[DCCP] ackvec: Remove unused dccpav_ack_ptr field from dccp_ackvec
[linux-2.6] / net / dccp / ackvec.c
1 /*
2  *  net/dccp/ackvec.c
3  *
4  *  An implementation of the DCCP protocol
5  *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
6  *
7  *      This program is free software; you can redistribute it and/or modify it
8  *      under the terms of the GNU General Public License as published by the
9  *      Free Software Foundation; version 2 of the License;
10  */
11
12 #include "ackvec.h"
13 #include "dccp.h"
14
15 #include <linux/dccp.h>
16 #include <linux/init.h>
17 #include <linux/errno.h>
18 #include <linux/kernel.h>
19 #include <linux/skbuff.h>
20 #include <linux/slab.h>
21
22 #include <net/sock.h>
23
24 static kmem_cache_t *dccp_ackvec_slab;
25 static kmem_cache_t *dccp_ackvec_record_slab;
26
27 static struct dccp_ackvec_record *dccp_ackvec_record_new(void)
28 {
29         struct dccp_ackvec_record *avr =
30                         kmem_cache_alloc(dccp_ackvec_record_slab, GFP_ATOMIC);
31
32         if (avr != NULL)
33                 INIT_LIST_HEAD(&avr->dccpavr_node);
34
35         return avr;
36 }
37
38 static void dccp_ackvec_record_delete(struct dccp_ackvec_record *avr)
39 {
40         if (unlikely(avr == NULL))
41                 return;
42         /* Check if deleting a linked record */
43         WARN_ON(!list_empty(&avr->dccpavr_node));
44         kmem_cache_free(dccp_ackvec_record_slab, avr);
45 }
46
47 static void dccp_ackvec_insert_avr(struct dccp_ackvec *av,
48                                    struct dccp_ackvec_record *avr)
49 {
50         /*
51          * AVRs are sorted by seqno. Since we are sending them in order, we
52          * just add the AVR at the head of the list.
53          * -sorbo.
54          */
55         if (!list_empty(&av->dccpav_records)) {
56                 const struct dccp_ackvec_record *head =
57                                         list_entry(av->dccpav_records.next,
58                                                    struct dccp_ackvec_record,
59                                                    dccpavr_node);
60                 BUG_ON(before48(avr->dccpavr_ack_seqno,
61                                 head->dccpavr_ack_seqno));
62         }
63
64         list_add(&avr->dccpavr_node, &av->dccpav_records);
65 }
66
67 int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
68 {
69         struct dccp_sock *dp = dccp_sk(sk);
70         struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
71         int len = av->dccpav_vec_len + 2;
72         struct timeval now;
73         u32 elapsed_time;
74         unsigned char *to, *from;
75         struct dccp_ackvec_record *avr;
76
77         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
78                 return -1;
79
80         dccp_timestamp(sk, &now);
81         elapsed_time = timeval_delta(&now, &av->dccpav_time) / 10;
82
83         if (elapsed_time != 0 &&
84             dccp_insert_option_elapsed_time(sk, skb, elapsed_time))
85                 return -1;
86
87         avr = dccp_ackvec_record_new();
88         if (avr == NULL)
89                 return -1;
90
91         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
92
93         to    = skb_push(skb, len);
94         *to++ = DCCPO_ACK_VECTOR_0;
95         *to++ = len;
96
97         len  = av->dccpav_vec_len;
98         from = av->dccpav_buf + av->dccpav_buf_head;
99
100         /* Check if buf_head wraps */
101         if ((int)av->dccpav_buf_head + len > DCCP_MAX_ACKVEC_LEN) {
102                 const u32 tailsize = DCCP_MAX_ACKVEC_LEN - av->dccpav_buf_head;
103
104                 memcpy(to, from, tailsize);
105                 to   += tailsize;
106                 len  -= tailsize;
107                 from = av->dccpav_buf;
108         }
109
110         memcpy(to, from, len);
111         /*
112          *      From RFC 4340, A.2:
113          *
114          *      For each acknowledgement it sends, the HC-Receiver will add an
115          *      acknowledgement record.  ack_seqno will equal the HC-Receiver
116          *      sequence number it used for the ack packet; ack_ptr will equal
117          *      buf_head; ack_ackno will equal buf_ackno; and ack_nonce will
118          *      equal buf_nonce.
