root/net/batman-adv/tp_meter.c

DEFINITIONS

1. batadv_tp_session_cookie
2. batadv_tp_cwnd
3. batadv_tp_update_cwnd
4. batadv_tp_update_rto
5. batadv_tp_batctl_notify
6. batadv_tp_batctl_error_notify
7. batadv_tp_list_find
8. batadv_tp_list_find_session
9. batadv_tp_vars_release
10. batadv_tp_vars_put
11. batadv_tp_sender_cleanup
12. batadv_tp_sender_end
13. batadv_tp_sender_shutdown
14. batadv_tp_sender_finish
15. batadv_tp_reset_sender_timer
16. batadv_tp_sender_timeout
17. batadv_tp_fill_prerandom
18. batadv_tp_send_msg
19. batadv_tp_recv_ack
20. batadv_tp_avail
21. batadv_tp_wait_available
22. batadv_tp_send
23. batadv_tp_start_kthread
24. batadv_tp_start
25. batadv_tp_stop
26. batadv_tp_reset_receiver_timer
27. batadv_tp_receiver_shutdown
28. batadv_tp_send_ack
29. batadv_tp_handle_out_of_order
30. batadv_tp_ack_unordered
31. batadv_tp_init_recv
32. batadv_tp_recv_msg
33. batadv_tp_meter_recv
34. batadv_tp_meter_init

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (C) 2012-2019  B.A.T.M.A.N. contributors:
   3  *
   4  * Edo Monticelli, Antonio Quartulli
   5  */
   6 
   7 #include "tp_meter.h"
   8 #include "main.h"
   9 
  10 #include <linux/atomic.h>
  11 #include <linux/build_bug.h>
  12 #include <linux/byteorder/generic.h>
  13 #include <linux/cache.h>
  14 #include <linux/compiler.h>
  15 #include <linux/err.h>
  16 #include <linux/etherdevice.h>
  17 #include <linux/gfp.h>
  18 #include <linux/if_ether.h>
  19 #include <linux/init.h>
  20 #include <linux/jiffies.h>
  21 #include <linux/kernel.h>
  22 #include <linux/kref.h>
  23 #include <linux/kthread.h>
  24 #include <linux/limits.h>
  25 #include <linux/list.h>
  26 #include <linux/netdevice.h>
  27 #include <linux/param.h>
  28 #include <linux/printk.h>
  29 #include <linux/random.h>
  30 #include <linux/rculist.h>
  31 #include <linux/rcupdate.h>
  32 #include <linux/sched.h>
  33 #include <linux/skbuff.h>
  34 #include <linux/slab.h>
  35 #include <linux/spinlock.h>
  36 #include <linux/stddef.h>
  37 #include <linux/string.h>
  38 #include <linux/timer.h>
  39 #include <linux/wait.h>
  40 #include <linux/workqueue.h>
  41 #include <uapi/linux/batadv_packet.h>
  42 #include <uapi/linux/batman_adv.h>
  43 
  44 #include "hard-interface.h"
  45 #include "log.h"
  46 #include "netlink.h"
  47 #include "originator.h"
  48 #include "send.h"
  49 
  50 /**
  51  * BATADV_TP_DEF_TEST_LENGTH - Default test length if not specified by the user
  52  *  in milliseconds
  53  */
  54 #define BATADV_TP_DEF_TEST_LENGTH 10000
  55 
  56 /**
  57  * BATADV_TP_AWND - Advertised window by the receiver (in bytes)
  58  */
  59 #define BATADV_TP_AWND 0x20000000
  60 
  61 /**
  62  * BATADV_TP_RECV_TIMEOUT - Receiver activity timeout. If the receiver does not
  63  *  get anything for such amount of milliseconds, the connection is killed
  64  */
  65 #define BATADV_TP_RECV_TIMEOUT 1000
  66 
  67 /**
  68  * BATADV_TP_MAX_RTO - Maximum sender timeout. If the sender RTO gets beyond
  69  * such amound of milliseconds, the receiver is considered unreachable and the
  70  * connection is killed
  71  */
  72 #define BATADV_TP_MAX_RTO 30000
  73 
  74 /**
  75  * BATADV_TP_FIRST_SEQ - First seqno of each session. The number is rather high
  76  *  in order to immediately trigger a wrap around (test purposes)
  77  */
  78 #define BATADV_TP_FIRST_SEQ ((u32)-1 - 2000)
  79 
  80 /**
  81  * BATADV_TP_PLEN - length of the payload (data after the batadv_unicast header)
  82  *  to simulate
  83  */
  84 #define BATADV_TP_PLEN (BATADV_TP_PACKET_LEN - ETH_HLEN - \
  85                         sizeof(struct batadv_unicast_packet))
  86 
  87 static u8 batadv_tp_prerandom[4096] __read_mostly;
  88 
  89 /**
  90  * batadv_tp_session_cookie() - generate session cookie based on session ids
  91  * @session: TP session identifier
  92  * @icmp_uid: icmp pseudo uid of the tp session
  93  *
  94  * Return: 32 bit tp_meter session cookie
  95  */
  96 static u32 batadv_tp_session_cookie(const u8 session[2], u8 icmp_uid)
  97 {
  98         u32 cookie;
  99 
 100         cookie = icmp_uid << 16;
 101         cookie |= session[0] << 8;
 102         cookie |= session[1];
 103 
 104         return cookie;
 105 }
 106 
 107 /**
 108  * batadv_tp_cwnd() - compute the new cwnd size
 109  * @base: base cwnd size value
 110  * @increment: the value to add to base to get the new size
 111  * @min: minumim cwnd value (usually MSS)
 112  *
 113  * Return the new cwnd size and ensures it does not exceed the Advertised
 114  * Receiver Window size. It is wrap around safe.
 115  * For details refer to Section 3.1 of RFC5681
 116  *
 117  * Return: new congestion window size in bytes
 118  */
 119 static u32 batadv_tp_cwnd(u32 base, u32 increment, u32 min)
 120 {
 121         u32 new_size = base + increment;
 122 
 123         /* check for wrap-around */
 124         if (new_size < base)
 125                 new_size = (u32)ULONG_MAX;
 126 
 127         new_size = min_t(u32, new_size, BATADV_TP_AWND);
 128 
 129         return max_t(u32, new_size, min);
 130 }
 131 
 132 /**
 133  * batadv_tp_updated_cwnd() - update the Congestion Windows
 134  * @tp_vars: the private data of the current TP meter session
 135  * @mss: maximum segment size of transmission
 136  *
 137  * 1) if the session is in Slow Start, the CWND has to be increased by 1
 138  * MSS every unique received ACK
 139  * 2) if the session is in Congestion Avoidance, the CWND has to be
 140  * increased by MSS * MSS / CWND for every unique received ACK
 141  */
 142 static void batadv_tp_update_cwnd(struct batadv_tp_vars *tp_vars, u32 mss)
 143 {
 144         spin_lock_bh(&tp_vars->cwnd_lock);
 145 
 146         /* slow start... */
 147         if (tp_vars->cwnd <= tp_vars->ss_threshold) {
 148                 tp_vars->dec_cwnd = 0;
 149                 tp_vars->cwnd = batadv_tp_cwnd(tp_vars->cwnd, mss, mss);
 150                 spin_unlock_bh(&tp_vars->cwnd_lock);
 151                 return;
 152         }
 153 
 154         /* increment CWND at least of 1 (section 3.1 of RFC5681) */
 155         tp_vars->dec_cwnd += max_t(u32, 1U << 3,
 156                                    ((mss * mss) << 6) / (tp_vars->cwnd << 3));
 157         if (tp_vars->dec_cwnd < (mss << 3)) {
 158                 spin_unlock_bh(&tp_vars->cwnd_lock);
 159                 return;
 160         }
 161 
 162         tp_vars->cwnd = batadv_tp_cwnd(tp_vars->cwnd, mss, mss);
 163         tp_vars->dec_cwnd = 0;
 164 
 165         spin_unlock_bh(&tp_vars->cwnd_lock);
 166 }
 167 
 168 /**
 169  * batadv_tp_update_rto() - calculate new retransmission timeout
 170  * @tp_vars: the private data of the current TP meter session
 171  * @new_rtt: new roundtrip time in msec
 172  */
 173 static void batadv_tp_update_rto(struct batadv_tp_vars *tp_vars,
 174                                  u32 new_rtt)
 175 {
 176         long m = new_rtt;
 177 
 178         /* RTT update
 179          * Details in Section 2.2 and 2.3 of RFC6298
 180          *
 181          * It's tricky to understand. Don't lose hair please.
