[DCCP] ackvec: Remove unused variables
[linux-2.6.git] / 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 #ifdef CONFIG_IP_DCCP_DEBUG
71         const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
72                                 "CLIENT tx: " : "server tx: ";
73 #endif
74         struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
75         int len = av->dccpav_vec_len + 2;
76         struct timeval now;
77         u32 elapsed_time;
78         unsigned char *to, *from;
79         struct dccp_ackvec_record *avr;
80
81         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
82                 return -1;
83
84         dccp_timestamp(sk, &now);
85         elapsed_time = timeval_delta(&now, &av->dccpav_time) / 10;
86
87         if (elapsed_time != 0 &&
88             dccp_insert_option_elapsed_time(sk, skb, elapsed_time))
89                 return -1;
90
91         avr = dccp_ackvec_record_new();
92         if (avr == NULL)
93                 return -1;
94
95         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
96
97         to    = skb_push(skb, len);
98         *to++ = DCCPO_ACK_VECTOR_0;
99         *to++ = len;
100
101         len  = av->dccpav_vec_len;
102         from = av->dccpav_buf + av->dccpav_buf_head;
103
104         /* Check if buf_head wraps */
105         if ((int)av->dccpav_buf_head + len > DCCP_MAX_ACKVEC_LEN) {
106                 const u32 tailsize = DCCP_MAX_ACKVEC_LEN - av->dccpav_buf_head;
107
108                 memcpy(to, from, tailsize);
109                 to   += tailsize;
110                 len  -= tailsize;
111                 from = av->dccpav_buf;
112         }
113
114         memcpy(to, from, len);
115         /*
116          *      From draft-ietf-dccp-spec-11.txt:
117          *
118          *      For each acknowledgement it sends, the HC-Receiver will add an
119          *      acknowledgement record.  ack_seqno will equal the HC-Receiver
120          *      sequence number it used for the ack packet; ack_ptr will equal
121          *      buf_head; ack_ackno will equal buf_ackno; and ack_nonce will
122          *      equal buf_nonce.
123          */
124         avr->dccpavr_ack_seqno = DCCP_SKB_CB(skb)->dccpd_seq;
125         avr->dccpavr_ack_ptr   = av->dccpav_buf_head;
126         avr->dccpavr_ack_ackno = av->dccpav_buf_ackno;
127         avr->dccpavr_ack_nonce = av->dccpav_buf_nonce;
128         avr->dccpavr_sent_len  = av->dccpav_vec_len;
129
130         dccp_ackvec_insert_avr(av, avr);
131
132         dccp_pr_debug("%sACK Vector 0, len=%d, ack_seqno=%llu, "
133                       "ack_ackno=%llu\n",
134                       debug_prefix, avr->dccpavr_sent_len,
135                       (unsigned long long)avr->dccpavr_ack_seqno,
136                       (unsigned long long)avr->dccpavr_ack_ackno);
137         return 0;
138 }
139
140 struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
141 {
142         struct dccp_ackvec *av = kmem_cache_alloc(dccp_ackvec_slab, priority);
143
144         if (av != NULL) {
145                 av->dccpav_buf_head     = DCCP_MAX_ACKVEC_LEN - 1;
146                 av->dccpav_buf_ackno    = DCCP_MAX_SEQNO + 1;
147                 av->dccpav_buf_nonce = av->dccpav_buf_nonce = 0;
148                 av->dccpav_ack_ptr      = 0;
149                 av->dccpav_time.tv_sec  = 0;
150                 av->dccpav_time.tv_usec = 0;
151                 av->dccpav_vec_len      = 0;
152                 INIT_LIST_HEAD(&av->dccpav_records);
153         }
154
155         return av;
156 }
157
158 void dccp_ackvec_free(struct dccp_ackvec *av)
159 {
160         if (unlikely(av == NULL))
161                 return;
162
163         if (!list_empty(&av->dccpav_records)) {
164                 struct dccp_ackvec_record *avr, *next;
165
166                 list_for_each_entry_safe(avr, next, &av->dccpav_records,
167                                          dccpavr_node) {
168                         list_del_init(&avr->dccpavr_node);
169                         dccp_ackvec_record_delete(avr);
170                 }
171         }
172
173         kmem_cache_free(dccp_ackvec_slab, av);
174 }
175
176 static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av,
177                                    const u8 index)
178 {
179         return av->dccpav_buf[index] & DCCP_ACKVEC_STATE_MASK;
180 }
181
182 static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av,
183                                  const u8 index)
184 {
185         return av->dccpav_buf[index] & DCCP_ACKVEC_LEN_MASK;
186 }
187
188 /*
189  * If several packets are missing, the HC-Receiver may prefer to enter multiple
190  * bytes with run length 0, rather than a single byte with a larger run length;
191  * this simplifies table updates if one of the missing packets arrives.
