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TOMOYO Linux Cross Reference
Linux/net/batman-adv/tp_meter.c

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  1 /* Copyright (C) 2012-2017  B.A.T.M.A.N. contributors:
  2  *
  3  * Edo Monticelli, Antonio Quartulli
  4  *
  5  * This program is free software; you can redistribute it and/or
  6  * modify it under the terms of version 2 of the GNU General Public
  7  * License as published by the Free Software Foundation.
  8  *
  9  * This program is distributed in the hope that it will be useful, but
 10  * WITHOUT ANY WARRANTY; without even the implied warranty of
 11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 12  * General Public License for more details.
 13  *
 14  * You should have received a copy of the GNU General Public License
 15  * along with this program; if not, see <http://www.gnu.org/licenses/>.
 16  */
 17 
 18 #include "tp_meter.h"
 19 #include "main.h"
 20 
 21 #include <linux/atomic.h>
 22 #include <linux/bug.h>
 23 #include <linux/byteorder/generic.h>
 24 #include <linux/cache.h>
 25 #include <linux/compiler.h>
 26 #include <linux/err.h>
 27 #include <linux/etherdevice.h>
 28 #include <linux/fs.h>
 29 #include <linux/if_ether.h>
 30 #include <linux/init.h>
 31 #include <linux/jiffies.h>
 32 #include <linux/kernel.h>
 33 #include <linux/kref.h>
 34 #include <linux/kthread.h>
 35 #include <linux/list.h>
 36 #include <linux/netdevice.h>
 37 #include <linux/param.h>
 38 #include <linux/printk.h>
 39 #include <linux/random.h>
 40 #include <linux/rculist.h>
 41 #include <linux/rcupdate.h>
 42 #include <linux/sched.h>
 43 #include <linux/skbuff.h>
 44 #include <linux/slab.h>
 45 #include <linux/spinlock.h>
 46 #include <linux/stddef.h>
 47 #include <linux/string.h>
 48 #include <linux/timer.h>
 49 #include <linux/wait.h>
 50 #include <linux/workqueue.h>
 51 #include <uapi/linux/batman_adv.h>
 52 
 53 #include "hard-interface.h"
 54 #include "log.h"
 55 #include "netlink.h"
 56 #include "originator.h"
 57 #include "packet.h"
 58 #include "send.h"
 59 
 60 /**
 61  * BATADV_TP_DEF_TEST_LENGTH - Default test length if not specified by the user
 62  *  in milliseconds
 63  */
 64 #define BATADV_TP_DEF_TEST_LENGTH 10000
 65 
 66 /**
 67  * BATADV_TP_AWND - Advertised window by the receiver (in bytes)
 68  */
 69 #define BATADV_TP_AWND 0x20000000
 70 
 71 /**
 72  * BATADV_TP_RECV_TIMEOUT - Receiver activity timeout. If the receiver does not
 73  *  get anything for such amount of milliseconds, the connection is killed
 74  */
 75 #define BATADV_TP_RECV_TIMEOUT 1000
 76 
 77 /**
 78  * BATADV_TP_MAX_RTO - Maximum sender timeout. If the sender RTO gets beyond
 79  * such amound of milliseconds, the receiver is considered unreachable and the
 80  * connection is killed
 81  */
 82 #define BATADV_TP_MAX_RTO 30000
 83 
 84 /**
 85  * BATADV_TP_FIRST_SEQ - First seqno of each session. The number is rather high
 86  *  in order to immediately trigger a wrap around (test purposes)
 87  */
 88 #define BATADV_TP_FIRST_SEQ ((u32)-1 - 2000)
 89 
 90 /**
 91  * BATADV_TP_PLEN - length of the payload (data after the batadv_unicast header)
 92  *  to simulate
 93  */
 94 #define BATADV_TP_PLEN (BATADV_TP_PACKET_LEN - ETH_HLEN - \
 95                         sizeof(struct batadv_unicast_packet))
 96 
 97 static u8 batadv_tp_prerandom[4096] __read_mostly;
 98 
 99 /**
100  * batadv_tp_session_cookie - generate session cookie based on session ids
101  * @session: TP session identifier
102  * @icmp_uid: icmp pseudo uid of the tp session
103  *
104  * Return: 32 bit tp_meter session cookie
105  */
106 static u32 batadv_tp_session_cookie(const u8 session[2], u8 icmp_uid)
107 {
108         u32 cookie;
109 
110         cookie = icmp_uid << 16;
111         cookie |= session[0] << 8;
112         cookie |= session[1];
113 
114         return cookie;
115 }
116 
117 /**
118  * batadv_tp_cwnd - compute the new cwnd size
119  * @base: base cwnd size value
120  * @increment: the value to add to base to get the new size
121  * @min: minumim cwnd value (usually MSS)
122  *
123  * Return the new cwnd size and ensures it does not exceed the Advertised
124  * Receiver Window size. It is wrap around safe.
125  * For details refer to Section 3.1 of RFC5681
126  *
127  * Return: new congestion window size in bytes
128  */
129 static u32 batadv_tp_cwnd(u32 base, u32 increment, u32 min)
130 {
131         u32 new_size = base + increment;
132 
133         /* check for wrap-around */
134         if (new_size < base)
135                 new_size = (u32)ULONG_MAX;
136 
137         new_size = min_t(u32, new_size, BATADV_TP_AWND);
138 
139         return max_t(u32, new_size, min);
140 }
141 
142 /**
143  * batadv_tp_updated_cwnd - update the Congestion Windows
144  * @tp_vars: the private data of the current TP meter session
145  * @mss: maximum segment size of transmission
146  *
147  * 1) if the session is in Slow Start, the CWND has to be increased by 1
148  * MSS every unique received ACK
149  * 2) if the session is in Congestion Avoidance, the CWND has to be
150  * increased by MSS * MSS / CWND for every unique received ACK
151  */
152 static void batadv_tp_update_cwnd(struct batadv_tp_vars *tp_vars, u32 mss)
153 {
154         spin_lock_bh(&tp_vars->cwnd_lock);
155 
156         /* slow start... */
157         if (tp_vars->cwnd <= tp_vars->ss_threshold) {
158                 tp_vars->dec_cwnd = 0;
159                 tp_vars->cwnd = batadv_tp_cwnd(tp_vars->cwnd, mss, mss);
160                 spin_unlock_bh(&tp_vars->cwnd_lock);
161                 return;
162         }
163 
164         /* increment CWND at least of 1 (section 3.1 of RFC5681) */
165         tp_vars->dec_cwnd += max_t(u32, 1U << 3,
166                                    ((mss * mss) << 6) / (tp_vars->cwnd << 3));
167         if (tp_vars->dec_cwnd < (mss << 3)) {
168                 spin_unlock_bh(&tp_vars->cwnd_lock);
169                 return;
170         }
171 
172         tp_vars->cwnd = batadv_tp_cwnd(tp_vars->cwnd, mss, mss);
173         tp_vars->dec_cwnd = 0;
174 
175         spin_unlock_bh(&tp_vars->cwnd_lock);
176 }
177 
178 /**
179  * batadv_tp_update_rto - calculate new retransmission timeout
180  * @tp_vars: the private data of the current TP meter session
181  * @new_rtt: new roundtrip time in msec
182  */
183 static void batadv_tp_update_rto(struct batadv_tp_vars *tp_vars,
184                                  u32 new_rtt)
185 {
186         long m = new_rtt;
187 
188         /* RTT update
189          * Details in Section 2.2 and 2.3 of RFC6298
190          *
191          * It's tricky to understand. Don't lose hair please.
