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         /* If the beacon had no TIM IE, or it was invalid, use 1 */
 118         if (beacon && !bss->dtim_period)
 119                 bss->dtim_period = 1;
 120
 121         /* replace old supported rates if we get new values */
 122         srlen = 0;
 123         if (elems->supp_rates) {
 124                 clen = IEEE80211_MAX_SUPP_RATES;
 125                 if (clen > elems->supp_rates_len)
 126                         clen = elems->supp_rates_len;
 127                 memcpy(bss->supp_rates, elems->supp_rates, clen);
 128                 srlen += clen;
 129         }
 130         if (elems->ext_supp_rates) {
 131                 clen = IEEE80211_MAX_SUPP_RATES - srlen;
 132                 if (clen > elems->ext_supp_rates_len)
 133                         clen = elems->ext_supp_rates_len;
 134                 memcpy(bss->supp_rates + srlen, elems->ext_supp_rates, clen);
 135                 srlen += clen;
 136         }
 137         if (srlen)
 138                 bss->supp_rates_len = srlen;
 139
 140         bss->wmm_used = elems->wmm_param || elems->wmm_info;
 141         bss->uapsd_supported = is_uapsd_supported(elems);
 142
 143         if (!beacon)
 144                 bss->last_probe_resp = jiffies;
 145
 146         return bss;
 147 }
 148
 149 ieee80211_rx_result
 150 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
 151 {
 152         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
 153         struct ieee80211_mgmt *mgmt;
 154         struct ieee80211_bss *bss;
 155         u8 *elements;
 156         struct ieee80211_channel *channel;
 157         size_t baselen;
 158         int freq;
 159         __le16 fc;
 160         bool presp, beacon = false;
 161         struct ieee802_11_elems elems;
 162
 163         if (skb->len < 2)
 164                 return RX_DROP_UNUSABLE;
 165
 166         mgmt = (struct ieee80211_mgmt *) skb->data;
 167         fc = mgmt->frame_control;
 168
 169         if (ieee80211_is_ctl(fc))
 170                 return RX_CONTINUE;
 171
 172         if (skb->len < 24)
 173                 return RX_DROP_MONITOR;
 174
 175         presp = ieee80211_is_probe_resp(fc);
 176         if (presp) {
 177                 /* ignore ProbeResp to foreign address */
 178                 if (memcmp(mgmt->da, sdata->vif.addr, ETH_ALEN))
 179                         return RX_DROP_MONITOR;
 180
 181                 presp = true;
 182                 elements = mgmt->u.probe_resp.variable;
 183                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 184         } else {
 185                 beacon = ieee80211_is_beacon(fc);
 186                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 187                 elements = mgmt->u.beacon.variable;
 188         }
 189
 190         if (!presp && !beacon)
 191                 return RX_CONTINUE;
 192
 193         if (baselen > skb->len)
 194                 return RX_DROP_MONITOR;
 195
 196         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
 197
 198         if (elems.ds_params && elems.ds_params_len == 1)
 199                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
 200         else
 201                 freq = rx_status->freq;
 202
 203         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
 204
 205         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 206                 return RX_DROP_MONITOR;
 207
 208         bss = ieee80211_bss_info_update(sdata->local, rx_status,
 209                                         mgmt, skb->len, &elems,
 210                                         channel, beacon);
 211         if (bss)
 212                 ieee80211_rx_bss_put(sdata->local, bss);
 213
 214         dev_kfree_skb(skb);
 215         return RX_QUEUED;
 216 }
 217
 218 /* return false if no more work */
 219 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 220 {
 221         struct cfg80211_scan_request *req = local->scan_req;
 222         enum ieee80211_band band;
 223         int i, ielen, n_chans;
 224
 225         do {
 226                 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
 227                         return false;
 228
 229                 band = local->hw_scan_band;
 230                 n_chans = 0;
 231                 for (i = 0; i < req->n_channels; i++) {
 232                         if (req->channels[i]->band == band) {
 233                                 local->hw_scan_req->channels[n_chans] =
 234                                                         req->channels[i];
 235                                 n_chans++;
 236                         }
 237                 }
 238
 239                 local->hw_scan_band++;
 240         } while (!n_chans);
 241
 242         local->hw_scan_req->n_channels = n_chans;
 243
 244         ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
 245                                          req->ie, req->ie_len, band);
 246         local->hw_scan_req->ie_len = ielen;
 247
 248         return true;
 249 }
 250
 251 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 252 {
 253         struct ieee80211_local *local = hw_to_local(hw);
 254         bool was_hw_scan;
 255
 256         trace_api_scan_completed(local, aborted);
 257
 258         mutex_lock(&local->mtx);
 259
 260         /*
 261          * It's ok to abort a not-yet-running scan (that
 262          * we have one at all will be verified by checking
 263          * local->scan_req next), but not to complete it
 264          * successfully.