192  */
193 static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av,
194                                                  const unsigned int packets,
195                                                  const unsigned char state)
196 {
197         unsigned int gap;
198         long new_head;
199
200         if (av->dccpav_vec_len + packets > DCCP_MAX_ACKVEC_LEN)
201                 return -ENOBUFS;
202
203         gap      = packets - 1;
204         new_head = av->dccpav_buf_head - packets;
205
206         if (new_head < 0) {
207                 if (gap > 0) {
208                         memset(av->dccpav_buf, DCCP_ACKVEC_STATE_NOT_RECEIVED,
209                                gap + new_head + 1);
210                         gap = -new_head;
211                 }
212                 new_head += DCCP_MAX_ACKVEC_LEN;
213         } 
214
215         av->dccpav_buf_head = new_head;
216
217         if (gap > 0)
218                 memset(av->dccpav_buf + av->dccpav_buf_head + 1,
219                        DCCP_ACKVEC_STATE_NOT_RECEIVED, gap);
220
221         av->dccpav_buf[av->dccpav_buf_head] = state;
222         av->dccpav_vec_len += packets;
223         return 0;
224 }
225
226 /*
227  * Implements the draft-ietf-dccp-spec-11.txt Appendix A
228  */
229 int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
230                     const u64 ackno, const u8 state)
231 {
232         /*
233          * Check at the right places if the buffer is full, if it is, tell the
234          * caller to start dropping packets till the HC-Sender acks our ACK
235          * vectors, when we will free up space in dccpav_buf.
236          *
237          * We may well decide to do buffer compression, etc, but for now lets
238          * just drop.
239          *
240          * From Appendix A:
241          *
242          *      Of course, the circular buffer may overflow, either when the
243          *      HC-Sender is sending data at a very high rate, when the
244          *      HC-Receiver's acknowledgements are not reaching the HC-Sender,
245          *      or when the HC-Sender is forgetting to acknowledge those acks
246          *      (so the HC-Receiver is unable to clean up old state). In this
247          *      case, the HC-Receiver should either compress the buffer (by
248          *      increasing run lengths when possible), transfer its state to
249          *      a larger buffer, or, as a last resort, drop all received
250          *      packets, without processing them whatsoever, until its buffer
251          *      shrinks again.
252          */
253
254         /* See if this is the first ackno being inserted */
255         if (av->dccpav_vec_len == 0) {
256                 av->dccpav_buf[av->dccpav_buf_head] = state;
257                 av->dccpav_vec_len = 1;
258         } else if (after48(ackno, av->dccpav_buf_ackno)) {
259                 const u64 delta = dccp_delta_seqno(av->dccpav_buf_ackno,
260                                                    ackno);
261
262                 /*
263                  * Look if the state of this packet is the same as the
264                  * previous ackno and if so if we can bump the head len.
265                  */
266                 if (delta == 1 &&
267                     dccp_ackvec_state(av, av->dccpav_buf_head) == state &&
268                     (dccp_ackvec_len(av, av->dccpav_buf_head) <
269                      DCCP_ACKVEC_LEN_MASK))
270                         av->dccpav_buf[av->dccpav_buf_head]++;
271                 else if (dccp_ackvec_set_buf_head_state(av, delta, state))
272                         return -ENOBUFS;
273         } else {
274                 /*
275                  * A.1.2.  Old Packets
276                  *
277                  *      When a packet with Sequence Number S arrives, and
278                  *      S <= buf_ackno, the HC-Receiver will scan the table
279                  *      for the byte corresponding to S. (Indexing structures
280                  *      could reduce the complexity of this scan.)
281                  */
282                 u64 delta = dccp_delta_seqno(ackno, av->dccpav_buf_ackno);
283                 u8 index = av->dccpav_buf_head;
284
285                 while (1) {
286                         const u8 len = dccp_ackvec_len(av, index);
287                         const u8 state = dccp_ackvec_state(av, index);
288                         /*
289                          * valid packets not yet in dccpav_buf have a reserved
290                          * entry, with a len equal to 0.
