net/mac80211/mesh_hwmp.c

   1 /*
   2  * Copyright (c) 2008, 2009 open80211s Ltd.
   3  * Author:     Luis Carlos Cobo <luisca@cozybit.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/slab.h>
  11 #include <linux/etherdevice.h>
  12 #include <asm/unaligned.h>
  13 #include "wme.h"
  14 #include "mesh.h"
  15
  16 #define TEST_FRAME_LEN  8192
  17 #define MAX_METRIC      0xffffffff
  18 #define ARITH_SHIFT     8
  19
  20 #define MAX_PREQ_QUEUE_LEN      64
  21
  22 static void mesh_queue_preq(struct mesh_path *, u8);
  23
  24 static inline u32 u32_field_get(const u8 *preq_elem, int offset, bool ae)
  25 {
  26         if (ae)
  27                 offset += 6;
  28         return get_unaligned_le32(preq_elem + offset);
  29 }
  30
  31 static inline u16 u16_field_get(const u8 *preq_elem, int offset, bool ae)
  32 {
  33         if (ae)
  34                 offset += 6;
  35         return get_unaligned_le16(preq_elem + offset);
  36 }
  37
  38 /* HWMP IE processing macros */
  39 #define AE_F                    (1<<6)
  40 #define AE_F_SET(x)             (*x & AE_F)
  41 #define PREQ_IE_FLAGS(x)        (*(x))
  42 #define PREQ_IE_HOPCOUNT(x)     (*(x + 1))
  43 #define PREQ_IE_TTL(x)          (*(x + 2))
  44 #define PREQ_IE_PREQ_ID(x)      u32_field_get(x, 3, 0)
  45 #define PREQ_IE_ORIG_ADDR(x)    (x + 7)
  46 #define PREQ_IE_ORIG_SN(x)      u32_field_get(x, 13, 0)
  47 #define PREQ_IE_LIFETIME(x)     u32_field_get(x, 17, AE_F_SET(x))
  48 #define PREQ_IE_METRIC(x)       u32_field_get(x, 21, AE_F_SET(x))
  49 #define PREQ_IE_TARGET_F(x)     (*(AE_F_SET(x) ? x + 32 : x + 26))
  50 #define PREQ_IE_TARGET_ADDR(x)  (AE_F_SET(x) ? x + 33 : x + 27)
  51 #define PREQ_IE_TARGET_SN(x)    u32_field_get(x, 33, AE_F_SET(x))
  52
  53
  54 #define PREP_IE_FLAGS(x)        PREQ_IE_FLAGS(x)
  55 #define PREP_IE_HOPCOUNT(x)     PREQ_IE_HOPCOUNT(x)
  56 #define PREP_IE_TTL(x)          PREQ_IE_TTL(x)
  57 #define PREP_IE_ORIG_ADDR(x)    (AE_F_SET(x) ? x + 27 : x + 21)
  58 #define PREP_IE_ORIG_SN(x)      u32_field_get(x, 27, AE_F_SET(x))
  59 #define PREP_IE_LIFETIME(x)     u32_field_get(x, 13, AE_F_SET(x))
  60 #define PREP_IE_METRIC(x)       u32_field_get(x, 17, AE_F_SET(x))
  61 #define PREP_IE_TARGET_ADDR(x)  (x + 3)
  62 #define PREP_IE_TARGET_SN(x)    u32_field_get(x, 9, 0)
  63
  64 #define PERR_IE_TTL(x)          (*(x))
  65 #define PERR_IE_TARGET_FLAGS(x) (*(x + 2))
  66 #define PERR_IE_TARGET_ADDR(x)  (x + 3)
  67 #define PERR_IE_TARGET_SN(x)    u32_field_get(x, 9, 0)
  68 #define PERR_IE_TARGET_RCODE(x) u16_field_get(x, 13, 0)
  69
  70 #define MSEC_TO_TU(x) (x*1000/1024)
  71 #define SN_GT(x, y) ((s32)(y - x) < 0)
  72 #define SN_LT(x, y) ((s32)(x - y) < 0)
  73 #define MAX_SANE_SN_DELTA 32
  74
  75 static inline u32 SN_DELTA(u32 x, u32 y)
  76 {
  77         return x >= y ? x - y : y - x;
  78 }
  79
  80 #define net_traversal_jiffies(s) \
  81         msecs_to_jiffies(s->u.mesh.mshcfg.dot11MeshHWMPnetDiameterTraversalTime)
  82 #define default_lifetime(s) \
  83         MSEC_TO_TU(s->u.mesh.mshcfg.dot11MeshHWMPactivePathTimeout)
  84 #define min_preq_int_jiff(s) \
  85         (msecs_to_jiffies(s->u.mesh.mshcfg.dot11MeshHWMPpreqMinInterval))
  86 #define max_preq_retries(s) (s->u.mesh.mshcfg.dot11MeshHWMPmaxPREQretries)
  87 #define disc_timeout_jiff(s) \
  88         msecs_to_jiffies(sdata->u.mesh.mshcfg.min_discovery_timeout)
  89 #define root_path_confirmation_jiffies(s) \
  90         msecs_to_jiffies(sdata->u.mesh.mshcfg.dot11MeshHWMPconfirmationInterval)
  91
  92 enum mpath_frame_type {
  93         MPATH_PREQ = 0,
  94         MPATH_PREP,
  95         MPATH_PERR,
  96         MPATH_RANN
  97 };
  98
  99 static const u8 broadcast_addr[ETH_ALEN] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
 100
 101 static int mesh_path_sel_frame_tx(enum mpath_frame_type action, u8 flags,
 102                                   const u8 *orig_addr, u32 orig_sn,
 103                                   u8 target_flags, const u8 *target,
 104                                   u32 target_sn, const u8 *da,
 105                                   u8 hop_count, u8 ttl,
 106                                   u32 lifetime, u32 metric, u32 preq_id,
 107                                   struct ieee80211_sub_if_data *sdata)
 108 {
 109         struct ieee80211_local *local = sdata->local;
 110         struct sk_buff *skb;
 111         struct ieee80211_mgmt *mgmt;
 112         u8 *pos, ie_len;
 113         int hdr_len = offsetof(struct ieee80211_mgmt, u.action.u.mesh_action) +
 114                       sizeof(mgmt->u.action.u.mesh_action);
 115
 116         skb = dev_alloc_skb(local->tx_headroom +
 117                             hdr_len +
 118                             2 + 37); /* max HWMP IE */
 119         if (!skb)
 120                 return -1;
 121         skb_reserve(skb, local->tx_headroom);
 122         mgmt = (struct ieee80211_mgmt *) skb_put(skb, hdr_len);
 123         memset(mgmt, 0, hdr_len);
 124         mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
 125                                           IEEE80211_STYPE_ACTION);
 126
 127         memcpy(mgmt->da, da, ETH_ALEN);
 128         memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
 129         /* BSSID == SA */
 130         memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
 131         mgmt->u.action.category = WLAN_CATEGORY_MESH_ACTION;
 132         mgmt->u.action.u.mesh_action.action_code =
 133                                         WLAN_MESH_ACTION_HWMP_PATH_SELECTION;
 134
 135         switch (action) {
 136         case MPATH_PREQ:
 137                 mhwmp_dbg(sdata, "sending PREQ to %pM\n", target);
 138                 ie_len = 37;
 139                 pos = skb_put(skb, 2 + ie_len);
 140                 *pos++ = WLAN_EID_PREQ;
 141                 break;
 142         case MPATH_PREP:
 143                 mhwmp_dbg(sdata, "sending PREP to %pM\n", orig_addr);
 144                 ie_len = 31;
 145                 pos = skb_put(skb, 2 + ie_len);
 146                 *pos++ = WLAN_EID_PREP;
 147                 break;
 148         case MPATH_RANN:
 149                 mhwmp_dbg(sdata, "sending RANN from %pM\n", orig_addr);
 150                 ie_len = sizeof(struct ieee80211_rann_ie);
 151                 pos = skb_put(skb, 2 + ie_len);
 152                 *pos++ = WLAN_EID_RANN;
 153                 break;
 154         default:
 155                 kfree_skb(skb);
 156                 return -ENOTSUPP;
 157         }
 158         *pos++ = ie_len;
 159         *pos++ = flags;
 160         *pos++ = hop_count;
 161         *pos++ = ttl;
 162         if (action == MPATH_PREP) {
 163                 memcpy(pos, target, ETH_ALEN);
 164                 pos += ETH_ALEN;
