1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Copyright (c) 2007 The University of Aberdeen, Scotland, UK
4 * Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
6 * An implementation of the DCCP protocol
8 * This code has been developed by the University of Waikato WAND
9 * research group. For further information please see http://www.wand.net.nz/
10 * or e-mail Ian McDonald - ian.mcdonald@jandi.co.nz
12 * This code also uses code from Lulea University, rereleased as GPL by its
14 * Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
16 * Changes to meet Linux coding standards, to make it meet latest ccid3 draft
17 * and to make it work as a loadable module in the DCCP stack written by
18 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
20 * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
23 #include <linux/string.h>
24 #include <linux/slab.h>
25 #include "packet_history.h"
26 #include "../../dccp.h"
29 * Transmitter History Routines
31 static struct kmem_cache
*tfrc_tx_hist_slab
;
33 int __init
tfrc_tx_packet_history_init(void)
35 tfrc_tx_hist_slab
= kmem_cache_create("tfrc_tx_hist",
36 sizeof(struct tfrc_tx_hist_entry
),
37 0, SLAB_HWCACHE_ALIGN
, NULL
);
38 return tfrc_tx_hist_slab
== NULL
? -ENOBUFS
: 0;
41 void tfrc_tx_packet_history_exit(void)
43 if (tfrc_tx_hist_slab
!= NULL
) {
44 kmem_cache_destroy(tfrc_tx_hist_slab
);
45 tfrc_tx_hist_slab
= NULL
;
49 int tfrc_tx_hist_add(struct tfrc_tx_hist_entry
**headp
, u64 seqno
)
51 struct tfrc_tx_hist_entry
*entry
= kmem_cache_alloc(tfrc_tx_hist_slab
, gfp_any());
56 entry
->stamp
= ktime_get_real();
62 void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry
**headp
)
64 struct tfrc_tx_hist_entry
*head
= *headp
;
66 while (head
!= NULL
) {
67 struct tfrc_tx_hist_entry
*next
= head
->next
;
69 kmem_cache_free(tfrc_tx_hist_slab
, head
);
77 * Receiver History Routines
79 static struct kmem_cache
*tfrc_rx_hist_slab
;
81 int __init
tfrc_rx_packet_history_init(void)
83 tfrc_rx_hist_slab
= kmem_cache_create("tfrc_rxh_cache",
84 sizeof(struct tfrc_rx_hist_entry
),
85 0, SLAB_HWCACHE_ALIGN
, NULL
);
86 return tfrc_rx_hist_slab
== NULL
? -ENOBUFS
: 0;
89 void tfrc_rx_packet_history_exit(void)
91 if (tfrc_rx_hist_slab
!= NULL
) {
92 kmem_cache_destroy(tfrc_rx_hist_slab
);
93 tfrc_rx_hist_slab
= NULL
;
97 static inline void tfrc_rx_hist_entry_from_skb(struct tfrc_rx_hist_entry
*entry
,
98 const struct sk_buff
*skb
,
101 const struct dccp_hdr
*dh
= dccp_hdr(skb
);
103 entry
->tfrchrx_seqno
= DCCP_SKB_CB(skb
)->dccpd_seq
;
104 entry
->tfrchrx_ccval
= dh
->dccph_ccval
;
105 entry
->tfrchrx_type
= dh
->dccph_type
;
106 entry
->tfrchrx_ndp
= ndp
;
107 entry
->tfrchrx_tstamp
= ktime_get_real();
110 void tfrc_rx_hist_add_packet(struct tfrc_rx_hist
*h
,
111 const struct sk_buff
*skb
,
114 struct tfrc_rx_hist_entry
*entry
= tfrc_rx_hist_last_rcv(h
);
116 tfrc_rx_hist_entry_from_skb(entry
, skb
, ndp
);
119 /* has the packet contained in skb been seen before? */
120 int tfrc_rx_hist_duplicate(struct tfrc_rx_hist
*h
, struct sk_buff
*skb
)
122 const u64 seq
= DCCP_SKB_CB(skb
)->dccpd_seq
;
125 if (dccp_delta_seqno(tfrc_rx_hist_loss_prev(h
)->tfrchrx_seqno
, seq
) <= 0)
128 for (i
= 1; i
<= h
->loss_count
; i
++)
129 if (tfrc_rx_hist_entry(h
, i
)->tfrchrx_seqno
== seq
)
135 static void tfrc_rx_hist_swap(struct tfrc_rx_hist
*h
, const u8 a
, const u8 b
)
137 const u8 idx_a
= tfrc_rx_hist_index(h
, a
),
138 idx_b
= tfrc_rx_hist_index(h
, b
);
140 swap(h
->ring
[idx_a
], h
->ring
[idx_b
]);
144 * Private helper functions for loss detection.