291                          */
292                         if (state == DCCP_ACKVEC_STATE_NOT_RECEIVED &&
293                             len == 0 && delta == 0) { /* Found our
294                                                          reserved seat! */
295                                 dccp_pr_debug("Found %llu reserved seat!\n",
296                                               (unsigned long long)ackno);
297                                 av->dccpav_buf[index] = state;
298                                 goto out;
299                         }
300                         /* len == 0 means one packet */
301                         if (delta < len + 1)
302                                 goto out_duplicate;
303
304                         delta -= len + 1;
305                         if (++index == DCCP_MAX_ACKVEC_LEN)
306                                 index = 0;
307                 }
308         }
309
310         av->dccpav_buf_ackno = ackno;
311         dccp_timestamp(sk, &av->dccpav_time);
312 out:
313         return 0;
314
315 out_duplicate:
316         /* Duplicate packet */
317         dccp_pr_debug("Received a dup or already considered lost "
318                       "packet: %llu\n", (unsigned long long)ackno);
319         return -EILSEQ;
320 }
321
322 #ifdef CONFIG_IP_DCCP_DEBUG
323 void dccp_ackvector_print(const u64 ackno, const unsigned char *vector, int len)
324 {
325         if (!dccp_debug)
326                 return;
327
328         printk("ACK vector len=%d, ackno=%llu |", len,
329                (unsigned long long)ackno);
330
331         while (len--) {
332                 const u8 state = (*vector & DCCP_ACKVEC_STATE_MASK) >> 6;
333                 const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
334
335                 printk("%d,%d|", state, rl);
336                 ++vector;
337         }
338
339         printk("\n");
340 }
341
342 void dccp_ackvec_print(const struct dccp_ackvec *av)
343 {
344         dccp_ackvector_print(av->dccpav_buf_ackno,
345                              av->dccpav_buf + av->dccpav_buf_head,
346                              av->dccpav_vec_len);
347 }
348 #endif
349
350 static void dccp_ackvec_throw_record(struct dccp_ackvec *av,
351                                      struct dccp_ackvec_record *avr)
352 {
353         struct dccp_ackvec_record *next;
354
355         /* sort out vector length */
356         if (av->dccpav_buf_head <= avr->dccpavr_ack_ptr)
357                 av->dccpav_vec_len = avr->dccpavr_ack_ptr - av->dccpav_buf_head;
358         else
359                 av->dccpav_vec_len = DCCP_MAX_ACKVEC_LEN - 1
360                                      - av->dccpav_buf_head
361                                      + avr->dccpavr_ack_ptr;
362
363         /* free records */
364         list_for_each_entry_safe_from(avr, next, &av->dccpav_records,
365                                       dccpavr_node) {
366                 list_del_init(&avr->dccpavr_node);
367                 dccp_ackvec_record_delete(avr);
368         }
369 }
370
371 void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, struct sock *sk,
372                                  const u64 ackno)
373 {
374         struct dccp_ackvec_record *avr;
375
376         /*
377          * If we traverse backwards, it should be faster when we have large
378          * windows. We will be receiving ACKs for stuff we sent a while back
379          * -sorbo.
380          */
381         list_for_each_entry_reverse(avr, &av->dccpav_records, dccpavr_node) {
382                 if (ackno == avr->dccpavr_ack_seqno) {
383 #ifdef CONFIG_IP_DCCP_DEBUG
384                         struct dccp_sock *dp = dccp_sk(sk);
385                         const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
386                                                 "CLIENT rx ack: " : "server rx ack: ";
387 #endif
388                         dccp_pr_debug("%sACK packet 0, len=%d, ack_seqno=%llu, "
389                                       "ack_ackno=%llu, ACKED!\n",
390                                       debug_prefix, 1,
391                                       (unsigned long long)avr->dccpavr_ack_seqno,
392                                       (unsigned long long)avr->dccpavr_ack_ackno);
393                         dccp_ackvec_throw_record(av, avr);
394                         break;
395                 }
396         }
397 }
398
399 static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av,
400                                             struct sock *sk, u64 ackno,
401                                             const unsigned char len,
402                                             const unsigned char *vector)
403 {
404         unsigned char i;
405         struct dccp_ackvec_record *avr;
406
407         /* Check if we actually sent an ACK vector */
408         if (list_empty(&av->dccpav_records))
409                 return;
410
411         i = len;
412         /*
413          * XXX
414          * I think it might be more efficient to work backwards. See comment on
415          * rcv_ackno. -sorbo.
