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 /* TODO: figure out how to avoid that the "current BSS" expires */
  16
  17 #include <linux/wireless.h>
  18 #include <linux/if_arp.h>
  19 #include <linux/rtnetlink.h>
  20 #include <net/mac80211.h>
  21 #include <net/iw_handler.h>
  22
  23 #include "ieee80211_i.h"
  24 #include "driver-ops.h"
  25 #include "mesh.h"
  26
  27 #define IEEE80211_PROBE_DELAY (HZ / 33)
  28 #define IEEE80211_CHANNEL_TIME (HZ / 33)
  29 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
  30
  31 struct ieee80211_bss *
  32 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
  33                      u8 *ssid, u8 ssid_len)
  34 {
  35         return (void *)cfg80211_get_bss(local->hw.wiphy,
  36                                         ieee80211_get_channel(local->hw.wiphy,
  37                                                               freq),
  38                                         bssid, ssid, ssid_len,
  39                                         0, 0);
  40 }
  41
  42 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
  43 {
  44         struct ieee80211_bss *bss = (void *)cbss;
  45
  46         kfree(bss_mesh_id(bss));
  47         kfree(bss_mesh_cfg(bss));
  48 }
  49
  50 void ieee80211_rx_bss_put(struct ieee80211_local *local,
  51                           struct ieee80211_bss *bss)
  52 {
  53         cfg80211_put_bss((struct cfg80211_bss *)bss);
  54 }
  55
  56 struct ieee80211_bss *
  57 ieee80211_bss_info_update(struct ieee80211_local *local,
  58                           struct ieee80211_rx_status *rx_status,
  59                           struct ieee80211_mgmt *mgmt,
  60                           size_t len,
  61                           struct ieee802_11_elems *elems,
  62                           struct ieee80211_channel *channel,
  63                           bool beacon)
  64 {
  65         struct ieee80211_bss *bss;
  66         int clen;
  67         s32 signal = 0;
  68
  69         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
  70                 signal = rx_status->signal * 100;
  71         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
  72                 signal = (rx_status->signal * 100) / local->hw.max_signal;
  73
  74         bss = (void *)cfg80211_inform_bss_frame(local->hw.wiphy, channel,
  75                                                 mgmt, len, signal, GFP_ATOMIC);
  76
  77         if (!bss)
  78                 return NULL;
  79
  80         bss->cbss.free_priv = ieee80211_rx_bss_free;
  81
  82         /* save the ERP value so that it is available at association time */
  83         if (elems->erp_info && elems->erp_info_len >= 1) {
  84                 bss->erp_value = elems->erp_info[0];
  85                 bss->has_erp_value = 1;
  86         }
  87
  88         if (elems->tim) {
  89                 struct ieee80211_tim_ie *tim_ie =
  90                         (struct ieee80211_tim_ie *)elems->tim;
  91                 bss->dtim_period = tim_ie->dtim_period;
  92         }
  93
  94         /* set default value for buggy APs */
  95         if (!elems->tim || bss->dtim_period == 0)
  96                 bss->dtim_period = 1;
  97
  98         bss->supp_rates_len = 0;
  99         if (elems->supp_rates) {
 100                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 101                 if (clen > elems->supp_rates_len)
 102                         clen = elems->supp_rates_len;
 103                 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
 104                        clen);
 105                 bss->supp_rates_len += clen;
 106         }
 107         if (elems->ext_supp_rates) {
 108                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 109                 if (clen > elems->ext_supp_rates_len)
 110                         clen = elems->ext_supp_rates_len;
 111                 memcpy(&bss->supp_rates[bss->supp_rates_len],
 112                        elems->ext_supp_rates, clen);
 113                 bss->supp_rates_len += clen;
 114         }
 115
 116         bss->wmm_used = elems->wmm_param || elems->wmm_info;
 117
 118         if (!beacon)
 119                 bss->last_probe_resp = jiffies;
 120
 121         return bss;
 122 }
 123
 124 ieee80211_rx_result
 125 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
 126 {
 127         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
 128         struct ieee80211_mgmt *mgmt;
 129         struct ieee80211_bss *bss;
 130         u8 *elements;
 131         struct ieee80211_channel *channel;
 132         size_t baselen;
 133         int freq;
 134         __le16 fc;
 135         bool presp, beacon = false;
