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 / 5)
  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 void ieee80211_rx_bss_remove(struct ieee80211_sub_if_data *sdata, u8 *bssid,
 125                              int freq, u8 *ssid, u8 ssid_len)
 126 {
 127         struct ieee80211_bss *bss;
 128         struct ieee80211_local *local = sdata->local;
 129
 130         bss = ieee80211_rx_bss_get(local, bssid, freq, ssid, ssid_len);
 131         if (bss) {
 132                 cfg80211_unlink_bss(local->hw.wiphy, (void *)bss);
 133                 ieee80211_rx_bss_put(local, bss);
 134         }
 135 }
 136
 137 ieee80211_rx_result
 138 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb,
 139                   struct ieee80211_rx_status *rx_status)
 140 {
 141         struct ieee80211_mgmt *mgmt;
 142         struct ieee80211_bss *bss;
 143         u8 *elements;
 144         struct ieee80211_channel *channel;
 145         size_t baselen;
 146         int freq;
 147         __le16 fc;
 148         bool presp, beacon = false;
 149         struct ieee802_11_elems elems;
 150
 151         if (skb->len < 2)
 152                 return RX_DROP_UNUSABLE;
 153
 154         mgmt = (struct ieee80211_mgmt *) skb->data;
 155         fc = mgmt->frame_control;
 156
 157         if (ieee80211_is_ctl(fc))
 158                 return RX_CONTINUE;
 159
 160         if (skb->len < 24)
 161                 return RX_DROP_MONITOR;
 162
 163         presp = ieee80211_is_probe_resp(fc);
 164         if (presp) {
 165                 /* ignore ProbeResp to foreign address */
 166                 if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
 167                         return RX_DROP_MONITOR;
 168
 169                 presp = true;
 170                 elements = mgmt->u.probe_resp.variable;
 171                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 172         } else {
 173                 beacon = ieee80211_is_beacon(fc);
 174                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 175                 elements = mgmt->u.beacon.variable;
 176         }
 177
 178         if (!presp && !beacon)
 179                 return RX_CONTINUE;
 180
 181         if (baselen > skb->len)
 182                 return RX_DROP_MONITOR;
 183
 184         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
 185
 186         if (elems.ds_params && elems.ds_params_len == 1)
 187                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
 188         else
 189                 freq = rx_status->freq;
 190
 191         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
 192
 193         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 194                 return RX_DROP_MONITOR;
 195
 196         bss = ieee80211_bss_info_update(sdata->local, rx_status,
 197                                         mgmt, skb->len, &elems,
 198                                         channel, beacon);
 199         if (bss)
 200                 ieee80211_rx_bss_put(sdata->local, bss);
 201
 202         dev_kfree_skb(skb);
 203         return RX_QUEUED;
 204 }
 205
 206 /*
 207  * inform AP that we will go to sleep so that it will buffer the frames
 208  * while we scan
 209  */
 210 static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
 211 {
 212         struct ieee80211_local *local = sdata->local;
 213         bool ps = false;
 214
 215         /* FIXME: what to do when local->pspolling is true? */
 216
 217         del_timer_sync(&local->dynamic_ps_timer);
 218         cancel_work_sync(&local->dynamic_ps_enable_work);
 219
 220         if (local->hw.conf.flags & IEEE80211_CONF_PS) {
 221                 ps = true;
 222                 local->hw.conf.flags &= ~IEEE80211_CONF_PS;
 223                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
 224         }
 225
 226         if (!ps || !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
 227                 /*
 228                  * If power save was enabled, no need to send a nullfunc
 229                  * frame because AP knows that we are sleeping. But if the
 230                  * hardware is creating the nullfunc frame for power save
 231                  * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
 232                  * enabled) and power save was enabled, the firmware just
 233                  * sent a null frame with power save disabled. So we need
 234                  * to send a new nullfunc frame to inform the AP that we
 235                  * are again sleeping.
 236                  */
 237                 ieee80211_send_nullfunc(local, sdata, 1);
 238 }
 239
 240 /* inform AP that we are awake again, unless power save is enabled */
 241 static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
 242 {
 243         struct ieee80211_local *local = sdata->local;
 244
 245         if (!local->ps_sdata)
 246                 ieee80211_send_nullfunc(local, sdata, 0);
 247         else {
 248                 /*
 249                  * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
 250                  * will send a nullfunc frame with the powersave bit set
 251                  * even though the AP already knows that we are sleeping.
 252                  * This could be avoided by sending a null frame with power
 253                  * save bit disabled before enabling the power save, but
 254                  * this doesn't gain anything.