192          * Inspired by tcp_rtt_estimator() tcp_input.c
193          */
194         if (tp_vars->srtt != 0) {
195                 m -= (tp_vars->srtt >> 3); /* m is now error in rtt est */
196                 tp_vars->srtt += m; /* rtt = 7/8 srtt + 1/8 new */
197                 if (m < 0)
198                         m = -m;
199 
200                 m -= (tp_vars->rttvar >> 2);
201                 tp_vars->rttvar += m; /* mdev ~= 3/4 rttvar + 1/4 new */
202         } else {
203                 /* first measure getting in */
204                 tp_vars->srtt = m << 3; /* take the measured time to be srtt */
205                 tp_vars->rttvar = m << 1; /* new_rtt / 2 */
206         }
207 
208         /* rto = srtt + 4 * rttvar.
209          * rttvar is scaled by 4, therefore doesn't need to be multiplied
210          */
211         tp_vars->rto = (tp_vars->srtt >> 3) + tp_vars->rttvar;
212 }
213 
214 /**
215  * batadv_tp_batctl_notify - send client status result to client
216  * @reason: reason for tp meter session stop
217  * @dst: destination of tp_meter session
218  * @bat_priv: the bat priv with all the soft interface information
219  * @start_time: start of transmission in jiffies
220  * @total_sent: bytes acked to the receiver
221  * @cookie: cookie of tp_meter session
222  */
223 static void batadv_tp_batctl_notify(enum batadv_tp_meter_reason reason,
224                                     const u8 *dst, struct batadv_priv *bat_priv,
225                                     unsigned long start_time, u64 total_sent,
226                                     u32 cookie)
227 {
228         u32 test_time;
229         u8 result;
230         u32 total_bytes;
231 
232         if (!batadv_tp_is_error(reason)) {
233                 result = BATADV_TP_REASON_COMPLETE;
234                 test_time = jiffies_to_msecs(jiffies - start_time);
235                 total_bytes = total_sent;
236         } else {
237                 result = reason;
238                 test_time = 0;
239                 total_bytes = 0;
240         }
241 
242         batadv_netlink_tpmeter_notify(bat_priv, dst, result, test_time,
243                                       total_bytes, cookie);
244 }
245 
246 /**
247  * batadv_tp_batctl_error_notify - send client error result to client
248  * @reason: reason for tp meter session stop
249  * @dst: destination of tp_meter session
250  * @bat_priv: the bat priv with all the soft interface information
251  * @cookie: cookie of tp_meter session
252  */
253 static void batadv_tp_batctl_error_notify(enum batadv_tp_meter_reason reason,
254                                           const u8 *dst,
255                                           struct batadv_priv *bat_priv,
256                                           u32 cookie)
257 {
258         batadv_tp_batctl_notify(reason, dst, bat_priv, 0, 0, cookie);
259 }
260 
261 /**
262  * batadv_tp_list_find - find a tp_vars object in the global list
263  * @bat_priv: the bat priv with all the soft interface information
264  * @dst: the other endpoint MAC address to look for
265  *
266  * Look for a tp_vars object matching dst as end_point and return it after
267  * having incremented the refcounter. Return NULL is not found
268  *
269  * Return: matching tp_vars or NULL when no tp_vars with @dst was found
270  */
271 static struct batadv_tp_vars *batadv_tp_list_find(struct batadv_priv *bat_priv,
272                                                   const u8 *dst)
273 {
274         struct batadv_tp_vars *pos, *tp_vars = NULL;
275 
276         rcu_read_lock();
277         hlist_for_each_entry_rcu(pos, &bat_priv->tp_list, list) {
278                 if (!batadv_compare_eth(pos->other_end, dst))
279                         continue;
280 
281                 /* most of the time this function is invoked during the normal
282                  * process..it makes sens to pay more when the session is
283                  * finished and to speed the process up during the measurement
284                  */
285                 if (unlikely(!kref_get_unless_zero(&pos->refcount)))
286                         continue;
287 
288                 tp_vars = pos;
289                 break;
290         }
291         rcu_read_unlock();
292 
293         return tp_vars;
294 }
295 
296 /**
297  * batadv_tp_list_find_session - find tp_vars session object in the global list
298  * @bat_priv: the bat priv with all the soft interface information
299  * @dst: the other endpoint MAC address to look for
300  * @session: session identifier
301  *
302  * Look for a tp_vars object matching dst as end_point, session as tp meter
303  * session and return it after having incremented the refcounter. Return NULL
304  * is not found
305  *
306  * Return: matching tp_vars or NULL when no tp_vars was found
307  */
308 static struct batadv_tp_vars *
309 batadv_tp_list_find_session(struct batadv_priv *bat_priv, const u8 *dst,
310                             const u8 *session)
311 {
312         struct batadv_tp_vars *pos, *tp_vars = NULL;
313 
314         rcu_read_lock();
315         hlist_for_each_entry_rcu(pos, &bat_priv->tp_list, list) {
316                 if (!batadv_compare_eth(pos->other_end, dst))
317                         continue;
318 
319                 if (memcmp(pos->session, session, sizeof(pos->session)) != 0)
320                         continue;
321 
322                 /* most of the time this function is invoked during the normal
323                  * process..it makes sense to pay more when the session is
324                  * finished and to speed the process up during the measurement
325                  */
326                 if (unlikely(!kref_get_unless_zero(&pos->refcount)))
327                         continue;
328 
329                 tp_vars = pos;
330                 break;
331         }
332         rcu_read_unlock();
333 
334         return tp_vars;
335 }
336 
337 /**
338  * batadv_tp_vars_release - release batadv_tp_vars from lists and queue for
339  *  free after rcu grace period
340  * @ref: kref pointer of the batadv_tp_vars
341  */
342 static void batadv_tp_vars_release(struct kref *ref)
343 {
344         struct batadv_tp_vars *tp_vars;
345         struct batadv_tp_unacked *un, *safe;
346 
347         tp_vars = container_of(ref, struct batadv_tp_vars, refcount);
348 
349         /* lock should not be needed because this object is now out of any
350          * context!
351          */
352         spin_lock_bh(&tp_vars->unacked_lock);
353         list_for_each_entry_safe(un, safe, &tp_vars->unacked_list, list) {
354                 list_del(&un->list);
355                 kfree(un);
356         }
357         spin_unlock_bh(&tp_vars->unacked_lock);
358 
359         kfree_rcu(tp_vars, rcu);
360 }
361 
362 /**
363  * batadv_tp_vars_put - decrement the batadv_tp_vars refcounter and possibly
364  *  release it
365  * @tp_vars: the private data of the current TP meter session to be free'd
366  */
367 static void batadv_tp_vars_put(struct batadv_tp_vars *tp_vars)
368 {
369         kref_put(&tp_vars->refcount, batadv_tp_vars_release);
370 }
371 
372 /**
373  * batadv_tp_sender_cleanup - cleanup sender data and drop and timer
374  * @bat_priv: the bat priv with all the soft interface information
375  * @tp_vars: the private data of the current TP meter session to cleanup
376  */
377 static void batadv_tp_sender_cleanup(struct batadv_priv *bat_priv,
378                                      struct batadv_tp_vars *tp_vars)
379 {
380         cancel_delayed_work(&tp_vars->finish_work);
381 
382         spin_lock_bh(&tp_vars->bat_priv->tp_list_lock);
383         hlist_del_rcu(&tp_vars->list);
384         spin_unlock_bh(&tp_vars->bat_priv->tp_list_lock);
385 
386         /* drop list reference */
387         batadv_tp_vars_put(tp_vars);
388 
389         atomic_dec(&tp_vars->bat_priv->tp_num);
390 
391         /* kill the timer and remove its reference */
392         del_timer_sync(&tp_vars->timer);
393         /* the worker might have rearmed itself therefore we kill it again. Note
394          * that if the worker should run again before invoking the following
395          * del_timer(), it would not re-arm itself once again because the status
396          * is OFF now
397          */
398         del_timer(&tp_vars->timer);
399         batadv_tp_vars_put(tp_vars);
400 }
401 
402 /**
403  * batadv_tp_sender_end - print info about ended session and inform client
404  * @bat_priv: the bat priv with all the soft interface information
405  * @tp_vars: the private data of the current TP meter session
406  */
407 static void batadv_tp_sender_end(struct batadv_priv *bat_priv,
408                                  struct batadv_tp_vars *tp_vars)
409 {
410         u32 session_cookie;
411 
412         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
413                    "Test towards %pM finished..shutting down (reason=%d)\n",
414                    tp_vars->other_end, tp_vars->reason);
415 
416         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
417                    "Last timing stats: SRTT=%ums RTTVAR=%ums RTO=%ums\n",
418                    tp_vars->srtt >> 3, tp_vars->rttvar >> 2, tp_vars->rto);
419 
420         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
421                    "Final values: cwnd=%u ss_threshold=%u\n",
422                    tp_vars->cwnd, tp_vars->ss_threshold);
423 
424         session_cookie = batadv_tp_session_cookie(tp_vars->session,
425                                                   tp_vars->icmp_uid);
426 
427         batadv_tp_batctl_notify(tp_vars->reason,
428                                 tp_vars->other_end,
429                                 bat_priv,
430                                 tp_vars->start_time,
431                                 atomic64_read(&tp_vars->tot_sent),
432                                 session_cookie);
433 }
434 
435 /**
436  * batadv_tp_sender_shutdown - let sender thread/timer stop gracefully
437  * @tp_vars: the private data of the current TP meter session
438  * @reason: reason for tp meter session stop
439  */
440 static void batadv_tp_sender_shutdown(struct batadv_tp_vars *tp_vars,
441                                       enum batadv_tp_meter_reason reason)
442 {
443         if (!atomic_dec_and_test(&tp_vars->sending))
444                 return;
445 
446         tp_vars->reason = reason;
447 }
448 
449 /**
450  * batadv_tp_sender_finish - stop sender session after test_length was reached
451  * @work: delayed work reference of the related tp_vars
452  */
453 static void batadv_tp_sender_finish(struct work_struct *work)
454 {
455         struct delayed_work *delayed_work;
456         struct batadv_tp_vars *tp_vars;
457 
458         delayed_work = to_delayed_work(work);
459         tp_vars = container_of(delayed_work, struct batadv_tp_vars,
460                                finish_work);
461 
462         batadv_tp_sender_shutdown(tp_vars, BATADV_TP_REASON_COMPLETE);
463 }
464 
465 /**
466  * batadv_tp_reset_sender_timer - reschedule the sender timer
467  * @tp_vars: the private TP meter data for this session
468  *
469  * Reschedule the timer using tp_vars->rto as delay
470  */
471 static void batadv_tp_reset_sender_timer(struct batadv_tp_vars *tp_vars)
472 {
473         /* most of the time this function is invoked while normal packet
474          * reception...
475          */
476         if (unlikely(atomic_read(&tp_vars->sending) == 0))
477                 /* timer ref will be dropped in batadv_tp_sender_cleanup */
478                 return;
479 
480         mod_timer(&tp_vars->timer, jiffies + msecs_to_jiffies(tp_vars->rto));
481 }
482 
483 /**
484  * batadv_tp_sender_timeout - timer that fires in case of packet loss
485  * @arg: address of the related tp_vars
486  *
487  * If fired it means that there was packet loss.
488  * Switch to Slow Start, set the ss_threshold to half of the current cwnd and
489  * reset the cwnd to 3*MSS
490  */
491 static void batadv_tp_sender_timeout(unsigned long arg)
492 {
493         struct batadv_tp_vars *tp_vars = (struct batadv_tp_vars *)arg;
494         struct batadv_priv *bat_priv = tp_vars->bat_priv;
495 
496         if (atomic_read(&tp_vars->sending) == 0)
497                 return;
498 
499         /* if the user waited long enough...shutdown the test */
500         if (unlikely(tp_vars->rto >= BATADV_TP_MAX_RTO)) {
501                 batadv_tp_sender_shutdown(tp_vars,
502                                           BATADV_TP_REASON_DST_UNREACHABLE);
503                 return;
504         }
505 
506         /* RTO exponential backoff
507          * Details in Section 5.5 of RFC6298
508          */
509         tp_vars->rto <<= 1;
510 
511         spin_lock_bh(&tp_vars->cwnd_lock);
512 
513         tp_vars->ss_threshold = tp_vars->cwnd >> 1;
514         if (tp_vars->ss_threshold < BATADV_TP_PLEN * 2)
515                 tp_vars->ss_threshold = BATADV_TP_PLEN * 2;
516 
517         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
518                    "Meter: RTO fired during test towards %pM! cwnd=%u new ss_thr=%u, resetting last_sent to %u\n",
519                    tp_vars->other_end, tp_vars->cwnd, tp_vars->ss_threshold,
520                    atomic_read(&tp_vars->last_acked));
521 
522         tp_vars->cwnd = BATADV_TP_PLEN * 3;
523 
524         spin_unlock_bh(&tp_vars->cwnd_lock);
525 
526         /* resend the non-ACKed packets.. */
527         tp_vars->last_sent = atomic_read(&tp_vars->last_acked);
528         wake_up(&tp_vars->more_bytes);
529 
530         batadv_tp_reset_sender_timer(tp_vars);
531 }
532 
533 /**
534  * batadv_tp_fill_prerandom - Fill buffer with prefetched random bytes
535  * @tp_vars: the private TP meter data for this session
536  * @buf: Buffer to fill with bytes
537  * @nbytes: amount of pseudorandom bytes
538  */
539 static void batadv_tp_fill_prerandom(struct batadv_tp_vars *tp_vars,
540                                      u8 *buf, size_t nbytes)
541 {
542         u32 local_offset;
543         size_t bytes_inbuf;
544         size_t to_copy;
545         size_t pos = 0;
546 
547         spin_lock_bh(&tp_vars->prerandom_lock);
548         local_offset = tp_vars->prerandom_offset;
549         tp_vars->prerandom_offset += nbytes;
550         tp_vars->prerandom_offset %= sizeof(batadv_tp_prerandom);
551         spin_unlock_bh(&tp_vars->prerandom_lock);
552 
553         while (nbytes) {
554                 local_offset %= sizeof(batadv_tp_prerandom);
555                 bytes_inbuf = sizeof(batadv_tp_prerandom) - local_offset;
556                 to_copy = min(nbytes, bytes_inbuf);
557 
558                 memcpy(&buf[pos], &batadv_tp_prerandom[local_offset], to_copy);
559                 pos += to_copy;
560                 nbytes -= to_copy;
561                 local_offset = 0;
562         }
563 }
564 
565 /**
566  * batadv_tp_send_msg - send a single message
567  * @tp_vars: the private TP meter data for this session
568  * @src: source mac address
569  * @orig_node: the originator of the destination
570  * @seqno: sequence number of this packet
571  * @len: length of the entire packet
572  * @session: session identifier
573  * @uid: local ICMP "socket" index
574  * @timestamp: timestamp in jiffies which is replied in ack
575  *
576  * Create and send a single TP Meter message.
577  *
578  * Return: 0 on success, BATADV_TP_REASON_DST_UNREACHABLE if the destination is
579  * not reachable, BATADV_TP_REASON_MEMORY_ERROR if the packet couldn't be
580  * allocated
581  */
582 static int batadv_tp_send_msg(struct batadv_tp_vars *tp_vars, const u8 *src,
583                               struct batadv_orig_node *orig_node,
584                               u32 seqno, size_t len, const u8 *session,
585                               int uid, u32 timestamp)
586 {
587         struct batadv_icmp_tp_packet *icmp;
588         struct sk_buff *skb;
589         int r;
590         u8 *data;
591         size_t data_len;
592 
593         skb = netdev_alloc_skb_ip_align(NULL, len + ETH_HLEN);
594         if (unlikely(!skb))
595                 return BATADV_TP_REASON_MEMORY_ERROR;
596 
597         skb_reserve(skb, ETH_HLEN);
598         icmp = skb_put(skb, sizeof(*icmp));
599 
600         /* fill the icmp header */
601         ether_addr_copy(icmp->dst, orig_node->orig);
602         ether_addr_copy(icmp->orig, src);
603         icmp->version = BATADV_COMPAT_VERSION;
604         icmp->packet_type = BATADV_ICMP;
605         icmp->ttl = BATADV_TTL;
606         icmp->msg_type = BATADV_TP;
607         icmp->uid = uid;
608 
609         icmp->subtype = BATADV_TP_MSG;
610         memcpy(icmp->session, session, sizeof(icmp->session));
611         icmp->seqno = htonl(seqno);
612         icmp->timestamp = htonl(timestamp);
613 
614         data_len = len - sizeof(*icmp);
615         data = skb_put(skb, data_len);
616         batadv_tp_fill_prerandom(tp_vars, data, data_len);
617 
618         r = batadv_send_skb_to_orig(skb, orig_node, NULL);
619         if (r == NET_XMIT_SUCCESS)
620                 return 0;
621 
622         return BATADV_TP_REASON_CANT_SEND;
623 }
624 
625 /**
626  * batadv_tp_recv_ack - ACK receiving function
627  * @bat_priv: the bat priv with all the soft interface information
628  * @skb: the buffer containing the received packet
629  *
630  * Process a received TP ACK packet
631  */
632 static void batadv_tp_recv_ack(struct batadv_priv *bat_priv,
633                                const struct sk_buff *skb)
634 {
635         struct batadv_hard_iface *primary_if = NULL;
636         struct batadv_orig_node *orig_node = NULL;
637         const struct batadv_icmp_tp_packet *icmp;
638         struct batadv_tp_vars *tp_vars;
639         size_t packet_len, mss;
640         u32 rtt, recv_ack, cwnd;
641         unsigned char *dev_addr;
642 
643         packet_len = BATADV_TP_PLEN;
644         mss = BATADV_TP_PLEN;
645         packet_len += sizeof(struct batadv_unicast_packet);
646 
647         icmp = (struct batadv_icmp_tp_packet *)skb->data;
648 
649         /* find the tp_vars */
650         tp_vars = batadv_tp_list_find_session(bat_priv, icmp->orig,
651                                               icmp->session);
652         if (unlikely(!tp_vars))
653                 return;
654 
655         if (unlikely(atomic_read(&tp_vars->sending) == 0))
656                 goto out;
657 
658         /* old ACK? silently drop it.. */
659         if (batadv_seq_before(ntohl(icmp->seqno),
660                               (u32)atomic_read(&tp_vars->last_acked)))
661                 goto out;
662 
663         primary_if = batadv_primary_if_get_selected(bat_priv);
664         if (unlikely(!primary_if))
665                 goto out;
666 
667         orig_node = batadv_orig_hash_find(bat_priv, icmp->orig);
668         if (unlikely(!orig_node))
669                 goto out;
670 
671         /* update RTO with the new sampled RTT, if any */
672         rtt = jiffies_to_msecs(jiffies) - ntohl(icmp->timestamp);
673         if (icmp->timestamp && rtt)
674                 batadv_tp_update_rto(tp_vars, rtt);
675 
676         /* ACK for new data... reset the timer */
677         batadv_tp_reset_sender_timer(tp_vars);
678 
679         recv_ack = ntohl(icmp->seqno);
680 
681         /* check if this ACK is a duplicate */
682         if (atomic_read(&tp_vars->last_acked) == recv_ack) {
683                 atomic_inc(&tp_vars->dup_acks);
684                 if (atomic_read(&tp_vars->dup_acks) != 3)
685                         goto out;
686 
687                 if (recv_ack >= tp_vars->recover)
688                         goto out;
689 
690                 /* if this is the third duplicate ACK do Fast Retransmit */
691                 batadv_tp_send_msg(tp_vars, primary_if->net_dev->dev_addr,
692                                    orig_node, recv_ack, packet_len,
693                                    icmp->session, icmp->uid,
694                                    jiffies_to_msecs(jiffies));
695 
696                 spin_lock_bh(&tp_vars->cwnd_lock);
697 
698                 /* Fast Recovery */
699                 tp_vars->fast_recovery = true;
700                 /* Set recover to the last outstanding seqno when Fast Recovery
701                  * is entered. RFC6582, Section 3.2, step 1
702                  */
703                 tp_vars->recover = tp_vars->last_sent;
704                 tp_vars->ss_threshold = tp_vars->cwnd >> 1;
705                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
706                            "Meter: Fast Recovery, (cur cwnd=%u) ss_thr=%u last_sent=%u recv_ack=%u\n",
707                            tp_vars->cwnd, tp_vars->ss_threshold,
708                            tp_vars->last_sent, recv_ack);
709                 tp_vars->cwnd = batadv_tp_cwnd(tp_vars->ss_threshold, 3 * mss,
710                                                mss);
711                 tp_vars->dec_cwnd = 0;
712                 tp_vars->last_sent = recv_ack;
713 
714                 spin_unlock_bh(&tp_vars->cwnd_lock);
715         } else {
716                 /* count the acked data */
717                 atomic64_add(recv_ack - atomic_read(&tp_vars->last_acked),
718                              &tp_vars->tot_sent);
719                 /* reset the duplicate ACKs counter */
720                 atomic_set(&tp_vars->dup_acks, 0);
721 
722                 if (tp_vars->fast_recovery) {
723                         /* partial ACK */
724                         if (batadv_seq_before(recv_ack, tp_vars->recover)) {
725                                 /* this is another hole in the window. React
726                                  * immediately as specified by NewReno (see
727                                  * Section 3.2 of RFC6582 for details)
728                                  */
729                                 dev_addr = primary_if->net_dev->dev_addr;
730                                 batadv_tp_send_msg(tp_vars, dev_addr,
731                                                    orig_node, recv_ack,
732                                                    packet_len, icmp->session,
733                                                    icmp->uid,
734                                                    jiffies_to_msecs(jiffies));
735                                 tp_vars->cwnd = batadv_tp_cwnd(tp_vars->cwnd,
736                                                                mss, mss);
737                         } else {
738                                 tp_vars->fast_recovery = false;
739                                 /* set cwnd to the value of ss_threshold at the
740                                  * moment that Fast Recovery was entered.
741                                  * RFC6582, Section 3.2, step 3
742                                  */
743                                 cwnd = batadv_tp_cwnd(tp_vars->ss_threshold, 0,
744                                                       mss);
745                                 tp_vars->cwnd = cwnd;
746                         }
747                         goto move_twnd;
748                 }
749 
750                 if (recv_ack - atomic_read(&tp_vars->last_acked) >= mss)
751                         batadv_tp_update_cwnd(tp_vars, mss);
752 move_twnd:
753                 /* move the Transmit Window */
754                 atomic_set(&tp_vars->last_acked, recv_ack);
755         }
756 
757         wake_up(&tp_vars->more_bytes);
758 out:
759         if (likely(primary_if))
760                 batadv_hardif_put(primary_if);
761         if (likely(orig_node))
762                 batadv_orig_node_put(orig_node);
763         if (likely(tp_vars))
764                 batadv_tp_vars_put(tp_vars);
765 }
766 
767 /**
768  * batadv_tp_avail - check if congestion window is not full
769  * @tp_vars: the private data of the current TP meter session
770  * @payload_len: size of the payload of a single message
771  *
772  * Return: true when congestion window is not full, false otherwise
773  */
774 static bool batadv_tp_avail(struct batadv_tp_vars *tp_vars,
775                             size_t payload_len)
776 {
777         u32 win_left, win_limit;
778 
779         win_limit = atomic_read(&tp_vars->last_acked) + tp_vars->cwnd;
780         win_left = win_limit - tp_vars->last_sent;
781 
782         return win_left >= payload_len;
783 }
784 
785 /**
786  * batadv_tp_wait_available - wait until congestion window becomes free or
787  *  timeout is reached
788  * @tp_vars: the private data of the current TP meter session
789  * @plen: size of the payload of a single message
790  *
791  * Return: 0 if the condition evaluated to false after the timeout elapsed,
792  *  1 if the condition evaluated to true after the timeout elapsed, the
793  *  remaining jiffies (at least 1) if the condition evaluated to true before
794  *  the timeout elapsed, or -ERESTARTSYS if it was interrupted by a signal.
795  */
796 static int batadv_tp_wait_available(struct batadv_tp_vars *tp_vars, size_t plen)
797 {
798         int ret;
799 
800         ret = wait_event_interruptible_timeout(tp_vars->more_bytes,
801                                                batadv_tp_avail(tp_vars, plen),
802                                                HZ / 10);
803 
804         return ret;
805 }
806 
807 /**
808  * batadv_tp_send - main sending thread of a tp meter session
809  * @arg: address of the related tp_vars
810  *
811  * Return: nothing, this function never returns
812  */
813 static int batadv_tp_send(void *arg)
814 {
815         struct batadv_tp_vars *tp_vars = arg;
816         struct batadv_priv *bat_priv = tp_vars->bat_priv;
817         struct batadv_hard_iface *primary_if = NULL;
818         struct batadv_orig_node *orig_node = NULL;
819         size_t payload_len, packet_len;
820         int err = 0;
821 
822         if (unlikely(tp_vars->role != BATADV_TP_SENDER)) {
823                 err = BATADV_TP_REASON_DST_UNREACHABLE;
824                 tp_vars->reason = err;
825                 goto out;
826         }
827 
828         orig_node = batadv_orig_hash_find(bat_priv, tp_vars->other_end);
829         if (unlikely(!orig_node)) {
830                 err = BATADV_TP_REASON_DST_UNREACHABLE;
831                 tp_vars->reason = err;
832                 goto out;
833         }
834 
835         primary_if = batadv_primary_if_get_selected(bat_priv);
836         if (unlikely(!primary_if)) {
837                 err = BATADV_TP_REASON_DST_UNREACHABLE;
838                 tp_vars->reason = err;
839                 goto out;
840         }
841 
842         /* assume that all the hard_interfaces have a correctly
843          * configured MTU, so use the soft_iface MTU as MSS.
844          * This might not be true and in that case the fragmentation
845          * should be used.
846          * Now, try to send the packet as it is
847          */
848         payload_len = BATADV_TP_PLEN;
849         BUILD_BUG_ON(sizeof(struct batadv_icmp_tp_packet) > BATADV_TP_PLEN);
850 
851         batadv_tp_reset_sender_timer(tp_vars);
852 
853         /* queue the worker in charge of terminating the test */
854         queue_delayed_work(batadv_event_workqueue, &tp_vars->finish_work,
855                            msecs_to_jiffies(tp_vars->test_length));
856 
857         while (atomic_read(&tp_vars->sending) != 0) {
858                 if (unlikely(!batadv_tp_avail(tp_vars, payload_len))) {
859                         batadv_tp_wait_available(tp_vars, payload_len);
860                         continue;
861                 }
862 
863                 /* to emulate normal unicast traffic, add to the payload len
864                  * the size of the unicast header
865                  */
866                 packet_len = payload_len + sizeof(struct batadv_unicast_packet);
867 
868                 err = batadv_tp_send_msg(tp_vars, primary_if->net_dev->dev_addr,
869                                          orig_node, tp_vars->last_sent,
870                                          packet_len,
871                                          tp_vars->session, tp_vars->icmp_uid,
872                                          jiffies_to_msecs(jiffies));
873 
874                 /* something went wrong during the preparation/transmission */
875                 if (unlikely(err && err != BATADV_TP_REASON_CANT_SEND)) {
876                         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
877                                    "Meter: %s() cannot send packets (%d)\n",
878                                    __func__, err);
879                         /* ensure nobody else tries to stop the thread now */
880                         if (atomic_dec_and_test(&tp_vars->sending))
881                                 tp_vars->reason = err;
882                         break;
883                 }
884 
885                 /* right-shift the TWND */
886                 if (!err)
887                         tp_vars->last_sent += payload_len;
888 
889                 cond_resched();
890         }
891 
892 out:
893         if (likely(primary_if))
894                 batadv_hardif_put(primary_if);
895         if (likely(orig_node))
896                 batadv_orig_node_put(orig_node);
897 
898         batadv_tp_sender_end(bat_priv, tp_vars);
899         batadv_tp_sender_cleanup(bat_priv, tp_vars);
900 
901         batadv_tp_vars_put(tp_vars);
902 
903         do_exit(0);
904 }
905 
906 /**
907  * batadv_tp_start_kthread - start new thread which manages the tp meter sender
908  * @tp_vars: the private data of the current TP meter session
909  */
910 static void batadv_tp_start_kthread(struct batadv_tp_vars *tp_vars)
911 {
912         struct task_struct *kthread;
913         struct batadv_priv *bat_priv = tp_vars->bat_priv;
914         u32 session_cookie;
915 
916         kref_get(&tp_vars->refcount);
917         kthread = kthread_create(batadv_tp_send, tp_vars, "kbatadv_tp_meter");
918         if (IS_ERR(kthread)) {
919                 session_cookie = batadv_tp_session_cookie(tp_vars->session,
920                                                           tp_vars->icmp_uid);
921                 pr_err("batadv: cannot create tp meter kthread\n");
922                 batadv_tp_batctl_error_notify(BATADV_TP_REASON_MEMORY_ERROR,
923                                               tp_vars->other_end,
924                                               bat_priv, session_cookie);
925 
926                 /* drop reserved reference for kthread */
927                 batadv_tp_vars_put(tp_vars);
928 
929                 /* cleanup of failed tp meter variables */
930                 batadv_tp_sender_cleanup(bat_priv, tp_vars);
931                 return;
932         }
933 
934         wake_up_process(kthread);
935 }
936 
937 /**
938  * batadv_tp_start - start a new tp meter session
939  * @bat_priv: the bat priv with all the soft interface information
940  * @dst: the receiver MAC address
941  * @test_length: test length in milliseconds
942  * @cookie: session cookie
943  */
944 void batadv_tp_start(struct batadv_priv *bat_priv, const u8 *dst,
945                      u32 test_length, u32 *cookie)
946 {
947         struct batadv_tp_vars *tp_vars;
948         u8 session_id[2];
949         u8 icmp_uid;
950         u32 session_cookie;
951 
952         get_random_bytes(session_id, sizeof(session_id));
953         get_random_bytes(&icmp_uid, 1);
954         session_cookie = batadv_tp_session_cookie(session_id, icmp_uid);
955         *cookie = session_cookie;
956 
957         /* look for an already existing test towards this node */
958         spin_lock_bh(&bat_priv->tp_list_lock);
959         tp_vars = batadv_tp_list_find(bat_priv, dst);
960         if (tp_vars) {
961                 spin_unlock_bh(&bat_priv->tp_list_lock);
962                 batadv_tp_vars_put(tp_vars);
963                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
964                            "Meter: test to or from the same node already ongoing, aborting\n");
965                 batadv_tp_batctl_error_notify(BATADV_TP_REASON_ALREADY_ONGOING,
966                                               dst, bat_priv, session_cookie);
967                 return;
968         }
969 
970         if (!atomic_add_unless(&bat_priv->tp_num, 1, BATADV_TP_MAX_NUM)) {
971                 spin_unlock_bh(&bat_priv->tp_list_lock);
972                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
973                            "Meter: too many ongoing sessions, aborting (SEND)\n");
974                 batadv_tp_batctl_error_notify(BATADV_TP_REASON_TOO_MANY, dst,
975                                               bat_priv, session_cookie);
976                 return;
977         }
978 
979         tp_vars = kmalloc(sizeof(*tp_vars), GFP_ATOMIC);
980         if (!tp_vars) {
981                 spin_unlock_bh(&bat_priv->tp_list_lock);
982                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
983                            "Meter: %s cannot allocate list elements\n",
984                            __func__);
985                 batadv_tp_batctl_error_notify(BATADV_TP_REASON_MEMORY_ERROR,
986                                               dst, bat_priv, session_cookie);
987                 return;
988         }
989 
990         /* initialize tp_vars */
991         ether_addr_copy(tp_vars->other_end, dst);
992         kref_init(&tp_vars->refcount);
993         tp_vars->role = BATADV_TP_SENDER;
994         atomic_set(&tp_vars->sending, 1);
995         memcpy(tp_vars->session, session_id, sizeof(session_id));
996         tp_vars->icmp_uid = icmp_uid;
997 
998         tp_vars->last_sent = BATADV_TP_FIRST_SEQ;
999         atomic_set(&tp_vars->last_acked, BATADV_TP_FIRST_SEQ);
1000         tp_vars->fast_recovery = false;
1001         tp_vars->recover = BATADV_TP_FIRST_SEQ;
1002 
1003         /* initialise the CWND to 3*MSS (Section 3.1 in RFC5681).
1004          * For batman-adv the MSS is the size of the payload received by the
1005          * soft_interface, hence its MTU
1006          */
1007         tp_vars->cwnd = BATADV_TP_PLEN * 3;
1008         /* at the beginning initialise the SS threshold to the biggest possible
1009          * window size, hence the AWND size
1010          */
1011         tp_vars->ss_threshold = BATADV_TP_AWND;
1012 
1013         /* RTO initial value is 3 seconds.
1014          * Details in Section 2.1 of RFC6298
1015          */
1016         tp_vars->rto = 1000;
1017         tp_vars->srtt = 0;
1018         tp_vars->rttvar = 0;
1019 
1020         atomic64_set(&tp_vars->tot_sent, 0);
1021 
1022         kref_get(&tp_vars->refcount);
1023         setup_timer(&tp_vars->timer, batadv_tp_sender_timeout,
1024                     (unsigned long)tp_vars);
1025 
1026         tp_vars->bat_priv = bat_priv;
1027         tp_vars->start_time = jiffies;
1028 
1029         init_waitqueue_head(&tp_vars->more_bytes);
1030 
1031         spin_lock_init(&tp_vars->unacked_lock);
1032         INIT_LIST_HEAD(&tp_vars->unacked_list);
1033 
1034         spin_lock_init(&tp_vars->cwnd_lock);
1035 
1036         tp_vars->prerandom_offset = 0;
1037         spin_lock_init(&tp_vars->prerandom_lock);
1038 
1039         kref_get(&tp_vars->refcount);
1040         hlist_add_head_rcu(&tp_vars->list, &bat_priv->tp_list);
1041         spin_unlock_bh(&bat_priv->tp_list_lock);
1042 
1043         tp_vars->test_length = test_length;
1044         if (!tp_vars->test_length)
1045                 tp_vars->test_length = BATADV_TP_DEF_TEST_LENGTH;
1046 
1047         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1048                    "Meter: starting throughput meter towards %pM (length=%ums)\n",
1049                    dst, test_length);
1050 
1051         /* init work item for finished tp tests */
1052         INIT_DELAYED_WORK(&tp_vars->finish_work, batadv_tp_sender_finish);
1053 
1054         /* start tp kthread. This way the write() call issued from userspace can
1055          * happily return and avoid to block
1056          */
1057         batadv_tp_start_kthread(tp_vars);
1058 
1059         /* don't return reference to new tp_vars */
1060         batadv_tp_vars_put(tp_vars);
1061 }
1062 
1063 /**
1064  * batadv_tp_stop - stop currently running tp meter session
1065  * @bat_priv: the bat priv with all the soft interface information
1066  * @dst: the receiver MAC address
1067  * @return_value: reason for tp meter session stop
1068  */
1069 void batadv_tp_stop(struct batadv_priv *bat_priv, const u8 *dst,
1070                     u8 return_value)
1071 {
1072         struct batadv_orig_node *orig_node;
1073         struct batadv_tp_vars *tp_vars;
1074 
1075         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1076                    "Meter: stopping test towards %pM\n", dst);
1077 
1078         orig_node = batadv_orig_hash_find(bat_priv, dst);
1079         if (!orig_node)
1080                 return;
1081 
1082         tp_vars = batadv_tp_list_find(bat_priv, orig_node->orig);
1083         if (!tp_vars) {
1084                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1085                            "Meter: trying to interrupt an already over connection\n");
1086                 goto out;
1087         }
1088 
1089         batadv_tp_sender_shutdown(tp_vars, return_value);
1090         batadv_tp_vars_put(tp_vars);
1091 out:
1092         batadv_orig_node_put(orig_node);
1093 }
1094 
1095 /**
1096  * batadv_tp_reset_receiver_timer - reset the receiver shutdown timer
1097  * @tp_vars: the private data of the current TP meter session
1098  *
1099  * start the receiver shutdown timer or reset it if already started
1100  */
1101 static void batadv_tp_reset_receiver_timer(struct batadv_tp_vars *tp_vars)
1102 {
1103         mod_timer(&tp_vars->timer,
1104                   jiffies + msecs_to_jiffies(BATADV_TP_RECV_TIMEOUT));
1105 }
1106 
1107 /**
1108  * batadv_tp_receiver_shutdown - stop a tp meter receiver when timeout is
1109  *  reached without received ack
1110  * @arg: address of the related tp_vars
1111  */
1112 static void batadv_tp_receiver_shutdown(unsigned long arg)
1113 {
1114         struct batadv_tp_vars *tp_vars = (struct batadv_tp_vars *)arg;
1115         struct batadv_tp_unacked *un, *safe;
1116         struct batadv_priv *bat_priv;
1117 
1118         bat_priv = tp_vars->bat_priv;
1119 
1120         /* if there is recent activity rearm the timer */
1121         if (!batadv_has_timed_out(tp_vars->last_recv_time,
1122                                   BATADV_TP_RECV_TIMEOUT)) {
1123                 /* reset the receiver shutdown timer */
1124                 batadv_tp_reset_receiver_timer(tp_vars);
1125                 return;
1126         }
1127 
1128         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1129                    "Shutting down for inactivity (more than %dms) from %pM\n",
1130                    BATADV_TP_RECV_TIMEOUT, tp_vars->other_end);
1131 
1132         spin_lock_bh(&tp_vars->bat_priv->tp_list_lock);
1133         hlist_del_rcu(&tp_vars->list);
1134         spin_unlock_bh(&tp_vars->bat_priv->tp_list_lock);
1135 
1136         /* drop list reference */
1137         batadv_tp_vars_put(tp_vars);
1138 
1139         atomic_dec(&bat_priv->tp_num);
1140 
1141         spin_lock_bh(&tp_vars->unacked_lock);
1142         list_for_each_entry_safe(un, safe, &tp_vars->unacked_list, list) {
1143                 list_del(&un->list);
1144                 kfree(un);
1145         }
1146         spin_unlock_bh(&tp_vars->unacked_lock);
1147 
1148         /* drop reference of timer */
1149         batadv_tp_vars_put(tp_vars);
1150 }
1151 
1152 /**
1153  * batadv_tp_send_ack - send an ACK packet
1154  * @bat_priv: the bat priv with all the soft interface information
1155  * @dst: the mac address of the destination originator
1156  * @seq: the sequence number to ACK
1157  * @timestamp: the timestamp to echo back in the ACK
1158  * @session: session identifier
1159  * @socket_index: local ICMP socket identifier
1160  *
1161  * Return: 0 on success, a positive integer representing the reason of the
1162  * failure otherwise
1163  */
1164 static int batadv_tp_send_ack(struct batadv_priv *bat_priv, const u8 *dst,
1165                               u32 seq, __be32 timestamp, const u8 *session,
1166                               int socket_index)
1167 {
1168         struct batadv_hard_iface *primary_if = NULL;
1169         struct batadv_orig_node *orig_node;
1170         struct batadv_icmp_tp_packet *icmp;
1171         struct sk_buff *skb;
1172         int r, ret;
1173 
1174         orig_node = batadv_orig_hash_find(bat_priv, dst);
1175         if (unlikely(!orig_node)) {
1176                 ret = BATADV_TP_REASON_DST_UNREACHABLE;
1177                 goto out;
1178         }
1179 
1180         primary_if = batadv_primary_if_get_selected(bat_priv);
1181         if (unlikely(!primary_if)) {
1182                 ret = BATADV_TP_REASON_DST_UNREACHABLE;
1183                 goto out;
1184         }
1185 
1186         skb = netdev_alloc_skb_ip_align(NULL, sizeof(*icmp) + ETH_HLEN);
1187         if (unlikely(!skb)) {
1188                 ret = BATADV_TP_REASON_MEMORY_ERROR;
1189                 goto out;
1190         }
1191 
1192         skb_reserve(skb, ETH_HLEN);
1193         icmp = skb_put(skb, sizeof(*icmp));
1194         icmp->packet_type = BATADV_ICMP;
1195         icmp->version = BATADV_COMPAT_VERSION;
1196         icmp->ttl = BATADV_TTL;
1197         icmp->msg_type = BATADV_TP;
1198         ether_addr_copy(icmp->dst, orig_node->orig);
1199         ether_addr_copy(icmp->orig, primary_if->net_dev->dev_addr);
1200         icmp->uid = socket_index;
1201 
1202         icmp->subtype = BATADV_TP_ACK;
1203         memcpy(icmp->session, session, sizeof(icmp->session));
1204         icmp->seqno = htonl(seq);
1205         icmp->timestamp = timestamp;
1206 
1207         /* send the ack */
1208         r = batadv_send_skb_to_orig(skb, orig_node, NULL);
1209         if (unlikely(r < 0) || (r == NET_XMIT_DROP)) {
1210                 ret = BATADV_TP_REASON_DST_UNREACHABLE;
1211                 goto out;
1212         }
1213         ret = 0;
1214 
1215 out:
1216         if (likely(orig_node))
1217                 batadv_orig_node_put(orig_node);
1218         if (likely(primary_if))
1219                 batadv_hardif_put(primary_if);
1220 
1221         return ret;
1222 }
1223 
1224 /**
1225  * batadv_tp_handle_out_of_order - store an out of order packet
1226  * @tp_vars: the private data of the current TP meter session
1227  * @skb: the buffer containing the received packet
1228  *
1229  * Store the out of order packet in the unacked list for late processing. This
1230  * packets are kept in this list so that they can be ACKed at once as soon as
1231  * all the previous packets have been received
1232  *
1233  * Return: true if the packed has been successfully processed, false otherwise
1234  */
1235 static bool batadv_tp_handle_out_of_order(struct batadv_tp_vars *tp_vars,
1236                                           const struct sk_buff *skb)
1237 {
1238         const struct batadv_icmp_tp_packet *icmp;
1239         struct batadv_tp_unacked *un, *new;
1240         u32 payload_len;
1241         bool added = false;
1242 
1243         new = kmalloc(sizeof(*new), GFP_ATOMIC);
1244         if (unlikely(!new))
1245                 return false;
1246 
1247         icmp = (struct batadv_icmp_tp_packet *)skb->data;
1248 
1249         new->seqno = ntohl(icmp->seqno);
1250         payload_len = skb->len - sizeof(struct batadv_unicast_packet);
1251         new->len = payload_len;
1252 
1253         spin_lock_bh(&tp_vars->unacked_lock);
1254         /* if the list is empty immediately attach this new object */
1255         if (list_empty(&tp_vars->unacked_list)) {
1256                 list_add(&new->list, &tp_vars->unacked_list);
1257                 goto out;
1258         }
1259 
1260         /* otherwise loop over the list and either drop the packet because this
1261          * is a duplicate or store it at the right position.
1262          *
1263          * The iteration is done in the reverse way because it is likely that
1264          * the last received packet (the one being processed now) has a bigger
1265          * seqno than all the others already stored.
1266          */
1267         list_for_each_entry_reverse(un, &tp_vars->unacked_list, list) {
1268                 /* check for duplicates */
1269                 if (new->seqno == un->seqno) {
1270                         if (new->len > un->len)
1271                                 un->len = new->len;
1272                         kfree(new);
1273                         added = true;
1274                         break;
1275                 }
1276 
1277                 /* look for the right position */
1278                 if (batadv_seq_before(new->seqno, un->seqno))
1279                         continue;
1280 
1281                 /* as soon as an entry having a bigger seqno is found, the new
1282                  * one is attached _after_ it. In this way the list is kept in
1283                  * ascending order
1284                  */
1285                 list_add_tail(&new->list, &un->list);
1286                 added = true;
1287                 break;
1288         }
1289 
1290         /* received packet with smallest seqno out of order; add it to front */
1291         if (!added)
1292                 list_add(&new->list, &tp_vars->unacked_list);
1293 
1294 out:
1295         spin_unlock_bh(&tp_vars->unacked_lock);
1296 
1297         return true;
1298 }
1299 
1300 /**
1301  * batadv_tp_ack_unordered - update number received bytes in current stream
1302  *  without gaps
1303  * @tp_vars: the private data of the current TP meter session
1304  */
1305 static void batadv_tp_ack_unordered(struct batadv_tp_vars *tp_vars)
1306 {
1307         struct batadv_tp_unacked *un, *safe;
1308         u32 to_ack;
1309 
1310         /* go through the unacked packet list and possibly ACK them as
1311          * well
1312          */
1313         spin_lock_bh(&tp_vars->unacked_lock);
1314         list_for_each_entry_safe(un, safe, &tp_vars->unacked_list, list) {
1315                 /* the list is ordered, therefore it is possible to stop as soon
1316                  * there is a gap between the last acked seqno and the seqno of
1317                  * the packet under inspection
1318                  */
1319                 if (batadv_seq_before(tp_vars->last_recv, un->seqno))
1320                         break;
1321 
1322                 to_ack = un->seqno + un->len - tp_vars->last_recv;
1323 
1324                 if (batadv_seq_before(tp_vars->last_recv, un->seqno + un->len))
1325                         tp_vars->last_recv += to_ack;
1326 
1327                 list_del(&un->list);
1328                 kfree(un);
1329         }
1330         spin_unlock_bh(&tp_vars->unacked_lock);
1331 }
1332 
1333 /**
1334  * batadv_tp_init_recv - return matching or create new receiver tp_vars
1335  * @bat_priv: the bat priv with all the soft interface information
1336  * @icmp: received icmp tp msg
1337  *
1338  * Return: corresponding tp_vars or NULL on errors
1339  */
1340 static struct batadv_tp_vars *
1341 batadv_tp_init_recv(struct batadv_priv *bat_priv,
1342                     const struct batadv_icmp_tp_packet *icmp)
1343 {
1344         struct batadv_tp_vars *tp_vars;
1345 
1346         spin_lock_bh(&bat_priv->tp_list_lock);
1347         tp_vars = batadv_tp_list_find_session(bat_priv, icmp->orig,
1348                                               icmp->session);
1349         if (tp_vars)
1350                 goto out_unlock;
1351 
1352         if (!atomic_add_unless(&bat_priv->tp_num, 1, BATADV_TP_MAX_NUM)) {
1353                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1354                            "Meter: too many ongoing sessions, aborting (RECV)\n");
1355                 goto out_unlock;
1356         }
1357 
1358         tp_vars = kmalloc(sizeof(*tp_vars), GFP_ATOMIC);
1359         if (!tp_vars)
1360                 goto out_unlock;
1361 
1362         ether_addr_copy(tp_vars->other_end, icmp->orig);
1363         tp_vars->role = BATADV_TP_RECEIVER;
1364         memcpy(tp_vars->session, icmp->session, sizeof(tp_vars->session));
1365         tp_vars->last_recv = BATADV_TP_FIRST_SEQ;
1366         tp_vars->bat_priv = bat_priv;
1367         kref_init(&tp_vars->refcount);
1368 
1369         spin_lock_init(&tp_vars->unacked_lock);
1370         INIT_LIST_HEAD(&tp_vars->unacked_list);
1371 
1372         kref_get(&tp_vars->refcount);
1373         hlist_add_head_rcu(&tp_vars->list, &bat_priv->tp_list);
1374 
1375         kref_get(&tp_vars->refcount);
1376         setup_timer(&tp_vars->timer, batadv_tp_receiver_shutdown,
1377                     (unsigned long)tp_vars);
1378 
1379         batadv_tp_reset_receiver_timer(tp_vars);
1380 
1381 out_unlock:
1382         spin_unlock_bh(&bat_priv->tp_list_lock);
1383 
1384         return tp_vars;
1385 }
1386 
1387 /**
1388  * batadv_tp_recv_msg - process a single data message
1389  * @bat_priv: the bat priv with all the soft interface information
1390  * @skb: the buffer containing the received packet
1391  *
1392  * Process a received TP MSG packet
1393  */
1394 static void batadv_tp_recv_msg(struct batadv_priv *bat_priv,
1395                                const struct sk_buff *skb)
1396 {
1397         const struct batadv_icmp_tp_packet *icmp;
1398         struct batadv_tp_vars *tp_vars;
1399         size_t packet_size;
1400         u32 seqno;
1401 
1402         icmp = (struct batadv_icmp_tp_packet *)skb->data;
1403 
1404         seqno = ntohl(icmp->seqno);
1405         /* check if this is the first seqno. This means that if the
1406          * first packet is lost, the tp meter does not work anymore!
1407          */
1408         if (seqno == BATADV_TP_FIRST_SEQ) {
1409                 tp_vars = batadv_tp_init_recv(bat_priv, icmp);
1410                 if (!tp_vars) {
1411                         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1412                                    "Meter: seqno != BATADV_TP_FIRST_SEQ cannot initiate connection\n");
1413                         goto out;
1414                 }
1415         } else {
1416                 tp_vars = batadv_tp_list_find_session(bat_priv, icmp->orig,
1417                                                       icmp->session);
1418                 if (!tp_vars) {
1419                         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1420                                    "Unexpected packet from %pM!\n",
1421                                    icmp->orig);
1422                         goto out;
1423                 }
1424         }
1425 
1426         if (unlikely(tp_vars->role != BATADV_TP_RECEIVER)) {
1427                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1428                            "Meter: dropping packet: not expected (role=%u)\n",
1429                            tp_vars->role);
1430                 goto out;
1431         }
1432 
1433         tp_vars->last_recv_time = jiffies;
1434 
1435         /* if the packet is a duplicate, it may be the case that an ACK has been
1436          * lost. Resend the ACK
1437          */
1438         if (batadv_seq_before(seqno, tp_vars->last_recv))
1439                 goto send_ack;
1440 
1441         /* if the packet is out of order enqueue it */
1442         if (ntohl(icmp->seqno) != tp_vars->last_recv) {
1443                 /* exit immediately (and do not send any ACK) if the packet has
1444                  * not been enqueued correctly
1445                  */
1446                 if (!batadv_tp_handle_out_of_order(tp_vars, skb))
1447                         goto out;
1448 
1449                 /* send a duplicate ACK */
1450                 goto send_ack;
1451         }
1452 
1453         /* if everything was fine count the ACKed bytes */
1454         packet_size = skb->len - sizeof(struct batadv_unicast_packet);
1455         tp_vars->last_recv += packet_size;
1456 
1457         /* check if this ordered message filled a gap.... */
1458         batadv_tp_ack_unordered(tp_vars);
1459 
1460 send_ack:
1461         /* send the ACK. If the received packet was out of order, the ACK that
1462          * is going to be sent is a duplicate (the sender will count them and
1463          * possibly enter Fast Retransmit as soon as it has reached 3)
1464          */
1465         batadv_tp_send_ack(bat_priv, icmp->orig, tp_vars->last_recv,
1466                            icmp->timestamp, icmp->session, icmp->uid);
1467 out:
1468         if (likely(tp_vars))
1469                 batadv_tp_vars_put(tp_vars);
1470 }
1471 
1472 /**
1473  * batadv_tp_meter_recv - main TP Meter receiving function
1474  * @bat_priv: the bat priv with all the soft interface information
1475  * @skb: the buffer containing the received packet
1476  */
1477 void batadv_tp_meter_recv(struct batadv_priv *bat_priv, struct sk_buff *skb)
1478 {
1479         struct batadv_icmp_tp_packet *icmp;
1480 
1481         icmp = (struct batadv_icmp_tp_packet *)skb->data;
1482 
1483         switch (icmp->subtype) {
1484         case BATADV_TP_MSG:
1485                 batadv_tp_recv_msg(bat_priv, skb);
1486                 break;
1487         case BATADV_TP_ACK:
1488                 batadv_tp_recv_ack(bat_priv, skb);
1489                 break;
1490         default:
1491                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1492                            "Received unknown TP Metric packet type %u\n",
1493                            icmp->subtype);
1494         }
1495         consume_skb(skb);
1496 }
1497 
1498 /**
1499  * batadv_tp_meter_init - initialize global tp_meter structures
1500  */
1501 void __init batadv_tp_meter_init(void)
1502 {
1503         get_random_bytes(batadv_tp_prerandom, sizeof(batadv_tp_prerandom));
1504 }
1505 

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