 165                 put_unaligned_le32(target_sn, pos);
 166                 pos += 4;
 167         } else {
 168                 if (action == MPATH_PREQ) {
 169                         put_unaligned_le32(preq_id, pos);
 170                         pos += 4;
 171                 }
 172                 memcpy(pos, orig_addr, ETH_ALEN);
 173                 pos += ETH_ALEN;
 174                 put_unaligned_le32(orig_sn, pos);
 175                 pos += 4;
 176         }
 177         put_unaligned_le32(lifetime, pos); /* interval for RANN */
 178         pos += 4;
 179         put_unaligned_le32(metric, pos);
 180         pos += 4;
 181         if (action == MPATH_PREQ) {
 182                 *pos++ = 1; /* destination count */
 183                 *pos++ = target_flags;
 184                 memcpy(pos, target, ETH_ALEN);
 185                 pos += ETH_ALEN;
 186                 put_unaligned_le32(target_sn, pos);
 187                 pos += 4;
 188         } else if (action == MPATH_PREP) {
 189                 memcpy(pos, orig_addr, ETH_ALEN);
 190                 pos += ETH_ALEN;
 191                 put_unaligned_le32(orig_sn, pos);
 192                 pos += 4;
 193         }
 194
 195         ieee80211_tx_skb(sdata, skb);
 196         return 0;
 197 }
 198
 199
 200 /*  Headroom is not adjusted.  Caller should ensure that skb has sufficient
 201  *  headroom in case the frame is encrypted. */
 202 static void prepare_frame_for_deferred_tx(struct ieee80211_sub_if_data *sdata,
 203                 struct sk_buff *skb)
 204 {
 205         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 206         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 207
 208         skb_reset_mac_header(skb);
 209         skb_reset_network_header(skb);
 210         skb_reset_transport_header(skb);
 211
 212         /* Send all internal mgmt frames on VO. Accordingly set TID to 7. */
 213         skb_set_queue_mapping(skb, IEEE80211_AC_VO);
 214         skb->priority = 7;
 215
 216         info->control.vif = &sdata->vif;
 217         info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;
 218         ieee80211_set_qos_hdr(sdata, skb);
 219         ieee80211_mps_set_frame_flags(sdata, NULL, hdr);
 220 }
 221
 222 /**
 223  * mesh_path_error_tx - Sends a PERR mesh management frame
 224  *
 225  * @ttl: allowed remaining hops
 226  * @target: broken destination
 227  * @target_sn: SN of the broken destination
 228  * @target_rcode: reason code for this PERR
 229  * @ra: node this frame is addressed to
 230  * @sdata: local mesh subif
 231  *
 232  * Note: This function may be called with driver locks taken that the driver
 233  * also acquires in the TX path.  To avoid a deadlock we don't transmit the
 234  * frame directly but add it to the pending queue instead.
 235  */
 236 int mesh_path_error_tx(struct ieee80211_sub_if_data *sdata,
 237                        u8 ttl, const u8 *target, u32 target_sn,
 238                        u16 target_rcode, const u8 *ra)
 239 {
 240         struct ieee80211_local *local = sdata->local;
 241         struct sk_buff *skb;
 242         struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
 243         struct ieee80211_mgmt *mgmt;
 244         u8 *pos, ie_len;
 245         int hdr_len = offsetof(struct ieee80211_mgmt, u.action.u.mesh_action) +
 246                       sizeof(mgmt->u.action.u.mesh_action);
 247
 248         if (time_before(jiffies, ifmsh->next_perr))
 249                 return -EAGAIN;
 250
 251         skb = dev_alloc_skb(local->tx_headroom +
 252                             sdata->encrypt_headroom +
 253                             IEEE80211_ENCRYPT_TAILROOM +
 254                             hdr_len +
 255                             2 + 15 /* PERR IE */);
 256         if (!skb)
 257                 return -1;
 258         skb_reserve(skb, local->tx_headroom + sdata->encrypt_headroom);
 259         mgmt = (struct ieee80211_mgmt *) skb_put(skb, hdr_len);
 260         memset(mgmt, 0, hdr_len);
 261         mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
 262                                           IEEE80211_STYPE_ACTION);
 263
 264         memcpy(mgmt->da, ra, ETH_ALEN);
 265         memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
 266         /* BSSID == SA */
 267         memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
 268         mgmt->u.action.category = WLAN_CATEGORY_MESH_ACTION;
 269         mgmt->u.action.u.mesh_action.action_code =
 270                                         WLAN_MESH_ACTION_HWMP_PATH_SELECTION;
 271         ie_len = 15;
 272         pos = skb_put(skb, 2 + ie_len);
 273         *pos++ = WLAN_EID_PERR;
 274         *pos++ = ie_len;
 275         /* ttl */
 276         *pos++ = ttl;
 277         /* number of destinations */
 278         *pos++ = 1;
 279         /* Flags field has AE bit only as defined in
 280          * sec 8.4.2.117 IEEE802.11-2012
 281          */
 282         *pos = 0;
 283         pos++;
 284         memcpy(pos, target, ETH_ALEN);
 285         pos += ETH_ALEN;
 286         put_unaligned_le32(target_sn, pos);
 287         pos += 4;
 288         put_unaligned_le16(target_rcode, pos);
 289
 290         /* see note in function header */
 291         prepare_frame_for_deferred_tx(sdata, skb);
 292         ifmsh->next_perr = TU_TO_EXP_TIME(
 293                                    ifmsh->mshcfg.dot11MeshHWMPperrMinInterval);
 294         ieee80211_add_pending_skb(local, skb);
 295         return 0;
 296 }
 297
 298 void ieee80211s_update_metric(struct ieee80211_local *local,
 299                 struct sta_info *sta, struct sk_buff *skb)
 300 {
 301         struct ieee80211_tx_info *txinfo = IEEE80211_SKB_CB(skb);
 302         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 303         int failed;
 304
 305         if (!ieee80211_is_data(hdr->frame_control))
 306                 return;
 307
 308         failed = !(txinfo->flags & IEEE80211_TX_STAT_ACK);
 309
 310         /* moving average, scaled to 100 */
 311         sta->mesh->fail_avg =
 312                 ((80 * sta->mesh->fail_avg + 5) / 100 + 20 * failed);
 313         if (sta->mesh->fail_avg > 95)
 314                 mesh_plink_broken(sta);
 315 }
 316
 317 static u32 airtime_link_metric_get(struct ieee80211_local *local,
 318                                    struct sta_info *sta)
 319 {
 320         struct rate_info rinfo;
 321         /* This should be adjusted for each device */
 322         int device_constant = 1 << ARITH_SHIFT;
 323         int test_frame_len = TEST_FRAME_LEN << ARITH_SHIFT;
 324         int s_unit = 1 << ARITH_SHIFT;
 325         int rate, err;
 326         u32 tx_time, estimated_retx;
 327         u64 result;
 328
 329         /* Try to get rate based on HW/SW RC algorithm.