 265          */
 266         if (WARN_ON(!local->scanning && !aborted))
 267                 aborted = true;
 268
 269         if (WARN_ON(!local->scan_req)) {
 270                 mutex_unlock(&local->mtx);
 271                 return;
 272         }
 273
 274         was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 275         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 276                 ieee80211_queue_delayed_work(&local->hw,
 277                                              &local->scan_work, 0);
 278                 mutex_unlock(&local->mtx);
 279                 return;
 280         }
 281
 282         kfree(local->hw_scan_req);
 283         local->hw_scan_req = NULL;
 284
 285         if (local->scan_req != local->int_scan_req)
 286                 cfg80211_scan_done(local->scan_req, aborted);
 287         local->scan_req = NULL;
 288         local->scan_sdata = NULL;
 289
 290         local->scanning = 0;
 291         local->scan_channel = NULL;
 292
 293         /* we only have to protect scan_req and hw/sw scan */
 294         mutex_unlock(&local->mtx);
 295
 296         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 297         if (was_hw_scan)
 298                 goto done;
 299
 300         ieee80211_configure_filter(local);
 301
 302         drv_sw_scan_complete(local);
 303
 304         ieee80211_offchannel_return(local, true);
 305
 306  done:
 307         mutex_lock(&local->mtx);
 308         ieee80211_recalc_idle(local);
 309         mutex_unlock(&local->mtx);
 310         ieee80211_mlme_notify_scan_completed(local);
 311         ieee80211_ibss_notify_scan_completed(local);
 312         ieee80211_mesh_notify_scan_completed(local);
 313         ieee80211_queue_work(&local->hw, &local->work_work);
 314 }
 315 EXPORT_SYMBOL(ieee80211_scan_completed);
 316
 317 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 318 {
 319         /*
 320          * Hardware/driver doesn't support hw_scan, so use software
 321          * scanning instead. First send a nullfunc frame with power save
 322          * bit on so that AP will buffer the frames for us while we are not
 323          * listening, then send probe requests to each channel and wait for
 324          * the responses. After all channels are scanned, tune back to the
 325          * original channel and send a nullfunc frame with power save bit
 326          * off to trigger the AP to send us all the buffered frames.
 327          *
 328          * Note that while local->sw_scanning is true everything else but
 329          * nullfunc frames and probe requests will be dropped in
 330          * ieee80211_tx_h_check_assoc().
 331          */
 332         drv_sw_scan_start(local);
 333
 334         ieee80211_offchannel_stop_beaconing(local);
 335
 336         local->leave_oper_channel_time = 0;
 337         local->next_scan_state = SCAN_DECISION;
 338         local->scan_channel_idx = 0;
 339
 340         drv_flush(local, false);
 341
 342         ieee80211_configure_filter(local);
 343
 344         ieee80211_queue_delayed_work(&local->hw,
 345                                      &local->scan_work,
 346                                      IEEE80211_CHANNEL_TIME);
 347
 348         return 0;
 349 }
 350
 351
 352 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 353                                   struct cfg80211_scan_request *req)
 354 {
 355         struct ieee80211_local *local = sdata->local;
 356         int rc;
 357
 358         if (local->scan_req)
 359                 return -EBUSY;
 360
 361         if (!list_empty(&local->work_list)) {
 362                 /* wait for the work to finish/time out */
 363                 local->scan_req = req;
 364                 local->scan_sdata = sdata;
 365                 return 0;
 366         }
 367
 368         if (local->ops->hw_scan) {
 369                 u8 *ies;
 370
 371                 local->hw_scan_req = kmalloc(
 372                                 sizeof(*local->hw_scan_req) +
 373                                 req->n_channels * sizeof(req->channels[0]) +
 374                                 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
 375                                 req->ie_len, GFP_KERNEL);
 376                 if (!local->hw_scan_req)
 377                         return -ENOMEM;
 378
 379                 local->hw_scan_req->ssids = req->ssids;
 380                 local->hw_scan_req->n_ssids = req->n_ssids;
 381                 ies = (u8 *)local->hw_scan_req +
 382                         sizeof(*local->hw_scan_req) +
 383                         req->n_channels * sizeof(req->channels[0]);
 384                 local->hw_scan_req->ie = ies;
 385
 386                 local->hw_scan_band = 0;
 387
 388                 /*
 389                  * After allocating local->hw_scan_req, we must
 390                  * go through until ieee80211_prep_hw_scan(), so
 391                  * anything that might be changed here and leave
 392                  * this function early must not go after this
 393                  * allocation.
