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 <linux/pm_qos_params.h>
  18 #include <net/sch_generic.h>
  19 #include <linux/slab.h>
  20 #include <net/mac80211.h>
  21
  22 #include "ieee80211_i.h"
  23 #include "driver-ops.h"
  24 #include "mesh.h"
  25
  26 #define IEEE80211_PROBE_DELAY (HZ / 33)
  27 #define IEEE80211_CHANNEL_TIME (HZ / 33)
  28 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
  29
  30 struct ieee80211_bss *
  31 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
  32                      u8 *ssid, u8 ssid_len)
  33 {
  34         struct cfg80211_bss *cbss;
  35
  36         cbss = cfg80211_get_bss(local->hw.wiphy,
  37                                 ieee80211_get_channel(local->hw.wiphy, freq),
  38                                 bssid, ssid, ssid_len, 0, 0);
  39         if (!cbss)
  40                 return NULL;
  41         return (void *)cbss->priv;
  42 }
  43
  44 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
  45 {
  46         struct ieee80211_bss *bss = (void *)cbss->priv;
  47
  48         kfree(bss_mesh_id(bss));
  49         kfree(bss_mesh_cfg(bss));
  50 }
  51
  52 void ieee80211_rx_bss_put(struct ieee80211_local *local,
  53                           struct ieee80211_bss *bss)
  54 {
  55         if (!bss)
  56                 return;
  57         cfg80211_put_bss(container_of((void *)bss, struct cfg80211_bss, priv));
  58 }
  59
  60 static bool is_uapsd_supported(struct ieee802_11_elems *elems)
  61 {
  62         u8 qos_info;
  63
  64         if (elems->wmm_info && elems->wmm_info_len == 7
  65             && elems->wmm_info[5] == 1)
  66                 qos_info = elems->wmm_info[6];
  67         else if (elems->wmm_param && elems->wmm_param_len == 24
  68                  && elems->wmm_param[5] == 1)
  69                 qos_info = elems->wmm_param[6];
  70         else
  71                 /* no valid wmm information or parameter element found */
  72                 return false;
  73
  74         return qos_info & IEEE80211_WMM_IE_AP_QOSINFO_UAPSD;
  75 }
  76
  77 struct ieee80211_bss *
  78 ieee80211_bss_info_update(struct ieee80211_local *local,
  79                           struct ieee80211_rx_status *rx_status,
  80                           struct ieee80211_mgmt *mgmt,
  81                           size_t len,
  82                           struct ieee802_11_elems *elems,
  83                           struct ieee80211_channel *channel,
  84                           bool beacon)
  85 {
  86         struct cfg80211_bss *cbss;
  87         struct ieee80211_bss *bss;
  88         int clen, srlen;
  89         s32 signal = 0;
  90
  91         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
  92                 signal = rx_status->signal * 100;
  93         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
  94                 signal = (rx_status->signal * 100) / local->hw.max_signal;
  95
  96         cbss = cfg80211_inform_bss_frame(local->hw.wiphy, channel,
  97                                          mgmt, len, signal, GFP_ATOMIC);
  98
  99         if (!cbss)
 100                 return NULL;
 101
 102         cbss->free_priv = ieee80211_rx_bss_free;
 103         bss = (void *)cbss->priv;
 104
 105         /* save the ERP value so that it is available at association time */
 106         if (elems->erp_info && elems->erp_info_len >= 1) {
 107                 bss->erp_value = elems->erp_info[0];
 108                 bss->has_erp_value = 1;
 109         }
 110
 111         if (elems->tim) {
 112                 struct ieee80211_tim_ie *tim_ie =
 113                         (struct ieee80211_tim_ie *)elems->tim;
 114                 bss->dtim_period = tim_ie->dtim_period;
 115         }
 116
 117         /* replace old supported rates if we get new values */
 118         srlen = 0;
 119         if (elems->supp_rates) {
 120                 clen = IEEE80211_MAX_SUPP_RATES;
 121                 if (clen > elems->supp_rates_len)
 122                         clen = elems->supp_rates_len;
 123                 memcpy(bss->supp_rates, elems->supp_rates, clen);
 124                 srlen += clen;
 125         }
 126         if (elems->ext_supp_rates) {
 127                 clen = IEEE80211_MAX_SUPP_RATES - srlen;
 128                 if (clen > elems->ext_supp_rates_len)
 129                         clen = elems->ext_supp_rates_len;
 130                 memcpy(bss->supp_rates + srlen, elems->ext_supp_rates, clen);
 131                 srlen += clen;
 132         }
 133         if (srlen)
 134                 bss->supp_rates_len = srlen;
 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         trace_api_scan_completed(local, aborted);
 253
 254         mutex_lock(&local->scan_mtx);
 255
 256         /*
 257          * It's ok to abort a not-yet-running scan (that
 258          * we have one at all will be verified by checking
 259          * local->scan_req next), but not to complete it
 260          * successfully.
 261          */
 262         if (WARN_ON(!local->scanning && !aborted))
 263                 aborted = true;
 264
 265         if (WARN_ON(!local->scan_req)) {
 266                 mutex_unlock(&local->scan_mtx);
 267                 return;
 268         }
 269
 270         was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 271         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 272                 ieee80211_queue_delayed_work(&local->hw,
 273                                              &local->scan_work, 0);
 274                 mutex_unlock(&local->scan_mtx);
 275                 return;
 276         }
 277
 278         kfree(local->hw_scan_req);
 279         local->hw_scan_req = NULL;
 280
 281         if (local->scan_req != local->int_scan_req)
 282                 cfg80211_scan_done(local->scan_req, aborted);
 283         local->scan_req = NULL;
 284         local->scan_sdata = NULL;
 285
 286         local->scanning = 0;
 287         local->scan_channel = NULL;
 288
 289         /* we only have to protect scan_req and hw/sw scan */
 290         mutex_unlock(&local->scan_mtx);
 291
 292         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 293         if (was_hw_scan)
 294                 goto done;
 295
 296         ieee80211_configure_filter(local);
 297
 298         drv_sw_scan_complete(local);
 299
 300         ieee80211_offchannel_return(local, true);
 301
 302  done:
 303         ieee80211_recalc_idle(local);
 304         ieee80211_mlme_notify_scan_completed(local);
 305         ieee80211_ibss_notify_scan_completed(local);
 306         ieee80211_mesh_notify_scan_completed(local);
 307         ieee80211_queue_work(&local->hw, &local->work_work);
 308 }
 309 EXPORT_SYMBOL(ieee80211_scan_completed);
 310
 311 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 312 {
 313         /*
 314          * Hardware/driver doesn't support hw_scan, so use software
 315          * scanning instead. First send a nullfunc frame with power save
 316          * bit on so that AP will buffer the frames for us while we are not
 317          * listening, then send probe requests to each channel and wait for
 318          * the responses. After all channels are scanned, tune back to the
 319          * original channel and send a nullfunc frame with power save bit
 320          * off to trigger the AP to send us all the buffered frames.
 321          *
 322          * Note that while local->sw_scanning is true everything else but
 323          * nullfunc frames and probe requests will be dropped in
 324          * ieee80211_tx_h_check_assoc().
 325          */
 326         drv_sw_scan_start(local);
 327
 328         ieee80211_offchannel_stop_beaconing(local);
 329
 330         local->leave_oper_channel_time = 0;
 331         local->next_scan_state = SCAN_DECISION;
 332         local->scan_channel_idx = 0;
 333
 334         drv_flush(local, false);
 335
 336         ieee80211_configure_filter(local);
 337
 338         ieee80211_queue_delayed_work(&local->hw,
 339                                      &local->scan_work,
 340                                      IEEE80211_CHANNEL_TIME);
 341
 342         return 0;
 343 }
 344
 345
 346 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 347                                   struct cfg80211_scan_request *req)
 348 {
 349         struct ieee80211_local *local = sdata->local;
 350         int rc;
 351
 352         if (local->scan_req)
 353                 return -EBUSY;
 354
 355         if (!list_empty(&local->work_list)) {
 356                 /* wait for the work to finish/time out */
 357                 local->scan_req = req;
 358                 local->scan_sdata = sdata;
 359                 return 0;
 360         }
 361
 362         if (local->ops->hw_scan) {
 363                 u8 *ies;
 364
 365                 local->hw_scan_req = kmalloc(
 366                                 sizeof(*local->hw_scan_req) +
 367                                 req->n_channels * sizeof(req->channels[0]) +
 368                                 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
 369                                 req->ie_len, GFP_KERNEL);
 370                 if (!local->hw_scan_req)
 371                         return -ENOMEM;
 372
 373                 local->hw_scan_req->ssids = req->ssids;
 374                 local->hw_scan_req->n_ssids = req->n_ssids;
 375                 ies = (u8 *)local->hw_scan_req +
 376                         sizeof(*local->hw_scan_req) +
 377                         req->n_channels * sizeof(req->channels[0]);
 378                 local->hw_scan_req->ie = ies;
 379
 380                 local->hw_scan_band = 0;
 381
 382                 /*
 383                  * After allocating local->hw_scan_req, we must
 384                  * go through until ieee80211_prep_hw_scan(), so
 385                  * anything that might be changed here and leave
 386                  * this function early must not go after this
 387                  * allocation.