119          */
120         avr->dccpavr_ack_seqno = DCCP_SKB_CB(skb)->dccpd_seq;
121         avr->dccpavr_ack_ptr   = av->dccpav_buf_head;
122         avr->dccpavr_ack_ackno = av->dccpav_buf_ackno;
123         avr->dccpavr_ack_nonce = av->dccpav_buf_nonce;
124         avr->dccpavr_sent_len  = av->dccpav_vec_len;
125
126         dccp_ackvec_insert_avr(av, avr);
127
128         dccp_pr_debug("%s ACK Vector 0, len=%d, ack_seqno=%llu, "
129                       "ack_ackno=%llu\n",
130                       dccp_role(sk), avr->dccpavr_sent_len,
131                       (unsigned long long)avr->dccpavr_ack_seqno,
132                       (unsigned long long)avr->dccpavr_ack_ackno);
133         return 0;
134 }
135
136 struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
137 {
138         struct dccp_ackvec *av = kmem_cache_alloc(dccp_ackvec_slab, priority);
139
140         if (av != NULL) {
141                 av->dccpav_buf_head     = DCCP_MAX_ACKVEC_LEN - 1;
142                 av->dccpav_buf_ackno    = DCCP_MAX_SEQNO + 1;
143                 av->dccpav_buf_nonce = av->dccpav_buf_nonce = 0;
144                 av->dccpav_time.tv_sec  = 0;
145                 av->dccpav_time.tv_usec = 0;
146                 av->dccpav_vec_len      = 0;
147                 INIT_LIST_HEAD(&av->dccpav_records);
148         }
149
150         return av;
151 }
152
153 void dccp_ackvec_free(struct dccp_ackvec *av)
154 {
155         if (unlikely(av == NULL))
156                 return;
157
158         if (!list_empty(&av->dccpav_records)) {
159                 struct dccp_ackvec_record *avr, *next;
160
161                 list_for_each_entry_safe(avr, next, &av->dccpav_records,
162                                          dccpavr_node) {
163                         list_del_init(&avr->dccpavr_node);
164                         dccp_ackvec_record_delete(avr);
165                 }
166         }
167
168         kmem_cache_free(dccp_ackvec_slab, av);
169 }
170
171 static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av,
172                                    const u8 index)
173 {
174         return av->dccpav_buf[index] & DCCP_ACKVEC_STATE_MASK;
175 }
176
177 static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av,
178                                  const u8 index)
179 {
180         return av->dccpav_buf[index] & DCCP_ACKVEC_LEN_MASK;
181 }
182
183 /*
184  * If several packets are missing, the HC-Receiver may prefer to enter multiple
185  * bytes with run length 0, rather than a single byte with a larger run length;
186  * this simplifies table updates if one of the missing packets arrives.
187  */
188 static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av,
189                                                  const unsigned int packets,
190                                                  const unsigned char state)
191 {
192         unsigned int gap;
193         long new_head;
194
195         if (av->dccpav_vec_len + packets > DCCP_MAX_ACKVEC_LEN)
196                 return -ENOBUFS;
197
198         gap      = packets - 1;
199         new_head = av->dccpav_buf_head - packets;
200
201         if (new_head < 0) {
202                 if (gap > 0) {
203                         memset(av->dccpav_buf, DCCP_ACKVEC_STATE_NOT_RECEIVED,
204                                gap + new_head + 1);
205                         gap = -new_head;
206                 }
207                 new_head += DCCP_MAX_ACKVEC_LEN;
208         } 
209
210         av->dccpav_buf_head = new_head;
211
212         if (gap > 0)
213                 memset(av->dccpav_buf + av->dccpav_buf_head + 1,
214                        DCCP_ACKVEC_STATE_NOT_RECEIVED, gap);
215
216         av->dccpav_buf[av->dccpav_buf_head] = state;
217         av->dccpav_vec_len += packets;
218         return 0;
219 }
220
221 /*
222  * Implements the RFC 4340, Appendix A
223  */
224 int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
225                     const u64 ackno, const u8 state)
226 {
227         /*
228          * Check at the right places if the buffer is full, if it is, tell the
229          * caller to start dropping packets till the HC-Sender acks our ACK
230          * vectors, when we will free up space in dccpav_buf.
231          *
232          * We may well decide to do buffer compression, etc, but for now lets
233          * just drop.
234          *
235          * From Appendix A.1.1 (`New Packets'):
236          *
237          *      Of course, the circular buffer may overflow, either when the
238          *      HC-Sender is sending data at a very high rate, when the
239          *      HC-Receiver's acknowledgements are not reaching the HC-Sender,
240          *      or when the HC-Sender is forgetting to acknowledge those acks
241          *      (so the HC-Receiver is unable to clean up old state). In this
242          *      case, the HC-Receiver should either compress the buffer (by
243          *      increasing run lengths when possible), transfer its state to
244          *      a larger buffer, or, as a last resort, drop all received
245          *      packets, without processing them whatsoever, until its buffer
246          *      shrinks again.