 136         struct ieee802_11_elems elems;
 137
 138         if (skb->len < 2)
 139                 return RX_DROP_UNUSABLE;
 140
 141         mgmt = (struct ieee80211_mgmt *) skb->data;
 142         fc = mgmt->frame_control;
 143
 144         if (ieee80211_is_ctl(fc))
 145                 return RX_CONTINUE;
 146
 147         if (skb->len < 24)
 148                 return RX_DROP_MONITOR;
 149
 150         presp = ieee80211_is_probe_resp(fc);
 151         if (presp) {
 152                 /* ignore ProbeResp to foreign address */
 153                 if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
 154                         return RX_DROP_MONITOR;
 155
 156                 presp = true;
 157                 elements = mgmt->u.probe_resp.variable;
 158                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 159         } else {
 160                 beacon = ieee80211_is_beacon(fc);
 161                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 162                 elements = mgmt->u.beacon.variable;
 163         }
 164
 165         if (!presp && !beacon)
 166                 return RX_CONTINUE;
 167
 168         if (baselen > skb->len)
 169                 return RX_DROP_MONITOR;
 170
 171         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
 172
 173         if (elems.ds_params && elems.ds_params_len == 1)
 174                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
 175         else
 176                 freq = rx_status->freq;
 177
 178         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
 179
 180         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 181                 return RX_DROP_MONITOR;
 182
 183         bss = ieee80211_bss_info_update(sdata->local, rx_status,
 184                                         mgmt, skb->len, &elems,
 185                                         channel, beacon);
 186         if (bss)
 187                 ieee80211_rx_bss_put(sdata->local, bss);
 188
 189         dev_kfree_skb(skb);
 190         return RX_QUEUED;
 191 }
 192
 193 /*
 194  * inform AP that we will go to sleep so that it will buffer the frames
 195  * while we scan
 196  */
 197 static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
 198 {
 199         struct ieee80211_local *local = sdata->local;
 200         bool ps = false;
 201
 202         /* FIXME: what to do when local->pspolling is true? */
 203
 204         del_timer_sync(&local->dynamic_ps_timer);
 205         cancel_work_sync(&local->dynamic_ps_enable_work);
 206
 207         if (local->hw.conf.flags & IEEE80211_CONF_PS) {
 208                 ps = true;
 209                 local->hw.conf.flags &= ~IEEE80211_CONF_PS;
 210                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
 211         }
 212
 213         if (!ps || !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
 214                 /*
 215                  * If power save was enabled, no need to send a nullfunc
 216                  * frame because AP knows that we are sleeping. But if the
 217                  * hardware is creating the nullfunc frame for power save
 218                  * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
 219                  * enabled) and power save was enabled, the firmware just
 220                  * sent a null frame with power save disabled. So we need
 221                  * to send a new nullfunc frame to inform the AP that we
 222                  * are again sleeping.
 223                  */
 224                 ieee80211_send_nullfunc(local, sdata, 1);
 225 }
 226
 227 /* inform AP that we are awake again, unless power save is enabled */
 228 static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
 229 {
 230         struct ieee80211_local *local = sdata->local;
 231
 232         if (!local->ps_sdata)
 233                 ieee80211_send_nullfunc(local, sdata, 0);
 234         else {
 235                 /*
 236                  * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
 237                  * will send a nullfunc frame with the powersave bit set
 238                  * even though the AP already knows that we are sleeping.
 239                  * This could be avoided by sending a null frame with power
 240                  * save bit disabled before enabling the power save, but
 241                  * this doesn't gain anything.
 242                  *
 243                  * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
 244                  * to send a nullfunc frame because AP already knows that
 245                  * we are sleeping, let's just enable power save mode in
 246                  * hardware.