 330          * Rate is returned in units of Kbps, correct this
 331          * to comply with airtime calculation units
 332          * Round up in case we get rate < 100Kbps
 333          */
 334         rate = DIV_ROUND_UP(sta_get_expected_throughput(sta), 100);
 335
 336         if (rate) {
 337                 err = 0;
 338         } else {
 339                 if (sta->mesh->fail_avg >= 100)
 340                         return MAX_METRIC;
 341
 342                 sta_set_rate_info_tx(sta, &sta->tx_stats.last_rate, &rinfo);
 343                 rate = cfg80211_calculate_bitrate(&rinfo);
 344                 if (WARN_ON(!rate))
 345                         return MAX_METRIC;
 346
 347                 err = (sta->mesh->fail_avg << ARITH_SHIFT) / 100;
 348         }
 349
 350         /* bitrate is in units of 100 Kbps, while we need rate in units of
 351          * 1Mbps. This will be corrected on tx_time computation.
 352          */
 353         tx_time = (device_constant + 10 * test_frame_len / rate);
 354         estimated_retx = ((1 << (2 * ARITH_SHIFT)) / (s_unit - err));
 355         result = (tx_time * estimated_retx) >> (2 * ARITH_SHIFT);
 356         return (u32)result;
 357 }
 358
 359 /**
 360  * hwmp_route_info_get - Update routing info to originator and transmitter
 361  *
 362  * @sdata: local mesh subif
 363  * @mgmt: mesh management frame
 364  * @hwmp_ie: hwmp information element (PREP or PREQ)
 365  * @action: type of hwmp ie
 366  *
 367  * This function updates the path routing information to the originator and the
 368  * transmitter of a HWMP PREQ or PREP frame.
 369  *
 370  * Returns: metric to frame originator or 0 if the frame should not be further
 371  * processed
 372  *
 373  * Notes: this function is the only place (besides user-provided info) where
 374  * path routing information is updated.
 375  */
 376 static u32 hwmp_route_info_get(struct ieee80211_sub_if_data *sdata,
 377                                struct ieee80211_mgmt *mgmt,
 378                                const u8 *hwmp_ie, enum mpath_frame_type action)
 379 {
 380         struct ieee80211_local *local = sdata->local;
 381         struct mesh_path *mpath;
 382         struct sta_info *sta;
 383         bool fresh_info;
 384         const u8 *orig_addr, *ta;
 385         u32 orig_sn, orig_metric;
 386         unsigned long orig_lifetime, exp_time;
 387         u32 last_hop_metric, new_metric;
 388         bool process = true;
 389
 390         rcu_read_lock();
 391         sta = sta_info_get(sdata, mgmt->sa);
 392         if (!sta) {
 393                 rcu_read_unlock();
 394                 return 0;
 395         }
 396
 397         last_hop_metric = airtime_link_metric_get(local, sta);
 398         /* Update and check originator routing info */
 399         fresh_info = true;
 400
 401         switch (action) {
 402         case MPATH_PREQ:
 403                 orig_addr = PREQ_IE_ORIG_ADDR(hwmp_ie);
 404                 orig_sn = PREQ_IE_ORIG_SN(hwmp_ie);
 405                 orig_lifetime = PREQ_IE_LIFETIME(hwmp_ie);
 406                 orig_metric = PREQ_IE_METRIC(hwmp_ie);
 407                 break;
 408         case MPATH_PREP:
 409                 /* Originator here refers to the MP that was the target in the
 410                  * Path Request. We divert from the nomenclature in the draft
 411                  * so that we can easily use a single function to gather path
 412                  * information from both PREQ and PREP frames.
 413                  */
 414                 orig_addr = PREP_IE_TARGET_ADDR(hwmp_ie);
 415                 orig_sn = PREP_IE_TARGET_SN(hwmp_ie);
 416                 orig_lifetime = PREP_IE_LIFETIME(hwmp_ie);
 417                 orig_metric = PREP_IE_METRIC(hwmp_ie);
 418                 break;
 419         default:
 420                 rcu_read_unlock();
 421                 return 0;
 422         }
 423         new_metric = orig_metric + last_hop_metric;
 424         if (new_metric < orig_metric)
 425                 new_metric = MAX_METRIC;
 426         exp_time = TU_TO_EXP_TIME(orig_lifetime);
 427
 428         if (ether_addr_equal(orig_addr, sdata->vif.addr)) {
 429                 /* This MP is the originator, we are not interested in this
 430                  * frame, except for updating transmitter's path info.