 255                  *
 256                  * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
 257                  * to send a nullfunc frame because AP already knows that
 258                  * we are sleeping, let's just enable power save mode in
 259                  * hardware.
 260                  */
 261                 local->hw.conf.flags |= IEEE80211_CONF_PS;
 262                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
 263         }
 264 }
 265
 266 static void ieee80211_restore_scan_ies(struct ieee80211_local *local)
 267 {
 268         kfree(local->scan_req->ie);
 269         local->scan_req->ie = local->orig_ies;
 270         local->scan_req->ie_len = local->orig_ies_len;
 271 }
 272
 273 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 274 {
 275         struct ieee80211_local *local = hw_to_local(hw);
 276         struct ieee80211_sub_if_data *sdata;
 277         bool was_hw_scan;
 278
 279         mutex_lock(&local->scan_mtx);
 280
 281         if (WARN_ON(!local->hw_scanning && !local->sw_scanning)) {
 282                 mutex_unlock(&local->scan_mtx);
 283                 return;
 284         }
 285
 286         if (WARN_ON(!local->scan_req)) {
 287                 mutex_unlock(&local->scan_mtx);
 288                 return;
 289         }
 290
 291         if (local->hw_scanning)
 292                 ieee80211_restore_scan_ies(local);
 293
 294         if (local->scan_req != &local->int_scan_req)
 295                 cfg80211_scan_done(local->scan_req, aborted);
 296         local->scan_req = NULL;
 297
 298         was_hw_scan = local->hw_scanning;
 299         local->hw_scanning = false;
 300         local->sw_scanning = false;
 301         local->scan_channel = NULL;
 302
 303         /* we only have to protect scan_req and hw/sw scan */
 304         mutex_unlock(&local->scan_mtx);
 305
 306         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 307         if (was_hw_scan)
 308                 goto done;
 309
 310         netif_tx_lock_bh(local->mdev);
 311         netif_addr_lock(local->mdev);
 312         local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
 313         drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
 314                              &local->filter_flags,
 315                              local->mdev->mc_count,
 316                              local->mdev->mc_list);
 317
 318         netif_addr_unlock(local->mdev);
 319         netif_tx_unlock_bh(local->mdev);
 320
 321         drv_sw_scan_complete(local);
 322
 323         mutex_lock(&local->iflist_mtx);
 324         list_for_each_entry(sdata, &local->interfaces, list) {
 325                 if (!netif_running(sdata->dev))
 326                         continue;
 327
 328                 /* Tell AP we're back */
 329                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 330                         if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) {
 331                                 ieee80211_scan_ps_disable(sdata);
 332                                 netif_tx_wake_all_queues(sdata->dev);
 333                         }
 334                 } else
 335                         netif_tx_wake_all_queues(sdata->dev);
 336
 337                 /* re-enable beaconing */
 338                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
 339                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
 340                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 341                         ieee80211_bss_info_change_notify(
 342                                 sdata, BSS_CHANGED_BEACON_ENABLED);
 343         }
 344         mutex_unlock(&local->iflist_mtx);
 345
 346  done:
 347         ieee80211_recalc_idle(local);
 348         ieee80211_mlme_notify_scan_completed(local);
 349         ieee80211_ibss_notify_scan_completed(local);
 350         ieee80211_mesh_notify_scan_completed(local);
 351 }
 352 EXPORT_SYMBOL(ieee80211_scan_completed);
 353
 354 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 355 {
 356         struct ieee80211_sub_if_data *sdata;
 357
 358         /*
 359          * Hardware/driver doesn't support hw_scan, so use software
 360          * scanning instead. First send a nullfunc frame with power save
 361          * bit on so that AP will buffer the frames for us while we are not
 362          * listening, then send probe requests to each channel and wait for
 363          * the responses. After all channels are scanned, tune back to the
 364          * original channel and send a nullfunc frame with power save bit
 365          * off to trigger the AP to send us all the buffered frames.
 366          *
 367          * Note that while local->sw_scanning is true everything else but
 368          * nullfunc frames and probe requests will be dropped in
 369          * ieee80211_tx_h_check_assoc().
