net/mac80211/scan.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Scanning implementation
   4  *
   5  * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
   6  * Copyright 2004, Instant802 Networks, Inc.
   7  * Copyright 2005, Devicescape Software, Inc.
   8  * Copyright 2006-2007  Jiri Benc <jbenc@suse.cz>
   9  * Copyright 2007, Michael Wu <flamingice@sourmilk.net>
  10  * Copyright 2013-2015  Intel Mobile Communications GmbH
  11  * Copyright 2016-2017  Intel Deutschland GmbH
  12  * Copyright (C) 2018-2020 Intel Corporation
  13  */
  14
  15 #include <linux/if_arp.h>
  16 #include <linux/etherdevice.h>
  17 #include <linux/rtnetlink.h>
  18 #include <net/sch_generic.h>
  19 #include <linux/slab.h>
  20 #include <linux/export.h>
  21 #include <linux/random.h>
  22 #include <net/mac80211.h>
  23
  24 #include "ieee80211_i.h"
  25 #include "driver-ops.h"
  26 #include "mesh.h"
  27
  28 #define IEEE80211_PROBE_DELAY (HZ / 33)
  29 #define IEEE80211_CHANNEL_TIME (HZ / 33)
  30 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 9)
  31
  32 void ieee80211_rx_bss_put(struct ieee80211_local *local,
  33                           struct ieee80211_bss *bss)
  34 {
  35         if (!bss)
  36                 return;
  37         cfg80211_put_bss(local->hw.wiphy,
  38                          container_of((void *)bss, struct cfg80211_bss, priv));
  39 }
  40
  41 static bool is_uapsd_supported(struct ieee802_11_elems *elems)
  42 {
  43         u8 qos_info;
  44
  45         if (elems->wmm_info && elems->wmm_info_len == 7
  46             && elems->wmm_info[5] == 1)
  47                 qos_info = elems->wmm_info[6];
  48         else if (elems->wmm_param && elems->wmm_param_len == 24
  49                  && elems->wmm_param[5] == 1)
  50                 qos_info = elems->wmm_param[6];
  51         else
  52                 /* no valid wmm information or parameter element found */
  53                 return false;
  54
  55         return qos_info & IEEE80211_WMM_IE_AP_QOSINFO_UAPSD;
  56 }
  57
  58 static void
  59 ieee80211_update_bss_from_elems(struct ieee80211_local *local,
  60                                 struct ieee80211_bss *bss,
  61                                 struct ieee802_11_elems *elems,
  62                                 struct ieee80211_rx_status *rx_status,
  63                                 bool beacon)
  64 {
  65         int clen, srlen;
  66
  67         if (beacon)
  68                 bss->device_ts_beacon = rx_status->device_timestamp;
  69         else
  70                 bss->device_ts_presp = rx_status->device_timestamp;
  71
  72         if (elems->parse_error) {
  73                 if (beacon)
  74                         bss->corrupt_data |= IEEE80211_BSS_CORRUPT_BEACON;
  75                 else
  76                         bss->corrupt_data |= IEEE80211_BSS_CORRUPT_PROBE_RESP;
  77         } else {
  78                 if (beacon)
  79                         bss->corrupt_data &= ~IEEE80211_BSS_CORRUPT_BEACON;
  80                 else
  81                         bss->corrupt_data &= ~IEEE80211_BSS_CORRUPT_PROBE_RESP;
  82         }
  83
  84         /* save the ERP value so that it is available at association time */
  85         if (elems->erp_info && (!elems->parse_error ||
  86                                 !(bss->valid_data & IEEE80211_BSS_VALID_ERP))) {
  87                 bss->erp_value = elems->erp_info[0];
  88                 bss->has_erp_value = true;
  89                 if (!elems->parse_error)
  90                         bss->valid_data |= IEEE80211_BSS_VALID_ERP;
  91         }
  92
  93         /* replace old supported rates if we get new values */
  94         if (!elems->parse_error ||
  95             !(bss->valid_data & IEEE80211_BSS_VALID_RATES)) {
  96                 srlen = 0;
  97                 if (elems->supp_rates) {
  98                         clen = IEEE80211_MAX_SUPP_RATES;
  99                         if (clen > elems->supp_rates_len)
 100                                 clen = elems->supp_rates_len;
 101                         memcpy(bss->supp_rates, elems->supp_rates, clen);
 102                         srlen += clen;
 103                 }
 104                 if (elems->ext_supp_rates) {
 105                         clen = IEEE80211_MAX_SUPP_RATES - srlen;
 106                         if (clen > elems->ext_supp_rates_len)
 107                                 clen = elems->ext_supp_rates_len;
 108                         memcpy(bss->supp_rates + srlen, elems->ext_supp_rates,
 109                                clen);
 110                         srlen += clen;
 111                 }
 112                 if (srlen) {
 113                         bss->supp_rates_len = srlen;
 114                         if (!elems->parse_error)
 115                                 bss->valid_data |= IEEE80211_BSS_VALID_RATES;
 116                 }
 117         }
 118
 119         if (!elems->parse_error ||
 120             !(bss->valid_data & IEEE80211_BSS_VALID_WMM)) {
 121                 bss->wmm_used = elems->wmm_param || elems->wmm_info;
 122                 bss->uapsd_supported = is_uapsd_supported(elems);
 123                 if (!elems->parse_error)
 124                         bss->valid_data |= IEEE80211_BSS_VALID_WMM;
 125         }
 126
 127         if (beacon) {
 128                 struct ieee80211_supported_band *sband =
 129                         local->hw.wiphy->bands[rx_status->band];
 130                 if (!(rx_status->encoding == RX_ENC_HT) &&
 131                     !(rx_status->encoding == RX_ENC_VHT))
 132                         bss->beacon_rate =
 133                                 &sband->bitrates[rx_status->rate_idx];
 134         }
 135
 136         if (elems->vht_cap_elem)
 137                 bss->vht_cap_info =
 138                         le32_to_cpu(elems->vht_cap_elem->vht_cap_info);
 139         else