 431                  */
 432                 process = false;
 433                 fresh_info = false;
 434         } else {
 435                 mpath = mesh_path_lookup(sdata, orig_addr);
 436                 if (mpath) {
 437                         spin_lock_bh(&mpath->state_lock);
 438                         if (mpath->flags & MESH_PATH_FIXED)
 439                                 fresh_info = false;
 440                         else if ((mpath->flags & MESH_PATH_ACTIVE) &&
 441                             (mpath->flags & MESH_PATH_SN_VALID)) {
 442                                 if (SN_GT(mpath->sn, orig_sn) ||
 443                                     (mpath->sn == orig_sn &&
 444                                      new_metric >= mpath->metric)) {
 445                                         process = false;
 446                                         fresh_info = false;
 447                                 }
 448                         } else if (!(mpath->flags & MESH_PATH_ACTIVE)) {
 449                                 bool have_sn, newer_sn, bounced;
 450
 451                                 have_sn = mpath->flags & MESH_PATH_SN_VALID;
 452                                 newer_sn = have_sn && SN_GT(orig_sn, mpath->sn);
 453                                 bounced = have_sn &&
 454                                           (SN_DELTA(orig_sn, mpath->sn) >
 455                                                         MAX_SANE_SN_DELTA);
 456
 457                                 if (!have_sn || newer_sn) {
 458                                         /* if SN is newer than what we had
 459                                          * then we can take it */;
 460                                 } else if (bounced) {
 461                                         /* if SN is way different than what
 462                                          * we had then assume the other side
 463                                          * rebooted or restarted */;
 464                                 } else {
 465                                         process = false;
 466                                         fresh_info = false;
 467                                 }
 468                         }
 469                 } else {
 470                         mpath = mesh_path_add(sdata, orig_addr);
 471                         if (IS_ERR(mpath)) {
 472                                 rcu_read_unlock();
 473                                 return 0;
 474                         }
 475                         spin_lock_bh(&mpath->state_lock);
 476                 }
 477
 478                 if (fresh_info) {
 479                         mesh_path_assign_nexthop(mpath, sta);
 480                         mpath->flags |= MESH_PATH_SN_VALID;
 481                         mpath->metric = new_metric;
 482                         mpath->sn = orig_sn;
 483                         mpath->exp_time = time_after(mpath->exp_time, exp_time)
 484                                           ?  mpath->exp_time : exp_time;
 485                         mesh_path_activate(mpath);
 486                         spin_unlock_bh(&mpath->state_lock);
 487                         mesh_path_tx_pending(mpath);
 488                         /* draft says preq_id should be saved to, but there does
 489                          * not seem to be any use for it, skipping by now
 490                          */
 491                 } else
 492                         spin_unlock_bh(&mpath->state_lock);
 493         }
 494
 495         /* Update and check transmitter routing info */
 496         ta = mgmt->sa;
 497         if (ether_addr_equal(orig_addr, ta))
 498                 fresh_info = false;
 499         else {
 500                 fresh_info = true;
 501
 502                 mpath = mesh_path_lookup(sdata, ta);
 503                 if (mpath) {
 504                         spin_lock_bh(&mpath->state_lock);
 505                         if ((mpath->flags & MESH_PATH_FIXED) ||
 506                                 ((mpath->flags & MESH_PATH_ACTIVE) &&
 507                                         (last_hop_metric > mpath->metric)))
 508                                 fresh_info = false;
 509                 } else {
 510                         mpath = mesh_path_add(sdata, ta);
 511                         if (IS_ERR(mpath)) {
 512                                 rcu_read_unlock();
 513                                 return 0;
 514                         }
 515                         spin_lock_bh(&mpath->state_lock);
 516                 }
 517
 518                 if (fresh_info) {
 519                         mesh_path_assign_nexthop(mpath, sta);
 520                         mpath->metric = last_hop_metric;
 521                         mpath->exp_time = time_after(mpath->exp_time, exp_time)
 522                                           ?  mpath->exp_time : exp_time;
 523                         mesh_path_activate(mpath);
 524                         spin_unlock_bh(&mpath->state_lock);
 525                         mesh_path_tx_pending(mpath);
 526                 } else
 527                         spin_unlock_bh(&mpath->state_lock);
 528         }
 529
 530         rcu_read_unlock();
 531
 532         return process ? new_metric : 0;
 533 }
 534
 535 static void hwmp_preq_frame_process(struct ieee80211_sub_if_data *sdata,
 536                                     struct ieee80211_mgmt *mgmt,
 537                                     const u8 *preq_elem, u32 orig_metric)
 538 {
 539         struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
 540         struct mesh_path *mpath = NULL;
 541         const u8 *target_addr, *orig_addr;
 542         const u8 *da;
 543         u8 target_flags, ttl, flags;
 544         u32 orig_sn, target_sn, lifetime, target_metric = 0;
 545         bool reply = false;
 546         bool forward = true;
 547         bool root_is_gate;
 548
 549         /* Update target SN, if present */
 550         target_addr = PREQ_IE_TARGET_ADDR(preq_elem);
 551         orig_addr = PREQ_IE_ORIG_ADDR(preq_elem);
 552         target_sn = PREQ_IE_TARGET_SN(preq_elem);
 553         orig_sn = PREQ_IE_ORIG_SN(preq_elem);
 554         target_flags = PREQ_IE_TARGET_F(preq_elem);
 555         /* Proactive PREQ gate announcements */
 556         flags = PREQ_IE_FLAGS(preq_elem);
 557         root_is_gate = !!(flags & RANN_FLAG_IS_GATE);
 558
 559         mhwmp_dbg(sdata, "received PREQ from %pM\n", orig_addr);
 560
 561         if (ether_addr_equal(target_addr, sdata->vif.addr)) {
 562                 mhwmp_dbg(sdata, "PREQ is for us\n");
 563                 forward = false;
 564                 reply = true;
 565                 target_metric = 0;
 566                 if (time_after(jiffies, ifmsh->last_sn_update +
 567                                         net_traversal_jiffies(sdata)) ||
 568                     time_before(jiffies, ifmsh->last_sn_update)) {
 569                         ++ifmsh->sn;
 570                         ifmsh->last_sn_update = jiffies;
 571                 }
 572                 target_sn = ifmsh->sn;
 573         } else if (is_broadcast_ether_addr(target_addr) &&
 574                    (target_flags & IEEE80211_PREQ_TO_FLAG)) {
 575                 rcu_read_lock();
 576                 mpath = mesh_path_lookup(sdata, orig_addr);
 577                 if (mpath) {
 578                         if (flags & IEEE80211_PREQ_PROACTIVE_PREP_FLAG) {
 579                                 reply = true;
 580                                 target_addr = sdata->vif.addr;
 581                                 target_sn = ++ifmsh->sn;
 582                                 target_metric = 0;
 583                                 ifmsh->last_sn_update = jiffies;
 584                         }
 585                         if (root_is_gate)
 586                                 mesh_path_add_gate(mpath);
 587                 }
 588                 rcu_read_unlock();
 589         } else {
 590                 rcu_read_lock();
 591                 mpath = mesh_path_lookup(sdata, target_addr);
 592                 if (mpath) {
 593                         if ((!(mpath->flags & MESH_PATH_SN_VALID)) ||
 594                                         SN_LT(mpath->sn, target_sn)) {
 595                                 mpath->sn = target_sn;
 596                                 mpath->flags |= MESH_PATH_SN_VALID;
 597                         } else if ((!(target_flags & IEEE80211_PREQ_TO_FLAG)) &&
 598                                         (mpath->flags & MESH_PATH_ACTIVE)) {
 599                                 reply = true;
 600                                 target_metric = mpath->metric;
 601                                 target_sn = mpath->sn;
 602                                 /* Case E2 of sec 13.10.9.3 IEEE 802.11-2012*/
 603                                 target_flags |= IEEE80211_PREQ_TO_FLAG;
 604                         }
 605                 }
 606                 rcu_read_unlock();
 607         }
 608
 609         if (reply) {
 610                 lifetime = PREQ_IE_LIFETIME(preq_elem);
 611                 ttl = ifmsh->mshcfg.element_ttl;
 612                 if (ttl != 0) {
 613                         mhwmp_dbg(sdata, "replying to the PREQ\n");
 614                         mesh_path_sel_frame_tx(MPATH_PREP, 0, orig_addr,
 615                                                orig_sn, 0, target_addr,
 616                                                target_sn, mgmt->sa, 0, ttl,
 617                                                lifetime, target_metric, 0,
 618                                                sdata);
 619                 } else {
 620                         ifmsh->mshstats.dropped_frames_ttl++;
 621                 }
 622         }
 623
 624         if (forward && ifmsh->mshcfg.dot11MeshForwarding) {
 625                 u32 preq_id;
 626                 u8 hopcount;
 627
 628                 ttl = PREQ_IE_TTL(preq_elem);
 629                 lifetime = PREQ_IE_LIFETIME(preq_elem);
 630                 if (ttl <= 1) {
 631                         ifmsh->mshstats.dropped_frames_ttl++;
 632                         return;
 633                 }
 634                 mhwmp_dbg(sdata, "forwarding the PREQ from %pM\n", orig_addr);
 635                 --ttl;
 636                 preq_id = PREQ_IE_PREQ_ID(preq_elem);
 637                 hopcount = PREQ_IE_HOPCOUNT(preq_elem) + 1;
 638                 da = (mpath && mpath->is_root) ?
