SAFE public projects git trees. - safe/jmp/linux-2.6/blob - net/mac80211/scan.c

   1 /*
   2  * Scanning implementation
   3  *
   4  * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
   5  * Copyright 2004, Instant802 Networks, Inc.
   6  * Copyright 2005, Devicescape Software, Inc.
   7  * Copyright 2006-2007  Jiri Benc <jbenc@suse.cz>
   8  * Copyright 2007, Michael Wu <flamingice@sourmilk.net>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  */
  14
  15 #include <linux/if_arp.h>
  16 #include <linux/rtnetlink.h>
  17 #include <net/mac80211.h>
  18
  19 #include "ieee80211_i.h"
  20 #include "driver-ops.h"
  21 #include "mesh.h"
  22
  23 #define IEEE80211_PROBE_DELAY (HZ / 33)
  24 #define IEEE80211_CHANNEL_TIME (HZ / 33)
  25 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
  26
  27 struct ieee80211_bss *
  28 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
  29                      u8 *ssid, u8 ssid_len)
  30 {
  31         struct cfg80211_bss *cbss;
  32
  33         cbss = cfg80211_get_bss(local->hw.wiphy,
  34                                 ieee80211_get_channel(local->hw.wiphy, freq),
  35                                 bssid, ssid, ssid_len, 0, 0);
  36         if (!cbss)
  37                 return NULL;
  38         return (void *)cbss->priv;
  39 }
  40
  41 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
  42 {
  43         struct ieee80211_bss *bss = (void *)cbss->priv;
  44
  45         kfree(bss_mesh_id(bss));
  46         kfree(bss_mesh_cfg(bss));
  47 }
  48
  49 void ieee80211_rx_bss_put(struct ieee80211_local *local,
  50                           struct ieee80211_bss *bss)
  51 {
  52         if (!bss)
  53                 return;
  54         cfg80211_put_bss(container_of((void *)bss, struct cfg80211_bss, priv));
  55 }
  56
  57 struct ieee80211_bss *
  58 ieee80211_bss_info_update(struct ieee80211_local *local,
  59                           struct ieee80211_rx_status *rx_status,
  60                           struct ieee80211_mgmt *mgmt,
  61                           size_t len,
  62                           struct ieee802_11_elems *elems,
  63                           struct ieee80211_channel *channel,
  64                           bool beacon)
  65 {
  66         struct cfg80211_bss *cbss;
  67         struct ieee80211_bss *bss;
  68         int clen;
  69         s32 signal = 0;
  70
  71         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
  72                 signal = rx_status->signal * 100;
  73         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
  74                 signal = (rx_status->signal * 100) / local->hw.max_signal;
  75
  76         cbss = cfg80211_inform_bss_frame(local->hw.wiphy, channel,
  77                                          mgmt, len, signal, GFP_ATOMIC);
  78
  79         if (!cbss)
  80                 return NULL;
  81
  82         cbss->free_priv = ieee80211_rx_bss_free;
  83         bss = (void *)cbss->priv;
  84
  85         /* save the ERP value so that it is available at association time */
  86         if (elems->erp_info && elems->erp_info_len >= 1) {
  87                 bss->erp_value = elems->erp_info[0];
  88                 bss->has_erp_value = 1;
  89         }
  90
  91         if (elems->tim) {
  92                 struct ieee80211_tim_ie *tim_ie =
  93                         (struct ieee80211_tim_ie *)elems->tim;
  94                 bss->dtim_period = tim_ie->dtim_period;
  95         }
  96
  97         /* set default value for buggy AP/no TIM element */
  98         if (bss->dtim_period == 0)
  99                 bss->dtim_period = 1;
 100
 101         bss->supp_rates_len = 0;
 102         if (elems->supp_rates) {
 103                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 104                 if (clen > elems->supp_rates_len)
 105                         clen = elems->supp_rates_len;
 106                 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
 107                        clen);
 108                 bss->supp_rates_len += clen;
 109         }
 110         if (elems->ext_supp_rates) {
 111                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 112                 if (clen > elems->ext_supp_rates_len)
 113                         clen = elems->ext_supp_rates_len;
 114                 memcpy(&bss->supp_rates[bss->supp_rates_len],
 115                        elems->ext_supp_rates, clen);
