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         /* set default value for buggy AP/no TIM element */
 115         if (bss->dtim_period == 0)
 116                 bss->dtim_period = 1;
 117
 118         bss->supp_rates_len = 0;
 119         if (elems->supp_rates) {
 120                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 121                 if (clen > elems->supp_rates_len)
 122                         clen = elems->supp_rates_len;
 123                 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
 124                        clen);
 125                 bss->supp_rates_len += clen;
 126         }
 127         if (elems->ext_supp_rates) {
 128                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 129                 if (clen > elems->ext_supp_rates_len)
 130                         clen = elems->ext_supp_rates_len;
 131                 memcpy(&bss->supp_rates[bss->supp_rates_len],
 132                        elems->ext_supp_rates, clen);
 133                 bss->supp_rates_len += clen;
 134         }
 135
 136         bss->wmm_used = elems->wmm_param || elems->wmm_info;
 137         bss->uapsd_supported = is_uapsd_supported(elems);
 138
 139         if (!beacon)
 140                 bss->last_probe_resp = jiffies;
 141
 142         return bss;
 143 }
 144
 145 ieee80211_rx_result
 146 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
 147 {
 148         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
 149         struct ieee80211_mgmt *mgmt;
 150         struct ieee80211_bss *bss;
 151         u8 *elements;
 152         struct ieee80211_channel *channel;
 153         size_t baselen;
 154         int freq;
 155         __le16 fc;
 156         bool presp, beacon = false;
 157         struct ieee802_11_elems elems;
 158
 159         if (skb->len < 2)
 160                 return RX_DROP_UNUSABLE;
 161
 162         mgmt = (struct ieee80211_mgmt *) skb->data;
 163         fc = mgmt->frame_control;
 164
 165         if (ieee80211_is_ctl(fc))
 166                 return RX_CONTINUE;
 167
 168         if (skb->len < 24)
 169                 return RX_DROP_MONITOR;
 170
 171         presp = ieee80211_is_probe_resp(fc);
 172         if (presp) {
 173                 /* ignore ProbeResp to foreign address */
 174                 if (memcmp(mgmt->da, sdata->vif.addr, ETH_ALEN))
 175                         return RX_DROP_MONITOR;
 176
 177                 presp = true;
 178                 elements = mgmt->u.probe_resp.variable;
 179                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 180         } else {
 181                 beacon = ieee80211_is_beacon(fc);
 182                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 183                 elements = mgmt->u.beacon.variable;
 184         }
 185
 186         if (!presp && !beacon)
 187                 return RX_CONTINUE;
 188
 189         if (baselen > skb->len)
 190                 return RX_DROP_MONITOR;
 191
 192         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
 193
 194         if (elems.ds_params && elems.ds_params_len == 1)
 195                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
 196         else
 197                 freq = rx_status->freq;
 198
 199         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
 200
 201         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 202                 return RX_DROP_MONITOR;
 203
 204         bss = ieee80211_bss_info_update(sdata->local, rx_status,
 205                                         mgmt, skb->len, &elems,
 206                                         channel, beacon);
 207         if (bss)
 208                 ieee80211_rx_bss_put(sdata->local, bss);
 209
 210         dev_kfree_skb(skb);
 211         return RX_QUEUED;
 212 }
 213
 214 /* return false if no more work */
 215 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 216 {
 217         struct cfg80211_scan_request *req = local->scan_req;
 218         enum ieee80211_band band;
 219         int i, ielen, n_chans;
 220
 221         do {
 222                 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
 223                         return false;
 224
 225                 band = local->hw_scan_band;
 226                 n_chans = 0;
 227                 for (i = 0; i < req->n_channels; i++) {
 228                         if (req->channels[i]->band == band) {
 229                                 local->hw_scan_req->channels[n_chans] =
 230                                                         req->channels[i];
 231                                 n_chans++;
 232                         }
 233                 }
 234
 235                 local->hw_scan_band++;
 236         } while (!n_chans);
 237
 238         local->hw_scan_req->n_channels = n_chans;
 239
 240         ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
 241                                          req->ie, req->ie_len, band);
 242         local->hw_scan_req->ie_len = ielen;
 243
 244         return true;
 245 }
 246
 247 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 248 {
 249         struct ieee80211_local *local = hw_to_local(hw);
 250         bool was_hw_scan;
 251
 252         mutex_lock(&local->scan_mtx);
 253
 254         /*
 255          * It's ok to abort a not-yet-running scan (that
 256          * we have one at all will be verified by checking
 257          * local->scan_req next), but not to complete it
 258          * successfully.