247          */
248
249         /* See if this is the first ackno being inserted */
250         if (av->dccpav_vec_len == 0) {
251                 av->dccpav_buf[av->dccpav_buf_head] = state;
252                 av->dccpav_vec_len = 1;
253         } else if (after48(ackno, av->dccpav_buf_ackno)) {
254                 const u64 delta = dccp_delta_seqno(av->dccpav_buf_ackno,
255                                                    ackno);
256
257                 /*
258                  * Look if the state of this packet is the same as the
259                  * previous ackno and if so if we can bump the head len.
260                  */
261                 if (delta == 1 &&
262                     dccp_ackvec_state(av, av->dccpav_buf_head) == state &&
263                     (dccp_ackvec_len(av, av->dccpav_buf_head) <
264                      DCCP_ACKVEC_LEN_MASK))
265                         av->dccpav_buf[av->dccpav_buf_head]++;
266                 else if (dccp_ackvec_set_buf_head_state(av, delta, state))
267                         return -ENOBUFS;
268         } else {
269                 /*
270                  * A.1.2.  Old Packets
271                  *
272                  *      When a packet with Sequence Number S <= buf_ackno
273                  *      arrives, the HC-Receiver will scan the table for
274                  *      the byte corresponding to S. (Indexing structures
275                  *      could reduce the complexity of this scan.)
276                  */
277                 u64 delta = dccp_delta_seqno(ackno, av->dccpav_buf_ackno);
278                 u8 index = av->dccpav_buf_head;
279
280                 while (1) {
281                         const u8 len = dccp_ackvec_len(av, index);
282                         const u8 state = dccp_ackvec_state(av, index);
283                         /*
284                          * valid packets not yet in dccpav_buf have a reserved
285                          * entry, with a len equal to 0.
286                          */
287                         if (state == DCCP_ACKVEC_STATE_NOT_RECEIVED &&
288                             len == 0 && delta == 0) { /* Found our
289                                                          reserved seat! */
290                                 dccp_pr_debug("Found %llu reserved seat!\n",
291                                               (unsigned long long)ackno);
292                                 av->dccpav_buf[index] = state;
293                                 goto out;
294                         }
295                         /* len == 0 means one packet */
296                         if (delta < len + 1)
297                                 goto out_duplicate;
298
299                         delta -= len + 1;
300                         if (++index == DCCP_MAX_ACKVEC_LEN)
301                                 index = 0;
302                 }
303         }
304
305         av->dccpav_buf_ackno = ackno;
306         dccp_timestamp(sk, &av->dccpav_time);
307 out:
308         return 0;
309
310 out_duplicate:
311         /* Duplicate packet */
312         dccp_pr_debug("Received a dup or already considered lost "
313                       "packet: %llu\n", (unsigned long long)ackno);
314         return -EILSEQ;
315 }
316
317 #ifdef CONFIG_IP_DCCP_DEBUG
318 void dccp_ackvector_print(const u64 ackno, const unsigned char *vector, int len)
319 {
320         dccp_pr_debug_cat("ACK vector len=%d, ackno=%llu |", len,
321                                         (unsigned long long)ackno);
322
323         while (len--) {
324                 const u8 state = (*vector & DCCP_ACKVEC_STATE_MASK) >> 6;
325                 const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
326
327                 dccp_pr_debug_cat("%d,%d|", state, rl);
328                 ++vector;
329         }
330
331         dccp_pr_debug_cat("\n");
332 }
333
334 void dccp_ackvec_print(const struct dccp_ackvec *av)
335 {
336         dccp_ackvector_print(av->dccpav_buf_ackno,
337                              av->dccpav_buf + av->dccpav_buf_head,
338                              av->dccpav_vec_len);
339 }
340 #endif
341
342 static void dccp_ackvec_throw_record(struct dccp_ackvec *av,
343                                      struct dccp_ackvec_record *avr)
344 {
345         struct dccp_ackvec_record *next;
346
347         /* sort out vector length */
348         if (av->dccpav_buf_head <= avr->dccpavr_ack_ptr)
349                 av->dccpav_vec_len = avr->dccpavr_ack_ptr - av->dccpav_buf_head;
350         else
351                 av->dccpav_vec_len = DCCP_MAX_ACKVEC_LEN - 1
352                                      - av->dccpav_buf_head
353                                      + avr->dccpavr_ack_ptr;
354
355         /* free records */
356         list_for_each_entry_safe_from(avr, next, &av->dccpav_records,
357                                       dccpavr_node) {
358                 list_del_init(&avr->dccpavr_node);
359                 dccp_ackvec_record_delete(avr);
360         }
361 }
362
363 void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, struct sock *sk,
364                                  const u64 ackno)
365 {
366         struct dccp_ackvec_record *avr;
367
368         /*
369          * If we traverse backwards, it should be faster when we have large
370          * windows. We will be receiving ACKs for stuff we sent a while back
371          * -sorbo.