 116                 bss->supp_rates_len += clen;
 117         }
 118
 119         bss->wmm_used = elems->wmm_param || elems->wmm_info;
 120
 121         if (!beacon)
 122                 bss->last_probe_resp = jiffies;
 123
 124         return bss;
 125 }
 126
 127 ieee80211_rx_result
 128 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
 129 {
 130         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
 131         struct ieee80211_mgmt *mgmt;
 132         struct ieee80211_bss *bss;
 133         u8 *elements;
 134         struct ieee80211_channel *channel;
 135         size_t baselen;
 136         int freq;
 137         __le16 fc;
 138         bool presp, beacon = false;
 139         struct ieee802_11_elems elems;
 140
 141         if (skb->len < 2)
 142                 return RX_DROP_UNUSABLE;
 143
 144         mgmt = (struct ieee80211_mgmt *) skb->data;
 145         fc = mgmt->frame_control;
 146
 147         if (ieee80211_is_ctl(fc))
 148                 return RX_CONTINUE;
 149
 150         if (skb->len < 24)
 151                 return RX_DROP_MONITOR;
 152
 153         presp = ieee80211_is_probe_resp(fc);
 154         if (presp) {
 155                 /* ignore ProbeResp to foreign address */
 156                 if (memcmp(mgmt->da, sdata->vif.addr, ETH_ALEN))
 157                         return RX_DROP_MONITOR;
 158
 159                 presp = true;
 160                 elements = mgmt->u.probe_resp.variable;
 161                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 162         } else {
 163                 beacon = ieee80211_is_beacon(fc);
 164                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 165                 elements = mgmt->u.beacon.variable;
 166         }
 167
 168         if (!presp && !beacon)
 169                 return RX_CONTINUE;
 170
 171         if (baselen > skb->len)
 172                 return RX_DROP_MONITOR;
 173
 174         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
 175
 176         if (elems.ds_params && elems.ds_params_len == 1)
 177                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
 178         else
 179                 freq = rx_status->freq;
 180
 181         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
 182
 183         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 184                 return RX_DROP_MONITOR;
 185
 186         bss = ieee80211_bss_info_update(sdata->local, rx_status,
 187                                         mgmt, skb->len, &elems,
 188                                         channel, beacon);
 189         if (bss)
 190                 ieee80211_rx_bss_put(sdata->local, bss);
 191
 192         dev_kfree_skb(skb);
 193         return RX_QUEUED;
 194 }
 195
 196 /* return false if no more work */
 197 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 198 {
 199         struct cfg80211_scan_request *req = local->scan_req;
 200         enum ieee80211_band band;
 201         int i, ielen, n_chans;
 202
 203         do {
 204                 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
 205                         return false;
 206
 207                 band = local->hw_scan_band;
 208                 n_chans = 0;
 209                 for (i = 0; i < req->n_channels; i++) {
 210                         if (req->channels[i]->band == band) {
 211                                 local->hw_scan_req->channels[n_chans] =
 212                                                         req->channels[i];
 213                                 n_chans++;
 214                         }
 215                 }
 216
 217                 local->hw_scan_band++;
 218         } while (!n_chans);
 219
 220         local->hw_scan_req->n_channels = n_chans;
 221
 222         ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
 223                                          req->ie, req->ie_len, band);
 224         local->hw_scan_req->ie_len = ielen;
 225
 226         return true;
 227 }
 228
 229 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 230 {
 231         struct ieee80211_local *local = hw_to_local(hw);
 232         bool was_hw_scan;
 233
 234         mutex_lock(&local->scan_mtx);
 235
 236         /*
 237          * It's ok to abort a not-yet-running scan (that
 238          * we have one at all will be verified by checking
 239          * local->scan_req next), but not to complete it
 240          * successfully.