 388                  */
 389         }
 390
 391         local->scan_req = req;
 392         local->scan_sdata = sdata;
 393
 394         if (local->ops->hw_scan)
 395                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 396         else
 397                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 398
 399         /*
 400          * Kicking off the scan need not be protected,
 401          * only the scan variable stuff, since now
 402          * local->scan_req is assigned and other callers
 403          * will abort their scan attempts.
 404          *
 405          * This avoids too many locking dependencies
 406          * so that the scan completed calls have more
 407          * locking freedom.
 408          */
 409
 410         ieee80211_recalc_idle(local);
 411         mutex_unlock(&local->scan_mtx);
 412
 413         if (local->ops->hw_scan) {
 414                 WARN_ON(!ieee80211_prep_hw_scan(local));
 415                 rc = drv_hw_scan(local, sdata, local->hw_scan_req);
 416         } else
 417                 rc = ieee80211_start_sw_scan(local);
 418
 419         mutex_lock(&local->scan_mtx);
 420
 421         if (rc) {
 422                 kfree(local->hw_scan_req);
 423                 local->hw_scan_req = NULL;
 424                 local->scanning = 0;
 425
 426                 ieee80211_recalc_idle(local);
 427
 428                 local->scan_req = NULL;
 429                 local->scan_sdata = NULL;
 430         }
 431
 432         return rc;
 433 }
 434
 435 static unsigned long
 436 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
 437 {
 438         /*
 439          * TODO: channel switching also consumes quite some time,
 440          * add that delay as well to get a better estimation
 441          */
 442         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN)
 443                 return IEEE80211_PASSIVE_CHANNEL_TIME;
 444         return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
 445 }
 446
 447 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
 448                                          unsigned long *next_delay)
 449 {
 450         bool associated = false;
 451         bool tx_empty = true;
 452         bool bad_latency;
 453         bool listen_int_exceeded;
 454         unsigned long min_beacon_int = 0;
 455         struct ieee80211_sub_if_data *sdata;
 456         struct ieee80211_channel *next_chan;
 457
 458         /* if no more bands/channels left, complete scan and advance to the idle state */
 459         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 460                 ieee80211_scan_completed(&local->hw, false);
 461                 return 1;
 462         }
 463
 464         /*
 465          * check if at least one STA interface is associated,
 466          * check if at least one STA interface has pending tx frames
 467          * and grab the lowest used beacon interval
 468          */
 469         mutex_lock(&local->iflist_mtx);
 470         list_for_each_entry(sdata, &local->interfaces, list) {
 471                 if (!ieee80211_sdata_running(sdata))
 472                         continue;
 473
 474                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 475                         if (sdata->u.mgd.associated) {
 476                                 associated = true;
 477
 478                                 if (sdata->vif.bss_conf.beacon_int <
 479                                     min_beacon_int || min_beacon_int == 0)
 480                                         min_beacon_int =
 481                                                 sdata->vif.bss_conf.beacon_int;
 482
 483                                 if (!qdisc_all_tx_empty(sdata->dev)) {
 484                                         tx_empty = false;
 485                                         break;
 486                                 }
 487                         }
 488                 }
 489         }
 490         mutex_unlock(&local->iflist_mtx);
 491
 492         if (local->scan_channel) {
 493                 /*
 494                  * we're currently scanning a different channel, let's
 495                  * see if we can scan another channel without interfering
 496                  * with the current traffic situation.
 497                  *
 498                  * Since we don't know if the AP has pending frames for us
 499                  * we can only check for our tx queues and use the current
 500                  * pm_qos requirements for rx. Hence, if no tx traffic occurs
 501                  * at all we will scan as many channels in a row as the pm_qos
 502                  * latency allows us to. Additionally we also check for the
 503                  * currently negotiated listen interval to prevent losing
 504                  * frames unnecessarily.
 505                  *
 506                  * Otherwise switch back to the operating channel.