 247                  */
 248                 local->hw.conf.flags |= IEEE80211_CONF_PS;
 249                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
 250         }
 251 }
 252
 253 static void ieee80211_restore_scan_ies(struct ieee80211_local *local)
 254 {
 255         kfree(local->scan_req->ie);
 256         local->scan_req->ie = local->orig_ies;
 257         local->scan_req->ie_len = local->orig_ies_len;
 258 }
 259
 260 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 261 {
 262         struct ieee80211_local *local = hw_to_local(hw);
 263         struct ieee80211_sub_if_data *sdata;
 264         bool was_hw_scan;
 265
 266         mutex_lock(&local->scan_mtx);
 267
 268         if (WARN_ON(!local->hw_scanning && !local->sw_scanning)) {
 269                 mutex_unlock(&local->scan_mtx);
 270                 return;
 271         }
 272
 273         if (WARN_ON(!local->scan_req)) {
 274                 mutex_unlock(&local->scan_mtx);
 275                 return;
 276         }
 277
 278         if (local->hw_scanning)
 279                 ieee80211_restore_scan_ies(local);
 280
 281         if (local->scan_req != &local->int_scan_req)
 282                 cfg80211_scan_done(local->scan_req, aborted);
 283         local->scan_req = NULL;
 284
 285         was_hw_scan = local->hw_scanning;
 286         local->hw_scanning = false;
 287         local->sw_scanning = false;
 288         local->scan_channel = NULL;
 289
 290         /* we only have to protect scan_req and hw/sw scan */
 291         mutex_unlock(&local->scan_mtx);
 292
 293         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 294         if (was_hw_scan)
 295                 goto done;
 296
 297         netif_tx_lock_bh(local->mdev);
 298         netif_addr_lock(local->mdev);
 299         local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
 300         drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
 301                              &local->filter_flags,
 302                              local->mdev->mc_count,
 303                              local->mdev->mc_list);
 304
 305         netif_addr_unlock(local->mdev);
 306         netif_tx_unlock_bh(local->mdev);
 307
 308         drv_sw_scan_complete(local);
 309
 310         mutex_lock(&local->iflist_mtx);
 311         list_for_each_entry(sdata, &local->interfaces, list) {
 312                 if (!netif_running(sdata->dev))
 313                         continue;
 314
 315                 /* Tell AP we're back */
 316                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 317                         if (sdata->u.mgd.associated) {
 318                                 ieee80211_scan_ps_disable(sdata);
 319                                 netif_tx_wake_all_queues(sdata->dev);
 320                         }
 321                 } else
 322                         netif_tx_wake_all_queues(sdata->dev);
 323
 324                 /* re-enable beaconing */
 325                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
 326                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
 327                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 328                         ieee80211_bss_info_change_notify(
 329                                 sdata, BSS_CHANGED_BEACON_ENABLED);
 330         }
 331         mutex_unlock(&local->iflist_mtx);
 332
 333  done:
 334         ieee80211_recalc_idle(local);
 335         ieee80211_mlme_notify_scan_completed(local);
 336         ieee80211_ibss_notify_scan_completed(local);
 337         ieee80211_mesh_notify_scan_completed(local);
 338 }
 339 EXPORT_SYMBOL(ieee80211_scan_completed);
 340
 341 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 342 {
 343         struct ieee80211_sub_if_data *sdata;
 344
 345         /*
 346          * Hardware/driver doesn't support hw_scan, so use software
 347          * scanning instead. First send a nullfunc frame with power save
 348          * bit on so that AP will buffer the frames for us while we are not
 349          * listening, then send probe requests to each channel and wait for
 350          * the responses. After all channels are scanned, tune back to the
 351          * original channel and send a nullfunc frame with power save bit
 352          * off to trigger the AP to send us all the buffered frames.
 353          *
 354          * Note that while local->sw_scanning is true everything else but
 355          * nullfunc frames and probe requests will be dropped in
 356          * ieee80211_tx_h_check_assoc().