 140                 bss->vht_cap_info = 0;
 141 }
 142
 143 struct ieee80211_bss *
 144 ieee80211_bss_info_update(struct ieee80211_local *local,
 145                           struct ieee80211_rx_status *rx_status,
 146                           struct ieee80211_mgmt *mgmt, size_t len,
 147                           struct ieee80211_channel *channel)
 148 {
 149         bool beacon = ieee80211_is_beacon(mgmt->frame_control) ||
 150                       ieee80211_is_s1g_beacon(mgmt->frame_control);
 151         struct cfg80211_bss *cbss, *non_tx_cbss;
 152         struct ieee80211_bss *bss, *non_tx_bss;
 153         struct cfg80211_inform_bss bss_meta = {
 154                 .boottime_ns = rx_status->boottime_ns,
 155         };
 156         bool signal_valid;
 157         struct ieee80211_sub_if_data *scan_sdata;
 158         struct ieee802_11_elems elems;
 159         size_t baselen;
 160         u8 *elements;
 161
 162         if (rx_status->flag & RX_FLAG_NO_SIGNAL_VAL)
 163                 bss_meta.signal = 0; /* invalid signal indication */
 164         else if (ieee80211_hw_check(&local->hw, SIGNAL_DBM))
 165                 bss_meta.signal = rx_status->signal * 100;
 166         else if (ieee80211_hw_check(&local->hw, SIGNAL_UNSPEC))
 167                 bss_meta.signal = (rx_status->signal * 100) / local->hw.max_signal;
 168
 169         bss_meta.scan_width = NL80211_BSS_CHAN_WIDTH_20;
 170         if (rx_status->bw == RATE_INFO_BW_5)
 171                 bss_meta.scan_width = NL80211_BSS_CHAN_WIDTH_5;
 172         else if (rx_status->bw == RATE_INFO_BW_10)
 173                 bss_meta.scan_width = NL80211_BSS_CHAN_WIDTH_10;
 174
 175         bss_meta.chan = channel;
 176
 177         rcu_read_lock();
 178         scan_sdata = rcu_dereference(local->scan_sdata);
 179         if (scan_sdata && scan_sdata->vif.type == NL80211_IFTYPE_STATION &&
 180             scan_sdata->vif.bss_conf.assoc &&
 181             ieee80211_have_rx_timestamp(rx_status)) {
 182                 bss_meta.parent_tsf =
 183                         ieee80211_calculate_rx_timestamp(local, rx_status,
 184                                                          len + FCS_LEN, 24);
 185                 ether_addr_copy(bss_meta.parent_bssid,
 186                                 scan_sdata->vif.bss_conf.bssid);
 187         }
 188         rcu_read_unlock();
 189
 190         cbss = cfg80211_inform_bss_frame_data(local->hw.wiphy, &bss_meta,
 191                                               mgmt, len, GFP_ATOMIC);
 192         if (!cbss)
 193                 return NULL;
 194
 195         if (ieee80211_is_probe_resp(mgmt->frame_control)) {
 196                 elements = mgmt->u.probe_resp.variable;
 197                 baselen = offsetof(struct ieee80211_mgmt,
 198                                    u.probe_resp.variable);
 199         } else if (ieee80211_is_s1g_beacon(mgmt->frame_control)) {
 200                 struct ieee80211_ext *ext = (void *) mgmt;
 201
 202                 baselen = offsetof(struct ieee80211_ext, u.s1g_beacon.variable);
 203                 elements = ext->u.s1g_beacon.variable;
 204         } else {
 205                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 206                 elements = mgmt->u.beacon.variable;
 207         }
 208
 209         if (baselen > len)
 210                 return NULL;
 211
 212         ieee802_11_parse_elems(elements, len - baselen, false, &elems,
 213                                mgmt->bssid, cbss->bssid);
 214
 215         /* In case the signal is invalid update the status */
 216         signal_valid = channel == cbss->channel;
 217         if (!signal_valid)
 218                 rx_status->flag |= RX_FLAG_NO_SIGNAL_VAL;
 219
 220         bss = (void *)cbss->priv;
 221         ieee80211_update_bss_from_elems(local, bss, &elems, rx_status, beacon);
 222
 223         list_for_each_entry(non_tx_cbss, &cbss->nontrans_list, nontrans_list) {
 224                 non_tx_bss = (void *)non_tx_cbss->priv;
 225
 226                 ieee80211_update_bss_from_elems(local, non_tx_bss, &elems,
 227                                                 rx_status, beacon);
 228         }
 229
 230         return bss;
 231 }
 232
 233 static bool ieee80211_scan_accept_presp(struct ieee80211_sub_if_data *sdata,
 234                                         u32 scan_flags, const u8 *da)
 235 {
 236         if (!sdata)
 237                 return false;
 238         /* accept broadcast for OCE */
 239         if (scan_flags & NL80211_SCAN_FLAG_ACCEPT_BCAST_PROBE_RESP &&
 240             is_broadcast_ether_addr(da))
 241                 return true;
 242         if (scan_flags & NL80211_SCAN_FLAG_RANDOM_ADDR)
 243                 return true;
 244         return ether_addr_equal(da, sdata->vif.addr);
 245 }
 246
 247 void ieee80211_scan_rx(struct ieee80211_local *local, struct sk_buff *skb)
 248 {
 249         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
 250         struct ieee80211_sub_if_data *sdata1, *sdata2;
 251         struct ieee80211_mgmt *mgmt = (void *)skb->data;
 252         struct ieee80211_bss *bss;
 253         struct ieee80211_channel *channel;
 254
 255         if (ieee80211_is_s1g_beacon(mgmt->frame_control)) {
 256                 if (skb->len < 15)
 257                         return;
 258         } else if (skb->len < 24 ||
 259                  (!ieee80211_is_probe_resp(mgmt->frame_control) &&
 260                   !ieee80211_is_beacon(mgmt->frame_control)))
 261                 return;
 262
 263         sdata1 = rcu_dereference(local->scan_sdata);
 264         sdata2 = rcu_dereference(local->sched_scan_sdata);
 265
 266         if (likely(!sdata1 && !sdata2))
 267                 return;
 268
 269         if (ieee80211_is_probe_resp(mgmt->frame_control)) {
 270                 struct cfg80211_scan_request *scan_req;
 271                 struct cfg80211_sched_scan_request *sched_scan_req;