 507                  */
 508                 next_chan = local->scan_req->channels[local->scan_channel_idx];
 509
 510                 bad_latency = time_after(jiffies +
 511                                 ieee80211_scan_get_channel_time(next_chan),
 512                                 local->leave_oper_channel_time +
 513                                 usecs_to_jiffies(pm_qos_request(PM_QOS_NETWORK_LATENCY)));
 514
 515                 listen_int_exceeded = time_after(jiffies +
 516                                 ieee80211_scan_get_channel_time(next_chan),
 517                                 local->leave_oper_channel_time +
 518                                 usecs_to_jiffies(min_beacon_int * 1024) *
 519                                 local->hw.conf.listen_interval);
 520
 521                 if (associated && ( !tx_empty || bad_latency ||
 522                     listen_int_exceeded))
 523                         local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
 524                 else
 525                         local->next_scan_state = SCAN_SET_CHANNEL;
 526         } else {
 527                 /*
 528                  * we're on the operating channel currently, let's
 529                  * leave that channel now to scan another one
 530                  */
 531                 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
 532         }
 533
 534         *next_delay = 0;
 535         return 0;
 536 }
 537
 538 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
 539                                                     unsigned long *next_delay)
 540 {
 541         ieee80211_offchannel_stop_station(local);
 542
 543         __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
 544
 545         /*
 546          * What if the nullfunc frames didn't arrive?
 547          */
 548         drv_flush(local, false);
 549         if (local->ops->flush)
 550                 *next_delay = 0;
 551         else
 552                 *next_delay = HZ / 10;
 553
 554         /* remember when we left the operating channel */
 555         local->leave_oper_channel_time = jiffies;
 556
 557         /* advance to the next channel to be scanned */
 558         local->next_scan_state = SCAN_SET_CHANNEL;
 559 }
 560
 561 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
 562                                                     unsigned long *next_delay)
 563 {
 564         /* switch back to the operating channel */
 565         local->scan_channel = NULL;
 566         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 567
 568         /*
 569          * Only re-enable station mode interface now; beaconing will be
 570          * re-enabled once the full scan has been completed.
 571          */
 572         ieee80211_offchannel_return(local, false);
 573
 574         __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
 575
 576         *next_delay = HZ / 5;
 577         local->next_scan_state = SCAN_DECISION;
 578 }
 579
 580 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 581                                              unsigned long *next_delay)
 582 {
 583         int skip;
 584         struct ieee80211_channel *chan;
 585
 586         skip = 0;
 587         chan = local->scan_req->channels[local->scan_channel_idx];
 588
 589         local->scan_channel = chan;
 590         if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 591                 skip = 1;
 592
 593         /* advance state machine to next channel/band */
 594         local->scan_channel_idx++;
 595
 596         if (skip) {
 597                 /* if we skip this channel return to the decision state */
 598                 local->next_scan_state = SCAN_DECISION;
 599                 return;
 600         }
 601
 602         /*
 603          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 604          * (which unfortunately doesn't say _why_ step a) is done,
 605          * but it waits for the probe delay or until a frame is
 606          * received - and the received frame would update the NAV).
 607          * For now, we do not support waiting until a frame is
 608          * received.
 609          *
 610          * In any case, it is not necessary for a passive scan.
 611          */
 612         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 613             !local->scan_req->n_ssids) {
 614                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 615                 local->next_scan_state = SCAN_DECISION;
 616                 return;
 617         }
 618
 619         /* active scan, send probes */
 620         *next_delay = IEEE80211_PROBE_DELAY;
 621         local->next_scan_state = SCAN_SEND_PROBE;
 622 }
 623
 624 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 625                                             unsigned long *next_delay)
 626 {
 627         int i;
 628         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 629
 630         for (i = 0; i < local->scan_req->n_ssids; i++)
 631                 ieee80211_send_probe_req(
 632                         sdata, NULL,
 633                         local->scan_req->ssids[i].ssid,
 634                         local->scan_req->ssids[i].ssid_len,
 635                         local->scan_req->ie, local->scan_req->ie_len);
 636
 637         /*
 638          * After sending probe requests, wait for probe responses
 639          * on the channel.