146 * In the descriptions, `Si' refers to the sequence number of entry number i,
147 * whose NDP count is `Ni' (lower case is used for variables).
148 * Note: All __xxx_loss functions expect that a test against duplicates has been
149 * performed already: the seqno of the skb must not be less than the seqno
150 * of loss_prev; and it must not equal that of any valid history entry.
152 static void __do_track_loss(struct tfrc_rx_hist
*h
, struct sk_buff
*skb
, u64 n1
)
154 u64 s0
= tfrc_rx_hist_loss_prev(h
)->tfrchrx_seqno
,
155 s1
= DCCP_SKB_CB(skb
)->dccpd_seq
;
157 if (!dccp_loss_free(s0
, s1
, n1
)) { /* gap between S0 and S1 */
159 tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h
, 1), skb
, n1
);
163 static void __one_after_loss(struct tfrc_rx_hist
*h
, struct sk_buff
*skb
, u32 n2
)
165 u64 s0
= tfrc_rx_hist_loss_prev(h
)->tfrchrx_seqno
,
166 s1
= tfrc_rx_hist_entry(h
, 1)->tfrchrx_seqno
,
167 s2
= DCCP_SKB_CB(skb
)->dccpd_seq
;
169 if (likely(dccp_delta_seqno(s1
, s2
) > 0)) { /* S1 < S2 */
171 tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h
, 2), skb
, n2
);
177 if (dccp_loss_free(s0
, s2
, n2
)) {
178 u64 n1
= tfrc_rx_hist_entry(h
, 1)->tfrchrx_ndp
;
180 if (dccp_loss_free(s2
, s1
, n1
)) {
181 /* hole is filled: S0, S2, and S1 are consecutive */
183 h
->loss_start
= tfrc_rx_hist_index(h
, 1);
185 /* gap between S2 and S1: just update loss_prev */
186 tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_loss_prev(h
), skb
, n2
);
188 } else { /* gap between S0 and S2 */
190 * Reorder history to insert S2 between S0 and S1
192 tfrc_rx_hist_swap(h
, 0, 3);
193 h
->loss_start
= tfrc_rx_hist_index(h
, 3);
194 tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h
, 1), skb
, n2
);
199 /* return 1 if a new loss event has been identified */
200 static int __two_after_loss(struct tfrc_rx_hist
*h
, struct sk_buff
*skb
, u32 n3
)
202 u64 s0
= tfrc_rx_hist_loss_prev(h
)->tfrchrx_seqno
,
203 s1
= tfrc_rx_hist_entry(h
, 1)->tfrchrx_seqno
,
204 s2
= tfrc_rx_hist_entry(h
, 2)->tfrchrx_seqno
,
205 s3
= DCCP_SKB_CB(skb
)->dccpd_seq
;
207 if (likely(dccp_delta_seqno(s2
, s3
) > 0)) { /* S2 < S3 */
209 tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h
, 3), skb
, n3
);
215 if (dccp_delta_seqno(s1
, s3
) > 0) { /* S1 < S3 < S2 */
217 * Reorder history to insert S3 between S1 and S2
219 tfrc_rx_hist_swap(h
, 2, 3);
220 tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h
, 2), skb
, n3
);
227 if (dccp_loss_free(s0
, s3
, n3
)) {
228 u64 n1
= tfrc_rx_hist_entry(h
, 1)->tfrchrx_ndp
;
230 if (dccp_loss_free(s3
, s1
, n1
)) {
231 /* hole between S0 and S1 filled by S3 */
232 u64 n2
= tfrc_rx_hist_entry(h
, 2)->tfrchrx_ndp
;
234 if (dccp_loss_free(s1
, s2
, n2
)) {
235 /* entire hole filled by S0, S3, S1, S2 */
236 h
->loss_start
= tfrc_rx_hist_index(h
, 2);
239 /* gap remains between S1 and S2 */
240 h
->loss_start
= tfrc_rx_hist_index(h
, 1);
244 } else /* gap exists between S3 and S1, loss_count stays at 2 */
245 tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_loss_prev(h
), skb
, n3
);
251 * The remaining case: S0 < S3 < S1 < S2; gap between S0 and S3
252 * Reorder history to insert S3 between S0 and S1.