 357          */
 358         drv_sw_scan_start(local);
 359
 360         mutex_lock(&local->iflist_mtx);
 361         list_for_each_entry(sdata, &local->interfaces, list) {
 362                 if (!netif_running(sdata->dev))
 363                         continue;
 364
 365                 /* disable beaconing */
 366                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
 367                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
 368                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 369                         ieee80211_bss_info_change_notify(
 370                                 sdata, BSS_CHANGED_BEACON_ENABLED);
 371
 372                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 373                         if (sdata->u.mgd.associated) {
 374                                 netif_tx_stop_all_queues(sdata->dev);
 375                                 ieee80211_scan_ps_enable(sdata);
 376                         }
 377                 } else
 378                         netif_tx_stop_all_queues(sdata->dev);
 379         }
 380         mutex_unlock(&local->iflist_mtx);
 381
 382         local->scan_state = SCAN_SET_CHANNEL;
 383         local->scan_channel_idx = 0;
 384
 385         netif_addr_lock_bh(local->mdev);
 386         local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
 387         drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
 388                              &local->filter_flags,
 389                              local->mdev->mc_count,
 390                              local->mdev->mc_list);
 391         netif_addr_unlock_bh(local->mdev);
 392
 393         /* TODO: start scan as soon as all nullfunc frames are ACKed */
 394         queue_delayed_work(local->hw.workqueue, &local->scan_work,
 395                            IEEE80211_CHANNEL_TIME);
 396
 397         return 0;
 398 }
 399
 400
 401 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 402                                   struct cfg80211_scan_request *req)
 403 {
 404         struct ieee80211_local *local = sdata->local;
 405         struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
 406         int rc;
 407
 408         if (local->scan_req)
 409                 return -EBUSY;
 410
 411         if (local->ops->hw_scan) {
 412                 u8 *ies;
 413                 int ielen;
 414
 415                 ies = kmalloc(2 + IEEE80211_MAX_SSID_LEN +
 416                               local->scan_ies_len + req->ie_len, GFP_KERNEL);
 417                 if (!ies)
 418                         return -ENOMEM;
 419
 420                 ielen = ieee80211_build_preq_ies(local, ies,
 421                                                  req->ie, req->ie_len);
 422                 local->orig_ies = req->ie;
 423                 local->orig_ies_len = req->ie_len;
 424                 req->ie = ies;
 425                 req->ie_len = ielen;
 426         }
 427
 428         local->scan_req = req;
 429         local->scan_sdata = sdata;
 430
 431         if (req != &local->int_scan_req &&
 432             sdata->vif.type == NL80211_IFTYPE_STATION &&
 433             !list_empty(&ifmgd->work_list)) {
 434                 /* actually wait for the work it's doing to finish/time out */
 435                 set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
 436                 return 0;
 437         }
 438
 439         if (local->ops->hw_scan)
 440                 local->hw_scanning = true;
 441         else
 442                 local->sw_scanning = true;
 443         /*
 444          * Kicking off the scan need not be protected,
 445          * only the scan variable stuff, since now
 446          * local->scan_req is assigned and other callers
 447          * will abort their scan attempts.
 448          *
 449          * This avoids getting a scan_mtx -> iflist_mtx
 450          * dependency, so that the scan completed calls
 451          * have more locking freedom.
 452          */
 453
 454         ieee80211_recalc_idle(local);
 455         mutex_unlock(&local->scan_mtx);
 456
 457         if (local->ops->hw_scan)
 458                 rc = drv_hw_scan(local, local->scan_req);
 459         else
 460                 rc = ieee80211_start_sw_scan(local);
 461
 462         mutex_lock(&local->scan_mtx);
 463
 464         if (rc) {
 465                 if (local->ops->hw_scan) {
 466                         local->hw_scanning = false;
 467                         ieee80211_restore_scan_ies(local);
 468                 } else
 469                         local->sw_scanning = false;
 470
 471                 ieee80211_recalc_idle(local);
 472
 473                 local->scan_req = NULL;
 474                 local->scan_sdata = NULL;
 475         }
 476
 477         return rc;
 478 }
 479
 480 void ieee80211_scan_work(struct work_struct *work)
 481 {
 482         struct ieee80211_local *local =
 483                 container_of(work, struct ieee80211_local, scan_work.work);
 484         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 485         struct ieee80211_channel *chan;
 486         int skip, i;
 487         unsigned long next_delay = 0;
 488
 489         mutex_lock(&local->scan_mtx);
 490         if (!sdata || !local->scan_req) {
 491                 mutex_unlock(&local->scan_mtx);
 492                 return;
 493         }
 494
 495         if (local->scan_req && !(local->sw_scanning || local->hw_scanning)) {
 496                 struct cfg80211_scan_request *req = local->scan_req;
 497                 int rc;
 498
 499                 local->scan_req = NULL;
 500
 501                 rc = __ieee80211_start_scan(sdata, req);
 502                 mutex_unlock(&local->scan_mtx);
 503
 504                 if (rc)
 505                         ieee80211_scan_completed(&local->hw, true);
 506                 return;
 507         }
 508
 509         mutex_unlock(&local->scan_mtx);
 510
 511         /*
 512          * Avoid re-scheduling when the sdata is going away.