 639                         mpath->rann_snd_addr : broadcast_addr;
 640
 641                 if (flags & IEEE80211_PREQ_PROACTIVE_PREP_FLAG) {
 642                         target_addr = PREQ_IE_TARGET_ADDR(preq_elem);
 643                         target_sn = PREQ_IE_TARGET_SN(preq_elem);
 644                 }
 645
 646                 mesh_path_sel_frame_tx(MPATH_PREQ, flags, orig_addr,
 647                                        orig_sn, target_flags, target_addr,
 648                                        target_sn, da, hopcount, ttl, lifetime,
 649                                        orig_metric, preq_id, sdata);
 650                 if (!is_multicast_ether_addr(da))
 651                         ifmsh->mshstats.fwded_unicast++;
 652                 else
 653                         ifmsh->mshstats.fwded_mcast++;
 654                 ifmsh->mshstats.fwded_frames++;
 655         }
 656 }
 657
 658
 659 static inline struct sta_info *
 660 next_hop_deref_protected(struct mesh_path *mpath)
 661 {
 662         return rcu_dereference_protected(mpath->next_hop,
 663                                          lockdep_is_held(&mpath->state_lock));
 664 }
 665
 666
 667 static void hwmp_prep_frame_process(struct ieee80211_sub_if_data *sdata,
 668                                     struct ieee80211_mgmt *mgmt,
 669                                     const u8 *prep_elem, u32 metric)
 670 {
 671         struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
 672         struct mesh_path *mpath;
 673         const u8 *target_addr, *orig_addr;
 674         u8 ttl, hopcount, flags;
 675         u8 next_hop[ETH_ALEN];
 676         u32 target_sn, orig_sn, lifetime;
 677
 678         mhwmp_dbg(sdata, "received PREP from %pM\n",
 679                   PREP_IE_TARGET_ADDR(prep_elem));
 680
 681         orig_addr = PREP_IE_ORIG_ADDR(prep_elem);
 682         if (ether_addr_equal(orig_addr, sdata->vif.addr))
 683                 /* destination, no forwarding required */
 684                 return;
 685
 686         if (!ifmsh->mshcfg.dot11MeshForwarding)
 687                 return;
 688
 689         ttl = PREP_IE_TTL(prep_elem);
 690         if (ttl <= 1) {
 691                 sdata->u.mesh.mshstats.dropped_frames_ttl++;
 692                 return;
 693         }
 694
 695         rcu_read_lock();
 696         mpath = mesh_path_lookup(sdata, orig_addr);
 697         if (mpath)
 698                 spin_lock_bh(&mpath->state_lock);
 699         else
 700                 goto fail;
 701         if (!(mpath->flags & MESH_PATH_ACTIVE)) {
 702                 spin_unlock_bh(&mpath->state_lock);
 703                 goto fail;
 704         }
 705         memcpy(next_hop, next_hop_deref_protected(mpath)->sta.addr, ETH_ALEN);
 706         spin_unlock_bh(&mpath->state_lock);
 707         --ttl;
 708         flags = PREP_IE_FLAGS(prep_elem);
 709         lifetime = PREP_IE_LIFETIME(prep_elem);
 710         hopcount = PREP_IE_HOPCOUNT(prep_elem) + 1;
 711         target_addr = PREP_IE_TARGET_ADDR(prep_elem);
 712         target_sn = PREP_IE_TARGET_SN(prep_elem);
 713         orig_sn = PREP_IE_ORIG_SN(prep_elem);
 714
 715         mesh_path_sel_frame_tx(MPATH_PREP, flags, orig_addr, orig_sn, 0,
 716                                target_addr, target_sn, next_hop, hopcount,
 717                                ttl, lifetime, metric, 0, sdata);
 718         rcu_read_unlock();
 719
 720         sdata->u.mesh.mshstats.fwded_unicast++;
 721         sdata->u.mesh.mshstats.fwded_frames++;
 722         return;
 723
 724 fail:
 725         rcu_read_unlock();
 726         sdata->u.mesh.mshstats.dropped_frames_no_route++;
 727 }
 728
 729 static void hwmp_perr_frame_process(struct ieee80211_sub_if_data *sdata,
 730                                     struct ieee80211_mgmt *mgmt,
 731                                     const u8 *perr_elem)
 732 {
 733         struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
 734         struct mesh_path *mpath;
 735         u8 ttl;
 736         const u8 *ta, *target_addr;
 737         u32 target_sn;
 738         u16 target_rcode;
 739
 740         ta = mgmt->sa;
 741         ttl = PERR_IE_TTL(perr_elem);
 742         if (ttl <= 1) {
 743                 ifmsh->mshstats.dropped_frames_ttl++;
 744                 return;
 745         }
 746         ttl--;
 747         target_addr = PERR_IE_TARGET_ADDR(perr_elem);
 748         target_sn = PERR_IE_TARGET_SN(perr_elem);
 749         target_rcode = PERR_IE_TARGET_RCODE(perr_elem);
 750
 751         rcu_read_lock();
 752         mpath = mesh_path_lookup(sdata, target_addr);
 753         if (mpath) {
 754                 struct sta_info *sta;
 755
 756                 spin_lock_bh(&mpath->state_lock);
 757                 sta = next_hop_deref_protected(mpath);
 758                 if (mpath->flags & MESH_PATH_ACTIVE &&
 759                     ether_addr_equal(ta, sta->sta.addr) &&
 760                     !(mpath->flags & MESH_PATH_FIXED) &&
 761                     (!(mpath->flags & MESH_PATH_SN_VALID) ||
 762                     SN_GT(target_sn, mpath->sn)  || target_sn == 0)) {
 763                         mpath->flags &= ~MESH_PATH_ACTIVE;
 764                         if (target_sn != 0)
 765                                 mpath->sn = target_sn;
 766                         else
 767                                 mpath->sn += 1;
 768                         spin_unlock_bh(&mpath->state_lock);
 769                         if (!ifmsh->mshcfg.dot11MeshForwarding)
 770                                 goto endperr;
 771                         mesh_path_error_tx(sdata, ttl, target_addr,
 772                                            target_sn, target_rcode,
 773                                            broadcast_addr);
 774                 } else
 775                         spin_unlock_bh(&mpath->state_lock);
 776         }
 777 endperr:
 778         rcu_read_unlock();
 779 }
 780
 781 static void hwmp_rann_frame_process(struct ieee80211_sub_if_data *sdata,
 782                                     struct ieee80211_mgmt *mgmt,
 783                                     const struct ieee80211_rann_ie *rann)
 784 {
 785         struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