 394                  */
 395         }
 396
 397         local->scan_req = req;
 398         local->scan_sdata = sdata;
 399
 400         if (local->ops->hw_scan)
 401                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 402         else
 403                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 404
 405         ieee80211_recalc_idle(local);
 406
 407         if (local->ops->hw_scan) {
 408                 WARN_ON(!ieee80211_prep_hw_scan(local));
 409                 rc = drv_hw_scan(local, sdata, local->hw_scan_req);
 410         } else
 411                 rc = ieee80211_start_sw_scan(local);
 412
 413         if (rc) {
 414                 kfree(local->hw_scan_req);
 415                 local->hw_scan_req = NULL;
 416                 local->scanning = 0;
 417
 418                 ieee80211_recalc_idle(local);
 419
 420                 local->scan_req = NULL;
 421                 local->scan_sdata = NULL;
 422         }
 423
 424         return rc;
 425 }
 426
 427 static unsigned long
 428 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
 429 {
 430         /*
 431          * TODO: channel switching also consumes quite some time,
 432          * add that delay as well to get a better estimation
 433          */
 434         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN)
 435                 return IEEE80211_PASSIVE_CHANNEL_TIME;
 436         return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
 437 }
 438
 439 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
 440                                          unsigned long *next_delay)
 441 {
 442         bool associated = false;
 443         bool tx_empty = true;
 444         bool bad_latency;
 445         bool listen_int_exceeded;
 446         unsigned long min_beacon_int = 0;
 447         struct ieee80211_sub_if_data *sdata;
 448         struct ieee80211_channel *next_chan;
 449
 450         /* if no more bands/channels left, complete scan and advance to the idle state */
 451         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 452                 ieee80211_scan_completed(&local->hw, false);
 453                 return 1;
 454         }
 455
 456         /*
 457          * check if at least one STA interface is associated,
 458          * check if at least one STA interface has pending tx frames
 459          * and grab the lowest used beacon interval
 460          */
 461         mutex_lock(&local->iflist_mtx);
 462         list_for_each_entry(sdata, &local->interfaces, list) {
 463                 if (!ieee80211_sdata_running(sdata))
 464                         continue;
 465
 466                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 467                         if (sdata->u.mgd.associated) {
 468                                 associated = true;
 469
 470                                 if (sdata->vif.bss_conf.beacon_int <
 471                                     min_beacon_int || min_beacon_int == 0)
 472                                         min_beacon_int =
 473                                                 sdata->vif.bss_conf.beacon_int;
 474
 475                                 if (!qdisc_all_tx_empty(sdata->dev)) {
 476                                         tx_empty = false;
 477                                         break;
 478                                 }
 479                         }
 480                 }
 481         }
 482         mutex_unlock(&local->iflist_mtx);
 483
 484         if (local->scan_channel) {
 485                 /*
 486                  * we're currently scanning a different channel, let's
 487                  * see if we can scan another channel without interfering
 488                  * with the current traffic situation.
 489                  *
 490                  * Since we don't know if the AP has pending frames for us
 491                  * we can only check for our tx queues and use the current
 492                  * pm_qos requirements for rx. Hence, if no tx traffic occurs
 493                  * at all we will scan as many channels in a row as the pm_qos
 494                  * latency allows us to. Additionally we also check for the
 495                  * currently negotiated listen interval to prevent losing
 496                  * frames unnecessarily.
 497                  *
 498                  * Otherwise switch back to the operating channel.
 499                  */
 500                 next_chan = local->scan_req->channels[local->scan_channel_idx];
 501
 502                 bad_latency = time_after(jiffies +
 503                                 ieee80211_scan_get_channel_time(next_chan),
 504                                 local->leave_oper_channel_time +
 505                                 usecs_to_jiffies(pm_qos_request(PM_QOS_NETWORK_LATENCY)));
 506
 507                 listen_int_exceeded = time_after(jiffies +
 508                                 ieee80211_scan_get_channel_time(next_chan),
 509                                 local->leave_oper_channel_time +
 510                                 usecs_to_jiffies(min_beacon_int * 1024) *
 511                                 local->hw.conf.listen_interval);
 512
 513                 if (associated && ( !tx_empty || bad_latency ||
 514                     listen_int_exceeded))
 515                         local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
 516                 else
 517                         local->next_scan_state = SCAN_SET_CHANNEL;
 518         } else {
 519                 /*
 520                  * we're on the operating channel currently, let's
 521                  * leave that channel now to scan another one
 522                  */
 523                 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
 524         }
 525
 526         *next_delay = 0;
 527         return 0;
 528 }
 529
 530 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
 531                                                     unsigned long *next_delay)
 532 {
 533         ieee80211_offchannel_stop_station(local);
 534
 535         __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
 536
 537         /*
 538          * What if the nullfunc frames didn't arrive?
 539          */
 540         drv_flush(local, false);
 541         if (local->ops->flush)
 542                 *next_delay = 0;
 543         else
 544                 *next_delay = HZ / 10;
 545
 546         /* remember when we left the operating channel */
 547         local->leave_oper_channel_time = jiffies;
 548
 549         /* advance to the next channel to be scanned */
 550         local->next_scan_state = SCAN_SET_CHANNEL;
 551 }
 552
 553 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
 554                                                     unsigned long *next_delay)
 555 {
 556         /* switch back to the operating channel */
 557         local->scan_channel = NULL;
 558         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 559
 560         /*
 561          * Only re-enable station mode interface now; beaconing will be
 562          * re-enabled once the full scan has been completed.
 563          */
 564         ieee80211_offchannel_return(local, false);
 565
 566         __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
 567
 568         *next_delay = HZ / 5;
 569         local->next_scan_state = SCAN_DECISION;
 570 }
 571
 572 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 573                                              unsigned long *next_delay)
 574 {
 575         int skip;
 576         struct ieee80211_channel *chan;
 577
 578         skip = 0;
 579         chan = local->scan_req->channels[local->scan_channel_idx];
 580
 581         local->scan_channel = chan;
 582         if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 583                 skip = 1;
 584
 585         /* advance state machine to next channel/band */
 586         local->scan_channel_idx++;
 587
 588         if (skip) {
 589                 /* if we skip this channel return to the decision state */
 590                 local->next_scan_state = SCAN_DECISION;
 591                 return;
 592         }
 593
 594         /*
 595          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 596          * (which unfortunately doesn't say _why_ step a) is done,
 597          * but it waits for the probe delay or until a frame is
 598          * received - and the received frame would update the NAV).
 599          * For now, we do not support waiting until a frame is
 600          * received.
 601          *
 602          * In any case, it is not necessary for a passive scan.
 603          */
 604         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 605             !local->scan_req->n_ssids) {
 606                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 607                 local->next_scan_state = SCAN_DECISION;
 608                 return;
 609         }
 610
 611         /* active scan, send probes */
 612         *next_delay = IEEE80211_PROBE_DELAY;
 613         local->next_scan_state = SCAN_SEND_PROBE;
 614 }
 615
 616 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 617                                             unsigned long *next_delay)
 618 {
 619         int i;
 620         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 621
 622         for (i = 0; i < local->scan_req->n_ssids; i++)
 623                 ieee80211_send_probe_req(
 624                         sdata, NULL,
 625                         local->scan_req->ssids[i].ssid,
 626                         local->scan_req->ssids[i].ssid_len,
 627                         local->scan_req->ie, local->scan_req->ie_len);
 628
 629         /*
 630          * After sending probe requests, wait for probe responses
 631          * on the channel.