 370          */
 371         drv_sw_scan_start(local);
 372
 373         mutex_lock(&local->iflist_mtx);
 374         list_for_each_entry(sdata, &local->interfaces, list) {
 375                 if (!netif_running(sdata->dev))
 376                         continue;
 377
 378                 /* disable beaconing */
 379                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
 380                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
 381                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 382                         ieee80211_bss_info_change_notify(
 383                                 sdata, BSS_CHANGED_BEACON_ENABLED);
 384
 385                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 386                         if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) {
 387                                 netif_tx_stop_all_queues(sdata->dev);
 388                                 ieee80211_scan_ps_enable(sdata);
 389                         }
 390                 } else
 391                         netif_tx_stop_all_queues(sdata->dev);
 392         }
 393         mutex_unlock(&local->iflist_mtx);
 394
 395         local->scan_state = SCAN_SET_CHANNEL;
 396         local->scan_channel_idx = 0;
 397
 398         netif_addr_lock_bh(local->mdev);
 399         local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
 400         drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
 401                              &local->filter_flags,
 402                              local->mdev->mc_count,
 403                              local->mdev->mc_list);
 404         netif_addr_unlock_bh(local->mdev);
 405
 406         /* TODO: start scan as soon as all nullfunc frames are ACKed */
 407         queue_delayed_work(local->hw.workqueue, &local->scan_work,
 408                            IEEE80211_CHANNEL_TIME);
 409
 410         return 0;
 411 }
 412
 413
 414 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 415                                   struct cfg80211_scan_request *req)
 416 {
 417         struct ieee80211_local *local = sdata->local;
 418         struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
 419         int rc;
 420
 421         if (local->scan_req)
 422                 return -EBUSY;
 423
 424         if (local->ops->hw_scan) {
 425                 u8 *ies;
 426                 int ielen;
 427
 428                 ies = kmalloc(2 + IEEE80211_MAX_SSID_LEN +
 429                               local->scan_ies_len + req->ie_len, GFP_KERNEL);
 430                 if (!ies)
 431                         return -ENOMEM;
 432
 433                 ielen = ieee80211_build_preq_ies(local, ies,
 434                                                  req->ie, req->ie_len);
 435                 local->orig_ies = req->ie;
 436                 local->orig_ies_len = req->ie_len;
 437                 req->ie = ies;
 438                 req->ie_len = ielen;
 439         }
 440
 441         local->scan_req = req;
 442         local->scan_sdata = sdata;
 443
 444         if (req != &local->int_scan_req &&
 445             sdata->vif.type == NL80211_IFTYPE_STATION &&
 446             (ifmgd->state == IEEE80211_STA_MLME_DIRECT_PROBE ||
 447              ifmgd->state == IEEE80211_STA_MLME_AUTHENTICATE ||
 448              ifmgd->state == IEEE80211_STA_MLME_ASSOCIATE)) {
 449                 /* actually wait for the assoc to finish/time out */
 450                 set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
 451                 return 0;
 452         }
 453
 454         if (local->ops->hw_scan)
 455                 local->hw_scanning = true;
 456         else
 457                 local->sw_scanning = true;
 458         /*
 459          * Kicking off the scan need not be protected,
 460          * only the scan variable stuff, since now
 461          * local->scan_req is assigned and other callers
 462          * will abort their scan attempts.
 463          *
 464          * This avoids getting a scan_mtx -> iflist_mtx
 465          * dependency, so that the scan completed calls
 466          * have more locking freedom.
 467          */
 468
 469         ieee80211_recalc_idle(local);
 470         mutex_unlock(&local->scan_mtx);
 471
 472         if (local->ops->hw_scan)
 473                 rc = drv_hw_scan(local, local->scan_req);
 474         else
 475                 rc = ieee80211_start_sw_scan(local);
 476
 477         mutex_lock(&local->scan_mtx);
 478
 479         if (rc) {
 480                 if (local->ops->hw_scan) {
 481                         local->hw_scanning = false;
 482                         ieee80211_restore_scan_ies(local);
 483                 } else
 484                         local->sw_scanning = false;
 485
 486                 ieee80211_recalc_idle(local);
 487
 488                 local->scan_req = NULL;
 489                 local->scan_sdata = NULL;
 490         }
 491
 492         return rc;
 493 }
 494
 495 void ieee80211_scan_work(struct work_struct *work)
 496 {
 497         struct ieee80211_local *local =
 498                 container_of(work, struct ieee80211_local, scan_work.work);
 499         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 500         struct ieee80211_channel *chan;
 501         int skip, i;
 502         unsigned long next_delay = 0;
 503
 504         mutex_lock(&local->scan_mtx);
 505         if (!sdata || !local->scan_req) {
 506                 mutex_unlock(&local->scan_mtx);
 507                 return;
 508         }
 509
 510         if (local->scan_req && !(local->sw_scanning || local->hw_scanning)) {
 511                 struct cfg80211_scan_request *req = local->scan_req;
 512                 int rc;
 513
 514                 local->scan_req = NULL;
 515
 516                 rc = __ieee80211_start_scan(sdata, req);
 517                 mutex_unlock(&local->scan_mtx);
 518
 519                 if (rc)
 520                         ieee80211_scan_completed(&local->hw, true);
 521                 return;
 522         }
 523
 524         mutex_unlock(&local->scan_mtx);
 525
 526         /*
 527          * Avoid re-scheduling when the sdata is going away.
 528          */
 529         if (!netif_running(sdata->dev)) {
 530                 ieee80211_scan_completed(&local->hw, true);
 531                 return;
 532         }
 533
 534         switch (local->scan_state) {
 535         case SCAN_SET_CHANNEL:
 536                 /* if no more bands/channels left, complete scan */
 537                 if (local->scan_channel_idx >= local->scan_req->n_channels) {
 538                         ieee80211_scan_completed(&local->hw, false);
 539                         return;
 540                 }
 541                 skip = 0;
 542                 chan = local->scan_req->channels[local->scan_channel_idx];
 543
 544                 if (chan->flags & IEEE80211_CHAN_DISABLED ||
 545                     (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
 546                      chan->flags & IEEE80211_CHAN_NO_IBSS))
 547                         skip = 1;
 548
 549                 if (!skip) {
 550                         local->scan_channel = chan;
 551                         if (ieee80211_hw_config(local,
 552                                                 IEEE80211_CONF_CHANGE_CHANNEL))
 553                                 skip = 1;
 554                 }
 555
 556                 /* advance state machine to next channel/band */
 557                 local->scan_channel_idx++;
 558
 559                 if (skip)
 560                         break;
 561
 562                 /*
 563                  * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 564                  * (which unfortunately doesn't say _why_ step a) is done,
 565                  * but it waits for the probe delay or until a frame is
 566                  * received - and the received frame would update the NAV).
 567                  * For now, we do not support waiting until a frame is
 568                  * received.
 569                  *
 570                  * In any case, it is not necessary for a passive scan.
 571                  */
 572                 if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 573                     !local->scan_req->n_ssids) {
 574                         next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 575                         break;
 576                 }
 577
 578                 next_delay = IEEE80211_PROBE_DELAY;
 579                 local->scan_state = SCAN_SEND_PROBE;
 580                 break;
 581         case SCAN_SEND_PROBE:
 582                 for (i = 0; i < local->scan_req->n_ssids; i++)
 583                         ieee80211_send_probe_req(
 584                                 sdata, NULL,
 585                                 local->scan_req->ssids[i].ssid,
 586                                 local->scan_req->ssids[i].ssid_len,
 587                                 local->scan_req->ie, local->scan_req->ie_len);
 588
 589                 /*
 590                  * After sending probe requests, wait for probe responses
 591                  * on the channel.
 592                  */
 593                 next_delay = IEEE80211_CHANNEL_TIME;
 594                 local->scan_state = SCAN_SET_CHANNEL;
 595                 break;
 596         }
 597
 598         queue_delayed_work(local->hw.workqueue, &local->scan_work,
 599                            next_delay);
 600 }
 601
 602 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 603                            struct cfg80211_scan_request *req)
 604 {
 605         int res;
 606
 607         mutex_lock(&sdata->local->scan_mtx);
 608         res = __ieee80211_start_scan(sdata, req);
 609         mutex_unlock(&sdata->local->scan_mtx);
 610
 611         return res;
 612 }
 613
 614 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 615                                     const u8 *ssid, u8 ssid_len)
 616 {
 617         struct ieee80211_local *local = sdata->local;
 618         int ret = -EBUSY;
 619
 620         mutex_lock(&local->scan_mtx);
 621
 622         /* busy scanning */
 623         if (local->scan_req)
 624                 goto unlock;
 625
 626         memcpy(local->int_scan_req.ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 627         local->int_scan_req.ssids[0].ssid_len = ssid_len;
 628
 629         ret = __ieee80211_start_scan(sdata, &sdata->local->int_scan_req);
 630  unlock:
 631         mutex_unlock(&local->scan_mtx);
 632         return ret;
 633 }
 634
 635 void ieee80211_scan_cancel(struct ieee80211_local *local)
 636 {
 637         bool swscan;
 638
 639         cancel_delayed_work_sync(&local->scan_work);
 640
 641         /*
 642          * Only call this function when a scan can't be
 643          * queued -- mostly at suspend under RTNL.
 644          */
 645         mutex_lock(&local->scan_mtx);
 646         swscan = local->sw_scanning;
 647         mutex_unlock(&local->scan_mtx);
 648
 649         if (swscan)
 650                 ieee80211_scan_completed(&local->hw, true);
 651 }