 786         struct ieee80211_local *local = sdata->local;
 787         struct sta_info *sta;
 788         struct mesh_path *mpath;
 789         u8 ttl, flags, hopcount;
 790         const u8 *orig_addr;
 791         u32 orig_sn, metric, metric_txsta, interval;
 792         bool root_is_gate;
 793
 794         ttl = rann->rann_ttl;
 795         flags = rann->rann_flags;
 796         root_is_gate = !!(flags & RANN_FLAG_IS_GATE);
 797         orig_addr = rann->rann_addr;
 798         orig_sn = le32_to_cpu(rann->rann_seq);
 799         interval = le32_to_cpu(rann->rann_interval);
 800         hopcount = rann->rann_hopcount;
 801         hopcount++;
 802         metric = le32_to_cpu(rann->rann_metric);
 803
 804         /*  Ignore our own RANNs */
 805         if (ether_addr_equal(orig_addr, sdata->vif.addr))
 806                 return;
 807
 808         mhwmp_dbg(sdata,
 809                   "received RANN from %pM via neighbour %pM (is_gate=%d)\n",
 810                   orig_addr, mgmt->sa, root_is_gate);
 811
 812         rcu_read_lock();
 813         sta = sta_info_get(sdata, mgmt->sa);
 814         if (!sta) {
 815                 rcu_read_unlock();
 816                 return;
 817         }
 818
 819         metric_txsta = airtime_link_metric_get(local, sta);
 820
 821         mpath = mesh_path_lookup(sdata, orig_addr);
 822         if (!mpath) {
 823                 mpath = mesh_path_add(sdata, orig_addr);
 824                 if (IS_ERR(mpath)) {
 825                         rcu_read_unlock();
 826                         sdata->u.mesh.mshstats.dropped_frames_no_route++;
 827                         return;
 828                 }
 829         }
 830
 831         if (!(SN_LT(mpath->sn, orig_sn)) &&
 832             !(mpath->sn == orig_sn && metric < mpath->rann_metric)) {
 833                 rcu_read_unlock();
 834                 return;
 835         }
 836
 837         if ((!(mpath->flags & (MESH_PATH_ACTIVE | MESH_PATH_RESOLVING)) ||
 838              (time_after(jiffies, mpath->last_preq_to_root +
 839                                   root_path_confirmation_jiffies(sdata)) ||
 840              time_before(jiffies, mpath->last_preq_to_root))) &&
 841              !(mpath->flags & MESH_PATH_FIXED) && (ttl != 0)) {
 842                 mhwmp_dbg(sdata,
 843                           "time to refresh root mpath %pM\n",
 844                           orig_addr);
 845                 mesh_queue_preq(mpath, PREQ_Q_F_START | PREQ_Q_F_REFRESH);
 846                 mpath->last_preq_to_root = jiffies;
 847         }
 848
 849         mpath->sn = orig_sn;
 850         mpath->rann_metric = metric + metric_txsta;
 851         mpath->is_root = true;
 852         /* Recording RANNs sender address to send individually
 853          * addressed PREQs destined for root mesh STA */
 854         memcpy(mpath->rann_snd_addr, mgmt->sa, ETH_ALEN);
 855
 856         if (root_is_gate)
 857                 mesh_path_add_gate(mpath);
 858
 859         if (ttl <= 1) {
 860                 ifmsh->mshstats.dropped_frames_ttl++;
 861                 rcu_read_unlock();
 862                 return;
 863         }
 864         ttl--;
 865
 866         if (ifmsh->mshcfg.dot11MeshForwarding) {
 867                 mesh_path_sel_frame_tx(MPATH_RANN, flags, orig_addr,
 868                                        orig_sn, 0, NULL, 0, broadcast_addr,
 869                                        hopcount, ttl, interval,
 870                                        metric + metric_txsta, 0, sdata);
 871         }
 872
 873         rcu_read_unlock();
 874 }
 875
 876
 877 void mesh_rx_path_sel_frame(struct ieee80211_sub_if_data *sdata,
 878                             struct ieee80211_mgmt *mgmt, size_t len)
 879 {
 880         struct ieee802_11_elems elems;
 881         size_t baselen;
 882         u32 path_metric;
 883         struct sta_info *sta;
 884
 885         /* need action_code */
 886         if (len < IEEE80211_MIN_ACTION_SIZE + 1)
 887                 return;
 888
 889         rcu_read_lock();
 890         sta = sta_info_get(sdata, mgmt->sa);
 891         if (!sta || sta->mesh->plink_state != NL80211_PLINK_ESTAB) {
 892                 rcu_read_unlock();
 893                 return;
 894         }
 895         rcu_read_unlock();
 896
 897         baselen = (u8 *) mgmt->u.action.u.mesh_action.variable - (u8 *) mgmt;
 898         ieee802_11_parse_elems(mgmt->u.action.u.mesh_action.variable,
 899                                len - baselen, false, &elems);
 900
 901         if (elems.preq) {
 902                 if (elems.preq_len != 37)
 903                         /* Right now we support just 1 destination and no AE */
 904                         return;
 905                 path_metric = hwmp_route_info_get(sdata, mgmt, elems.preq,
 906                                                   MPATH_PREQ);
 907                 if (path_metric)
 908                         hwmp_preq_frame_process(sdata, mgmt, elems.preq,
 909                                                 path_metric);
 910         }
 911         if (elems.prep) {
 912                 if (elems.prep_len != 31)
 913                         /* Right now we support no AE */
 914                         return;
 915                 path_metric = hwmp_route_info_get(sdata, mgmt, elems.prep,
 916                                                   MPATH_PREP);
 917                 if (path_metric)
 918                         hwmp_prep_frame_process(sdata, mgmt, elems.prep,
 919                                                 path_metric);
 920         }
 921         if (elems.perr) {
 922                 if (elems.perr_len != 15)
 923                         /* Right now we support only one destination per PERR */
 924                         return;
 925                 hwmp_perr_frame_process(sdata, mgmt, elems.perr);
 926         }
 927         if (elems.rann)
 928                 hwmp_rann_frame_process(sdata, mgmt, elems.rann);
 929 }
 930
 931 /**
 932  * mesh_queue_preq - queue a PREQ to a given destination
 933  *
 934  * @mpath: mesh path to discover
 935  * @flags: special attributes of the PREQ to be sent
 936  *
 937  * Locking: the function must be called from within a rcu read lock block.
