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         spin_lock_bh(&local->filter_lock);
 298         local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
 299         drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
 300                              &local->filter_flags,
 301                              local->mc_count,
 302                              local->mc_list);
 303         spin_unlock_bh(&local->filter_lock);
 304
 305         drv_sw_scan_complete(local);
 306
 307         mutex_lock(&local->iflist_mtx);
 308         list_for_each_entry(sdata, &local->interfaces, list) {
 309                 if (!netif_running(sdata->dev))
 310                         continue;
 311
 312                 /* Tell AP we're back */
 313                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 314                         if (sdata->u.mgd.associated) {
 315                                 ieee80211_scan_ps_disable(sdata);
 316                                 netif_tx_wake_all_queues(sdata->dev);
 317                         }
 318                 } else
 319                         netif_tx_wake_all_queues(sdata->dev);
 320
 321                 /* re-enable beaconing */
 322                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
 323                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
 324                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 325                         ieee80211_bss_info_change_notify(
 326                                 sdata, BSS_CHANGED_BEACON_ENABLED);
 327         }
 328         mutex_unlock(&local->iflist_mtx);
 329
 330  done:
 331         ieee80211_recalc_idle(local);
 332         ieee80211_mlme_notify_scan_completed(local);
 333         ieee80211_ibss_notify_scan_completed(local);
 334         ieee80211_mesh_notify_scan_completed(local);
 335 }
 336 EXPORT_SYMBOL(ieee80211_scan_completed);
 337
 338 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 339 {
 340         struct ieee80211_sub_if_data *sdata;
 341
 342         /*
 343          * Hardware/driver doesn't support hw_scan, so use software
 344          * scanning instead. First send a nullfunc frame with power save
 345          * bit on so that AP will buffer the frames for us while we are not
 346          * listening, then send probe requests to each channel and wait for
 347          * the responses. After all channels are scanned, tune back to the
 348          * original channel and send a nullfunc frame with power save bit
 349          * off to trigger the AP to send us all the buffered frames.
 350          *
 351          * Note that while local->sw_scanning is true everything else but
 352          * nullfunc frames and probe requests will be dropped in
 353          * ieee80211_tx_h_check_assoc().
 354          */
 355         drv_sw_scan_start(local);
 356
 357         mutex_lock(&local->iflist_mtx);
 358         list_for_each_entry(sdata, &local->interfaces, list) {
 359                 if (!netif_running(sdata->dev))
 360                         continue;
 361
 362                 /* disable beaconing */
 363                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
 364                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
 365                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 366                         ieee80211_bss_info_change_notify(
 367                                 sdata, BSS_CHANGED_BEACON_ENABLED);
 368
 369                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 370                         if (sdata->u.mgd.associated) {
 371                                 netif_tx_stop_all_queues(sdata->dev);
 372                                 ieee80211_scan_ps_enable(sdata);
 373                         }
 374                 } else
 375                         netif_tx_stop_all_queues(sdata->dev);
 376         }
 377         mutex_unlock(&local->iflist_mtx);
 378
 379         local->scan_state = SCAN_SET_CHANNEL;
 380         local->scan_channel_idx = 0;
 381
 382         spin_lock_bh(&local->filter_lock);
 383         local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
 384         drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
 385                              &local->filter_flags,
 386                              local->mc_count,
 387                              local->mc_list);
