
46 static struct kmem_cache
*tfrc_tx_hist_slab
;
48 int __init
tfrc_tx_packet_history_init(void)
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;
56 void tfrc_tx_packet_history_exit(void)
58 if (tfrc_tx_hist_slab
!= NULL
) {
59 kmem_cache_destroy(tfrc_tx_hist_slab
);
60 tfrc_tx_hist_slab
= NULL
;
64 int tfrc_tx_hist_add(struct tfrc_tx_hist_entry
**headp
, u64 seqno
)
66 struct tfrc_tx_hist_entry
*entry
= kmem_cache_alloc(tfrc_tx_hist_slab
, gfp_any());
71 entry
->stamp
= ktime_get_real();
76 EXPORT_SYMBOL_GPL(tfrc_tx_hist_add
);
78 void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry
**headp
)
80 struct tfrc_tx_hist_entry
*head
= *headp
;
82 while (head
!= NULL
) {
83 struct tfrc_tx_hist_entry
*next
= head
->next
;
85 kmem_cache_free(tfrc_tx_hist_slab
, head
);
91 EXPORT_SYMBOL_GPL(tfrc_tx_hist_purge
);
94 * Receiver History Routines
96 static struct kmem_cache
*tfrc_rx_hist_slab
;
98 int __init
tfrc_rx_packet_history_init(void)
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;
106 void tfrc_rx_packet_history_exit(void)
108 if (tfrc_rx_hist_slab
!= NULL
) {
109 kmem_cache_destroy(tfrc_rx_hist_slab
);
110 tfrc_rx_hist_slab
= NULL
;
114 static inline void tfrc_rx_hist_entry_from_skb(struct tfrc_rx_hist_entry
*entry
,
115 const struct sk_buff
*skb
,
118 const struct dccp_hdr
*dh
= dccp_hdr(skb
);
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();
127 void tfrc_rx_hist_add_packet(struct tfrc_rx_hist
*h
,
128 const struct sk_buff
*skb
,
131 struct tfrc_rx_hist_entry
*entry
= tfrc_rx_hist_last_rcv(h
);
133 tfrc_rx_hist_entry_from_skb(entry
, skb
, ndp
);
135 EXPORT_SYMBOL_GPL(tfrc_rx_hist_add_packet
);
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
)
140 const u64 seq
= DCCP_SKB_CB(skb
)->dccpd_seq
;
143 if (dccp_delta_seqno(tfrc_rx_hist_loss_prev(h
)->tfrchrx_seqno
, seq
) <= 0)
146 for (i
= 1; i
<= h
->loss_count
; i
++)
147 if (tfrc_rx_hist_entry(h
, i
)->tfrchrx_seqno
== seq
)
152 EXPORT_SYMBOL_GPL(tfrc_rx_hist_duplicate
);
154 static void tfrc_rx_hist_swap(struct tfrc_rx_hist
*h
, const u8 a
, const u8 b
)
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
];
160 h
->ring
[idx_a
] = h
->ring
[idx_b
];
161 h
->ring
[idx_b
] = tmp
;
165 * Private helper functions for loss detection.
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).
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.
173 static void __do_track_loss(struct tfrc_rx_hist
*h
, struct sk_buff
*skb
, u64 n1
)
175 u64 s0
= tfrc_rx_hist_loss_prev(h
)->tfrchrx_seqno
,
176 s1
= DCCP_SKB_CB(skb
)->dccpd_seq
;
178 if (!dccp_loss_free(s0
, s1
, n1
)) { /* gap between S0 and S1 */
180 tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h
, 1), skb
, n1
);
184 static void __one_after_loss(struct tfrc_rx_hist
*h
, struct sk_buff
*skb
, u32 n2
)
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
;
190 if (likely(dccp_delta_seqno(s1
, s2
) > 0)) { /* S1 < S2 */
192 tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h
, 2), skb
, n2
);
198 if (dccp_loss_free(s0
, s2
, n2
)) {
199 u64 n1
= tfrc_rx_hist_entry(h
, 1)->tfrchrx_ndp
;
201 if (dccp_loss_free(s2
, s1
, n1
)) {
202 /* hole is filled: S0, S2, and S1 are consecutive */
204 h
->loss_start
= tfrc_rx_hist_index(h
, 1);
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
);
209 } else { /* gap between S0 and S2 */
211 * Reorder history to insert S2 between S0 and S1
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
);
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
)
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
;
228 if (likely(dccp_delta_seqno(s2
, s3
) > 0)) { /* S2 < S3 */
230 tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h
, 3), skb
, n3
);
236 if (dccp_delta_seqno(s1
, s3
) > 0) { /* S1 < S3 < S2 */
238 * Reorder history to insert S3 between S1 and S2
240 tfrc_rx_hist_swap(h
, 2, 3);
241 tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h
, 2), skb
, n3
);
248 if (dccp_loss_free(s0
, s3
, n3
)) {
249 u64 n1
= tfrc_rx_hist_entry(h
, 1)->tfrchrx_ndp
;
251 if (dccp_loss_free(s3
, s1
, n1
)) {
252 /* hole between S0 and S1 filled by S3 */
253 u64 n2
= tfrc_rx_hist_entry(h
, 2)->tfrchrx_ndp
;
255 if (dccp_loss_free(s1
, s2
, n2
)) {
256 /* entire hole filled by S0, S3, S1, S2 */
257 h
->loss_start
= tfrc_rx_hist_index(h
, 2);
260 /* gap remains between S1 and S2 */
261 h
->loss_start
= tfrc_rx_hist_index(h
, 1);
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
);
272 * The remaining case: S0 < S3 < S1 < S2; gap between S0 and S3
273 * Reorder history to insert S3 between S0 and S1.