 632          */
 633         *next_delay = IEEE80211_CHANNEL_TIME;
 634         local->next_scan_state = SCAN_DECISION;
 635 }
 636
 637 void ieee80211_scan_work(struct work_struct *work)
 638 {
 639         struct ieee80211_local *local =
 640                 container_of(work, struct ieee80211_local, scan_work.work);
 641         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 642         unsigned long next_delay = 0;
 643
 644         mutex_lock(&local->mtx);
 645         if (!sdata || !local->scan_req) {
 646                 mutex_unlock(&local->mtx);
 647                 return;
 648         }
 649
 650         if (local->hw_scan_req) {
 651                 int rc = drv_hw_scan(local, sdata, local->hw_scan_req);
 652                 mutex_unlock(&local->mtx);
 653                 if (rc)
 654                         ieee80211_scan_completed(&local->hw, true);
 655                 return;
 656         }
 657
 658         if (local->scan_req && !local->scanning) {
 659                 struct cfg80211_scan_request *req = local->scan_req;
 660                 int rc;
 661
 662                 local->scan_req = NULL;
 663                 local->scan_sdata = NULL;
 664
 665                 rc = __ieee80211_start_scan(sdata, req);
 666                 mutex_unlock(&local->mtx);
 667
 668                 if (rc)
 669                         ieee80211_scan_completed(&local->hw, true);
 670                 return;
 671         }
 672
 673         mutex_unlock(&local->mtx);
 674
 675         /*
 676          * Avoid re-scheduling when the sdata is going away.
 677          */
 678         if (!ieee80211_sdata_running(sdata)) {
 679                 ieee80211_scan_completed(&local->hw, true);
 680                 return;
 681         }
 682
 683         /*
 684          * as long as no delay is required advance immediately
 685          * without scheduling a new work
 686          */
 687         do {
 688                 switch (local->next_scan_state) {
 689                 case SCAN_DECISION:
 690                         if (ieee80211_scan_state_decision(local, &next_delay))
 691                                 return;
 692                         break;
 693                 case SCAN_SET_CHANNEL:
 694                         ieee80211_scan_state_set_channel(local, &next_delay);
 695                         break;
 696                 case SCAN_SEND_PROBE:
 697                         ieee80211_scan_state_send_probe(local, &next_delay);
 698                         break;
 699                 case SCAN_LEAVE_OPER_CHANNEL:
 700                         ieee80211_scan_state_leave_oper_channel(local, &next_delay);
 701                         break;
 702                 case SCAN_ENTER_OPER_CHANNEL:
 703                         ieee80211_scan_state_enter_oper_channel(local, &next_delay);
 704                         break;
 705                 }
 706         } while (next_delay == 0);
 707
 708         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
 709 }
 710
 711 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 712                            struct cfg80211_scan_request *req)
 713 {
 714         int res;
 715
 716         mutex_lock(&sdata->local->mtx);
 717         res = __ieee80211_start_scan(sdata, req);
 718         mutex_unlock(&sdata->local->mtx);
 719
 720         return res;
 721 }
 722
 723 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 724                                     const u8 *ssid, u8 ssid_len,
 725                                     struct ieee80211_channel *chan)
 726 {
 727         struct ieee80211_local *local = sdata->local;
 728         int ret = -EBUSY;
 729         enum ieee80211_band band;
 730
 731         mutex_lock(&local->mtx);
 732
 733         /* busy scanning */
 734         if (local->scan_req)
 735                 goto unlock;
 736
 737         /* fill internal scan request */
 738         if (!chan) {
 739                 int i, nchan = 0;
 740
 741                 for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
 742                         if (!local->hw.wiphy->bands[band])
 743                                 continue;
 744                         for (i = 0;
 745                              i < local->hw.wiphy->bands[band]->n_channels;
 746                              i++) {
 747                                 local->int_scan_req->channels[nchan] =
 748                                     &local->hw.wiphy->bands[band]->channels[i];
 749                                 nchan++;
 750                         }
 751                 }
 752
 753                 local->int_scan_req->n_channels = nchan;
 754         } else {
 755                 local->int_scan_req->channels[0] = chan;
 756                 local->int_scan_req->n_channels = 1;
 757         }
 758
 759         local->int_scan_req->ssids = &local->scan_ssid;
 760         local->int_scan_req->n_ssids = 1;
 761         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 762         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 763
 764         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 765  unlock:
 766         mutex_unlock(&local->mtx);
 767         return ret;
 768 }
 769
 770 void ieee80211_scan_cancel(struct ieee80211_local *local)
 771 {
 772         bool abortscan;
 773
 774         cancel_delayed_work_sync(&local->scan_work);
 775
 776         /*
 777          * Only call this function when a scan can't be
 778          * queued -- mostly at suspend under RTNL.
 779          */
 780         mutex_lock(&local->mtx);
 781         abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
 782                     (!local->scanning && local->scan_req);
 783         mutex_unlock(&local->mtx);
 784
 785         if (abortscan)
 786                 ieee80211_scan_completed(&local->hw, true);
 787 }