416          */
417         avr = list_entry(av->dccpav_records.next, struct dccp_ackvec_record,
418                          dccpavr_node);
419         while (i--) {
420                 const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
421                 u64 ackno_end_rl;
422
423                 dccp_set_seqno(&ackno_end_rl, ackno - rl);
424
425                 /*
426                  * If our AVR sequence number is greater than the ack, go
427                  * forward in the AVR list until it is not so.
428                  */
429                 list_for_each_entry_from(avr, &av->dccpav_records,
430                                          dccpavr_node) {
431                         if (!after48(avr->dccpavr_ack_seqno, ackno))
432                                 goto found;
433                 }
434                 /* End of the dccpav_records list, not found, exit */
435                 break;
436 found:
437                 if (between48(avr->dccpavr_ack_seqno, ackno_end_rl, ackno)) {
438                         const u8 state = *vector & DCCP_ACKVEC_STATE_MASK;
439                         if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED) {
440 #ifdef CONFIG_IP_DCCP_DEBUG
441                                 struct dccp_sock *dp = dccp_sk(sk);
442                                 const char *debug_prefix =
443                                         dp->dccps_role == DCCP_ROLE_CLIENT ?
444                                         "CLIENT rx ack: " : "server rx ack: ";
445 #endif
446                                 dccp_pr_debug("%sACK vector 0, len=%d, "
447                                               "ack_seqno=%llu, ack_ackno=%llu, "
448                                               "ACKED!\n",
449                                               debug_prefix, len,
450                                               (unsigned long long)
451                                               avr->dccpavr_ack_seqno,
452                                               (unsigned long long)
453                                               avr->dccpavr_ack_ackno);
454                                 dccp_ackvec_throw_record(av, avr);
455                                 break;
456                         }
457                         /*
458                          * If it wasn't received, continue scanning... we might
459                          * find another one.
460                          */
461                 }
462
463                 dccp_set_seqno(&ackno, ackno_end_rl - 1);
464                 ++vector;
465         }
466 }
467
468 int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
469                       const u8 opt, const u8 *value, const u8 len)
470 {
471         if (len > DCCP_MAX_ACKVEC_LEN)
472                 return -1;
473
474         /* dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq, value, len); */
475         dccp_ackvec_check_rcv_ackvector(dccp_sk(sk)->dccps_hc_rx_ackvec, sk,
476                                         DCCP_SKB_CB(skb)->dccpd_ack_seq,
477                                         len, value);
478         return 0;
479 }
480
481 static char dccp_ackvec_slab_msg[] __initdata =
482         KERN_CRIT "DCCP: Unable to create ack vectors slab caches\n";
483
484 int __init dccp_ackvec_init(void)
485 {
486         dccp_ackvec_slab = kmem_cache_create("dccp_ackvec",
487                                              sizeof(struct dccp_ackvec), 0,
488                                              SLAB_HWCACHE_ALIGN, NULL, NULL);
489         if (dccp_ackvec_slab == NULL)
490                 goto out_err;
491
492         dccp_ackvec_record_slab =
493                         kmem_cache_create("dccp_ackvec_record",
494                                           sizeof(struct dccp_ackvec_record),
495                                           0, SLAB_HWCACHE_ALIGN, NULL, NULL);
496         if (dccp_ackvec_record_slab == NULL)
497                 goto out_destroy_slab;
498
499         return 0;
500
501 out_destroy_slab:
502         kmem_cache_destroy(dccp_ackvec_slab);
503         dccp_ackvec_slab = NULL;
504 out_err:
505         printk(dccp_ackvec_slab_msg);
506         return -ENOBUFS;
507 }
508
509 void dccp_ackvec_exit(void)
510 {
511         if (dccp_ackvec_slab != NULL) {
512                 kmem_cache_destroy(dccp_ackvec_slab);
513                 dccp_ackvec_slab = NULL;
514         }
515         if (dccp_ackvec_record_slab != NULL) {
516                 kmem_cache_destroy(dccp_ackvec_record_slab);
517                 dccp_ackvec_record_slab = NULL;
518         }
519 }