 938  *
 939  */
 940 static void mesh_queue_preq(struct mesh_path *mpath, u8 flags)
 941 {
 942         struct ieee80211_sub_if_data *sdata = mpath->sdata;
 943         struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
 944         struct mesh_preq_queue *preq_node;
 945
 946         preq_node = kmalloc(sizeof(struct mesh_preq_queue), GFP_ATOMIC);
 947         if (!preq_node) {
 948                 mhwmp_dbg(sdata, "could not allocate PREQ node\n");
 949                 return;
 950         }
 951
 952         spin_lock_bh(&ifmsh->mesh_preq_queue_lock);
 953         if (ifmsh->preq_queue_len == MAX_PREQ_QUEUE_LEN) {
 954                 spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
 955                 kfree(preq_node);
 956                 if (printk_ratelimit())
 957                         mhwmp_dbg(sdata, "PREQ node queue full\n");
 958                 return;
 959         }
 960
 961         spin_lock(&mpath->state_lock);
 962         if (mpath->flags & MESH_PATH_REQ_QUEUED) {
 963                 spin_unlock(&mpath->state_lock);
 964                 spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
 965                 kfree(preq_node);
 966                 return;
 967         }
 968
 969         memcpy(preq_node->dst, mpath->dst, ETH_ALEN);
 970         preq_node->flags = flags;
 971
 972         mpath->flags |= MESH_PATH_REQ_QUEUED;
 973         spin_unlock(&mpath->state_lock);
 974
 975         list_add_tail(&preq_node->list, &ifmsh->preq_queue.list);
 976         ++ifmsh->preq_queue_len;
 977         spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
 978
 979         if (time_after(jiffies, ifmsh->last_preq + min_preq_int_jiff(sdata)))
 980                 ieee80211_queue_work(&sdata->local->hw, &sdata->work);
 981
 982         else if (time_before(jiffies, ifmsh->last_preq)) {
 983                 /* avoid long wait if did not send preqs for a long time
 984                  * and jiffies wrapped around
 985                  */
 986                 ifmsh->last_preq = jiffies - min_preq_int_jiff(sdata) - 1;
 987                 ieee80211_queue_work(&sdata->local->hw, &sdata->work);
 988         } else
 989                 mod_timer(&ifmsh->mesh_path_timer, ifmsh->last_preq +
 990                                                 min_preq_int_jiff(sdata));
 991 }
 992
 993 /**
 994  * mesh_path_start_discovery - launch a path discovery from the PREQ queue
 995  *
 996  * @sdata: local mesh subif
 997  */
 998 void mesh_path_start_discovery(struct ieee80211_sub_if_data *sdata)
 999 {
1000         struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
1001         struct mesh_preq_queue *preq_node;
1002         struct mesh_path *mpath;
1003         u8 ttl, target_flags = 0;
1004         const u8 *da;
1005         u32 lifetime;
1006
1007         spin_lock_bh(&ifmsh->mesh_preq_queue_lock);
1008         if (!ifmsh->preq_queue_len ||
1009                 time_before(jiffies, ifmsh->last_preq +
1010                                 min_preq_int_jiff(sdata))) {
1011                 spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
1012                 return;
1013         }
1014
1015         preq_node = list_first_entry(&ifmsh->preq_queue.list,
1016                         struct mesh_preq_queue, list);
1017         list_del(&preq_node->list);
1018         --ifmsh->preq_queue_len;
1019         spin_unlock_bh(&ifmsh->mesh_preq_queue_lock);
1020
1021         rcu_read_lock();
1022         mpath = mesh_path_lookup(sdata, preq_node->dst);
1023         if (!mpath)
1024                 goto enddiscovery;
1025
1026         spin_lock_bh(&mpath->state_lock);
1027         if (mpath->flags & (MESH_PATH_DELETED | MESH_PATH_FIXED)) {
1028                 spin_unlock_bh(&mpath->state_lock);
1029                 goto enddiscovery;
1030         }
1031         mpath->flags &= ~MESH_PATH_REQ_QUEUED;
1032         if (preq_node->flags & PREQ_Q_F_START) {
1033                 if (mpath->flags & MESH_PATH_RESOLVING) {
1034                         spin_unlock_bh(&mpath->state_lock);
1035                         goto enddiscovery;
1036                 } else {
1037                         mpath->flags &= ~MESH_PATH_RESOLVED;
1038                         mpath->flags |= MESH_PATH_RESOLVING;
1039                         mpath->discovery_retries = 0;
1040                         mpath->discovery_timeout = disc_timeout_jiff(sdata);
1041                 }
1042         } else if (!(mpath->flags & MESH_PATH_RESOLVING) ||
1043                         mpath->flags & MESH_PATH_RESOLVED) {
1044                 mpath->flags &= ~MESH_PATH_RESOLVING;
1045                 spin_unlock_bh(&mpath->state_lock);
1046                 goto enddiscovery;
1047         }
1048
1049         ifmsh->last_preq = jiffies;
1050
1051         if (time_after(jiffies, ifmsh->last_sn_update +
1052                                 net_traversal_jiffies(sdata)) ||
1053             time_before(jiffies, ifmsh->last_sn_update)) {
1054                 ++ifmsh->sn;
1055                 sdata->u.mesh.last_sn_update = jiffies;
1056         }
1057         lifetime = default_lifetime(sdata);
1058         ttl = sdata->u.mesh.mshcfg.element_ttl;
1059         if (ttl == 0) {
1060                 sdata->u.mesh.mshstats.dropped_frames_ttl++;
1061                 spin_unlock_bh(&mpath->state_lock);
1062                 goto enddiscovery;
1063         }
1064
1065         if (preq_node->flags & PREQ_Q_F_REFRESH)
1066                 target_flags |= IEEE80211_PREQ_TO_FLAG;
1067         else
1068                 target_flags &= ~IEEE80211_PREQ_TO_FLAG;
1069
1070         spin_unlock_bh(&mpath->state_lock);
1071         da = (mpath->is_root) ? mpath->rann_snd_addr : broadcast_addr;
1072         mesh_path_sel_frame_tx(MPATH_PREQ, 0, sdata->vif.addr, ifmsh->sn,
1073                                target_flags, mpath->dst, mpath->sn, da, 0,
1074                                ttl, lifetime, 0, ifmsh->preq_id++, sdata);
1075         mod_timer(&mpath->timer, jiffies + mpath->discovery_timeout);
1076
1077 enddiscovery:
1078         rcu_read_unlock();
1079         kfree(preq_node);
1080 }
1081
1082 /**
1083  * mesh_nexthop_resolve - lookup next hop; conditionally start path discovery
1084  *
1085  * @skb: 802.11 frame to be sent
1086  * @sdata: network subif the frame will be sent through
1087  *
1088  * Lookup next hop for given skb and start path discovery if no
1089  * forwarding information is found.
1090  *
1091  * Returns: 0 if the next hop was found and -ENOENT if the frame was queued.
1092  * skb is freeed here if no mpath could be allocated.