 259          */
 260         if (WARN_ON(!local->scanning && !aborted))
 261                 aborted = true;
 262
 263         if (WARN_ON(!local->scan_req)) {
 264                 mutex_unlock(&local->scan_mtx);
 265                 return;
 266         }
 267
 268         was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 269         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 270                 ieee80211_queue_delayed_work(&local->hw,
 271                                              &local->scan_work, 0);
 272                 mutex_unlock(&local->scan_mtx);
 273                 return;
 274         }
 275
 276         kfree(local->hw_scan_req);
 277         local->hw_scan_req = NULL;
 278
 279         if (local->scan_req != local->int_scan_req)
 280                 cfg80211_scan_done(local->scan_req, aborted);
 281         local->scan_req = NULL;
 282         local->scan_sdata = NULL;
 283
 284         local->scanning = 0;
 285         local->scan_channel = NULL;
 286
 287         /* we only have to protect scan_req and hw/sw scan */
 288         mutex_unlock(&local->scan_mtx);
 289
 290         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 291         if (was_hw_scan)
 292                 goto done;
 293
 294         ieee80211_configure_filter(local);
 295
 296         drv_sw_scan_complete(local);
 297
 298         ieee80211_offchannel_return(local, true);
 299
 300  done:
 301         ieee80211_recalc_idle(local);
 302         ieee80211_mlme_notify_scan_completed(local);
 303         ieee80211_ibss_notify_scan_completed(local);
 304         ieee80211_mesh_notify_scan_completed(local);
 305         ieee80211_queue_work(&local->hw, &local->work_work);
 306 }
 307 EXPORT_SYMBOL(ieee80211_scan_completed);
 308
 309 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 310 {
 311         /*
 312          * Hardware/driver doesn't support hw_scan, so use software
 313          * scanning instead. First send a nullfunc frame with power save
 314          * bit on so that AP will buffer the frames for us while we are not
 315          * listening, then send probe requests to each channel and wait for
 316          * the responses. After all channels are scanned, tune back to the
 317          * original channel and send a nullfunc frame with power save bit
 318          * off to trigger the AP to send us all the buffered frames.
 319          *
 320          * Note that while local->sw_scanning is true everything else but
 321          * nullfunc frames and probe requests will be dropped in
 322          * ieee80211_tx_h_check_assoc().
 323          */
 324         drv_sw_scan_start(local);
 325
 326         ieee80211_offchannel_stop_beaconing(local);
 327
 328         local->next_scan_state = SCAN_DECISION;
 329         local->scan_channel_idx = 0;
 330
 331         drv_flush(local, false);
 332
 333         ieee80211_configure_filter(local);
 334
 335         ieee80211_queue_delayed_work(&local->hw,
 336                                      &local->scan_work,
 337                                      IEEE80211_CHANNEL_TIME);
 338
 339         return 0;
 340 }
 341
 342
 343 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 344                                   struct cfg80211_scan_request *req)
 345 {
 346         struct ieee80211_local *local = sdata->local;
 347         int rc;
 348
 349         if (local->scan_req)
 350                 return -EBUSY;
 351
 352         if (local->ops->hw_scan) {
 353                 u8 *ies;
 354
 355                 local->hw_scan_req = kmalloc(
 356                                 sizeof(*local->hw_scan_req) +
 357                                 req->n_channels * sizeof(req->channels[0]) +
 358                                 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
 359                                 req->ie_len, GFP_KERNEL);
 360                 if (!local->hw_scan_req)
 361                         return -ENOMEM;
 362
 363                 local->hw_scan_req->ssids = req->ssids;
 364                 local->hw_scan_req->n_ssids = req->n_ssids;
 365                 ies = (u8 *)local->hw_scan_req +
 366                         sizeof(*local->hw_scan_req) +
 367                         req->n_channels * sizeof(req->channels[0]);
 368                 local->hw_scan_req->ie = ies;
 369
 370                 local->hw_scan_band = 0;
 371         }
 372
 373         local->scan_req = req;
 374         local->scan_sdata = sdata;
 375
 376         if (!list_empty(&local->work_list)) {
 377                 /* wait for the work to finish/time out */
 378                 return 0;
 379         }
 380
 381         if (local->ops->hw_scan)
 382                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 383         else
 384                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 385         /*
 386          * Kicking off the scan need not be protected,
 387          * only the scan variable stuff, since now
 388          * local->scan_req is assigned and other callers
 389          * will abort their scan attempts.
 390          *
 391          * This avoids getting a scan_mtx -> iflist_mtx
 392          * dependency, so that the scan completed calls
 393          * have more locking freedom.