372          */
373         list_for_each_entry_reverse(avr, &av->dccpav_records, dccpavr_node) {
374                 if (ackno == avr->dccpavr_ack_seqno) {
375                         dccp_pr_debug("%s ACK packet 0, len=%d, ack_seqno=%llu, "
376                                       "ack_ackno=%llu, ACKED!\n",
377                                       dccp_role(sk), 1,
378                                       (unsigned long long)avr->dccpavr_ack_seqno,
379                                       (unsigned long long)avr->dccpavr_ack_ackno);
380                         dccp_ackvec_throw_record(av, avr);
381                         break;
382                 } else if (avr->dccpavr_ack_seqno > ackno)
383                         break; /* old news */
384         }
385 }
386
387 static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av,
388                                             struct sock *sk, u64 ackno,
389                                             const unsigned char len,
390                                             const unsigned char *vector)
391 {
392         unsigned char i;
393         struct dccp_ackvec_record *avr;
394
395         /* Check if we actually sent an ACK vector */
396         if (list_empty(&av->dccpav_records))
397                 return;
398
399         i = len;
400         /*
401          * XXX
402          * I think it might be more efficient to work backwards. See comment on
403          * rcv_ackno. -sorbo.
404          */
405         avr = list_entry(av->dccpav_records.next, struct dccp_ackvec_record,
406                          dccpavr_node);
407         while (i--) {
408                 const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
409                 u64 ackno_end_rl;
410
411                 dccp_set_seqno(&ackno_end_rl, ackno - rl);
412
413                 /*
414                  * If our AVR sequence number is greater than the ack, go
415                  * forward in the AVR list until it is not so.
416                  */
417                 list_for_each_entry_from(avr, &av->dccpav_records,
418                                          dccpavr_node) {
419                         if (!after48(avr->dccpavr_ack_seqno, ackno))
420                                 goto found;
421                 }
422                 /* End of the dccpav_records list, not found, exit */
423                 break;
424 found:
425                 if (between48(avr->dccpavr_ack_seqno, ackno_end_rl, ackno)) {
426                         const u8 state = *vector & DCCP_ACKVEC_STATE_MASK;
427                         if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED) {
428                                 dccp_pr_debug("%s ACK vector 0, len=%d, "
429                                               "ack_seqno=%llu, ack_ackno=%llu, "
430                                               "ACKED!\n",
431                                               dccp_role(sk), len,
432                                               (unsigned long long)
433                                               avr->dccpavr_ack_seqno,
434                                               (unsigned long long)
435                                               avr->dccpavr_ack_ackno);
436                                 dccp_ackvec_throw_record(av, avr);
437                                 break;
438                         }
439                         /*
440                          * If it wasn't received, continue scanning... we might
441                          * find another one.
442                          */
443                 }
444
445                 dccp_set_seqno(&ackno, ackno_end_rl - 1);
446                 ++vector;
447         }
448 }
449
450 int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
451                       const u8 opt, const u8 *value, const u8 len)
452 {
453         if (len > DCCP_MAX_ACKVEC_LEN)
454                 return -1;
455
456         /* dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq, value, len); */
457         dccp_ackvec_check_rcv_ackvector(dccp_sk(sk)->dccps_hc_rx_ackvec, sk,
458                                         DCCP_SKB_CB(skb)->dccpd_ack_seq,
459                                         len, value);
460         return 0;
461 }
462
463 int __init dccp_ackvec_init(void)
464 {
465         dccp_ackvec_slab = kmem_cache_create("dccp_ackvec",
466                                              sizeof(struct dccp_ackvec), 0,
467                                              SLAB_HWCACHE_ALIGN, NULL, NULL);
468         if (dccp_ackvec_slab == NULL)
469                 goto out_err;
470
471         dccp_ackvec_record_slab =
472                         kmem_cache_create("dccp_ackvec_record",
473                                           sizeof(struct dccp_ackvec_record),
474                                           0, SLAB_HWCACHE_ALIGN, NULL, NULL);
475         if (dccp_ackvec_record_slab == NULL)
476                 goto out_destroy_slab;
477
478         return 0;
479
480 out_destroy_slab:
481         kmem_cache_destroy(dccp_ackvec_slab);
482         dccp_ackvec_slab = NULL;
483 out_err:
484         DCCP_CRIT("Unable to create Ack Vector slab cache");
485         return -ENOBUFS;
486 }
487
488 void dccp_ackvec_exit(void)
489 {
490         if (dccp_ackvec_slab != NULL) {
491                 kmem_cache_destroy(dccp_ackvec_slab);
492                 dccp_ackvec_slab = NULL;
493         }
494         if (dccp_ackvec_record_slab != NULL) {
495                 kmem_cache_destroy(dccp_ackvec_record_slab);
496                 dccp_ackvec_record_slab = NULL;
497         }
498 }