 388         spin_unlock_bh(&local->filter_lock);
 389
 390         /* TODO: start scan as soon as all nullfunc frames are ACKed */
 391         queue_delayed_work(local->hw.workqueue, &local->scan_work,
 392                            IEEE80211_CHANNEL_TIME);
 393
 394         return 0;
 395 }
 396
 397
 398 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 399                                   struct cfg80211_scan_request *req)
 400 {
 401         struct ieee80211_local *local = sdata->local;
 402         struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
 403         int rc;
 404
 405         if (local->scan_req)
 406                 return -EBUSY;
 407
 408         if (local->ops->hw_scan) {
 409                 u8 *ies;
 410                 int ielen;
 411
 412                 ies = kmalloc(2 + IEEE80211_MAX_SSID_LEN +
 413                               local->scan_ies_len + req->ie_len, GFP_KERNEL);
 414                 if (!ies)
 415                         return -ENOMEM;
 416
 417                 ielen = ieee80211_build_preq_ies(local, ies,
 418                                                  req->ie, req->ie_len);
 419                 local->orig_ies = req->ie;
 420                 local->orig_ies_len = req->ie_len;
 421                 req->ie = ies;
 422                 req->ie_len = ielen;
 423         }
 424
 425         local->scan_req = req;
 426         local->scan_sdata = sdata;
 427
 428         if (req != &local->int_scan_req &&
 429             sdata->vif.type == NL80211_IFTYPE_STATION &&
 430             !list_empty(&ifmgd->work_list)) {
 431                 /* actually wait for the work it's doing to finish/time out */
 432                 set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
 433                 return 0;
 434         }
 435
 436         if (local->ops->hw_scan)
 437                 local->hw_scanning = true;
 438         else
 439                 local->sw_scanning = true;
 440         /*
 441          * Kicking off the scan need not be protected,
 442          * only the scan variable stuff, since now
 443          * local->scan_req is assigned and other callers
 444          * will abort their scan attempts.
 445          *
 446          * This avoids getting a scan_mtx -> iflist_mtx
 447          * dependency, so that the scan completed calls
 448          * have more locking freedom.
 449          */
 450
 451         ieee80211_recalc_idle(local);
 452         mutex_unlock(&local->scan_mtx);
 453
 454         if (local->ops->hw_scan)
 455                 rc = drv_hw_scan(local, local->scan_req);
 456         else
 457                 rc = ieee80211_start_sw_scan(local);
 458
 459         mutex_lock(&local->scan_mtx);
 460
 461         if (rc) {
 462                 if (local->ops->hw_scan) {
 463                         local->hw_scanning = false;
 464                         ieee80211_restore_scan_ies(local);
 465                 } else
 466                         local->sw_scanning = false;
 467
 468                 ieee80211_recalc_idle(local);
 469
 470                 local->scan_req = NULL;
 471                 local->scan_sdata = NULL;
 472         }
 473
 474         return rc;
 475 }
 476
 477 void ieee80211_scan_work(struct work_struct *work)
 478 {
 479         struct ieee80211_local *local =
 480                 container_of(work, struct ieee80211_local, scan_work.work);
 481         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 482         struct ieee80211_channel *chan;
 483         int skip, i;
 484         unsigned long next_delay = 0;
 485
 486         mutex_lock(&local->scan_mtx);
 487         if (!sdata || !local->scan_req) {
 488                 mutex_unlock(&local->scan_mtx);
 489                 return;
 490         }
 491
 492         if (local->scan_req && !(local->sw_scanning || local->hw_scanning)) {
 493                 struct cfg80211_scan_request *req = local->scan_req;
 494                 int rc;
 495
 496                 local->scan_req = NULL;
 497
 498                 rc = __ieee80211_start_scan(sdata, req);
 499                 mutex_unlock(&local->scan_mtx);
 500
 501                 if (rc)
 502                         ieee80211_scan_completed(&local->hw, true);
 503                 return;
 504         }
 505
 506         mutex_unlock(&local->scan_mtx);
 507
 508         /*
 509          * Avoid re-scheduling when the sdata is going away.
 510          */
 511         if (!netif_running(sdata->dev)) {
 512                 ieee80211_scan_completed(&local->hw, true);
 513                 return;
 514         }
 515
 516         switch (local->scan_state) {
 517         case SCAN_SET_CHANNEL:
 518                 /* if no more bands/channels left, complete scan */
 519                 if (local->scan_channel_idx >= local->scan_req->n_channels) {
 520                         ieee80211_scan_completed(&local->hw, false);
 521                         return;
 522                 }
 523                 skip = 0;
 524                 chan = local->scan_req->channels[local->scan_channel_idx];
 525
 526                 if (chan->flags & IEEE80211_CHAN_DISABLED ||
 527                     (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
 528                      chan->flags & IEEE80211_CHAN_NO_IBSS))
 529                         skip = 1;
 530
 531                 if (!skip) {
 532                         local->scan_channel = chan;
 533                         if (ieee80211_hw_config(local,
 534                                                 IEEE80211_CONF_CHANGE_CHANNEL))
 535                                 skip = 1;
 536                 }
 537
 538                 /* advance state machine to next channel/band */
 539                 local->scan_channel_idx++;
 540
 541                 if (skip)
 542                         break;
 543
 544                 /*
 545                  * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 546                  * (which unfortunately doesn't say _why_ step a) is done,
 547                  * but it waits for the probe delay or until a frame is
 548                  * received - and the received frame would update the NAV).
 549                  * For now, we do not support waiting until a frame is
 550                  * received.
 551                  *
 552                  * In any case, it is not necessary for a passive scan.
 553                  */
 554                 if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 555                     !local->scan_req->n_ssids) {
 556                         next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 557                         break;
 558                 }
 559
 560                 next_delay = IEEE80211_PROBE_DELAY;
 561                 local->scan_state = SCAN_SEND_PROBE;
 562                 break;
 563         case SCAN_SEND_PROBE:
 564                 for (i = 0; i < local->scan_req->n_ssids; i++)
 565                         ieee80211_send_probe_req(
 566                                 sdata, NULL,
 567                                 local->scan_req->ssids[i].ssid,
 568                                 local->scan_req->ssids[i].ssid_len,
 569                                 local->scan_req->ie, local->scan_req->ie_len);
 570
 571                 /*
 572                  * After sending probe requests, wait for probe responses
 573                  * on the channel.
 574                  */
 575                 next_delay = IEEE80211_CHANNEL_TIME;
 576                 local->scan_state = SCAN_SET_CHANNEL;
 577                 break;
 578         }
 579
 580         queue_delayed_work(local->hw.workqueue, &local->scan_work,
 581                            next_delay);
 582 }
 583
 584 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 585                            struct cfg80211_scan_request *req)
 586 {
 587         int res;
 588
 589         mutex_lock(&sdata->local->scan_mtx);
 590         res = __ieee80211_start_scan(sdata, req);
 591         mutex_unlock(&sdata->local->scan_mtx);
 592
 593         return res;
 594 }
 595
 596 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 597                                     const u8 *ssid, u8 ssid_len)
 598 {
 599         struct ieee80211_local *local = sdata->local;
 600         int ret = -EBUSY;
 601
 602         mutex_lock(&local->scan_mtx);
 603
 604         /* busy scanning */
 605         if (local->scan_req)
 606                 goto unlock;
 607
 608         memcpy(local->int_scan_req.ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 609         local->int_scan_req.ssids[0].ssid_len = ssid_len;
 610
 611         ret = __ieee80211_start_scan(sdata, &sdata->local->int_scan_req);
 612  unlock:
 613         mutex_unlock(&local->scan_mtx);
 614         return ret;
 615 }
 616
 617 void ieee80211_scan_cancel(struct ieee80211_local *local)
 618 {
 619         bool swscan;
 620
 621         cancel_delayed_work_sync(&local->scan_work);
 622
 623         /*
 624          * Only call this function when a scan can't be
 625          * queued -- mostly at suspend under RTNL.
 626          */
 627         mutex_lock(&local->scan_mtx);
 628         swscan = local->sw_scanning;
 629         mutex_unlock(&local->scan_mtx);
 630
 631         if (swscan)
 632                 ieee80211_scan_completed(&local->hw, true);
 633 }