 394          */
 395
 396         ieee80211_recalc_idle(local);
 397         mutex_unlock(&local->scan_mtx);
 398
 399         if (local->ops->hw_scan) {
 400                 WARN_ON(!ieee80211_prep_hw_scan(local));
 401                 rc = drv_hw_scan(local, local->hw_scan_req);
 402         } else
 403                 rc = ieee80211_start_sw_scan(local);
 404
 405         mutex_lock(&local->scan_mtx);
 406
 407         if (rc) {
 408                 kfree(local->hw_scan_req);
 409                 local->hw_scan_req = NULL;
 410                 local->scanning = 0;
 411
 412                 ieee80211_recalc_idle(local);
 413
 414                 local->scan_req = NULL;
 415                 local->scan_sdata = NULL;
 416         }
 417
 418         return rc;
 419 }
 420
 421 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
 422                                          unsigned long *next_delay)
 423 {
 424         bool associated = false;
 425         struct ieee80211_sub_if_data *sdata;
 426
 427         /* if no more bands/channels left, complete scan and advance to the idle state */
 428         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 429                 ieee80211_scan_completed(&local->hw, false);
 430                 return 1;
 431         }
 432
 433         /* check if at least one STA interface is associated */
 434         mutex_lock(&local->iflist_mtx);
 435         list_for_each_entry(sdata, &local->interfaces, list) {
 436                 if (!ieee80211_sdata_running(sdata))
 437                         continue;
 438
 439                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 440                         if (sdata->u.mgd.associated) {
 441                                 associated = true;
 442                                 break;
 443                         }
 444                 }
 445         }
 446         mutex_unlock(&local->iflist_mtx);
 447
 448         if (local->scan_channel) {
 449                 /*
 450                  * we're currently scanning a different channel, let's
 451                  * switch back to the operating channel now if at least
 452                  * one interface is associated. Otherwise just scan the
 453                  * next channel
 454                  */
 455                 if (associated)
 456                         local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
 457                 else
 458                         local->next_scan_state = SCAN_SET_CHANNEL;
 459         } else {
 460                 /*
 461                  * we're on the operating channel currently, let's
 462                  * leave that channel now to scan another one
 463                  */
 464                 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
 465         }
 466
 467         *next_delay = 0;
 468         return 0;
 469 }
 470
 471 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
 472                                                     unsigned long *next_delay)
 473 {
 474         ieee80211_offchannel_stop_station(local);
 475
 476         __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
 477
 478         /*
 479          * What if the nullfunc frames didn't arrive?
 480          */
 481         drv_flush(local, false);
 482         if (local->ops->flush)
 483                 *next_delay = 0;
 484         else
 485                 *next_delay = HZ / 10;
 486
 487         /* advance to the next channel to be scanned */
 488         local->next_scan_state = SCAN_SET_CHANNEL;
 489 }
 490
 491 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
 492                                                     unsigned long *next_delay)
 493 {
 494         /* switch back to the operating channel */
 495         local->scan_channel = NULL;
 496         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 497
 498         /*
 499          * Only re-enable station mode interface now; beaconing will be
 500          * re-enabled once the full scan has been completed.
 501          */
 502         ieee80211_offchannel_return(local, false);
 503
 504         __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
 505
 506         *next_delay = HZ / 5;
 507         local->next_scan_state = SCAN_DECISION;
 508 }
 509
 510 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 511                                              unsigned long *next_delay)
 512 {
 513         int skip;
 514         struct ieee80211_channel *chan;
 515
 516         skip = 0;
 517         chan = local->scan_req->channels[local->scan_channel_idx];
 518
 519         local->scan_channel = chan;
 520         if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 521                 skip = 1;
 522
 523         /* advance state machine to next channel/band */
 524         local->scan_channel_idx++;
 525
 526         if (skip) {
 527                 /* if we skip this channel return to the decision state */
 528                 local->next_scan_state = SCAN_DECISION;
 529                 return;
 530         }
 531
 532         /*
 533          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 534          * (which unfortunately doesn't say _why_ step a) is done,
 535          * but it waits for the probe delay or until a frame is
 536          * received - and the received frame would update the NAV).
 537          * For now, we do not support waiting until a frame is
 538          * received.
 539          *
 540          * In any case, it is not necessary for a passive scan.
 541          */
 542         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 543             !local->scan_req->n_ssids) {
 544                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 545                 local->next_scan_state = SCAN_DECISION;
 546                 return;
 547         }
 548
 549         /* active scan, send probes */
 550         *next_delay = IEEE80211_PROBE_DELAY;
 551         local->next_scan_state = SCAN_SEND_PROBE;
 552 }
 553
 554 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 555                                             unsigned long *next_delay)
 556 {
 557         int i;
 558         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 559
 560         for (i = 0; i < local->scan_req->n_ssids; i++)
 561                 ieee80211_send_probe_req(
 562                         sdata, NULL,
 563                         local->scan_req->ssids[i].ssid,
 564                         local->scan_req->ssids[i].ssid_len,
 565                         local->scan_req->ie, local->scan_req->ie_len);
 566
 567         /*
 568          * After sending probe requests, wait for probe responses
 569          * on the channel.
 570          */
 571         *next_delay = IEEE80211_CHANNEL_TIME;
 572         local->next_scan_state = SCAN_DECISION;
 573 }
 574
 575 void ieee80211_scan_work(struct work_struct *work)
 576 {
 577         struct ieee80211_local *local =
 578                 container_of(work, struct ieee80211_local, scan_work.work);
 579         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 580         unsigned long next_delay = 0;
 581
 582         mutex_lock(&local->scan_mtx);
 583         if (!sdata || !local->scan_req) {
 584                 mutex_unlock(&local->scan_mtx);
 585                 return;
 586         }
 587
 588         if (local->hw_scan_req) {
 589                 int rc = drv_hw_scan(local, local->hw_scan_req);
 590                 mutex_unlock(&local->scan_mtx);
 591                 if (rc)
 592                         ieee80211_scan_completed(&local->hw, true);
 593                 return;
 594         }
 595
 596         if (local->scan_req && !local->scanning) {
 597                 struct cfg80211_scan_request *req = local->scan_req;
 598                 int rc;
 599
 600                 local->scan_req = NULL;
 601                 local->scan_sdata = NULL;
 602
 603                 rc = __ieee80211_start_scan(sdata, req);
 604                 mutex_unlock(&local->scan_mtx);
 605
 606                 if (rc)
 607                         ieee80211_scan_completed(&local->hw, true);
 608                 return;
 609         }
 610
 611         mutex_unlock(&local->scan_mtx);
 612
 613         /*
 614          * Avoid re-scheduling when the sdata is going away.
 615          */
 616         if (!ieee80211_sdata_running(sdata)) {
 617                 ieee80211_scan_completed(&local->hw, true);
 618                 return;
 619         }
 620
 621         /*
 622          * as long as no delay is required advance immediately
 623          * without scheduling a new work
 624          */
 625         do {
 626                 switch (local->next_scan_state) {
 627                 case SCAN_DECISION:
 628                         if (ieee80211_scan_state_decision(local, &next_delay))
 629                                 return;
 630                         break;
 631                 case SCAN_SET_CHANNEL:
 632                         ieee80211_scan_state_set_channel(local, &next_delay);
 633                         break;
 634                 case SCAN_SEND_PROBE:
 635                         ieee80211_scan_state_send_probe(local, &next_delay);
 636                         break;
 637                 case SCAN_LEAVE_OPER_CHANNEL:
 638                         ieee80211_scan_state_leave_oper_channel(local, &next_delay);
 639                         break;
 640                 case SCAN_ENTER_OPER_CHANNEL:
 641                         ieee80211_scan_state_enter_oper_channel(local, &next_delay);
 642                         break;
 643                 }
 644         } while (next_delay == 0);
 645
 646         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
 647 }
 648
 649 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 650                            struct cfg80211_scan_request *req)
 651 {
 652         int res;
 653
 654         mutex_lock(&sdata->local->scan_mtx);
 655         res = __ieee80211_start_scan(sdata, req);
 656         mutex_unlock(&sdata->local->scan_mtx);
 657
 658         return res;
 659 }
 660
 661 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 662                                     const u8 *ssid, u8 ssid_len)
 663 {
 664         struct ieee80211_local *local = sdata->local;
 665         int ret = -EBUSY;
 666
 667         mutex_lock(&local->scan_mtx);
 668
 669         /* busy scanning */
 670         if (local->scan_req)
 671                 goto unlock;
 672
 673         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 674         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 675
 676         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 677  unlock:
 678         mutex_unlock(&local->scan_mtx);
 679         return ret;
 680 }
 681
 682 void ieee80211_scan_cancel(struct ieee80211_local *local)
 683 {
 684         bool abortscan;
 685
 686         cancel_delayed_work_sync(&local->scan_work);
 687
 688         /*
 689          * Only call this function when a scan can't be
 690          * queued -- mostly at suspend under RTNL.
 691          */
 692         mutex_lock(&local->scan_mtx);
 693         abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
 694                     (!local->scanning && local->scan_req);
 695         mutex_unlock(&local->scan_mtx);
 696
 697         if (abortscan)
 698                 ieee80211_scan_completed(&local->hw, true);
 699 }