 182          * Inspired by tcp_rtt_estimator() tcp_input.c
 183          */
 184         if (tp_vars->srtt != 0) {
 185                 m -= (tp_vars->srtt >> 3); /* m is now error in rtt est */
 186                 tp_vars->srtt += m; /* rtt = 7/8 srtt + 1/8 new */
 187                 if (m < 0)
 188                         m = -m;
 189 
 190                 m -= (tp_vars->rttvar >> 2);
 191                 tp_vars->rttvar += m; /* mdev ~= 3/4 rttvar + 1/4 new */
 192         } else {
 193                 /* first measure getting in */
 194                 tp_vars->srtt = m << 3; /* take the measured time to be srtt */
 195                 tp_vars->rttvar = m << 1; /* new_rtt / 2 */
 196         }
 197 
 198         /* rto = srtt + 4 * rttvar.
 199          * rttvar is scaled by 4, therefore doesn't need to be multiplied
 200          */
 201         tp_vars->rto = (tp_vars->srtt >> 3) + tp_vars->rttvar;
 202 }
 203 
 204 /**
 205  * batadv_tp_batctl_notify() - send client status result to client
 206  * @reason: reason for tp meter session stop
 207  * @dst: destination of tp_meter session
 208  * @bat_priv: the bat priv with all the soft interface information
 209  * @start_time: start of transmission in jiffies
 210  * @total_sent: bytes acked to the receiver
 211  * @cookie: cookie of tp_meter session
 212  */
 213 static void batadv_tp_batctl_notify(enum batadv_tp_meter_reason reason,
 214                                     const u8 *dst, struct batadv_priv *bat_priv,
 215                                     unsigned long start_time, u64 total_sent,
 216                                     u32 cookie)
 217 {
 218         u32 test_time;
 219         u8 result;
 220         u32 total_bytes;
 221 
 222         if (!batadv_tp_is_error(reason)) {
 223                 result = BATADV_TP_REASON_COMPLETE;
 224                 test_time = jiffies_to_msecs(jiffies - start_time);
 225                 total_bytes = total_sent;
 226         } else {
 227                 result = reason;
 228                 test_time = 0;
 229                 total_bytes = 0;
 230         }
 231 
 232         batadv_netlink_tpmeter_notify(bat_priv, dst, result, test_time,
 233                                       total_bytes, cookie);
 234 }
 235 
 236 /**
 237  * batadv_tp_batctl_error_notify() - send client error result to client
 238  * @reason: reason for tp meter session stop
 239  * @dst: destination of tp_meter session
 240  * @bat_priv: the bat priv with all the soft interface information
 241  * @cookie: cookie of tp_meter session
 242  */
 243 static void batadv_tp_batctl_error_notify(enum batadv_tp_meter_reason reason,
 244                                           const u8 *dst,
 245                                           struct batadv_priv *bat_priv,
 246                                           u32 cookie)
 247 {
 248         batadv_tp_batctl_notify(reason, dst, bat_priv, 0, 0, cookie);
 249 }
 250 
 251 /**
 252  * batadv_tp_list_find() - find a tp_vars object in the global list
 253  * @bat_priv: the bat priv with all the soft interface information
 254  * @dst: the other endpoint MAC address to look for
 255  *
 256  * Look for a tp_vars object matching dst as end_point and return it after
 257  * having incremented the refcounter. Return NULL is not found
 258  *
 259  * Return: matching tp_vars or NULL when no tp_vars with @dst was found
 260  */
 261 static struct batadv_tp_vars *batadv_tp_list_find(struct batadv_priv *bat_priv,
 262                                                   const u8 *dst)
 263 {
 264         struct batadv_tp_vars *pos, *tp_vars = NULL;
 265 
 266         rcu_read_lock();
 267         hlist_for_each_entry_rcu(pos, &bat_priv->tp_list, list) {
 268                 if (!batadv_compare_eth(pos->other_end, dst))
 269                         continue;
 270 
 271                 /* most of the time this function is invoked during the normal
 272                  * process..it makes sens to pay more when the session is
 273                  * finished and to speed the process up during the measurement
 274                  */
 275                 if (unlikely(!kref_get_unless_zero(&pos->refcount)))
 276                         continue;
 277 
 278                 tp_vars = pos;
 279                 break;
 280         }
 281         rcu_read_unlock();
 282 
 283         return tp_vars;
 284 }
 285 
 286 /**
 287  * batadv_tp_list_find_session() - find tp_vars session object in the global
 288  *  list
 289  * @bat_priv: the bat priv with all the soft interface information
 290  * @dst: the other endpoint MAC address to look for
 291  * @session: session identifier
 292  *
 293  * Look for a tp_vars object matching dst as end_point, session as tp meter
 294  * session and return it after having incremented the refcounter. Return NULL
 295  * is not found
 296  *
 297  * Return: matching tp_vars or NULL when no tp_vars was found
 298  */
 299 static struct batadv_tp_vars *
 300 batadv_tp_list_find_session(struct batadv_priv *bat_priv, const u8 *dst,
 301                             const u8 *session)
 302 {
 303         struct batadv_tp_vars *pos, *tp_vars = NULL;
 304 
 305         rcu_read_lock();
 306         hlist_for_each_entry_rcu(pos, &bat_priv->tp_list, list) {
 307                 if (!batadv_compare_eth(pos->other_end, dst))
 308                         continue;
 309 
 310                 if (memcmp(pos->session, session, sizeof(pos->session)) != 0)
 311                         continue;
 312 
 313                 /* most of the time this function is invoked during the normal
 314                  * process..it makes sense to pay more when the session is
 315                  * finished and to speed the process up during the measurement
 316                  */
 317                 if (unlikely(!kref_get_unless_zero(&pos->refcount)))
 318                         continue;
 319 
 320                 tp_vars = pos;
 321                 break;
 322         }
 323         rcu_read_unlock();
 324 
 325         return tp_vars;
 326 }
 327 
 328 /**
 329  * batadv_tp_vars_release() - release batadv_tp_vars from lists and queue for
 330  *  free after rcu grace period
 331  * @ref: kref pointer of the batadv_tp_vars
 332  */
 333 static void batadv_tp_vars_release(struct kref *ref)
 334 {
 335         struct batadv_tp_vars *tp_vars;
 336         struct batadv_tp_unacked *un, *safe;
 337 
 338         tp_vars = container_of(ref, struct batadv_tp_vars, refcount);
 339 
 340         /* lock should not be needed because this object is now out of any
 341          * context!