 241          */
 242         if (WARN_ON(!local->scanning && !aborted))
 243                 aborted = true;
 244
 245         if (WARN_ON(!local->scan_req)) {
 246                 mutex_unlock(&local->scan_mtx);
 247                 return;
 248         }
 249
 250         was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 251         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 252                 ieee80211_queue_delayed_work(&local->hw,
 253                                              &local->scan_work, 0);
 254                 mutex_unlock(&local->scan_mtx);
 255                 return;
 256         }
 257
 258         kfree(local->hw_scan_req);
 259         local->hw_scan_req = NULL;
 260
 261         if (local->scan_req != local->int_scan_req)
 262                 cfg80211_scan_done(local->scan_req, aborted);
 263         local->scan_req = NULL;
 264         local->scan_sdata = NULL;
 265
 266         local->scanning = 0;
 267         local->scan_channel = NULL;
 268
 269         /* we only have to protect scan_req and hw/sw scan */
 270         mutex_unlock(&local->scan_mtx);
 271
 272         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 273         if (was_hw_scan)
 274                 goto done;
 275
 276         ieee80211_configure_filter(local);
 277
 278         drv_sw_scan_complete(local);
 279
 280         ieee80211_offchannel_return(local, true);
 281
 282  done:
 283         ieee80211_recalc_idle(local);
 284         ieee80211_mlme_notify_scan_completed(local);
 285         ieee80211_ibss_notify_scan_completed(local);
 286         ieee80211_mesh_notify_scan_completed(local);
 287 }
 288 EXPORT_SYMBOL(ieee80211_scan_completed);
 289
 290 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 291 {
 292         /*
 293          * Hardware/driver doesn't support hw_scan, so use software
 294          * scanning instead. First send a nullfunc frame with power save
 295          * bit on so that AP will buffer the frames for us while we are not
 296          * listening, then send probe requests to each channel and wait for
 297          * the responses. After all channels are scanned, tune back to the
 298          * original channel and send a nullfunc frame with power save bit
 299          * off to trigger the AP to send us all the buffered frames.
 300          *
 301          * Note that while local->sw_scanning is true everything else but
 302          * nullfunc frames and probe requests will be dropped in
 303          * ieee80211_tx_h_check_assoc().
 304          */
 305         drv_sw_scan_start(local);
 306
 307         ieee80211_offchannel_stop_beaconing(local);
 308
 309         local->next_scan_state = SCAN_DECISION;
 310         local->scan_channel_idx = 0;
 311
 312         drv_flush(local, false);
 313
 314         ieee80211_configure_filter(local);
 315
 316         ieee80211_queue_delayed_work(&local->hw,
 317                                      &local->scan_work,
 318                                      IEEE80211_CHANNEL_TIME);
 319
 320         return 0;
 321 }
 322
 323
 324 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 325                                   struct cfg80211_scan_request *req)
 326 {
 327         struct ieee80211_local *local = sdata->local;
 328         int rc;
 329
 330         if (local->scan_req)
 331                 return -EBUSY;
 332
 333         if (local->ops->hw_scan) {
 334                 u8 *ies;
 335
 336                 local->hw_scan_req = kmalloc(
 337                                 sizeof(*local->hw_scan_req) +
 338                                 req->n_channels * sizeof(req->channels[0]) +
 339                                 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
 340                                 req->ie_len, GFP_KERNEL);
 341                 if (!local->hw_scan_req)
 342                         return -ENOMEM;
 343
 344                 local->hw_scan_req->ssids = req->ssids;
 345                 local->hw_scan_req->n_ssids = req->n_ssids;
 346                 ies = (u8 *)local->hw_scan_req +
 347                         sizeof(*local->hw_scan_req) +
 348                         req->n_channels * sizeof(req->channels[0]);
 349                 local->hw_scan_req->ie = ies;
 350
 351                 local->hw_scan_band = 0;
 352         }
 353
 354         local->scan_req = req;
 355         local->scan_sdata = sdata;
 356
 357         if (!list_empty(&local->work_list)) {
 358                 /* wait for the work to finish/time out */
 359                 return 0;
 360         }
 361
 362         if (local->ops->hw_scan)
 363                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 364         else
 365                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 366         /*
 367          * Kicking off the scan need not be protected,
 368          * only the scan variable stuff, since now
 369          * local->scan_req is assigned and other callers
 370          * will abort their scan attempts.
 371          *
 372          * This avoids getting a scan_mtx -> iflist_mtx
 373          * dependency, so that the scan completed calls
 374          * have more locking freedom.