 272                 u32 scan_req_flags = 0, sched_scan_req_flags = 0;
 273
 274                 scan_req = rcu_dereference(local->scan_req);
 275                 sched_scan_req = rcu_dereference(local->sched_scan_req);
 276
 277                 if (scan_req)
 278                         scan_req_flags = scan_req->flags;
 279
 280                 if (sched_scan_req)
 281                         sched_scan_req_flags = sched_scan_req->flags;
 282
 283                 /* ignore ProbeResp to foreign address or non-bcast (OCE)
 284                  * unless scanning with randomised address
 285                  */
 286                 if (!ieee80211_scan_accept_presp(sdata1, scan_req_flags,
 287                                                  mgmt->da) &&
 288                     !ieee80211_scan_accept_presp(sdata2, sched_scan_req_flags,
 289                                                  mgmt->da))
 290                         return;
 291         }
 292
 293         channel = ieee80211_get_channel_khz(local->hw.wiphy,
 294                                         ieee80211_rx_status_to_khz(rx_status));
 295
 296         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 297                 return;
 298
 299         bss = ieee80211_bss_info_update(local, rx_status,
 300                                         mgmt, skb->len,
 301                                         channel);
 302         if (bss)
 303                 ieee80211_rx_bss_put(local, bss);
 304 }
 305
 306 static void
 307 ieee80211_prepare_scan_chandef(struct cfg80211_chan_def *chandef,
 308                                enum nl80211_bss_scan_width scan_width)
 309 {
 310         memset(chandef, 0, sizeof(*chandef));
 311         switch (scan_width) {
 312         case NL80211_BSS_CHAN_WIDTH_5:
 313                 chandef->width = NL80211_CHAN_WIDTH_5;
 314                 break;
 315         case NL80211_BSS_CHAN_WIDTH_10:
 316                 chandef->width = NL80211_CHAN_WIDTH_10;
 317                 break;
 318         default:
 319                 chandef->width = NL80211_CHAN_WIDTH_20_NOHT;
 320                 break;
 321         }
 322 }
 323
 324 /* return false if no more work */
 325 static bool ieee80211_prep_hw_scan(struct ieee80211_sub_if_data *sdata)
 326 {
 327         struct ieee80211_local *local = sdata->local;
 328         struct cfg80211_scan_request *req;
 329         struct cfg80211_chan_def chandef;
 330         u8 bands_used = 0;
 331         int i, ielen, n_chans;
 332         u32 flags = 0;
 333
 334         req = rcu_dereference_protected(local->scan_req,
 335                                         lockdep_is_held(&local->mtx));
 336
 337         if (test_bit(SCAN_HW_CANCELLED, &local->scanning))
 338                 return false;
 339
 340         if (ieee80211_hw_check(&local->hw, SINGLE_SCAN_ON_ALL_BANDS)) {
 341                 for (i = 0; i < req->n_channels; i++) {
 342                         local->hw_scan_req->req.channels[i] = req->channels[i];
 343                         bands_used |= BIT(req->channels[i]->band);
 344                 }
 345
 346                 n_chans = req->n_channels;
 347         } else {
 348                 do {
 349                         if (local->hw_scan_band == NUM_NL80211_BANDS)
 350                                 return false;
 351
 352                         n_chans = 0;
 353
 354                         for (i = 0; i < req->n_channels; i++) {
 355                                 if (req->channels[i]->band !=
 356                                     local->hw_scan_band)
 357                                         continue;
 358                                 local->hw_scan_req->req.channels[n_chans] =
 359                                                         req->channels[i];
 360                                 n_chans++;
 361                                 bands_used |= BIT(req->channels[i]->band);
 362                         }
 363
 364                         local->hw_scan_band++;
 365                 } while (!n_chans);
 366         }
 367
 368         local->hw_scan_req->req.n_channels = n_chans;
 369         ieee80211_prepare_scan_chandef(&chandef, req->scan_width);
 370
 371         if (req->flags & NL80211_SCAN_FLAG_MIN_PREQ_CONTENT)
 372                 flags |= IEEE80211_PROBE_FLAG_MIN_CONTENT;
 373
 374         ielen = ieee80211_build_preq_ies(sdata,
 375                                          (u8 *)local->hw_scan_req->req.ie,
 376                                          local->hw_scan_ies_bufsize,
 377                                          &local->hw_scan_req->ies,
 378                                          req->ie, req->ie_len,
 379                                          bands_used, req->rates, &chandef,
 380                                          flags);
 381         local->hw_scan_req->req.ie_len = ielen;
 382         local->hw_scan_req->req.no_cck = req->no_cck;
 383         ether_addr_copy(local->hw_scan_req->req.mac_addr, req->mac_addr);
 384         ether_addr_copy(local->hw_scan_req->req.mac_addr_mask,
 385                         req->mac_addr_mask);
 386         ether_addr_copy(local->hw_scan_req->req.bssid, req->bssid);
 387
 388         return true;
 389 }
 390
 391 static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 392 {
 393         struct ieee80211_local *local = hw_to_local(hw);
 394         bool hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 395         bool was_scanning = local->scanning;
 396         struct cfg80211_scan_request *scan_req;
 397         struct ieee80211_sub_if_data *scan_sdata;
 398         struct ieee80211_sub_if_data *sdata;
 399
 400         lockdep_assert_held(&local->mtx);
 401
 402         /*
 403          * It's ok to abort a not-yet-running scan (that
 404          * we have one at all will be verified by checking
 405          * local->scan_req next), but not to complete it
 406          * successfully.
 407          */
 408         if (WARN_ON(!local->scanning && !aborted))
 409                 aborted = true;
 410
 411         if (WARN_ON(!local->scan_req))
 412                 return;
 413
 414         scan_sdata = rcu_dereference_protected(local->scan_sdata,
 415                                                lockdep_is_held(&local->mtx));
 416
 417         if (hw_scan && !aborted &&
 418             !ieee80211_hw_check(&local->hw, SINGLE_SCAN_ON_ALL_BANDS) &&
 419             ieee80211_prep_hw_scan(scan_sdata)) {
 420                 int rc;
 421
 422                 rc = drv_hw_scan(local,
 423                         rcu_dereference_protected(local->scan_sdata,
 424                                                   lockdep_is_held(&local->mtx)),
 425                         local->hw_scan_req);
 426
 427                 if (rc == 0)
 428                         return;
 429
 430                 /* HW scan failed and is going to be reported as aborted,
 431                  * so clear old scan info.
 432                  */
 433                 memset(&local->scan_info, 0, sizeof(local->scan_info));
 434                 aborted = true;
 435         }
 436
 437         kfree(local->hw_scan_req);
 438         local->hw_scan_req = NULL;
 439
 440         scan_req = rcu_dereference_protected(local->scan_req,
 441                                              lockdep_is_held(&local->mtx));
 442
 443         if (scan_req != local->int_scan_req) {
 444                 local->scan_info.aborted = aborted;
 445                 cfg80211_scan_done(scan_req, &local->scan_info);
 446         }
 447         RCU_INIT_POINTER(local->scan_req, NULL);
 448         RCU_INIT_POINTER(local->scan_sdata, NULL);
 449
 450         local->scanning = 0;
 451         local->scan_chandef.chan = NULL;
 452
 453         /* Set power back to normal operating levels. */
 454         ieee80211_hw_config(local, 0);
 455
 456         if (!hw_scan) {
 457                 ieee80211_configure_filter(local);
 458                 drv_sw_scan_complete(local, scan_sdata);
 459                 ieee80211_offchannel_return(local);
 460         }
 461
 462         ieee80211_recalc_idle(local);
 463
 464         ieee80211_mlme_notify_scan_completed(local);
 465         ieee80211_ibss_notify_scan_completed(local);
 466
 467         /* Requeue all the work that might have been ignored while
 468          * the scan was in progress; if there was none this will
 469          * just be a no-op for the particular interface.
 470          */
 471         list_for_each_entry_rcu(sdata, &local->interfaces, list) {
 472                 if (ieee80211_sdata_running(sdata))
 473                         ieee80211_queue_work(&sdata->local->hw, &sdata->work);
 474         }
 475
 476         if (was_scanning)
 477                 ieee80211_start_next_roc(local);
 478 }
 479
 480 void ieee80211_scan_completed(struct ieee80211_hw *hw,
 481                               struct cfg80211_scan_info *info)
 482 {
 483         struct ieee80211_local *local = hw_to_local(hw);
 484
 485         trace_api_scan_completed(local, info->aborted);
 486
 487         set_bit(SCAN_COMPLETED, &local->scanning);
 488         if (info->aborted)
 489                 set_bit(SCAN_ABORTED, &local->scanning);
 490
 491         memcpy(&local->scan_info, info, sizeof(*info));
 492
 493         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, 0);
 494 }
 495 EXPORT_SYMBOL(ieee80211_scan_completed);
 496
 497 static int ieee80211_start_sw_scan(struct ieee80211_local *local,
 498                                    struct ieee80211_sub_if_data *sdata)
 499 {
 500         /* Software scan is not supported in multi-channel cases */
 501         if (local->use_chanctx)
 502                 return -EOPNOTSUPP;
 503
 504         /*
 505          * Hardware/driver doesn't support hw_scan, so use software
 506          * scanning instead. First send a nullfunc frame with power save
 507          * bit on so that AP will buffer the frames for us while we are not
 508          * listening, then send probe requests to each channel and wait for
 509          * the responses. After all channels are scanned, tune back to the
 510          * original channel and send a nullfunc frame with power save bit
 511          * off to trigger the AP to send us all the buffered frames.
 512          *
 513          * Note that while local->sw_scanning is true everything else but
 514          * nullfunc frames and probe requests will be dropped in
 515          * ieee80211_tx_h_check_assoc().
 516          */
 517         drv_sw_scan_start(local, sdata, local->scan_addr);
 518
 519         local->leave_oper_channel_time = jiffies;
 520         local->next_scan_state = SCAN_DECISION;
 521         local->scan_channel_idx = 0;
 522
 523         ieee80211_offchannel_stop_vifs(local);
 524
 525         /* ensure nullfunc is transmitted before leaving operating channel */
 526         ieee80211_flush_queues(local, NULL, false);
 527
 528         ieee80211_configure_filter(local);
 529
 530         /* We need to set power level at maximum rate for scanning. */
 531         ieee80211_hw_config(local, 0);
 532
 533         ieee80211_queue_delayed_work(&local->hw,
 534                                      &local->scan_work, 0);
 535
 536         return 0;
 537 }
 538
 539 static bool __ieee80211_can_leave_ch(struct ieee80211_sub_if_data *sdata)
 540 {
 541         struct ieee80211_local *local = sdata->local;
 542         struct ieee80211_sub_if_data *sdata_iter;
 543
 544         if (!ieee80211_is_radar_required(local))
 545                 return true;
 546
 547         if (!regulatory_pre_cac_allowed(local->hw.wiphy))
 548                 return false;
 549
 550         mutex_lock(&local->iflist_mtx);
 551         list_for_each_entry(sdata_iter, &local->interfaces, list) {
 552                 if (sdata_iter->wdev.cac_started) {
 553                         mutex_unlock(&local->iflist_mtx);
 554                         return false;
 555                 }
 556         }
 557         mutex_unlock(&local->iflist_mtx);
 558
 559         return true;
 560 }
 561
 562 static bool ieee80211_can_scan(struct ieee80211_local *local,
 563                                struct ieee80211_sub_if_data *sdata)
 564 {
 565         if (!__ieee80211_can_leave_ch(sdata))
 566                 return false;
 567
 568         if (!list_empty(&local->roc_list))
 569                 return false;
 570
 571         if (sdata->vif.type == NL80211_IFTYPE_STATION &&
 572             sdata->u.mgd.flags & IEEE80211_STA_CONNECTION_POLL)
 573                 return false;
 574
 575         return true;
 576 }
 577
 578 void ieee80211_run_deferred_scan(struct ieee80211_local *local)
 579 {
 580         lockdep_assert_held(&local->mtx);
 581
 582         if (!local->scan_req || local->scanning)
 583                 return;
 584
 585         if (!ieee80211_can_scan(local,