 342          */
 343         spin_lock_bh(&tp_vars->unacked_lock);
 344         list_for_each_entry_safe(un, safe, &tp_vars->unacked_list, list) {
 345                 list_del(&un->list);
 346                 kfree(un);
 347         }
 348         spin_unlock_bh(&tp_vars->unacked_lock);
 349 
 350         kfree_rcu(tp_vars, rcu);
 351 }
 352 
 353 /**
 354  * batadv_tp_vars_put() - decrement the batadv_tp_vars refcounter and possibly
 355  *  release it
 356  * @tp_vars: the private data of the current TP meter session to be free'd
 357  */
 358 static void batadv_tp_vars_put(struct batadv_tp_vars *tp_vars)
 359 {
 360         kref_put(&tp_vars->refcount, batadv_tp_vars_release);
 361 }
 362 
 363 /**
 364  * batadv_tp_sender_cleanup() - cleanup sender data and drop and timer
 365  * @bat_priv: the bat priv with all the soft interface information
 366  * @tp_vars: the private data of the current TP meter session to cleanup
 367  */
 368 static void batadv_tp_sender_cleanup(struct batadv_priv *bat_priv,
 369                                      struct batadv_tp_vars *tp_vars)
 370 {
 371         cancel_delayed_work(&tp_vars->finish_work);
 372 
 373         spin_lock_bh(&tp_vars->bat_priv->tp_list_lock);
 374         hlist_del_rcu(&tp_vars->list);
 375         spin_unlock_bh(&tp_vars->bat_priv->tp_list_lock);
 376 
 377         /* drop list reference */
 378         batadv_tp_vars_put(tp_vars);
 379 
 380         atomic_dec(&tp_vars->bat_priv->tp_num);
 381 
 382         /* kill the timer and remove its reference */
 383         del_timer_sync(&tp_vars->timer);
 384         /* the worker might have rearmed itself therefore we kill it again. Note
 385          * that if the worker should run again before invoking the following
 386          * del_timer(), it would not re-arm itself once again because the status
 387          * is OFF now
 388          */
 389         del_timer(&tp_vars->timer);
 390         batadv_tp_vars_put(tp_vars);
 391 }
 392 
 393 /**
 394  * batadv_tp_sender_end() - print info about ended session and inform client
 395  * @bat_priv: the bat priv with all the soft interface information
 396  * @tp_vars: the private data of the current TP meter session
 397  */
 398 static void batadv_tp_sender_end(struct batadv_priv *bat_priv,
 399                                  struct batadv_tp_vars *tp_vars)
 400 {
 401         u32 session_cookie;
 402 
 403         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 404                    "Test towards %pM finished..shutting down (reason=%d)\n",
 405                    tp_vars->other_end, tp_vars->reason);
 406 
 407         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 408                    "Last timing stats: SRTT=%ums RTTVAR=%ums RTO=%ums\n",
 409                    tp_vars->srtt >> 3, tp_vars->rttvar >> 2, tp_vars->rto);
 410 
 411         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 412                    "Final values: cwnd=%u ss_threshold=%u\n",
 413                    tp_vars->cwnd, tp_vars->ss_threshold);
 414 
 415         session_cookie = batadv_tp_session_cookie(tp_vars->session,
 416                                                   tp_vars->icmp_uid);
 417 
 418         batadv_tp_batctl_notify(tp_vars->reason,
 419                                 tp_vars->other_end,
 420                                 bat_priv,
 421                                 tp_vars->start_time,
 422                                 atomic64_read(&tp_vars->tot_sent),
 423                                 session_cookie);
 424 }
 425 
 426 /**
 427  * batadv_tp_sender_shutdown() - let sender thread/timer stop gracefully
 428  * @tp_vars: the private data of the current TP meter session
 429  * @reason: reason for tp meter session stop
 430  */
 431 static void batadv_tp_sender_shutdown(struct batadv_tp_vars *tp_vars,
 432                                       enum batadv_tp_meter_reason reason)
 433 {
 434         if (!atomic_dec_and_test(&tp_vars->sending))
 435                 return;
 436 
 437         tp_vars->reason = reason;
 438 }
 439 
 440 /**
 441  * batadv_tp_sender_finish() - stop sender session after test_length was reached
 442  * @work: delayed work reference of the related tp_vars
 443  */
 444 static void batadv_tp_sender_finish(struct work_struct *work)
 445 {
 446         struct delayed_work *delayed_work;
 447         struct batadv_tp_vars *tp_vars;
 448 
 449         delayed_work = to_delayed_work(work);
 450         tp_vars = container_of(delayed_work, struct batadv_tp_vars,
 451                                finish_work);
 452 
 453         batadv_tp_sender_shutdown(tp_vars, BATADV_TP_REASON_COMPLETE);
 454 }
 455 
 456 /**
 457  * batadv_tp_reset_sender_timer() - reschedule the sender timer
 458  * @tp_vars: the private TP meter data for this session
 459  *
 460  * Reschedule the timer using tp_vars->rto as delay
 461  */
 462 static void batadv_tp_reset_sender_timer(struct batadv_tp_vars *tp_vars)
 463 {
 464         /* most of the time this function is invoked while normal packet
 465          * reception...
 466          */
 467         if (unlikely(atomic_read(&tp_vars->sending) == 0))
 468                 /* timer ref will be dropped in batadv_tp_sender_cleanup */
 469                 return;
 470 
 471         mod_timer(&tp_vars->timer, jiffies + msecs_to_jiffies(tp_vars->rto));
 472 }
 473 
 474 /**
 475  * batadv_tp_sender_timeout() - timer that fires in case of packet loss
 476  * @t: address to timer_list inside tp_vars
 477  *
 478  * If fired it means that there was packet loss.
 479  * Switch to Slow Start, set the ss_threshold to half of the current cwnd and
 480  * reset the cwnd to 3*MSS
 481  */
 482 static void batadv_tp_sender_timeout(struct timer_list *t)
 483 {
 484         struct batadv_tp_vars *tp_vars = from_timer(tp_vars, t, timer);
 485         struct batadv_priv *bat_priv = tp_vars->bat_priv;
 486 
 487         if (atomic_read(&tp_vars->sending) == 0)
 488                 return;
 489 
 490         /* if the user waited long enough...shutdown the test */
 491         if (unlikely(tp_vars->rto >= BATADV_TP_MAX_RTO)) {
 492                 batadv_tp_sender_shutdown(tp_vars,
 493                                           BATADV_TP_REASON_DST_UNREACHABLE);
 494                 return;
 495         }
 496 
 497         /* RTO exponential backoff
 498          * Details in Section 5.5 of RFC6298
 499          */
 500         tp_vars->rto <<= 1;
 501 
 502         spin_lock_bh(&tp_vars->cwnd_lock);
 503 
 504         tp_vars->ss_threshold = tp_vars->cwnd >> 1;
 505         if (tp_vars->ss_threshold < BATADV_TP_PLEN * 2)
 506                 tp_vars->ss_threshold = BATADV_TP_PLEN * 2;
 507 
 508         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 509                    "Meter: RTO fired during test towards %pM! cwnd=%u new ss_thr=%u, resetting last_sent to %u\n",
 510                    tp_vars->other_end, tp_vars->cwnd, tp_vars->ss_threshold,
 511                    atomic_read(&tp_vars->last_acked));
 512 
 513         tp_vars->cwnd = BATADV_TP_PLEN * 3;
 514 
 515         spin_unlock_bh(&tp_vars->cwnd_lock);
 516 
 517         /* resend the non-ACKed packets.. */
 518         tp_vars->last_sent = atomic_read(&tp_vars->last_acked);
 519         wake_up(&tp_vars->more_bytes);
 520 
 521         batadv_tp_reset_sender_timer(tp_vars);
 522 }
 523 
 524 /**
 525  * batadv_tp_fill_prerandom() - Fill buffer with prefetched random bytes
 526  * @tp_vars: the private TP meter data for this session
 527  * @buf: Buffer to fill with bytes
 528  * @nbytes: amount of pseudorandom bytes
 529  */
 530 static void batadv_tp_fill_prerandom(struct batadv_tp_vars *tp_vars,
 531                                      u8 *buf, size_t nbytes)
 532 {
 533         u32 local_offset;
 534         size_t bytes_inbuf;
 535         size_t to_copy;
 536         size_t pos = 0;
 537 
 538         spin_lock_bh(&tp_vars->prerandom_lock);
 539         local_offset = tp_vars->prerandom_offset;
 540         tp_vars->prerandom_offset += nbytes;
 541         tp_vars->prerandom_offset %= sizeof(batadv_tp_prerandom);
 542         spin_unlock_bh(&tp_vars->prerandom_lock);
 543 
 544         while (nbytes) {
 545                 local_offset %= sizeof(batadv_tp_prerandom);
 546                 bytes_inbuf = sizeof(batadv_tp_prerandom) - local_offset;
 547                 to_copy = min(nbytes, bytes_inbuf);
 548 
 549                 memcpy(&buf[pos], &batadv_tp_prerandom[local_offset], to_copy);
 550                 pos += to_copy;
 551                 nbytes -= to_copy;
 552                 local_offset = 0;
 553         }
 554 }
 555 
 556 /**
 557  * batadv_tp_send_msg() - send a single message
 558  * @tp_vars: the private TP meter data for this session
 559  * @src: source mac address
 560  * @orig_node: the originator of the destination
 561  * @seqno: sequence number of this packet
 562  * @len: length of the entire packet
 563  * @session: session identifier
 564  * @uid: local ICMP "socket" index
 565  * @timestamp: timestamp in jiffies which is replied in ack
 566  *
 567  * Create and send a single TP Meter message.
 568  *
 569  * Return: 0 on success, BATADV_TP_REASON_DST_UNREACHABLE if the destination is
 570  * not reachable, BATADV_TP_REASON_MEMORY_ERROR if the packet couldn't be
 571  * allocated
 572  */
 573 static int batadv_tp_send_msg(struct batadv_tp_vars *tp_vars, const u8 *src,
 574                               struct batadv_orig_node *orig_node,
 575                               u32 seqno, size_t len, const u8 *session,
 576                               int uid, u32 timestamp)
 577 {
 578         struct batadv_icmp_tp_packet *icmp;
 579         struct sk_buff *skb;
 580         int r;
 581         u8 *data;
 582         size_t data_len;
 583 
 584         skb = netdev_alloc_skb_ip_align(NULL, len + ETH_HLEN);
 585         if (unlikely(!skb))
 586                 return BATADV_TP_REASON_MEMORY_ERROR;
 587 
 588         skb_reserve(skb, ETH_HLEN);
 589         icmp = skb_put(skb, sizeof(*icmp));
 590 
 591         /* fill the icmp header */
 592         ether_addr_copy(icmp->dst, orig_node->orig);
 593         ether_addr_copy(icmp->orig, src);
 594         icmp->version = BATADV_COMPAT_VERSION;
 595         icmp->packet_type = BATADV_ICMP;
 596         icmp->ttl = BATADV_TTL;
 597         icmp->msg_type = BATADV_TP;
 598         icmp->uid = uid;
 599 
 600         icmp->subtype = BATADV_TP_MSG;
 601         memcpy(icmp->session, session, sizeof(icmp->session));
 602         icmp->seqno = htonl(seqno);
 603         icmp->timestamp = htonl(timestamp);
 604 
 605         data_len = len - sizeof(*icmp);
 606         data = skb_put(skb, data_len);
 607         batadv_tp_fill_prerandom(tp_vars, data, data_len);
 608 
 609         r = batadv_send_skb_to_orig(skb, orig_node, NULL);
 610         if (r == NET_XMIT_SUCCESS)
 611                 return 0;
 612 
 613         return BATADV_TP_REASON_CANT_SEND;
 614 }
 615 
 616 /**
 617  * batadv_tp_recv_ack() - ACK receiving function
 618  * @bat_priv: the bat priv with all the soft interface information
 619  * @skb: the buffer containing the received packet
 620  *
 621  * Process a received TP ACK packet
 622  */
 623 static void batadv_tp_recv_ack(struct batadv_priv *bat_priv,
 624                                const struct sk_buff *skb)
 625 {
 626         struct batadv_hard_iface *primary_if = NULL;
 627         struct batadv_orig_node *orig_node = NULL;
 628         const struct batadv_icmp_tp_packet *icmp;
 629         struct batadv_tp_vars *tp_vars;
 630         size_t packet_len, mss;
 631         u32 rtt, recv_ack, cwnd;
 632         unsigned char *dev_addr;
 633 
 634         packet_len = BATADV_TP_PLEN;
 635         mss = BATADV_TP_PLEN;
 636         packet_len += sizeof(struct batadv_unicast_packet);
 637 
 638         icmp = (struct batadv_icmp_tp_packet *)skb->data;
 639 
 640         /* find the tp_vars */
 641         tp_vars = batadv_tp_list_find_session(bat_priv, icmp->orig,
 642                                               icmp->session);
 643         if (unlikely(!tp_vars))
 644                 return;
 645 
 646         if (unlikely(atomic_read(&tp_vars->sending) == 0))
 647                 goto out;
 648 
 649         /* old ACK? silently drop it.. */
 650         if (batadv_seq_before(ntohl(icmp->seqno),
 651                               (u32)atomic_read(&tp_vars->last_acked)))
 652                 goto out;
 653 
 654         primary_if = batadv_primary_if_get_selected(bat_priv);
 655         if (unlikely(!primary_if))
 656                 goto out;
 657 
 658         orig_node = batadv_orig_hash_find(bat_priv, icmp->orig);
 659         if (unlikely(!orig_node))
 660                 goto out;
 661 
 662         /* update RTO with the new sampled RTT, if any */
 663         rtt = jiffies_to_msecs(jiffies) - ntohl(icmp->timestamp);
 664         if (icmp->timestamp && rtt)
 665                 batadv_tp_update_rto(tp_vars, rtt);
 666 
 667         /* ACK for new data... reset the timer */
 668         batadv_tp_reset_sender_timer(tp_vars);
 669 
 670         recv_ack = ntohl(icmp->seqno);
 671 
 672         /* check if this ACK is a duplicate */
 673         if (atomic_read(&tp_vars->last_acked) == recv_ack) {
 674                 atomic_inc(&tp_vars->dup_acks);
 675                 if (atomic_read(&tp_vars->dup_acks) != 3)
 676                         goto out;
 677 
 678                 if (recv_ack >= tp_vars->recover)
 679                         goto out;
 680 
 681                 /* if this is the third duplicate ACK do Fast Retransmit */
 682                 batadv_tp_send_msg(tp_vars, primary_if->net_dev->dev_addr,
 683                                    orig_node, recv_ack, packet_len,
 684                                    icmp->session, icmp->uid,
 685                                    jiffies_to_msecs(jiffies));
 686 
 687                 spin_lock_bh(&tp_vars->cwnd_lock);
 688 
 689                 /* Fast Recovery */
 690                 tp_vars->fast_recovery = true;
 691                 /* Set recover to the last outstanding seqno when Fast Recovery
 692                  * is entered. RFC6582, Section 3.2, step 1
 693                  */
 694                 tp_vars->recover = tp_vars->last_sent;
 695                 tp_vars->ss_threshold = tp_vars->cwnd >> 1;
 696                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 697                            "Meter: Fast Recovery, (cur cwnd=%u) ss_thr=%u last_sent=%u recv_ack=%u\n",
 698                            tp_vars->cwnd, tp_vars->ss_threshold,
 699                            tp_vars->last_sent, recv_ack);
 700                 tp_vars->cwnd = batadv_tp_cwnd(tp_vars->ss_threshold, 3 * mss,
 701                                                mss);
 702                 tp_vars->dec_cwnd = 0;
 703                 tp_vars->last_sent = recv_ack;
 704 
 705                 spin_unlock_bh(&tp_vars->cwnd_lock);
 706         } else {
 707                 /* count the acked data */
 708                 atomic64_add(recv_ack - atomic_read(&tp_vars->last_acked),
 709                              &tp_vars->tot_sent);
 710                 /* reset the duplicate ACKs counter */
 711                 atomic_set(&tp_vars->dup_acks, 0);
 712 
 713                 if (tp_vars->fast_recovery) {
 714                         /* partial ACK */
 715                         if (batadv_seq_before(recv_ack, tp_vars->recover)) {
 716                                 /* this is another hole in the window. React
 717                                  * immediately as specified by NewReno (see
 718                                  * Section 3.2 of RFC6582 for details)
 719                                  */
 720                                 dev_addr = primary_if->net_dev->dev_addr;
 721                                 batadv_tp_send_msg(tp_vars, dev_addr,
 722                                                    orig_node, recv_ack,
 723                                                    packet_len, icmp->session,
 724                                                    icmp->uid,
 725                                                    jiffies_to_msecs(jiffies));
 726                                 tp_vars->cwnd = batadv_tp_cwnd(tp_vars->cwnd,
 727                                                                mss, mss);
 728                         } else {
 729                                 tp_vars->fast_recovery = false;
 730                                 /* set cwnd to the value of ss_threshold at the
 731                                  * moment that Fast Recovery was entered.
 732                                  * RFC6582, Section 3.2, step 3
 733                                  */
 734                                 cwnd = batadv_tp_cwnd(tp_vars->ss_threshold, 0,
 735                                                       mss);
 736                                 tp_vars->cwnd = cwnd;
 737                         }
 738                         goto move_twnd;
 739                 }
 740 
 741                 if (recv_ack - atomic_read(&tp_vars->last_acked) >= mss)
 742                         batadv_tp_update_cwnd(tp_vars, mss);
 743 move_twnd:
 744                 /* move the Transmit Window */
 745                 atomic_set(&tp_vars->last_acked, recv_ack);
 746         }
 747 
 748         wake_up(&tp_vars->more_bytes);
 749 out:
 750         if (likely(primary_if))
 751                 batadv_hardif_put(primary_if);
 752         if (likely(orig_node))
 753                 batadv_orig_node_put(orig_node);
 754         if (likely(tp_vars))
 755                 batadv_tp_vars_put(tp_vars);
 756 }
 757 
 758 /**
 759  * batadv_tp_avail() - check if congestion window is not full
 760  * @tp_vars: the private data of the current TP meter session
 761  * @payload_len: size of the payload of a single message
 762  *
 763  * Return: true when congestion window is not full, false otherwise
 764  */
 765 static bool batadv_tp_avail(struct batadv_tp_vars *tp_vars,
 766                             size_t payload_len)
 767 {
 768         u32 win_left, win_limit;
 769 
 770         win_limit = atomic_read(&tp_vars->last_acked) + tp_vars->cwnd;
 771         win_left = win_limit - tp_vars->last_sent;
 772 
 773         return win_left >= payload_len;
 774 }
 775 
 776 /**
 777  * batadv_tp_wait_available() - wait until congestion window becomes free or
 778  *  timeout is reached
 779  * @tp_vars: the private data of the current TP meter session
 780  * @plen: size of the payload of a single message
 781  *
 782  * Return: 0 if the condition evaluated to false after the timeout elapsed,
 783  *  1 if the condition evaluated to true after the timeout elapsed, the
 784  *  remaining jiffies (at least 1) if the condition evaluated to true before
 785  *  the timeout elapsed, or -ERESTARTSYS if it was interrupted by a signal.
 786  */
 787 static int batadv_tp_wait_available(struct batadv_tp_vars *tp_vars, size_t plen)
 788 {
 789         int ret;
 790 
 791         ret = wait_event_interruptible_timeout(tp_vars->more_bytes,
 792                                                batadv_tp_avail(tp_vars, plen),
 793                                                HZ / 10);
 794 
 795         return ret;
 796 }
 797 
 798 /**
 799  * batadv_tp_send() - main sending thread of a tp meter session
 800  * @arg: address of the related tp_vars
 801  *
 802  * Return: nothing, this function never returns
 803  */
 804 static int batadv_tp_send(void *arg)
 805 {
 806         struct batadv_tp_vars *tp_vars = arg;
 807         struct batadv_priv *bat_priv = tp_vars->bat_priv;
 808         struct batadv_hard_iface *primary_if = NULL;
 809         struct batadv_orig_node *orig_node = NULL;
 810         size_t payload_len, packet_len;
 811         int err = 0;
 812 
 813         if (unlikely(tp_vars->role != BATADV_TP_SENDER)) {
 814                 err = BATADV_TP_REASON_DST_UNREACHABLE;
 815                 tp_vars->reason = err;
 816                 goto out;
 817         }
 818 
 819         orig_node = batadv_orig_hash_find(bat_priv, tp_vars->other_end);
 820         if (unlikely(!orig_node)) {
 821                 err = BATADV_TP_REASON_DST_UNREACHABLE;
 822                 tp_vars->reason = err;
 823                 goto out;
 824         }
 825 
 826         primary_if = batadv_primary_if_get_selected(bat_priv);
 827         if (unlikely(!primary_if)) {
 828                 err = BATADV_TP_REASON_DST_UNREACHABLE;
 829                 tp_vars->reason = err;
 830                 goto out;
 831         }
 832 
 833         /* assume that all the hard_interfaces have a correctly
 834          * configured MTU, so use the soft_iface MTU as MSS.
 835          * This might not be true and in that case the fragmentation
 836          * should be used.
 837          * Now, try to send the packet as it is
 838          */
 839         payload_len = BATADV_TP_PLEN;
 840         BUILD_BUG_ON(sizeof(struct batadv_icmp_tp_packet) > BATADV_TP_PLEN);
 841 
 842         batadv_tp_reset_sender_timer(tp_vars);
 843 
 844         /* queue the worker in charge of terminating the test */
 845         queue_delayed_work(batadv_event_workqueue, &tp_vars->finish_work,
 846                            msecs_to_jiffies(tp_vars->test_length));
 847 
 848         while (atomic_read(&tp_vars->sending) != 0) {
 849                 if (unlikely(!batadv_tp_avail(tp_vars, payload_len))) {
 850                         batadv_tp_wait_available(tp_vars, payload_len);
 851                         continue;
 852                 }
 853 
 854                 /* to emulate normal unicast traffic, add to the payload len
 855                  * the size of the unicast header
 856                  */
 857                 packet_len = payload_len + sizeof(struct batadv_unicast_packet);
 858 
 859                 err = batadv_tp_send_msg(tp_vars, primary_if->net_dev->dev_addr,
 860                                          orig_node, tp_vars->last_sent,
 861                                          packet_len,
 862                                          tp_vars->session, tp_vars->icmp_uid,
 863                                          jiffies_to_msecs(jiffies));
 864 
 865                 /* something went wrong during the preparation/transmission */
 866                 if (unlikely(err && err != BATADV_TP_REASON_CANT_SEND)) {
 867                         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 868                                    "Meter: %s() cannot send packets (%d)\n",
 869                                    __func__, err);
 870                         /* ensure nobody else tries to stop the thread now */
 871                         if (atomic_dec_and_test(&tp_vars->sending))
 872                                 tp_vars->reason = err;
 873                         break;
 874                 }
 875 
 876                 /* right-shift the TWND */
 877                 if (!err)
 878                         tp_vars->last_sent += payload_len;
 879 
 880                 cond_resched();
 881         }
 882 
 883 out:
 884         if (likely(primary_if))
 885                 batadv_hardif_put(primary_if);
 886         if (likely(orig_node))
 887                 batadv_orig_node_put(orig_node);
 888 
 889         batadv_tp_sender_end(bat_priv, tp_vars);
 890         batadv_tp_sender_cleanup(bat_priv, tp_vars);
 891 
 892         batadv_tp_vars_put(tp_vars);
 893 
 894         do_exit(0);
 895 }
 896 
 897 /**
 898  * batadv_tp_start_kthread() - start new thread which manages the tp meter
 899  *  sender
 900  * @tp_vars: the private data of the current TP meter session
 901  */
 902 static void batadv_tp_start_kthread(struct batadv_tp_vars *tp_vars)
 903 {
 904         struct task_struct *kthread;
 905         struct batadv_priv *bat_priv = tp_vars->bat_priv;
 906         u32 session_cookie;
 907 
 908         kref_get(&tp_vars->refcount);
 909         kthread = kthread_create(batadv_tp_send, tp_vars, "kbatadv_tp_meter");
 910         if (IS_ERR(kthread)) {
 911                 session_cookie = batadv_tp_session_cookie(tp_vars->session,
 912                                                           tp_vars->icmp_uid);
 913                 pr_err("batadv: cannot create tp meter kthread\n");
 914                 batadv_tp_batctl_error_notify(BATADV_TP_REASON_MEMORY_ERROR,
 915                                               tp_vars->other_end,
 916                                               bat_priv, session_cookie);
 917 
 918                 /* drop reserved reference for kthread */
 919                 batadv_tp_vars_put(tp_vars);
 920 
 921                 /* cleanup of failed tp meter variables */
 922                 batadv_tp_sender_cleanup(bat_priv, tp_vars);
 923                 return;
 924         }
 925 
 926         wake_up_process(kthread);
 927 }
 928 
 929 /**
 930  * batadv_tp_start() - start a new tp meter session
 931  * @bat_priv: the bat priv with all the soft interface information
 932  * @dst: the receiver MAC address
 933  * @test_length: test length in milliseconds
 934  * @cookie: session cookie
 935  */
 936 void batadv_tp_start(struct batadv_priv *bat_priv, const u8 *dst,
 937                      u32 test_length, u32 *cookie)
 938 {
 939         struct batadv_tp_vars *tp_vars;
 940         u8 session_id[2];
 941         u8 icmp_uid;
 942         u32 session_cookie;
 943 
 944         get_random_bytes(session_id, sizeof(session_id));
 945         get_random_bytes(&icmp_uid, 1);
 946         session_cookie = batadv_tp_session_cookie(session_id, icmp_uid);
 947         *cookie = session_cookie;
 948 
 949         /* look for an already existing test towards this node */
 950         spin_lock_bh(&bat_priv->tp_list_lock);
 951         tp_vars = batadv_tp_list_find(bat_priv, dst);
 952         if (tp_vars) {
 953                 spin_unlock_bh(&bat_priv->tp_list_lock);
 954                 batadv_tp_vars_put(tp_vars);
 955                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 956                            "Meter: test to or from the same node already ongoing, aborting\n");
 957                 batadv_tp_batctl_error_notify(BATADV_TP_REASON_ALREADY_ONGOING,
 958                                               dst, bat_priv, session_cookie);
 959                 return;
 960         }
 961 
 962         if (!atomic_add_unless(&bat_priv->tp_num, 1, BATADV_TP_MAX_NUM)) {
 963                 spin_unlock_bh(&bat_priv->tp_list_lock);
 964                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 965                            "Meter: too many ongoing sessions, aborting (SEND)\n");
 966                 batadv_tp_batctl_error_notify(BATADV_TP_REASON_TOO_MANY, dst,
 967                                               bat_priv, session_cookie);
 968                 return;
 969         }
 970 
 971         tp_vars = kmalloc(sizeof(*tp_vars), GFP_ATOMIC);
 972         if (!tp_vars) {
 973                 spin_unlock_bh(&bat_priv->tp_list_lock);
 974                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 975                            "Meter: %s cannot allocate list elements\n",
 976                            __func__);
 977                 batadv_tp_batctl_error_notify(BATADV_TP_REASON_MEMORY_ERROR,
 978                                               dst, bat_priv, session_cookie);
 979                 return;
 980         }
 981 
 982         /* initialize tp_vars */
 983         ether_addr_copy(tp_vars->other_end, dst);
 984         kref_init(&tp_vars->refcount);
 985         tp_vars->role = BATADV_TP_SENDER;
 986         atomic_set(&tp_vars->sending, 1);
 987         memcpy(tp_vars->session, session_id, sizeof(session_id));
 988         tp_vars->icmp_uid = icmp_uid;
 989 
 990         tp_vars->last_sent = BATADV_TP_FIRST_SEQ;
 991         atomic_set(&tp_vars->last_acked, BATADV_TP_FIRST_SEQ);
 992         tp_vars->fast_recovery = false;
 993         tp_vars->recover = BATADV_TP_FIRST_SEQ;
 994 
 995         /* initialise the CWND to 3*MSS (Section 3.1 in RFC5681).
 996          * For batman-adv the MSS is the size of the payload received by the
 997          * soft_interface, hence its MTU
 998          */
 999         tp_vars->cwnd = BATADV_TP_PLEN * 3;
1000         /* at the beginning initialise the SS threshold to the biggest possible
1001          * window size, hence the AWND size
1002          */
1003         tp_vars->ss_threshold = BATADV_TP_AWND;
1004 
1005         /* RTO initial value is 3 seconds.
1006          * Details in Section 2.1 of RFC6298
1007          */
1008         tp_vars->rto = 1000;
1009         tp_vars->srtt = 0;
1010         tp_vars->rttvar = 0;
1011 
1012         atomic64_set(&tp_vars->tot_sent, 0);
1013 
1014         kref_get(&tp_vars->refcount);
1015         timer_setup(&tp_vars->timer, batadv_tp_sender_timeout, 0);
1016 
1017         tp_vars->bat_priv = bat_priv;
1018         tp_vars->start_time = jiffies;
1019 
1020         init_waitqueue_head(&tp_vars->more_bytes);
1021 
1022         spin_lock_init(&tp_vars->unacked_lock);
1023         INIT_LIST_HEAD(&tp_vars->unacked_list);
1024 
1025         spin_lock_init(&tp_vars->cwnd_lock);
1026 
1027         tp_vars->prerandom_offset = 0;
1028         spin_lock_init(&tp_vars->prerandom_lock);
1029 
1030         kref_get(&tp_vars->refcount);
1031         hlist_add_head_rcu(&tp_vars->list, &bat_priv->tp_list);
1032         spin_unlock_bh(&bat_priv->tp_list_lock);
1033 
1034         tp_vars->test_length = test_length;
1035         if (!tp_vars->test_length)
1036                 tp_vars->test_length = BATADV_TP_DEF_TEST_LENGTH;
1037 
1038         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1039                    "Meter: starting throughput meter towards %pM (length=%ums)\n",
1040                    dst, test_length);
1041 
1042         /* init work item for finished tp tests */
1043         INIT_DELAYED_WORK(&tp_vars->finish_work, batadv_tp_sender_finish);
1044 
1045         /* start tp kthread. This way the write() call issued from userspace can
1046          * happily return and avoid to block
1047          */
1048         batadv_tp_start_kthread(tp_vars);
1049 
1050         /* don't return reference to new tp_vars */
1051         batadv_tp_vars_put(tp_vars);
1052 }
1053 
1054 /**
1055  * batadv_tp_stop() - stop currently running tp meter session
1056  * @bat_priv: the bat priv with all the soft interface information
1057  * @dst: the receiver MAC address
1058  * @return_value: reason for tp meter session stop
1059  */
1060 void batadv_tp_stop(struct batadv_priv *bat_priv, const u8 *dst,
1061                     u8 return_value)
1062 {
1063         struct batadv_orig_node *orig_node;
1064         struct batadv_tp_vars *tp_vars;
1065 
1066         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1067                    "Meter: stopping test towards %pM\n", dst);
1068 
1069         orig_node = batadv_orig_hash_find(bat_priv, dst);
1070         if (!orig_node)
1071                 return;
1072 
1073         tp_vars = batadv_tp_list_find(bat_priv, orig_node->orig);
1074         if (!tp_vars) {
1075                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1076                            "Meter: trying to interrupt an already over connection\n");
1077                 goto out;
1078         }
1079 
1080         batadv_tp_sender_shutdown(tp_vars, return_value);
1081         batadv_tp_vars_put(tp_vars);
1082 out:
1083         batadv_orig_node_put(orig_node);
1084 }
1085 
1086 /**
1087  * batadv_tp_reset_receiver_timer() - reset the receiver shutdown timer
1088  * @tp_vars: the private data of the current TP meter session
1089  *
1090  * start the receiver shutdown timer or reset it if already started
1091  */
1092 static void batadv_tp_reset_receiver_timer(struct batadv_tp_vars *tp_vars)
1093 {
1094         mod_timer(&tp_vars->timer,
1095                   jiffies + msecs_to_jiffies(BATADV_TP_RECV_TIMEOUT));
1096 }
1097 
1098 /**
1099  * batadv_tp_receiver_shutdown() - stop a tp meter receiver when timeout is
1100  *  reached without received ack
1101  * @t: address to timer_list inside tp_vars
1102  */
1103 static void batadv_tp_receiver_shutdown(struct timer_list *t)
1104 {
1105         struct batadv_tp_vars *tp_vars = from_timer(tp_vars, t, timer);
1106         struct batadv_tp_unacked *un, *safe;
1107         struct batadv_priv *bat_priv;
1108 
1109         bat_priv = tp_vars->bat_priv;
1110 
1111         /* if there is recent activity rearm the timer */
1112         if (!batadv_has_timed_out(tp_vars->last_recv_time,
1113                                   BATADV_TP_RECV_TIMEOUT)) {
1114                 /* reset the receiver shutdown timer */
1115                 batadv_tp_reset_receiver_timer(tp_vars);
1116                 return;
1117         }
1118 
1119         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1120                    "Shutting down for inactivity (more than %dms) from %pM\n",
1121                    BATADV_TP_RECV_TIMEOUT, tp_vars->other_end);
1122 
1123         spin_lock_bh(&tp_vars->bat_priv->tp_list_lock);
1124         hlist_del_rcu(&tp_vars->list);
1125         spin_unlock_bh(&tp_vars->bat_priv->tp_list_lock);
1126 
1127         /* drop list reference */
1128         batadv_tp_vars_put(tp_vars);
1129 
1130         atomic_dec(&bat_priv->tp_num);
1131 
1132         spin_lock_bh(&tp_vars->unacked_lock);
1133         list_for_each_entry_safe(un, safe, &tp_vars->unacked_list, list) {
1134                 list_del(&un->list);
1135                 kfree(un);
1136         }
1137         spin_unlock_bh(&tp_vars->unacked_lock);
1138 
1139         /* drop reference of timer */
1140         batadv_tp_vars_put(tp_vars);
1141 }
1142 
1143 /**
1144  * batadv_tp_send_ack() - send an ACK packet
1145  * @bat_priv: the bat priv with all the soft interface information
1146  * @dst: the mac address of the destination originator
1147  * @seq: the sequence number to ACK
1148  * @timestamp: the timestamp to echo back in the ACK
1149  * @session: session identifier
1150  * @socket_index: local ICMP socket identifier
1151  *
1152  * Return: 0 on success, a positive integer representing the reason of the
1153  * failure otherwise
1154  */
1155 static int batadv_tp_send_ack(struct batadv_priv *bat_priv, const u8 *dst,
1156                               u32 seq, __be32 timestamp, const u8 *session,
1157                               int socket_index)
1158 {
1159         struct batadv_hard_iface *primary_if = NULL;
1160         struct batadv_orig_node *orig_node;
1161         struct batadv_icmp_tp_packet *icmp;
1162         struct sk_buff *skb;
1163         int r, ret;
1164 
1165         orig_node = batadv_orig_hash_find(bat_priv, dst);
1166         if (unlikely(!orig_node)) {
1167                 ret = BATADV_TP_REASON_DST_UNREACHABLE;
1168                 goto out;
1169         }
1170 
1171         primary_if = batadv_primary_if_get_selected(bat_priv);
1172         if (unlikely(!primary_if)) {
1173                 ret = BATADV_TP_REASON_DST_UNREACHABLE;
1174                 goto out;
1175         }
1176 
1177         skb = netdev_alloc_skb_ip_align(NULL, sizeof(*icmp) + ETH_HLEN);
1178         if (unlikely(!skb)) {
1179                 ret = BATADV_TP_REASON_MEMORY_ERROR;
1180                 goto out;
1181         }
1182 
1183         skb_reserve(skb, ETH_HLEN);
1184         icmp = skb_put(skb, sizeof(*icmp));
1185         icmp->packet_type = BATADV_ICMP;
1186         icmp->version = BATADV_COMPAT_VERSION;
1187         icmp->ttl = BATADV_TTL;
1188         icmp->msg_type = BATADV_TP;
1189         ether_addr_copy(icmp->dst, orig_node->orig);
1190         ether_addr_copy(icmp->orig, primary_if->net_dev->dev_addr);
1191         icmp->uid = socket_index;
1192 
1193         icmp->subtype = BATADV_TP_ACK;
1194         memcpy(icmp->session, session, sizeof(icmp->session));
1195         icmp->seqno = htonl(seq);
1196         icmp->timestamp = timestamp;
1197 
1198         /* send the ack */
1199         r = batadv_send_skb_to_orig(skb, orig_node, NULL);
1200         if (unlikely(r < 0) || r == NET_XMIT_DROP) {
1201                 ret = BATADV_TP_REASON_DST_UNREACHABLE;
1202                 goto out;
1203         }
1204         ret = 0;
1205 
1206 out:
1207         if (likely(orig_node))
1208                 batadv_orig_node_put(orig_node);
1209         if (likely(primary_if))
1210                 batadv_hardif_put(primary_if);
1211 
1212         return ret;
1213 }
1214 
1215 /**
1216  * batadv_tp_handle_out_of_order() - store an out of order packet
1217  * @tp_vars: the private data of the current TP meter session
1218  * @skb: the buffer containing the received packet
1219  *
1220  * Store the out of order packet in the unacked list for late processing. This
1221  * packets are kept in this list so that they can be ACKed at once as soon as
1222  * all the previous packets have been received
1223  *
1224  * Return: true if the packed has been successfully processed, false otherwise
1225  */
1226 static bool batadv_tp_handle_out_of_order(struct batadv_tp_vars *tp_vars,
1227                                           const struct sk_buff *skb)
1228 {
1229         const struct batadv_icmp_tp_packet *icmp;
1230         struct batadv_tp_unacked *un, *new;
1231         u32 payload_len;
1232         bool added = false;
1233 
1234         new = kmalloc(sizeof(*new), GFP_ATOMIC);
1235         if (unlikely(!new))
1236                 return false;
1237 
1238         icmp = (struct batadv_icmp_tp_packet *)skb->data;
1239 
1240         new->seqno = ntohl(icmp->seqno);
1241         payload_len = skb->len - sizeof(struct batadv_unicast_packet);
1242         new->len = payload_len;
1243 
1244         spin_lock_bh(&tp_vars->unacked_lock);
1245         /* if the list is empty immediately attach this new object */
1246         if (list_empty(&tp_vars->unacked_list)) {
1247                 list_add(&new->list, &tp_vars->unacked_list);
1248                 goto out;
1249         }
1250 
1251         /* otherwise loop over the list and either drop the packet because this
1252          * is a duplicate or store it at the right position.
1253          *
1254          * The iteration is done in the reverse way because it is likely that
1255          * the last received packet (the one being processed now) has a bigger
1256          * seqno than all the others already stored.
1257          */
1258         list_for_each_entry_reverse(un, &tp_vars->unacked_list, list) {
1259                 /* check for duplicates */
1260                 if (new->seqno == un->seqno) {
1261                         if (new->len > un->len)
1262                                 un->len = new->len;
1263                         kfree(new);
1264                         added = true;
1265                         break;
1266                 }
1267 
1268                 /* look for the right position */
1269                 if (batadv_seq_before(new->seqno, un->seqno))
1270                         continue;
1271 
1272                 /* as soon as an entry having a bigger seqno is found, the new
1273                  * one is attached _after_ it. In this way the list is kept in
1274                  * ascending order
1275                  */
1276                 list_add_tail(&new->list, &un->list);
1277                 added = true;
1278                 break;
1279         }
1280 
1281         /* received packet with smallest seqno out of order; add it to front */
1282         if (!added)
1283                 list_add(&new->list, &tp_vars->unacked_list);
1284 
1285 out:
1286         spin_unlock_bh(&tp_vars->unacked_lock);
1287 
1288         return true;
1289 }
1290 
1291 /**
1292  * batadv_tp_ack_unordered() - update number received bytes in current stream
1293  *  without gaps
1294  * @tp_vars: the private data of the current TP meter session
1295  */
1296 static void batadv_tp_ack_unordered(struct batadv_tp_vars *tp_vars)
1297 {
1298         struct batadv_tp_unacked *un, *safe;
1299         u32 to_ack;
1300 
1301         /* go through the unacked packet list and possibly ACK them as
1302          * well
1303          */
1304         spin_lock_bh(&tp_vars->unacked_lock);
1305         list_for_each_entry_safe(un, safe, &tp_vars->unacked_list, list) {
1306                 /* the list is ordered, therefore it is possible to stop as soon
1307                  * there is a gap between the last acked seqno and the seqno of
1308                  * the packet under inspection
1309                  */
1310                 if (batadv_seq_before(tp_vars->last_recv, un->seqno))
1311                         break;
1312 
1313                 to_ack = un->seqno + un->len - tp_vars->last_recv;
1314 
1315                 if (batadv_seq_before(tp_vars->last_recv, un->seqno + un->len))
1316                         tp_vars->last_recv += to_ack;
1317 
1318                 list_del(&un->list);
1319                 kfree(un);
1320         }
1321         spin_unlock_bh(&tp_vars->unacked_lock);
1322 }
1323 
1324 /**
1325  * batadv_tp_init_recv() - return matching or create new receiver tp_vars
1326  * @bat_priv: the bat priv with all the soft interface information
1327  * @icmp: received icmp tp msg
1328  *
1329  * Return: corresponding tp_vars or NULL on errors
1330  */
1331 static struct batadv_tp_vars *
1332 batadv_tp_init_recv(struct batadv_priv *bat_priv,
1333                     const struct batadv_icmp_tp_packet *icmp)
1334 {
1335         struct batadv_tp_vars *tp_vars;
1336 
1337         spin_lock_bh(&bat_priv->tp_list_lock);
1338         tp_vars = batadv_tp_list_find_session(bat_priv, icmp->orig,
1339                                               icmp->session);
1340         if (tp_vars)
1341                 goto out_unlock;
1342 
1343         if (!atomic_add_unless(&bat_priv->tp_num, 1, BATADV_TP_MAX_NUM)) {
1344                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1345                            "Meter: too many ongoing sessions, aborting (RECV)\n");
1346                 goto out_unlock;
1347         }
1348 
1349         tp_vars = kmalloc(sizeof(*tp_vars), GFP_ATOMIC);
1350         if (!tp_vars)
1351                 goto out_unlock;
1352 
1353         ether_addr_copy(tp_vars->other_end, icmp->orig);
1354         tp_vars->role = BATADV_TP_RECEIVER;
1355         memcpy(tp_vars->session, icmp->session, sizeof(tp_vars->session));
1356         tp_vars->last_recv = BATADV_TP_FIRST_SEQ;
1357         tp_vars->bat_priv = bat_priv;
1358         kref_init(&tp_vars->refcount);
1359 
1360         spin_lock_init(&tp_vars->unacked_lock);
1361         INIT_LIST_HEAD(&tp_vars->unacked_list);
1362 
1363         kref_get(&tp_vars->refcount);
1364         hlist_add_head_rcu(&tp_vars->list, &bat_priv->tp_list);
1365 
1366         kref_get(&tp_vars->refcount);
1367         timer_setup(&tp_vars->timer, batadv_tp_receiver_shutdown, 0);
1368 
1369         batadv_tp_reset_receiver_timer(tp_vars);
1370 
1371 out_unlock:
1372         spin_unlock_bh(&bat_priv->tp_list_lock);
1373 
1374         return tp_vars;
1375 }
1376 
1377 /**
1378  * batadv_tp_recv_msg() - process a single data message
1379  * @bat_priv: the bat priv with all the soft interface information
1380  * @skb: the buffer containing the received packet
1381  *
1382  * Process a received TP MSG packet
1383  */
1384 static void batadv_tp_recv_msg(struct batadv_priv *bat_priv,
1385                                const struct sk_buff *skb)
1386 {
1387         const struct batadv_icmp_tp_packet *icmp;
1388         struct batadv_tp_vars *tp_vars;
1389         size_t packet_size;
1390         u32 seqno;
1391 
1392         icmp = (struct batadv_icmp_tp_packet *)skb->data;
1393 
1394         seqno = ntohl(icmp->seqno);
1395         /* check if this is the first seqno. This means that if the
1396          * first packet is lost, the tp meter does not work anymore!
1397          */
1398         if (seqno == BATADV_TP_FIRST_SEQ) {
1399                 tp_vars = batadv_tp_init_recv(bat_priv, icmp);
1400                 if (!tp_vars) {
1401                         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1402                                    "Meter: seqno != BATADV_TP_FIRST_SEQ cannot initiate connection\n");
1403                         goto out;
1404                 }
1405         } else {
1406                 tp_vars = batadv_tp_list_find_session(bat_priv, icmp->orig,
1407                                                       icmp->session);
1408                 if (!tp_vars) {
1409                         batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1410                                    "Unexpected packet from %pM!\n",
1411                                    icmp->orig);
1412                         goto out;
1413                 }
1414         }
1415 
1416         if (unlikely(tp_vars->role != BATADV_TP_RECEIVER)) {
1417                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1418                            "Meter: dropping packet: not expected (role=%u)\n",
1419                            tp_vars->role);
1420                 goto out;
1421         }
1422 
1423         tp_vars->last_recv_time = jiffies;
1424 
1425         /* if the packet is a duplicate, it may be the case that an ACK has been
1426          * lost. Resend the ACK
1427          */
1428         if (batadv_seq_before(seqno, tp_vars->last_recv))
1429                 goto send_ack;
1430 
1431         /* if the packet is out of order enqueue it */
1432         if (ntohl(icmp->seqno) != tp_vars->last_recv) {
1433                 /* exit immediately (and do not send any ACK) if the packet has
1434                  * not been enqueued correctly
1435                  */
1436                 if (!batadv_tp_handle_out_of_order(tp_vars, skb))
1437                         goto out;
1438 
1439                 /* send a duplicate ACK */
1440                 goto send_ack;
1441         }
1442 
1443         /* if everything was fine count the ACKed bytes */
1444         packet_size = skb->len - sizeof(struct batadv_unicast_packet);
1445         tp_vars->last_recv += packet_size;
1446 
1447         /* check if this ordered message filled a gap.... */
1448         batadv_tp_ack_unordered(tp_vars);
1449 
1450 send_ack:
1451         /* send the ACK. If the received packet was out of order, the ACK that
1452          * is going to be sent is a duplicate (the sender will count them and
1453          * possibly enter Fast Retransmit as soon as it has reached 3)
1454          */
1455         batadv_tp_send_ack(bat_priv, icmp->orig, tp_vars->last_recv,
1456                            icmp->timestamp, icmp->session, icmp->uid);
1457 out:
1458         if (likely(tp_vars))
1459                 batadv_tp_vars_put(tp_vars);
1460 }
1461 
1462 /**
1463  * batadv_tp_meter_recv() - main TP Meter receiving function
1464  * @bat_priv: the bat priv with all the soft interface information
1465  * @skb: the buffer containing the received packet
1466  */
1467 void batadv_tp_meter_recv(struct batadv_priv *bat_priv, struct sk_buff *skb)
1468 {
1469         struct batadv_icmp_tp_packet *icmp;
1470 
1471         icmp = (struct batadv_icmp_tp_packet *)skb->data;
1472 
1473         switch (icmp->subtype) {
1474         case BATADV_TP_MSG:
1475                 batadv_tp_recv_msg(bat_priv, skb);
1476                 break;
1477         case BATADV_TP_ACK:
1478                 batadv_tp_recv_ack(bat_priv, skb);
1479                 break;
1480         default:
1481                 batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
1482                            "Received unknown TP Metric packet type %u\n",
1483                            icmp->subtype);
1484         }
1485         consume_skb(skb);
1486 }
1487 
1488 /**
1489  * batadv_tp_meter_init() - initialize global tp_meter structures
1490  */
1491 void __init batadv_tp_meter_init(void)
1492 {
1493         get_random_bytes(batadv_tp_prerandom, sizeof(batadv_tp_prerandom));
1494 }