 513          */
 514         if (!netif_running(sdata->dev)) {
 515                 ieee80211_scan_completed(&local->hw, true);
 516                 return;
 517         }
 518
 519         switch (local->scan_state) {
 520         case SCAN_SET_CHANNEL:
 521                 /* if no more bands/channels left, complete scan */
 522                 if (local->scan_channel_idx >= local->scan_req->n_channels) {
 523                         ieee80211_scan_completed(&local->hw, false);
 524                         return;
 525                 }
 526                 skip = 0;
 527                 chan = local->scan_req->channels[local->scan_channel_idx];
 528
 529                 if (chan->flags & IEEE80211_CHAN_DISABLED ||
 530                     (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
 531                      chan->flags & IEEE80211_CHAN_NO_IBSS))
 532                         skip = 1;
 533
 534                 if (!skip) {
 535                         local->scan_channel = chan;
 536                         if (ieee80211_hw_config(local,
 537                                                 IEEE80211_CONF_CHANGE_CHANNEL))
 538                                 skip = 1;
 539                 }
 540
 541                 /* advance state machine to next channel/band */
 542                 local->scan_channel_idx++;
 543
 544                 if (skip)
 545                         break;
 546
 547                 /*
 548                  * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 549                  * (which unfortunately doesn't say _why_ step a) is done,
 550                  * but it waits for the probe delay or until a frame is
 551                  * received - and the received frame would update the NAV).
 552                  * For now, we do not support waiting until a frame is
 553                  * received.
 554                  *
 555                  * In any case, it is not necessary for a passive scan.
 556                  */
 557                 if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 558                     !local->scan_req->n_ssids) {
 559                         next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 560                         break;
 561                 }
 562
 563                 next_delay = IEEE80211_PROBE_DELAY;
 564                 local->scan_state = SCAN_SEND_PROBE;
 565                 break;
 566         case SCAN_SEND_PROBE:
 567                 for (i = 0; i < local->scan_req->n_ssids; i++)
 568                         ieee80211_send_probe_req(
 569                                 sdata, NULL,
 570                                 local->scan_req->ssids[i].ssid,
 571                                 local->scan_req->ssids[i].ssid_len,
 572                                 local->scan_req->ie, local->scan_req->ie_len);
 573
 574                 /*
 575                  * After sending probe requests, wait for probe responses
 576                  * on the channel.
 577                  */
 578                 next_delay = IEEE80211_CHANNEL_TIME;
 579                 local->scan_state = SCAN_SET_CHANNEL;
 580                 break;
 581         }
 582
 583         queue_delayed_work(local->hw.workqueue, &local->scan_work,
 584                            next_delay);
 585 }
 586
 587 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 588                            struct cfg80211_scan_request *req)
 589 {
 590         int res;
 591
 592         mutex_lock(&sdata->local->scan_mtx);
 593         res = __ieee80211_start_scan(sdata, req);
 594         mutex_unlock(&sdata->local->scan_mtx);
 595
 596         return res;
 597 }
 598
 599 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 600                                     const u8 *ssid, u8 ssid_len)
 601 {
 602         struct ieee80211_local *local = sdata->local;
 603         int ret = -EBUSY;
 604
 605         mutex_lock(&local->scan_mtx);
 606
 607         /* busy scanning */
 608         if (local->scan_req)
 609                 goto unlock;
 610
 611         memcpy(local->int_scan_req.ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 612         local->int_scan_req.ssids[0].ssid_len = ssid_len;
 613
 614         ret = __ieee80211_start_scan(sdata, &sdata->local->int_scan_req);
 615  unlock:
 616         mutex_unlock(&local->scan_mtx);
 617         return ret;
 618 }
 619
 620 void ieee80211_scan_cancel(struct ieee80211_local *local)
 621 {
 622         bool swscan;
 623
 624         cancel_delayed_work_sync(&local->scan_work);
 625
 626         /*
 627          * Only call this function when a scan can't be
 628          * queued -- mostly at suspend under RTNL.
 629          */
 630         mutex_lock(&local->scan_mtx);
 631         swscan = local->sw_scanning;
 632         mutex_unlock(&local->scan_mtx);
 633
 634         if (swscan)
 635                 ieee80211_scan_completed(&local->hw, true);
 636 }