1093  */
1094 int mesh_nexthop_resolve(struct ieee80211_sub_if_data *sdata,
1095                          struct sk_buff *skb)
1096 {
1097         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
1098         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
1099         struct mesh_path *mpath;
1100         struct sk_buff *skb_to_free = NULL;
1101         u8 *target_addr = hdr->addr3;
1102         int err = 0;
1103
1104         /* Nulls are only sent to peers for PS and should be pre-addressed */
1105         if (ieee80211_is_qos_nullfunc(hdr->frame_control))
1106                 return 0;
1107
1108         rcu_read_lock();
1109         err = mesh_nexthop_lookup(sdata, skb);
1110         if (!err)
1111                 goto endlookup;
1112
1113         /* no nexthop found, start resolving */
1114         mpath = mesh_path_lookup(sdata, target_addr);
1115         if (!mpath) {
1116                 mpath = mesh_path_add(sdata, target_addr);
1117                 if (IS_ERR(mpath)) {
1118                         mesh_path_discard_frame(sdata, skb);
1119                         err = PTR_ERR(mpath);
1120                         goto endlookup;
1121                 }
1122         }
1123
1124         if (!(mpath->flags & MESH_PATH_RESOLVING))
1125                 mesh_queue_preq(mpath, PREQ_Q_F_START);
1126
1127         if (skb_queue_len(&mpath->frame_queue) >= MESH_FRAME_QUEUE_LEN)
1128                 skb_to_free = skb_dequeue(&mpath->frame_queue);
1129
1130         info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;
1131         ieee80211_set_qos_hdr(sdata, skb);
1132         skb_queue_tail(&mpath->frame_queue, skb);
1133         err = -ENOENT;
1134         if (skb_to_free)
1135                 mesh_path_discard_frame(sdata, skb_to_free);
1136
1137 endlookup:
1138         rcu_read_unlock();
1139         return err;
1140 }
1141
1142 /**
1143  * mesh_nexthop_lookup - put the appropriate next hop on a mesh frame. Calling
1144  * this function is considered "using" the associated mpath, so preempt a path
1145  * refresh if this mpath expires soon.
1146  *
1147  * @skb: 802.11 frame to be sent
1148  * @sdata: network subif the frame will be sent through
1149  *
1150  * Returns: 0 if the next hop was found. Nonzero otherwise.
1151  */
1152 int mesh_nexthop_lookup(struct ieee80211_sub_if_data *sdata,
1153                         struct sk_buff *skb)
1154 {
1155         struct mesh_path *mpath;
1156         struct sta_info *next_hop;
1157         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
1158         u8 *target_addr = hdr->addr3;
1159         int err = -ENOENT;
1160
1161         rcu_read_lock();
1162         mpath = mesh_path_lookup(sdata, target_addr);
1163
1164         if (!mpath || !(mpath->flags & MESH_PATH_ACTIVE))
1165                 goto endlookup;
1166
1167         if (time_after(jiffies,
1168                        mpath->exp_time -
1169                        msecs_to_jiffies(sdata->u.mesh.mshcfg.path_refresh_time)) &&
1170             ether_addr_equal(sdata->vif.addr, hdr->addr4) &&
1171             !(mpath->flags & MESH_PATH_RESOLVING) &&
1172             !(mpath->flags & MESH_PATH_FIXED))
1173                 mesh_queue_preq(mpath, PREQ_Q_F_START | PREQ_Q_F_REFRESH);
1174
1175         next_hop = rcu_dereference(mpath->next_hop);
1176         if (next_hop) {
1177                 memcpy(hdr->addr1, next_hop->sta.addr, ETH_ALEN);
1178                 memcpy(hdr->addr2, sdata->vif.addr, ETH_ALEN);
1179                 ieee80211_mps_set_frame_flags(sdata, next_hop, hdr);
1180                 err = 0;
1181         }
1182
1183 endlookup:
1184         rcu_read_unlock();
1185         return err;
1186 }
1187
1188 void mesh_path_timer(unsigned long data)
1189 {
1190         struct mesh_path *mpath = (void *) data;
1191         struct ieee80211_sub_if_data *sdata = mpath->sdata;
1192         int ret;
1193
1194         if (sdata->local->quiescing)
1195                 return;
1196
1197         spin_lock_bh(&mpath->state_lock);
1198         if (mpath->flags & MESH_PATH_RESOLVED ||
1199                         (!(mpath->flags & MESH_PATH_RESOLVING))) {
1200                 mpath->flags &= ~(MESH_PATH_RESOLVING | MESH_PATH_RESOLVED);
1201                 spin_unlock_bh(&mpath->state_lock);
1202         } else if (mpath->discovery_retries < max_preq_retries(sdata)) {
1203                 ++mpath->discovery_retries;
1204                 mpath->discovery_timeout *= 2;
1205                 mpath->flags &= ~MESH_PATH_REQ_QUEUED;
1206                 spin_unlock_bh(&mpath->state_lock);
1207                 mesh_queue_preq(mpath, 0);
1208         } else {
1209                 mpath->flags &= ~(MESH_PATH_RESOLVING |
1210                                   MESH_PATH_RESOLVED |
1211                                   MESH_PATH_REQ_QUEUED);
1212                 mpath->exp_time = jiffies;
1213                 spin_unlock_bh(&mpath->state_lock);
1214                 if (!mpath->is_gate && mesh_gate_num(sdata) > 0) {
1215                         ret = mesh_path_send_to_gates(mpath);
1216                         if (ret)
1217                                 mhwmp_dbg(sdata, "no gate was reachable\n");
1218                 } else
1219                         mesh_path_flush_pending(mpath);
1220         }
1221 }
1222
1223 void mesh_path_tx_root_frame(struct ieee80211_sub_if_data *sdata)
1224 {
1225         struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
1226         u32 interval = ifmsh->mshcfg.dot11MeshHWMPRannInterval;
1227         u8 flags, target_flags = 0;
1228
1229         flags = (ifmsh->mshcfg.dot11MeshGateAnnouncementProtocol)
1230                         ? RANN_FLAG_IS_GATE : 0;
1231
1232         switch (ifmsh->mshcfg.dot11MeshHWMPRootMode) {
1233         case IEEE80211_PROACTIVE_RANN:
1234                 mesh_path_sel_frame_tx(MPATH_RANN, flags, sdata->vif.addr,
1235                                        ++ifmsh->sn, 0, NULL, 0, broadcast_addr,
1236                                        0, ifmsh->mshcfg.element_ttl,
1237                                        interval, 0, 0, sdata);
1238                 break;
1239         case IEEE80211_PROACTIVE_PREQ_WITH_PREP:
1240                 flags |= IEEE80211_PREQ_PROACTIVE_PREP_FLAG;
1241         case IEEE80211_PROACTIVE_PREQ_NO_PREP:
1242                 interval = ifmsh->mshcfg.dot11MeshHWMPactivePathToRootTimeout;
1243                 target_flags |= IEEE80211_PREQ_TO_FLAG |
1244                                 IEEE80211_PREQ_USN_FLAG;
1245                 mesh_path_sel_frame_tx(MPATH_PREQ, flags, sdata->vif.addr,
1246                                        ++ifmsh->sn, target_flags,
1247                                        (u8 *) broadcast_addr, 0, broadcast_addr,
1248                                        0, ifmsh->mshcfg.element_ttl, interval,
1249                                        0, ifmsh->preq_id++, sdata);
1250                 break;
1251         default:
1252                 mhwmp_dbg(sdata, "Proactive mechanism not supported\n");
1253                 return;
1254         }
1255 }