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
);
283 /* recycle RX history records to continue loss detection if necessary */
284 static void __three_after_loss(struct tfrc_rx_hist
*h
)
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.
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
,
296 n3
= tfrc_rx_hist_entry(h
, 3)->tfrchrx_ndp
;
298 if (dccp_loss_free(s1
, s2
, n2
)) {
300 if (dccp_loss_free(s2
, s3
, n3
)) {
301 /* no gap between S2 and S3: entire hole is filled */
302 h
->loss_start
= tfrc_rx_hist_index(h
, 3);
305 /* gap between S2 and S3 */
306 h
->loss_start
= tfrc_rx_hist_index(h
, 2);
310 } else { /* gap between S1 and S2 */
311 h
->loss_start
= tfrc_rx_hist_index(h
, 1);
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.
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.
331 int tfrc_rx_handle_loss(struct tfrc_rx_hist
*h
,
332 struct tfrc_loss_hist
*lh
,
333 struct sk_buff
*skb
, const u64 ndp
,
334 u32 (*calc_first_li
)(struct sock
*), struct sock
*sk
)
338 if (tfrc_rx_hist_duplicate(h
, skb
))
341 if (h
->loss_count
== 0) {
342 __do_track_loss(h
, skb
, ndp
);
343 } else if (h
->loss_count
== 1) {
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
)) {
349 * Update Loss Interval database and recycle RX records
351 is_new_loss
= tfrc_lh_interval_add(lh
, h
, calc_first_li
, sk
);
352 __three_after_loss(h
);
356 EXPORT_SYMBOL_GPL(tfrc_rx_handle_loss
);
358 void tfrc_rx_hist_purge(struct tfrc_rx_hist
*h
)
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
]);
368 EXPORT_SYMBOL_GPL(tfrc_rx_hist_purge
);
370 static int tfrc_rx_hist_alloc(struct tfrc_rx_hist
*h
)
374 memset(h
, 0, sizeof(*h
));
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
);
386 int tfrc_rx_hist_init(struct tfrc_rx_hist
*h
, struct sock
*sk
)
388 if (tfrc_rx_hist_alloc(h
))
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.
395 tfrc_rx_hist_loss_prev(h
)->tfrchrx_seqno
= dccp_sk(sk
)->dccps_gsr
;
398 EXPORT_SYMBOL_GPL(tfrc_rx_hist_init
);
401 * tfrc_rx_hist_rtt_last_s - reference entry to compute RTT samples against
403 static inline struct tfrc_rx_hist_entry
*
404 tfrc_rx_hist_rtt_last_s(const struct tfrc_rx_hist
*h
)
410 * tfrc_rx_hist_rtt_prev_s: previously suitable (wrt rtt_last_s) RTT-sampling entry
412 static inline struct tfrc_rx_hist_entry
*
413 tfrc_rx_hist_rtt_prev_s(const struct tfrc_rx_hist
*h
)
415 return h
->ring
[h
->rtt_sample_prev
];
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.
423 u32
tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist
*h
, const struct sk_buff
*skb
)
426 delta_v
= SUB16(dccp_hdr(skb
)->dccph_ccval
,
427 tfrc_rx_hist_rtt_last_s(h
)->tfrchrx_ccval
);
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
);
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
);
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.
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
;
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
;
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
;
464 h
->rtt_sample_prev
= 0; /* use current entry as next reference */
465 keep_ref_for_next_time
:
469 EXPORT_SYMBOL_GPL(tfrc_rx_hist_sample_rtt
);
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