 375          */
 376
 377         ieee80211_recalc_idle(local);
 378         mutex_unlock(&local->scan_mtx);
 379
 380         if (local->ops->hw_scan) {
 381                 WARN_ON(!ieee80211_prep_hw_scan(local));
 382                 rc = drv_hw_scan(local, local->hw_scan_req);
 383         } else
 384                 rc = ieee80211_start_sw_scan(local);
 385
 386         mutex_lock(&local->scan_mtx);
 387
 388         if (rc) {
 389                 kfree(local->hw_scan_req);
 390                 local->hw_scan_req = NULL;
 391                 local->scanning = 0;
 392
 393                 ieee80211_recalc_idle(local);
 394
 395                 local->scan_req = NULL;
 396                 local->scan_sdata = NULL;
 397         }
 398
 399         return rc;
 400 }
 401
 402 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
 403                                          unsigned long *next_delay)
 404 {
 405         bool associated = false;
 406         struct ieee80211_sub_if_data *sdata;
 407
 408         /* if no more bands/channels left, complete scan and advance to the idle state */
 409         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 410                 ieee80211_scan_completed(&local->hw, false);
 411                 return 1;
 412         }
 413
 414         /* check if at least one STA interface is associated */
 415         mutex_lock(&local->iflist_mtx);
 416         list_for_each_entry(sdata, &local->interfaces, list) {
 417                 if (!ieee80211_sdata_running(sdata))
 418                         continue;
 419
 420                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 421                         if (sdata->u.mgd.associated) {
 422                                 associated = true;
 423                                 break;
 424                         }
 425                 }
 426         }
 427         mutex_unlock(&local->iflist_mtx);
 428
 429         if (local->scan_channel) {
 430                 /*
 431                  * we're currently scanning a different channel, let's
 432                  * switch back to the operating channel now if at least
 433                  * one interface is associated. Otherwise just scan the
 434                  * next channel
 435                  */
 436                 if (associated)
 437                         local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
 438                 else
 439                         local->next_scan_state = SCAN_SET_CHANNEL;
 440         } else {
 441                 /*
 442                  * we're on the operating channel currently, let's
 443                  * leave that channel now to scan another one
 444                  */
 445                 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
 446         }
 447
 448         *next_delay = 0;
 449         return 0;
 450 }
 451
 452 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
 453                                                     unsigned long *next_delay)
 454 {
 455         ieee80211_offchannel_stop_station(local);
 456
 457         __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
 458
 459         /*
 460          * What if the nullfunc frames didn't arrive?
 461          */
 462         drv_flush(local, false);
 463         if (local->ops->flush)
 464                 *next_delay = 0;
 465         else
 466                 *next_delay = HZ / 10;
 467
 468         /* advance to the next channel to be scanned */
 469         local->next_scan_state = SCAN_SET_CHANNEL;
 470 }
 471
 472 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
 473                                                     unsigned long *next_delay)
 474 {
 475         /* switch back to the operating channel */
 476         local->scan_channel = NULL;
 477         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 478
 479         /*
 480          * Only re-enable station mode interface now; beaconing will be
 481          * re-enabled once the full scan has been completed.
 482          */
 483         ieee80211_offchannel_return(local, false);
 484
 485         __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
 486
 487         *next_delay = HZ / 5;
 488         local->next_scan_state = SCAN_DECISION;
 489 }
 490
 491 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 492                                              unsigned long *next_delay)
 493 {
 494         int skip;
 495         struct ieee80211_channel *chan;
 496
 497         skip = 0;
 498         chan = local->scan_req->channels[local->scan_channel_idx];
 499
 500         local->scan_channel = chan;
 501         if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 502                 skip = 1;
 503
 504         /* advance state machine to next channel/band */
 505         local->scan_channel_idx++;
 506
 507         if (skip) {
 508                 /* if we skip this channel return to the decision state */
 509                 local->next_scan_state = SCAN_DECISION;
 510                 return;
 511         }
 512
 513         /*
 514          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 515          * (which unfortunately doesn't say _why_ step a) is done,
 516          * but it waits for the probe delay or until a frame is
 517          * received - and the received frame would update the NAV).
 518          * For now, we do not support waiting until a frame is
 519          * received.
 520          *
 521          * In any case, it is not necessary for a passive scan.
 522          */
 523         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 524             !local->scan_req->n_ssids) {
 525                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 526                 local->next_scan_state = SCAN_DECISION;
 527                 return;
 528         }
 529
 530         /* active scan, send probes */
 531         *next_delay = IEEE80211_PROBE_DELAY;
 532         local->next_scan_state = SCAN_SEND_PROBE;
 533 }
 534
 535 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 536                                             unsigned long *next_delay)
 537 {
 538         int i;
 539         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 540
 541         for (i = 0; i < local->scan_req->n_ssids; i++)
 542                 ieee80211_send_probe_req(
 543                         sdata, NULL,
 544                         local->scan_req->ssids[i].ssid,
 545                         local->scan_req->ssids[i].ssid_len,
 546                         local->scan_req->ie, local->scan_req->ie_len);
 547
 548         /*
 549          * After sending probe requests, wait for probe responses
 550          * on the channel.