254 tfrc_rx_hist_swap(h
, 0, 3);
255 h
->loss_start
= tfrc_rx_hist_index(h
, 3);
256 tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h
, 1), skb
, n3
);
262 /* recycle RX history records to continue loss detection if necessary */
263 static void __three_after_loss(struct tfrc_rx_hist
*h
)
266 * At this stage we know already that there is a gap between S0 and S1
267 * (since S0 was the highest sequence number received before detecting
268 * the loss). To recycle the loss record, it is thus only necessary to
269 * check for other possible gaps between S1/S2 and between S2/S3.
271 u64 s1
= tfrc_rx_hist_entry(h
, 1)->tfrchrx_seqno
,
272 s2
= tfrc_rx_hist_entry(h
, 2)->tfrchrx_seqno
,
273 s3
= tfrc_rx_hist_entry(h
, 3)->tfrchrx_seqno
;
274 u64 n2
= tfrc_rx_hist_entry(h
, 2)->tfrchrx_ndp
,
275 n3
= tfrc_rx_hist_entry(h
, 3)->tfrchrx_ndp
;
277 if (dccp_loss_free(s1
, s2
, n2
)) {
279 if (dccp_loss_free(s2
, s3
, n3
)) {
280 /* no gap between S2 and S3: entire hole is filled */
281 h
->loss_start
= tfrc_rx_hist_index(h
, 3);
284 /* gap between S2 and S3 */
285 h
->loss_start
= tfrc_rx_hist_index(h
, 2);
289 } else { /* gap between S1 and S2 */
290 h
->loss_start
= tfrc_rx_hist_index(h
, 1);
296 * tfrc_rx_handle_loss - Loss detection and further processing
297 * @h: The non-empty RX history object
298 * @lh: Loss Intervals database to update
299 * @skb: Currently received packet
300 * @ndp: The NDP count belonging to @skb
301 * @calc_first_li: Caller-dependent computation of first loss interval in @lh
302 * @sk: Used by @calc_first_li (see tfrc_lh_interval_add)
304 * Chooses action according to pending loss, updates LI database when a new
305 * loss was detected, and does required post-processing. Returns 1 when caller
306 * should send feedback, 0 otherwise.
307 * Since it also takes care of reordering during loss detection and updates the
308 * records accordingly, the caller should not perform any more RX history
309 * operations when loss_count is greater than 0 after calling this function.