 640          */
 641         *next_delay = IEEE80211_CHANNEL_TIME;
 642         local->next_scan_state = SCAN_DECISION;
 643 }
 644
 645 void ieee80211_scan_work(struct work_struct *work)
 646 {
 647         struct ieee80211_local *local =
 648                 container_of(work, struct ieee80211_local, scan_work.work);
 649         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 650         unsigned long next_delay = 0;
 651
 652         mutex_lock(&local->scan_mtx);
 653         if (!sdata || !local->scan_req) {
 654                 mutex_unlock(&local->scan_mtx);
 655                 return;
 656         }
 657
 658         if (local->hw_scan_req) {
 659                 int rc = drv_hw_scan(local, sdata, local->hw_scan_req);
 660                 mutex_unlock(&local->scan_mtx);
 661                 if (rc)
 662                         ieee80211_scan_completed(&local->hw, true);
 663                 return;
 664         }
 665
 666         if (local->scan_req && !local->scanning) {
 667                 struct cfg80211_scan_request *req = local->scan_req;
 668                 int rc;
 669
 670                 local->scan_req = NULL;
 671                 local->scan_sdata = NULL;
 672
 673                 rc = __ieee80211_start_scan(sdata, req);
 674                 mutex_unlock(&local->scan_mtx);
 675
 676                 if (rc)
 677                         ieee80211_scan_completed(&local->hw, true);
 678                 return;
 679         }
 680
 681         mutex_unlock(&local->scan_mtx);
 682
 683         /*
 684          * Avoid re-scheduling when the sdata is going away.
 685          */
 686         if (!ieee80211_sdata_running(sdata)) {
 687                 ieee80211_scan_completed(&local->hw, true);
 688                 return;
 689         }
 690
 691         /*
 692          * as long as no delay is required advance immediately
 693          * without scheduling a new work
 694          */
 695         do {
 696                 switch (local->next_scan_state) {
 697                 case SCAN_DECISION:
 698                         if (ieee80211_scan_state_decision(local, &next_delay))
 699                                 return;
 700                         break;
 701                 case SCAN_SET_CHANNEL:
 702                         ieee80211_scan_state_set_channel(local, &next_delay);
 703                         break;
 704                 case SCAN_SEND_PROBE:
 705                         ieee80211_scan_state_send_probe(local, &next_delay);
 706                         break;
 707                 case SCAN_LEAVE_OPER_CHANNEL:
 708                         ieee80211_scan_state_leave_oper_channel(local, &next_delay);
 709                         break;
 710                 case SCAN_ENTER_OPER_CHANNEL:
 711                         ieee80211_scan_state_enter_oper_channel(local, &next_delay);
 712                         break;
 713                 }
 714         } while (next_delay == 0);
 715
 716         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
 717 }
 718
 719 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 720                            struct cfg80211_scan_request *req)
 721 {
 722         int res;
 723
 724         mutex_lock(&sdata->local->scan_mtx);
 725         res = __ieee80211_start_scan(sdata, req);
 726         mutex_unlock(&sdata->local->scan_mtx);
 727
 728         return res;
 729 }
 730
 731 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 732                                     const u8 *ssid, u8 ssid_len,
 733                                     struct ieee80211_channel *chan)
 734 {
 735         struct ieee80211_local *local = sdata->local;
 736         int ret = -EBUSY;
 737         enum nl80211_band band;
 738
 739         mutex_lock(&local->scan_mtx);
 740
 741         /* busy scanning */
 742         if (local->scan_req)
 743                 goto unlock;
 744
 745         /* fill internal scan request */
 746         if (!chan) {
 747                 int i, nchan = 0;
 748
 749                 for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
 750                         if (!local->hw.wiphy->bands[band])
 751                                 continue;
 752                         for (i = 0;
 753                              i < local->hw.wiphy->bands[band]->n_channels;
 754                              i++) {
 755                                 local->int_scan_req->channels[nchan] =
 756                                     &local->hw.wiphy->bands[band]->channels[i];
 757                                 nchan++;
 758                         }
 759                 }
 760
 761                 local->int_scan_req->n_channels = nchan;
 762         } else {
 763                 local->int_scan_req->channels[0] = chan;
 764                 local->int_scan_req->n_channels = 1;
 765         }
 766
 767         local->int_scan_req->ssids = &local->scan_ssid;
 768         local->int_scan_req->n_ssids = 1;
 769         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 770         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 771
 772         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 773  unlock:
 774         mutex_unlock(&local->scan_mtx);
 775         return ret;
 776 }
 777
 778 void ieee80211_scan_cancel(struct ieee80211_local *local)
 779 {
 780         bool abortscan;
 781
 782         cancel_delayed_work_sync(&local->scan_work);
 783
 784         /*
 785          * Only call this function when a scan can't be
 786          * queued -- mostly at suspend under RTNL.
 787          */
 788         mutex_lock(&local->scan_mtx);
 789         abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
 790                     (!local->scanning && local->scan_req);
 791         mutex_unlock(&local->scan_mtx);
 792
 793         if (abortscan)
 794                 ieee80211_scan_completed(&local->hw, true);
 795 }