 551          */
 552         *next_delay = IEEE80211_CHANNEL_TIME;
 553         local->next_scan_state = SCAN_DECISION;
 554 }
 555
 556 void ieee80211_scan_work(struct work_struct *work)
 557 {
 558         struct ieee80211_local *local =
 559                 container_of(work, struct ieee80211_local, scan_work.work);
 560         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 561         unsigned long next_delay = 0;
 562
 563         mutex_lock(&local->scan_mtx);
 564         if (!sdata || !local->scan_req) {
 565                 mutex_unlock(&local->scan_mtx);
 566                 return;
 567         }
 568
 569         if (local->hw_scan_req) {
 570                 int rc = drv_hw_scan(local, local->hw_scan_req);
 571                 mutex_unlock(&local->scan_mtx);
 572                 if (rc)
 573                         ieee80211_scan_completed(&local->hw, true);
 574                 return;
 575         }
 576
 577         if (local->scan_req && !local->scanning) {
 578                 struct cfg80211_scan_request *req = local->scan_req;
 579                 int rc;
 580
 581                 local->scan_req = NULL;
 582                 local->scan_sdata = NULL;
 583
 584                 rc = __ieee80211_start_scan(sdata, req);
 585                 mutex_unlock(&local->scan_mtx);
 586
 587                 if (rc)
 588                         ieee80211_scan_completed(&local->hw, true);
 589                 return;
 590         }
 591
 592         mutex_unlock(&local->scan_mtx);
 593
 594         /*
 595          * Avoid re-scheduling when the sdata is going away.
 596          */
 597         if (!ieee80211_sdata_running(sdata)) {
 598                 ieee80211_scan_completed(&local->hw, true);
 599                 return;
 600         }
 601
 602         /*
 603          * as long as no delay is required advance immediately
 604          * without scheduling a new work
 605          */
 606         do {
 607                 switch (local->next_scan_state) {
 608                 case SCAN_DECISION:
 609                         if (ieee80211_scan_state_decision(local, &next_delay))
 610                                 return;
 611                         break;
 612                 case SCAN_SET_CHANNEL:
 613                         ieee80211_scan_state_set_channel(local, &next_delay);
 614                         break;
 615                 case SCAN_SEND_PROBE:
 616                         ieee80211_scan_state_send_probe(local, &next_delay);
 617                         break;
 618                 case SCAN_LEAVE_OPER_CHANNEL:
 619                         ieee80211_scan_state_leave_oper_channel(local, &next_delay);
 620                         break;
 621                 case SCAN_ENTER_OPER_CHANNEL:
 622                         ieee80211_scan_state_enter_oper_channel(local, &next_delay);
 623                         break;
 624                 }
 625         } while (next_delay == 0);
 626
 627         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
 628 }
 629
 630 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 631                            struct cfg80211_scan_request *req)
 632 {
 633         int res;
 634
 635         mutex_lock(&sdata->local->scan_mtx);
 636         res = __ieee80211_start_scan(sdata, req);
 637         mutex_unlock(&sdata->local->scan_mtx);
 638
 639         return res;
 640 }
 641
 642 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 643                                     const u8 *ssid, u8 ssid_len)
 644 {
 645         struct ieee80211_local *local = sdata->local;
 646         int ret = -EBUSY;
 647
 648         mutex_lock(&local->scan_mtx);
 649
 650         /* busy scanning */
 651         if (local->scan_req)
 652                 goto unlock;
 653
 654         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 655         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 656
 657         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 658  unlock:
 659         mutex_unlock(&local->scan_mtx);
 660         return ret;
 661 }
 662
 663 void ieee80211_scan_cancel(struct ieee80211_local *local)
 664 {
 665         bool abortscan;
 666
 667         cancel_delayed_work_sync(&local->scan_work);
 668
 669         /*
 670          * Only call this function when a scan can't be
 671          * queued -- mostly at suspend under RTNL.
 672          */
 673         mutex_lock(&local->scan_mtx);
 674         abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
 675                     (!local->scanning && local->scan_req);
 676         mutex_unlock(&local->scan_mtx);
 677
 678         if (abortscan)
 679                 ieee80211_scan_completed(&local->hw, true);
 680 }