311 int tfrc_rx_handle_loss(struct tfrc_rx_hist
*h
,
312 struct tfrc_loss_hist
*lh
,
313 struct sk_buff
*skb
, const u64 ndp
,
314 u32 (*calc_first_li
)(struct sock
*), struct sock
*sk
)
318 if (h
->loss_count
== 0) {
319 __do_track_loss(h
, skb
, ndp
);
320 } else if (h
->loss_count
== 1) {
321 __one_after_loss(h
, skb
, ndp
);
322 } else if (h
->loss_count
!= 2) {
323 DCCP_BUG("invalid loss_count %d", h
->loss_count
);
324 } else if (__two_after_loss(h
, skb
, ndp
)) {
326 * Update Loss Interval database and recycle RX records
328 is_new_loss
= tfrc_lh_interval_add(lh
, h
, calc_first_li
, sk
);
329 __three_after_loss(h
);
334 int tfrc_rx_hist_alloc(struct tfrc_rx_hist
*h
)
338 for (i
= 0; i
<= TFRC_NDUPACK
; i
++) {
339 h
->ring
[i
] = kmem_cache_alloc(tfrc_rx_hist_slab
, GFP_ATOMIC
);
340 if (h
->ring
[i
] == NULL
)
344 h
->loss_count
= h
->loss_start
= 0;
349 kmem_cache_free(tfrc_rx_hist_slab
, h
->ring
[i
]);
355 void tfrc_rx_hist_purge(struct tfrc_rx_hist
*h
)
359 for (i
= 0; i
<= TFRC_NDUPACK
; ++i
)
360 if (h
->ring
[i
] != NULL
) {
361 kmem_cache_free(tfrc_rx_hist_slab
, h
->ring
[i
]);
367 * tfrc_rx_hist_rtt_last_s - reference entry to compute RTT samples against
369 static inline struct tfrc_rx_hist_entry
*
370 tfrc_rx_hist_rtt_last_s(const struct tfrc_rx_hist
*h
)
376 * tfrc_rx_hist_rtt_prev_s - previously suitable (wrt rtt_last_s) RTT-sampling entry
378 static inline struct tfrc_rx_hist_entry
*
379 tfrc_rx_hist_rtt_prev_s(const struct tfrc_rx_hist
*h
)
381 return h
->ring
[h
->rtt_sample_prev
];
385 * tfrc_rx_hist_sample_rtt - Sample RTT from timestamp / CCVal
386 * Based on ideas presented in RFC 4342, 8.1. Returns 0 if it was not able
387 * to compute a sample with given data - calling function should check this.
389 u32
tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist
*h
, const struct sk_buff
*skb
)
392 delta_v
= SUB16(dccp_hdr(skb
)->dccph_ccval
,
393 tfrc_rx_hist_rtt_last_s(h
)->tfrchrx_ccval
);
395 if (delta_v
< 1 || delta_v
> 4) { /* unsuitable CCVal delta */
396 if (h
->rtt_sample_prev
== 2) { /* previous candidate stored */
397 sample
= SUB16(tfrc_rx_hist_rtt_prev_s(h
)->tfrchrx_ccval
,
398 tfrc_rx_hist_rtt_last_s(h
)->tfrchrx_ccval
);
400 sample
= 4 / sample
*
401 ktime_us_delta(tfrc_rx_hist_rtt_prev_s(h
)->tfrchrx_tstamp
,
402 tfrc_rx_hist_rtt_last_s(h
)->tfrchrx_tstamp
);
404 * FIXME: This condition is in principle not
405 * possible but occurs when CCID is used for
406 * two-way data traffic. I have tried to trace
407 * it, but the cause does not seem to be here.
409 DCCP_BUG("please report to dccp@vger.kernel.org"
410 " => prev = %u, last = %u",
411 tfrc_rx_hist_rtt_prev_s(h
)->tfrchrx_ccval
,
412 tfrc_rx_hist_rtt_last_s(h
)->tfrchrx_ccval
);
413 } else if (delta_v
< 1) {
414 h
->rtt_sample_prev
= 1;
415 goto keep_ref_for_next_time
;
418 } else if (delta_v
== 4) /* optimal match */
419 sample
= ktime_to_us(net_timedelta(tfrc_rx_hist_rtt_last_s(h
)->tfrchrx_tstamp
));
420 else { /* suboptimal match */
421 h
->rtt_sample_prev
= 2;
422 goto keep_ref_for_next_time
;
425 if (unlikely(sample
> DCCP_SANE_RTT_MAX
)) {
426 DCCP_WARN("RTT sample %u too large, using max\n", sample
);
427 sample
= DCCP_SANE_RTT_MAX
;
430 h
->rtt_sample_prev
= 0; /* use current entry as next reference */
431 keep_ref_for_next_time
: