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 static bool is_uapsd_supported(struct ieee802_11_elems *elems)
  58 {
  59         u8 qos_info;
  60
  61         if (elems->wmm_info && elems->wmm_info_len == 7
  62             && elems->wmm_info[5] == 1)
  63                 qos_info = elems->wmm_info[6];
  64         else if (elems->wmm_param && elems->wmm_param_len == 24
  65                  && elems->wmm_param[5] == 1)
  66                 qos_info = elems->wmm_param[6];
  67         else
  68                 /* no valid wmm information or parameter element found */
  69                 return false;
  70
  71         return qos_info & IEEE80211_WMM_IE_AP_QOSINFO_UAPSD;
  72 }
  73
  74 struct ieee80211_bss *
  75 ieee80211_bss_info_update(struct ieee80211_local *local,
  76                           struct ieee80211_rx_status *rx_status,
  77                           struct ieee80211_mgmt *mgmt,
  78                           size_t len,
  79                           struct ieee802_11_elems *elems,
  80                           struct ieee80211_channel *channel,
  81                           bool beacon)
  82 {
  83         struct cfg80211_bss *cbss;
  84         struct ieee80211_bss *bss;
  85         int clen;
  86         s32 signal = 0;
  87
  88         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
  89                 signal = rx_status->signal * 100;
  90         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
  91                 signal = (rx_status->signal * 100) / local->hw.max_signal;
  92
  93         cbss = cfg80211_inform_bss_frame(local->hw.wiphy, channel,
  94                                          mgmt, len, signal, GFP_ATOMIC);
  95
  96         if (!cbss)
  97                 return NULL;
  98
  99         cbss->free_priv = ieee80211_rx_bss_free;
 100         bss = (void *)cbss->priv;
 101
 102         /* save the ERP value so that it is available at association time */
 103         if (elems->erp_info && elems->erp_info_len >= 1) {
 104                 bss->erp_value = elems->erp_info[0];
 105                 bss->has_erp_value = 1;
 106         }
 107
 108         if (elems->tim) {
 109                 struct ieee80211_tim_ie *tim_ie =
 110                         (struct ieee80211_tim_ie *)elems->tim;
 111                 bss->dtim_period = tim_ie->dtim_period;
 112         }
 113
 114         bss->supp_rates_len = 0;
 115         if (elems->supp_rates) {
 116                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 117                 if (clen > elems->supp_rates_len)
 118                         clen = elems->supp_rates_len;
 119                 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
 120                        clen);
 121                 bss->supp_rates_len += clen;
 122         }
 123         if (elems->ext_supp_rates) {
 124                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 125                 if (clen > elems->ext_supp_rates_len)
 126                         clen = elems->ext_supp_rates_len;
 127                 memcpy(&bss->supp_rates[bss->supp_rates_len],
 128                        elems->ext_supp_rates, clen);
 129                 bss->supp_rates_len += clen;
 130         }
 131
 132         bss->wmm_used = elems->wmm_param || elems->wmm_info;
 133         bss->uapsd_supported = is_uapsd_supported(elems);
 134
 135         if (!beacon)
 136                 bss->last_probe_resp = jiffies;
 137
 138         return bss;
 139 }
 140
 141 ieee80211_rx_result
 142 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
 143 {
 144         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
 145         struct ieee80211_mgmt *mgmt;
 146         struct ieee80211_bss *bss;
 147         u8 *elements;
 148         struct ieee80211_channel *channel;
 149         size_t baselen;
 150         int freq;
 151         __le16 fc;
 152         bool presp, beacon = false;
 153         struct ieee802_11_elems elems;
 154
 155         if (skb->len < 2)
 156                 return RX_DROP_UNUSABLE;
 157
 158         mgmt = (struct ieee80211_mgmt *) skb->data;
 159         fc = mgmt->frame_control;
 160
 161         if (ieee80211_is_ctl(fc))
 162                 return RX_CONTINUE;
 163
 164         if (skb->len < 24)
 165                 return RX_DROP_MONITOR;
 166
 167         presp = ieee80211_is_probe_resp(fc);
 168         if (presp) {
 169                 /* ignore ProbeResp to foreign address */
 170                 if (memcmp(mgmt->da, sdata->vif.addr, ETH_ALEN))
 171                         return RX_DROP_MONITOR;
 172
 173                 presp = true;
 174                 elements = mgmt->u.probe_resp.variable;
 175                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 176         } else {
 177                 beacon = ieee80211_is_beacon(fc);
 178                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 179                 elements = mgmt->u.beacon.variable;
 180         }
 181
 182         if (!presp && !beacon)
 183                 return RX_CONTINUE;
 184
 185         if (baselen > skb->len)
 186                 return RX_DROP_MONITOR;
 187
 188         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
 189
 190         if (elems.ds_params && elems.ds_params_len == 1)
 191                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
 192         else
 193                 freq = rx_status->freq;
 194
 195         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
 196
 197         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 198                 return RX_DROP_MONITOR;
 199
 200         bss = ieee80211_bss_info_update(sdata->local, rx_status,
 201                                         mgmt, skb->len, &elems,
 202                                         channel, beacon);
 203         if (bss)
 204                 ieee80211_rx_bss_put(sdata->local, bss);
 205
 206         dev_kfree_skb(skb);
 207         return RX_QUEUED;
 208 }
 209
 210 /* return false if no more work */
 211 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 212 {
 213         struct cfg80211_scan_request *req = local->scan_req;
 214         enum ieee80211_band band;
 215         int i, ielen, n_chans;
 216
 217         do {
 218                 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
 219                         return false;
 220
 221                 band = local->hw_scan_band;
 222                 n_chans = 0;
 223                 for (i = 0; i < req->n_channels; i++) {
 224                         if (req->channels[i]->band == band) {
 225                                 local->hw_scan_req->channels[n_chans] =
 226                                                         req->channels[i];
 227                                 n_chans++;
 228                         }
 229                 }
 230
 231                 local->hw_scan_band++;
 232         } while (!n_chans);
 233
 234         local->hw_scan_req->n_channels = n_chans;
 235
 236         ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
 237                                          req->ie, req->ie_len, band);
 238         local->hw_scan_req->ie_len = ielen;
 239
 240         return true;
 241 }
 242
 243 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 244 {
 245         struct ieee80211_local *local = hw_to_local(hw);
 246         bool was_hw_scan;
 247
 248         mutex_lock(&local->scan_mtx);
 249
 250         /*
 251          * It's ok to abort a not-yet-running scan (that
 252          * we have one at all will be verified by checking
 253          * local->scan_req next), but not to complete it
 254          * successfully.
 255          */
 256         if (WARN_ON(!local->scanning && !aborted))
 257                 aborted = true;
 258
 259         if (WARN_ON(!local->scan_req)) {
 260                 mutex_unlock(&local->scan_mtx);
 261                 return;
 262         }
 263
 264         was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 265         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 266                 ieee80211_queue_delayed_work(&local->hw,
 267                                              &local->scan_work, 0);
 268                 mutex_unlock(&local->scan_mtx);
 269                 return;
 270         }
 271
 272         kfree(local->hw_scan_req);
 273         local->hw_scan_req = NULL;
 274
 275         if (local->scan_req != local->int_scan_req)
 276                 cfg80211_scan_done(local->scan_req, aborted);
 277         local->scan_req = NULL;
 278         local->scan_sdata = NULL;
 279
 280         local->scanning = 0;
 281         local->scan_channel = NULL;
 282
 283         /* we only have to protect scan_req and hw/sw scan */
 284         mutex_unlock(&local->scan_mtx);
 285
 286         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 287         if (was_hw_scan)
 288                 goto done;
 289
 290         ieee80211_configure_filter(local);
 291
 292         drv_sw_scan_complete(local);
 293
 294         ieee80211_offchannel_return(local, true);
 295
 296  done:
 297         ieee80211_recalc_idle(local);
 298         ieee80211_mlme_notify_scan_completed(local);
 299         ieee80211_ibss_notify_scan_completed(local);
 300         ieee80211_mesh_notify_scan_completed(local);
 301         ieee80211_queue_work(&local->hw, &local->work_work);
 302 }
 303 EXPORT_SYMBOL(ieee80211_scan_completed);
 304
 305 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 306 {
 307         /*
 308          * Hardware/driver doesn't support hw_scan, so use software
 309          * scanning instead. First send a nullfunc frame with power save
 310          * bit on so that AP will buffer the frames for us while we are not
 311          * listening, then send probe requests to each channel and wait for
 312          * the responses. After all channels are scanned, tune back to the
 313          * original channel and send a nullfunc frame with power save bit
 314          * off to trigger the AP to send us all the buffered frames.
 315          *
 316          * Note that while local->sw_scanning is true everything else but
 317          * nullfunc frames and probe requests will be dropped in
 318          * ieee80211_tx_h_check_assoc().
 319          */
 320         drv_sw_scan_start(local);
 321
 322         ieee80211_offchannel_stop_beaconing(local);
 323
 324         local->next_scan_state = SCAN_DECISION;
 325         local->scan_channel_idx = 0;
 326
 327         drv_flush(local, false);
 328
 329         ieee80211_configure_filter(local);
 330
 331         ieee80211_queue_delayed_work(&local->hw,
 332                                      &local->scan_work,
 333                                      IEEE80211_CHANNEL_TIME);
 334
 335         return 0;
 336 }
 337
 338
 339 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 340                                   struct cfg80211_scan_request *req)
 341 {
 342         struct ieee80211_local *local = sdata->local;
 343         int rc;
 344
 345         if (local->scan_req)
 346                 return -EBUSY;
 347
 348         if (local->ops->hw_scan) {
 349                 u8 *ies;
 350
 351                 local->hw_scan_req = kmalloc(
 352                                 sizeof(*local->hw_scan_req) +
 353                                 req->n_channels * sizeof(req->channels[0]) +
 354                                 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
 355                                 req->ie_len, GFP_KERNEL);
 356                 if (!local->hw_scan_req)
 357                         return -ENOMEM;
 358
 359                 local->hw_scan_req->ssids = req->ssids;
 360                 local->hw_scan_req->n_ssids = req->n_ssids;
 361                 ies = (u8 *)local->hw_scan_req +
 362                         sizeof(*local->hw_scan_req) +
 363                         req->n_channels * sizeof(req->channels[0]);
 364                 local->hw_scan_req->ie = ies;
 365
 366                 local->hw_scan_band = 0;
 367         }
 368
 369         local->scan_req = req;
 370         local->scan_sdata = sdata;
 371
 372         if (!list_empty(&local->work_list)) {
 373                 /* wait for the work to finish/time out */
 374                 return 0;
 375         }
 376
 377         if (local->ops->hw_scan)
 378                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 379         else
 380                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 381         /*
 382          * Kicking off the scan need not be protected,
 383          * only the scan variable stuff, since now
 384          * local->scan_req is assigned and other callers
 385          * will abort their scan attempts.
 386          *
 387          * This avoids getting a scan_mtx -> iflist_mtx
 388          * dependency, so that the scan completed calls
 389          * have more locking freedom.
 390          */
 391
 392         ieee80211_recalc_idle(local);
 393         mutex_unlock(&local->scan_mtx);
 394
 395         if (local->ops->hw_scan) {
 396                 WARN_ON(!ieee80211_prep_hw_scan(local));
 397                 rc = drv_hw_scan(local, local->hw_scan_req);
 398         } else
 399                 rc = ieee80211_start_sw_scan(local);
 400
 401         mutex_lock(&local->scan_mtx);
 402
 403         if (rc) {
 404                 kfree(local->hw_scan_req);
 405                 local->hw_scan_req = NULL;
 406                 local->scanning = 0;
 407
 408                 ieee80211_recalc_idle(local);
 409
 410                 local->scan_req = NULL;
 411                 local->scan_sdata = NULL;
 412         }
 413
 414         return rc;
 415 }
 416
 417 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
 418                                          unsigned long *next_delay)
 419 {
 420         bool associated = false;
 421         struct ieee80211_sub_if_data *sdata;
 422
 423         /* if no more bands/channels left, complete scan and advance to the idle state */
 424         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 425                 ieee80211_scan_completed(&local->hw, false);
 426                 return 1;
 427         }
 428
 429         /* check if at least one STA interface is associated */
 430         mutex_lock(&local->iflist_mtx);
 431         list_for_each_entry(sdata, &local->interfaces, list) {
 432                 if (!ieee80211_sdata_running(sdata))
 433                         continue;
 434
 435                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 436                         if (sdata->u.mgd.associated) {
 437                                 associated = true;
 438                                 break;
 439                         }
 440                 }
 441         }
 442         mutex_unlock(&local->iflist_mtx);
 443
 444         if (local->scan_channel) {
 445                 /*
 446                  * we're currently scanning a different channel, let's
 447                  * switch back to the operating channel now if at least
 448                  * one interface is associated. Otherwise just scan the
 449                  * next channel
 450                  */
 451                 if (associated)
 452                         local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
 453                 else
 454                         local->next_scan_state = SCAN_SET_CHANNEL;
 455         } else {
 456                 /*
 457                  * we're on the operating channel currently, let's
 458                  * leave that channel now to scan another one
 459                  */
 460                 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
 461         }
 462
 463         *next_delay = 0;
 464         return 0;
 465 }
 466
 467 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
 468                                                     unsigned long *next_delay)
 469 {
 470         ieee80211_offchannel_stop_station(local);
 471
 472         __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
 473
 474         /*
 475          * What if the nullfunc frames didn't arrive?
 476          */
 477         drv_flush(local, false);
 478         if (local->ops->flush)
 479                 *next_delay = 0;
 480         else
 481                 *next_delay = HZ / 10;
 482
 483         /* advance to the next channel to be scanned */
 484         local->next_scan_state = SCAN_SET_CHANNEL;
 485 }
 486
 487 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
 488                                                     unsigned long *next_delay)
 489 {
 490         /* switch back to the operating channel */
 491         local->scan_channel = NULL;
 492         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 493
 494         /*
 495          * Only re-enable station mode interface now; beaconing will be
 496          * re-enabled once the full scan has been completed.
 497          */
 498         ieee80211_offchannel_return(local, false);
 499
 500         __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
 501
 502         *next_delay = HZ / 5;
 503         local->next_scan_state = SCAN_DECISION;
 504 }
 505
 506 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 507                                              unsigned long *next_delay)
 508 {
 509         int skip;
 510         struct ieee80211_channel *chan;
 511
 512         skip = 0;
 513         chan = local->scan_req->channels[local->scan_channel_idx];
 514
 515         local->scan_channel = chan;
 516         if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 517                 skip = 1;
 518
 519         /* advance state machine to next channel/band */
 520         local->scan_channel_idx++;
 521
 522         if (skip) {
 523                 /* if we skip this channel return to the decision state */
 524                 local->next_scan_state = SCAN_DECISION;
 525                 return;
 526         }
 527
 528         /*
 529          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 530          * (which unfortunately doesn't say _why_ step a) is done,
 531          * but it waits for the probe delay or until a frame is
 532          * received - and the received frame would update the NAV).
 533          * For now, we do not support waiting until a frame is
 534          * received.
 535          *
 536          * In any case, it is not necessary for a passive scan.
 537          */
 538         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 539             !local->scan_req->n_ssids) {
 540                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 541                 local->next_scan_state = SCAN_DECISION;
 542                 return;
 543         }
 544
 545         /* active scan, send probes */
 546         *next_delay = IEEE80211_PROBE_DELAY;
 547         local->next_scan_state = SCAN_SEND_PROBE;
 548 }
 549
 550 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 551                                             unsigned long *next_delay)
 552 {
 553         int i;
 554         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 555
 556         for (i = 0; i < local->scan_req->n_ssids; i++)
 557                 ieee80211_send_probe_req(
 558                         sdata, NULL,
 559                         local->scan_req->ssids[i].ssid,
 560                         local->scan_req->ssids[i].ssid_len,
 561                         local->scan_req->ie, local->scan_req->ie_len);
 562
 563         /*
 564          * After sending probe requests, wait for probe responses
 565          * on the channel.
 566          */
 567         *next_delay = IEEE80211_CHANNEL_TIME;
 568         local->next_scan_state = SCAN_DECISION;
 569 }
 570
 571 void ieee80211_scan_work(struct work_struct *work)
 572 {
 573         struct ieee80211_local *local =
 574                 container_of(work, struct ieee80211_local, scan_work.work);
 575         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 576         unsigned long next_delay = 0;
 577
 578         mutex_lock(&local->scan_mtx);
 579         if (!sdata || !local->scan_req) {
 580                 mutex_unlock(&local->scan_mtx);
 581                 return;
 582         }
 583
 584         if (local->hw_scan_req) {
 585                 int rc = drv_hw_scan(local, local->hw_scan_req);
 586                 mutex_unlock(&local->scan_mtx);
 587                 if (rc)
 588                         ieee80211_scan_completed(&local->hw, true);
 589                 return;
 590         }
 591
 592         if (local->scan_req && !local->scanning) {
 593                 struct cfg80211_scan_request *req = local->scan_req;
 594                 int rc;
 595
 596                 local->scan_req = NULL;
 597                 local->scan_sdata = NULL;
 598
 599                 rc = __ieee80211_start_scan(sdata, req);
 600                 mutex_unlock(&local->scan_mtx);
 601
 602                 if (rc)
 603                         ieee80211_scan_completed(&local->hw, true);
 604                 return;
 605         }
 606
 607         mutex_unlock(&local->scan_mtx);
 608
 609         /*
 610          * Avoid re-scheduling when the sdata is going away.
 611          */
 612         if (!ieee80211_sdata_running(sdata)) {
 613                 ieee80211_scan_completed(&local->hw, true);
 614                 return;
 615         }
 616
 617         /*
 618          * as long as no delay is required advance immediately
 619          * without scheduling a new work
 620          */
 621         do {
 622                 switch (local->next_scan_state) {
 623                 case SCAN_DECISION:
 624                         if (ieee80211_scan_state_decision(local, &next_delay))
 625                                 return;
 626                         break;
 627                 case SCAN_SET_CHANNEL:
 628                         ieee80211_scan_state_set_channel(local, &next_delay);
 629                         break;
 630                 case SCAN_SEND_PROBE:
 631                         ieee80211_scan_state_send_probe(local, &next_delay);
 632                         break;
 633                 case SCAN_LEAVE_OPER_CHANNEL:
 634                         ieee80211_scan_state_leave_oper_channel(local, &next_delay);
 635                         break;
 636                 case SCAN_ENTER_OPER_CHANNEL:
 637                         ieee80211_scan_state_enter_oper_channel(local, &next_delay);
 638                         break;
 639                 }
 640         } while (next_delay == 0);
 641
 642         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
 643 }
 644
 645 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 646                            struct cfg80211_scan_request *req)
 647 {
 648         int res;
 649
 650         mutex_lock(&sdata->local->scan_mtx);
 651         res = __ieee80211_start_scan(sdata, req);
 652         mutex_unlock(&sdata->local->scan_mtx);
 653
 654         return res;
 655 }
 656
 657 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 658                                     const u8 *ssid, u8 ssid_len)
 659 {
 660         struct ieee80211_local *local = sdata->local;
 661         int ret = -EBUSY;
 662
 663         mutex_lock(&local->scan_mtx);
 664
 665         /* busy scanning */
 666         if (local->scan_req)
 667                 goto unlock;
 668
 669         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 670         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 671
 672         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 673  unlock:
 674         mutex_unlock(&local->scan_mtx);
 675         return ret;
 676 }
 677
 678 void ieee80211_scan_cancel(struct ieee80211_local *local)
 679 {
 680         bool abortscan;
 681
 682         cancel_delayed_work_sync(&local->scan_work);
 683
 684         /*
 685          * Only call this function when a scan can't be
 686          * queued -- mostly at suspend under RTNL.
 687          */
 688         mutex_lock(&local->scan_mtx);
 689         abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
 690                     (!local->scanning && local->scan_req);
 691         mutex_unlock(&local->scan_mtx);
 692
 693         if (abortscan)
 694                 ieee80211_scan_completed(&local->hw, true);
 695 }