 586                                 rcu_dereference_protected(
 587                                         local->scan_sdata,
 588                                         lockdep_is_held(&local->mtx))))
 589                 return;
 590
 591         ieee80211_queue_delayed_work(&local->hw, &local->scan_work,
 592                                      round_jiffies_relative(0));
 593 }
 594
 595 static void ieee80211_send_scan_probe_req(struct ieee80211_sub_if_data *sdata,
 596                                           const u8 *src, const u8 *dst,
 597                                           const u8 *ssid, size_t ssid_len,
 598                                           const u8 *ie, size_t ie_len,
 599                                           u32 ratemask, u32 flags, u32 tx_flags,
 600                                           struct ieee80211_channel *channel)
 601 {
 602         struct sk_buff *skb;
 603
 604         skb = ieee80211_build_probe_req(sdata, src, dst, ratemask, channel,
 605                                         ssid, ssid_len,
 606                                         ie, ie_len, flags);
 607
 608         if (skb) {
 609                 if (flags & IEEE80211_PROBE_FLAG_RANDOM_SN) {
 610                         struct ieee80211_hdr *hdr = (void *)skb->data;
 611                         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 612                         u16 sn = get_random_u32();
 613
 614                         info->control.flags |= IEEE80211_TX_CTRL_NO_SEQNO;
 615                         hdr->seq_ctrl =
 616                                 cpu_to_le16(IEEE80211_SN_TO_SEQ(sn));
 617                 }
 618                 IEEE80211_SKB_CB(skb)->flags |= tx_flags;
 619                 ieee80211_tx_skb_tid_band(sdata, skb, 7, channel->band);
 620         }
 621 }
 622
 623 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 624                                             unsigned long *next_delay)
 625 {
 626         int i;
 627         struct ieee80211_sub_if_data *sdata;
 628         struct cfg80211_scan_request *scan_req;
 629         enum nl80211_band band = local->hw.conf.chandef.chan->band;
 630         u32 flags = 0, tx_flags;
 631
 632         scan_req = rcu_dereference_protected(local->scan_req,
 633                                              lockdep_is_held(&local->mtx));
 634
 635         tx_flags = IEEE80211_TX_INTFL_OFFCHAN_TX_OK;
 636         if (scan_req->no_cck)
 637                 tx_flags |= IEEE80211_TX_CTL_NO_CCK_RATE;
 638         if (scan_req->flags & NL80211_SCAN_FLAG_MIN_PREQ_CONTENT)
 639                 flags |= IEEE80211_PROBE_FLAG_MIN_CONTENT;
 640         if (scan_req->flags & NL80211_SCAN_FLAG_RANDOM_SN)
 641                 flags |= IEEE80211_PROBE_FLAG_RANDOM_SN;
 642
 643         sdata = rcu_dereference_protected(local->scan_sdata,
 644                                           lockdep_is_held(&local->mtx));
 645
 646         for (i = 0; i < scan_req->n_ssids; i++)
 647                 ieee80211_send_scan_probe_req(
 648                         sdata, local->scan_addr, scan_req->bssid,
 649                         scan_req->ssids[i].ssid, scan_req->ssids[i].ssid_len,
 650                         scan_req->ie, scan_req->ie_len,
 651                         scan_req->rates[band], flags,
 652                         tx_flags, local->hw.conf.chandef.chan);
 653
 654         /*
 655          * After sending probe requests, wait for probe responses
 656          * on the channel.
 657          */
 658         *next_delay = IEEE80211_CHANNEL_TIME;
 659         local->next_scan_state = SCAN_DECISION;
 660 }
 661
 662 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 663                                   struct cfg80211_scan_request *req)
 664 {
 665         struct ieee80211_local *local = sdata->local;
 666         bool hw_scan = local->ops->hw_scan;
 667         int rc;
 668
 669         lockdep_assert_held(&local->mtx);
 670
 671         if (local->scan_req)
 672                 return -EBUSY;
 673
 674         if (!__ieee80211_can_leave_ch(sdata))
 675                 return -EBUSY;
 676
 677         if (!ieee80211_can_scan(local, sdata)) {
 678                 /* wait for the work to finish/time out */
 679                 rcu_assign_pointer(local->scan_req, req);
 680                 rcu_assign_pointer(local->scan_sdata, sdata);
 681                 return 0;
 682         }
 683
 684  again:
 685         if (hw_scan) {
 686                 u8 *ies;
 687
 688                 local->hw_scan_ies_bufsize = local->scan_ies_len + req->ie_len;
 689
 690                 if (ieee80211_hw_check(&local->hw, SINGLE_SCAN_ON_ALL_BANDS)) {
 691                         int i, n_bands = 0;
 692                         u8 bands_counted = 0;
 693
 694                         for (i = 0; i < req->n_channels; i++) {
 695                                 if (bands_counted & BIT(req->channels[i]->band))
 696                                         continue;
 697                                 bands_counted |= BIT(req->channels[i]->band);
 698                                 n_bands++;
 699                         }
 700
 701                         local->hw_scan_ies_bufsize *= n_bands;
 702                 }
 703
 704                 local->hw_scan_req = kmalloc(
 705                                 sizeof(*local->hw_scan_req) +
 706                                 req->n_channels * sizeof(req->channels[0]) +
 707                                 local->hw_scan_ies_bufsize, GFP_KERNEL);
 708                 if (!local->hw_scan_req)
 709                         return -ENOMEM;
 710
 711                 local->hw_scan_req->req.ssids = req->ssids;
 712                 local->hw_scan_req->req.n_ssids = req->n_ssids;
 713                 ies = (u8 *)local->hw_scan_req +
 714                         sizeof(*local->hw_scan_req) +
 715                         req->n_channels * sizeof(req->channels[0]);
 716                 local->hw_scan_req->req.ie = ies;
 717                 local->hw_scan_req->req.flags = req->flags;
 718                 eth_broadcast_addr(local->hw_scan_req->req.bssid);
 719                 local->hw_scan_req->req.duration = req->duration;
 720                 local->hw_scan_req->req.duration_mandatory =
 721                         req->duration_mandatory;
 722
 723                 local->hw_scan_band = 0;
 724                 local->hw_scan_req->req.n_6ghz_params = req->n_6ghz_params;
 725                 local->hw_scan_req->req.scan_6ghz_params =
 726                         req->scan_6ghz_params;
 727                 local->hw_scan_req->req.scan_6ghz = req->scan_6ghz;
 728
 729                 /*
 730                  * After allocating local->hw_scan_req, we must
 731                  * go through until ieee80211_prep_hw_scan(), so
 732                  * anything that might be changed here and leave
 733                  * this function early must not go after this
 734                  * allocation.
 735                  */
 736         }
 737
 738         rcu_assign_pointer(local->scan_req, req);
 739         rcu_assign_pointer(local->scan_sdata, sdata);
 740
 741         if (req->flags & NL80211_SCAN_FLAG_RANDOM_ADDR)
 742                 get_random_mask_addr(local->scan_addr,
 743                                      req->mac_addr,
 744                                      req->mac_addr_mask);
 745         else
 746                 memcpy(local->scan_addr, sdata->vif.addr, ETH_ALEN);
 747
 748         if (hw_scan) {
 749                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 750         } else if ((req->n_channels == 1) &&
 751                    (req->channels[0] == local->_oper_chandef.chan)) {
 752                 /*
 753                  * If we are scanning only on the operating channel
 754                  * then we do not need to stop normal activities
 755                  */
 756                 unsigned long next_delay;
 757
 758                 __set_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning);
 759
 760                 ieee80211_recalc_idle(local);
 761
 762                 /* Notify driver scan is starting, keep order of operations
 763                  * same as normal software scan, in case that matters. */
 764                 drv_sw_scan_start(local, sdata, local->scan_addr);
 765
 766                 ieee80211_configure_filter(local); /* accept probe-responses */
 767
 768                 /* We need to ensure power level is at max for scanning. */
 769                 ieee80211_hw_config(local, 0);
 770
 771                 if ((req->channels[0]->flags & (IEEE80211_CHAN_NO_IR |
 772                                                 IEEE80211_CHAN_RADAR)) ||
 773                     !req->n_ssids) {
 774                         next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 775                 } else {
 776                         ieee80211_scan_state_send_probe(local, &next_delay);
 777                         next_delay = IEEE80211_CHANNEL_TIME;
 778                 }
 779
 780                 /* Now, just wait a bit and we are all done! */
 781                 ieee80211_queue_delayed_work(&local->hw, &local->scan_work,
 782                                              next_delay);
 783                 return 0;
 784         } else {
 785                 /* Do normal software scan */
 786                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 787         }
 788
 789         ieee80211_recalc_idle(local);
 790
 791         if (hw_scan) {
 792                 WARN_ON(!ieee80211_prep_hw_scan(sdata));
 793                 rc = drv_hw_scan(local, sdata, local->hw_scan_req);
 794         } else {
 795                 rc = ieee80211_start_sw_scan(local, sdata);
 796         }
 797
 798         if (rc) {
 799                 kfree(local->hw_scan_req);
 800                 local->hw_scan_req = NULL;
 801                 local->scanning = 0;
 802
 803                 ieee80211_recalc_idle(local);
 804
 805                 local->scan_req = NULL;
 806                 RCU_INIT_POINTER(local->scan_sdata, NULL);
 807         }
 808
 809         if (hw_scan && rc == 1) {
 810                 /*
 811                  * we can't fall back to software for P2P-GO
 812                  * as it must update NoA etc.
 813                  */
 814                 if (ieee80211_vif_type_p2p(&sdata->vif) ==
 815                                 NL80211_IFTYPE_P2P_GO)
 816                         return -EOPNOTSUPP;
 817                 hw_scan = false;
 818                 goto again;
 819         }
 820
 821         return rc;
 822 }
 823
 824 static unsigned long
 825 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
 826 {
 827         /*
 828          * TODO: channel switching also consumes quite some time,
 829          * add that delay as well to get a better estimation
 830          */
 831         if (chan->flags & (IEEE80211_CHAN_NO_IR | IEEE80211_CHAN_RADAR))
 832                 return IEEE80211_PASSIVE_CHANNEL_TIME;
 833         return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
 834 }
 835
 836 static void ieee80211_scan_state_decision(struct ieee80211_local *local,
 837                                           unsigned long *next_delay)
 838 {
 839         bool associated = false;
 840         bool tx_empty = true;
 841         bool bad_latency;
 842         struct ieee80211_sub_if_data *sdata;
 843         struct ieee80211_channel *next_chan;
 844         enum mac80211_scan_state next_scan_state;
 845         struct cfg80211_scan_request *scan_req;
 846
 847         /*
 848          * check if at least one STA interface is associated,
 849          * check if at least one STA interface has pending tx frames
 850          * and grab the lowest used beacon interval
 851          */
 852         mutex_lock(&local->iflist_mtx);
 853         list_for_each_entry(sdata, &local->interfaces, list) {
 854                 if (!ieee80211_sdata_running(sdata))
 855                         continue;
 856
 857                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 858                         if (sdata->u.mgd.associated) {
 859                                 associated = true;
 860
 861                                 if (!qdisc_all_tx_empty(sdata->dev)) {
 862                                         tx_empty = false;
 863                                         break;
 864                                 }
 865                         }
 866                 }
 867         }
 868         mutex_unlock(&local->iflist_mtx);
 869
 870         scan_req = rcu_dereference_protected(local->scan_req,
 871                                              lockdep_is_held(&local->mtx));
 872
 873         next_chan = scan_req->channels[local->scan_channel_idx];
 874
 875         /*
 876          * we're currently scanning a different channel, let's
 877          * see if we can scan another channel without interfering
 878          * with the current traffic situation.
 879          *
 880          * Keep good latency, do not stay off-channel more than 125 ms.
 881          */
 882
 883         bad_latency = time_after(jiffies +
 884                                  ieee80211_scan_get_channel_time(next_chan),
 885                                  local->leave_oper_channel_time + HZ / 8);
 886
 887         if (associated && !tx_empty) {
 888                 if (scan_req->flags & NL80211_SCAN_FLAG_LOW_PRIORITY)
 889                         next_scan_state = SCAN_ABORT;
 890                 else
 891                         next_scan_state = SCAN_SUSPEND;
 892         } else if (associated && bad_latency) {
 893                 next_scan_state = SCAN_SUSPEND;
 894         } else {
 895                 next_scan_state = SCAN_SET_CHANNEL;
 896         }
 897
 898         local->next_scan_state = next_scan_state;
 899
 900         *next_delay = 0;
 901 }
 902
 903 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 904                                              unsigned long *next_delay)
 905 {
 906         int skip;
 907         struct ieee80211_channel *chan;
 908         enum nl80211_bss_scan_width oper_scan_width;
 909         struct cfg80211_scan_request *scan_req;
 910
 911         scan_req = rcu_dereference_protected(local->scan_req,
 912                                              lockdep_is_held(&local->mtx));
 913
 914         skip = 0;
 915         chan = scan_req->channels[local->scan_channel_idx];
 916
 917         local->scan_chandef.chan = chan;
 918         local->scan_chandef.center_freq1 = chan->center_freq;
 919         local->scan_chandef.freq1_offset = chan->freq_offset;
 920         local->scan_chandef.center_freq2 = 0;
 921
 922         /* For scanning on the S1G band, ignore scan_width (which is constant
 923          * across all channels) for now since channel width is specific to each
 924          * channel. Detect the required channel width here and likely revisit
 925          * later. Maybe scan_width could be used to build the channel scan list?
 926          */
 927         if (chan->band == NL80211_BAND_S1GHZ) {
 928                 local->scan_chandef.width = ieee80211_s1g_channel_width(chan);
 929                 goto set_channel;
 930         }
 931
 932         switch (scan_req->scan_width) {
 933         case NL80211_BSS_CHAN_WIDTH_5:
 934                 local->scan_chandef.width = NL80211_CHAN_WIDTH_5;
 935                 break;
 936         case NL80211_BSS_CHAN_WIDTH_10:
 937                 local->scan_chandef.width = NL80211_CHAN_WIDTH_10;
 938                 break;
 939         default:
 940         case NL80211_BSS_CHAN_WIDTH_20:
 941                 /* If scanning on oper channel, use whatever channel-type
 942                  * is currently in use.
 943                  */
 944                 oper_scan_width = cfg80211_chandef_to_scan_width(
 945                                         &local->_oper_chandef);
 946                 if (chan == local->_oper_chandef.chan &&
 947                     oper_scan_width == scan_req->scan_width)
 948                         local->scan_chandef = local->_oper_chandef;
 949                 else
 950                         local->scan_chandef.width = NL80211_CHAN_WIDTH_20_NOHT;
 951                 break;
 952         case NL80211_BSS_CHAN_WIDTH_1:
 953         case NL80211_BSS_CHAN_WIDTH_2:
 954                 /* shouldn't get here, S1G handled above */
 955                 WARN_ON(1);
 956                 break;
 957         }
 958
 959 set_channel:
 960         if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 961                 skip = 1;
 962
 963         /* advance state machine to next channel/band */
 964         local->scan_channel_idx++;
 965
 966         if (skip) {
 967                 /* if we skip this channel return to the decision state */
 968                 local->next_scan_state = SCAN_DECISION;
 969                 return;
 970         }
 971
 972         /*
 973          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 974          * (which unfortunately doesn't say _why_ step a) is done,
 975          * but it waits for the probe delay or until a frame is
 976          * received - and the received frame would update the NAV).
 977          * For now, we do not support waiting until a frame is
 978          * received.
 979          *
 980          * In any case, it is not necessary for a passive scan.
 981          */
 982         if ((chan->flags & (IEEE80211_CHAN_NO_IR | IEEE80211_CHAN_RADAR)) ||
 983             !scan_req->n_ssids) {
 984                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 985                 local->next_scan_state = SCAN_DECISION;
 986                 return;
 987         }
 988
 989         /* active scan, send probes */
 990         *next_delay = IEEE80211_PROBE_DELAY;
 991         local->next_scan_state = SCAN_SEND_PROBE;
 992 }
 993
 994 static void ieee80211_scan_state_suspend(struct ieee80211_local *local,
 995                                          unsigned long *next_delay)
 996 {
 997         /* switch back to the operating channel */
 998         local->scan_chandef.chan = NULL;
 999         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
1000
1001         /* disable PS */
1002         ieee80211_offchannel_return(local);
1003
1004         *next_delay = HZ / 5;
1005         /* afterwards, resume scan & go to next channel */
1006         local->next_scan_state = SCAN_RESUME;
1007 }
1008
1009 static void ieee80211_scan_state_resume(struct ieee80211_local *local,
1010                                         unsigned long *next_delay)
1011 {
1012         ieee80211_offchannel_stop_vifs(local);
1013
1014         if (local->ops->flush) {
1015                 ieee80211_flush_queues(local, NULL, false);
1016                 *next_delay = 0;
1017         } else
1018                 *next_delay = HZ / 10;
1019
1020         /* remember when we left the operating channel */
1021         local->leave_oper_channel_time = jiffies;
1022
1023         /* advance to the next channel to be scanned */
1024         local->next_scan_state = SCAN_SET_CHANNEL;
1025 }
1026
1027 void ieee80211_scan_work(struct work_struct *work)
1028 {
1029         struct ieee80211_local *local =
1030                 container_of(work, struct ieee80211_local, scan_work.work);
1031         struct ieee80211_sub_if_data *sdata;
1032         struct cfg80211_scan_request *scan_req;
1033         unsigned long next_delay = 0;
1034         bool aborted;
1035
1036         mutex_lock(&local->mtx);
1037
1038         if (!ieee80211_can_run_worker(local)) {
1039                 aborted = true;
1040                 goto out_complete;
1041         }
1042
1043         sdata = rcu_dereference_protected(local->scan_sdata,
1044                                           lockdep_is_held(&local->mtx));
1045         scan_req = rcu_dereference_protected(local->scan_req,
1046                                              lockdep_is_held(&local->mtx));
1047
1048         /* When scanning on-channel, the first-callback means completed. */
1049         if (test_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning)) {
1050                 aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
1051                 goto out_complete;
1052         }
1053
1054         if (test_and_clear_bit(SCAN_COMPLETED, &local->scanning)) {
1055                 aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
1056                 goto out_complete;
1057         }
1058
1059         if (!sdata || !scan_req)
1060                 goto out;
1061
1062         if (!local->scanning) {
1063                 int rc;
1064
1065                 RCU_INIT_POINTER(local->scan_req, NULL);
1066                 RCU_INIT_POINTER(local->scan_sdata, NULL);
1067
1068                 rc = __ieee80211_start_scan(sdata, scan_req);
1069                 if (rc) {
1070                         /* need to complete scan in cfg80211 */
1071                         rcu_assign_pointer(local->scan_req, scan_req);
1072                         aborted = true;
1073                         goto out_complete;
1074                 } else
1075                         goto out;
1076         }
1077
1078         /*
1079          * as long as no delay is required advance immediately
1080          * without scheduling a new work
1081          */
1082         do {
1083                 if (!ieee80211_sdata_running(sdata)) {
1084                         aborted = true;
1085                         goto out_complete;
1086                 }
1087
1088                 switch (local->next_scan_state) {
1089                 case SCAN_DECISION:
1090                         /* if no more bands/channels left, complete scan */
1091                         if (local->scan_channel_idx >= scan_req->n_channels) {
1092                                 aborted = false;
1093                                 goto out_complete;
1094                         }
1095                         ieee80211_scan_state_decision(local, &next_delay);
1096                         break;
1097                 case SCAN_SET_CHANNEL:
1098                         ieee80211_scan_state_set_channel(local, &next_delay);
1099                         break;
1100                 case SCAN_SEND_PROBE:
1101                         ieee80211_scan_state_send_probe(local, &next_delay);
1102                         break;
1103                 case SCAN_SUSPEND:
1104                         ieee80211_scan_state_suspend(local, &next_delay);
1105                         break;
1106                 case SCAN_RESUME:
1107                         ieee80211_scan_state_resume(local, &next_delay);
1108                         break;
1109                 case SCAN_ABORT:
1110                         aborted = true;
1111                         goto out_complete;
1112                 }
1113         } while (next_delay == 0);
1114
1115         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
1116         goto out;
1117
1118 out_complete:
1119         __ieee80211_scan_completed(&local->hw, aborted);
1120 out:
1121         mutex_unlock(&local->mtx);
1122 }
1123
1124 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
1125                            struct cfg80211_scan_request *req)
1126 {
1127         int res;
1128
1129         mutex_lock(&sdata->local->mtx);
1130         res = __ieee80211_start_scan(sdata, req);
1131         mutex_unlock(&sdata->local->mtx);
1132
1133         return res;
1134 }
1135
1136 int ieee80211_request_ibss_scan(struct ieee80211_sub_if_data *sdata,
1137                                 const u8 *ssid, u8 ssid_len,
1138                                 struct ieee80211_channel **channels,
1139                                 unsigned int n_channels,
1140                                 enum nl80211_bss_scan_width scan_width)
1141 {
1142         struct ieee80211_local *local = sdata->local;
1143         int ret = -EBUSY, i, n_ch = 0;
1144         enum nl80211_band band;
1145
1146         mutex_lock(&local->mtx);
1147
1148         /* busy scanning */
1149         if (local->scan_req)
1150                 goto unlock;
1151
1152         /* fill internal scan request */
1153         if (!channels) {
1154                 int max_n;
1155
1156                 for (band = 0; band < NUM_NL80211_BANDS; band++) {
1157                         if (!local->hw.wiphy->bands[band] ||
1158                             band == NL80211_BAND_6GHZ)
1159                                 continue;
1160
1161                         max_n = local->hw.wiphy->bands[band]->n_channels;
1162                         for (i = 0; i < max_n; i++) {
1163                                 struct ieee80211_channel *tmp_ch =
1164                                     &local->hw.wiphy->bands[band]->channels[i];
1165
1166                                 if (tmp_ch->flags & (IEEE80211_CHAN_NO_IR |
1167                                                      IEEE80211_CHAN_DISABLED))
1168                                         continue;
1169
1170                                 local->int_scan_req->channels[n_ch] = tmp_ch;
1171                                 n_ch++;
1172                         }
1173                 }
1174
1175                 if (WARN_ON_ONCE(n_ch == 0))
1176                         goto unlock;
1177
1178                 local->int_scan_req->n_channels = n_ch;
1179         } else {
1180                 for (i = 0; i < n_channels; i++) {
1181                         if (channels[i]->flags & (IEEE80211_CHAN_NO_IR |
1182                                                   IEEE80211_CHAN_DISABLED))
1183                                 continue;
1184
1185                         local->int_scan_req->channels[n_ch] = channels[i];
1186                         n_ch++;
1187                 }
1188
1189                 if (WARN_ON_ONCE(n_ch == 0))
1190                         goto unlock;
1191
1192                 local->int_scan_req->n_channels = n_ch;
1193         }
1194
1195         local->int_scan_req->ssids = &local->scan_ssid;
1196         local->int_scan_req->n_ssids = 1;
1197         local->int_scan_req->scan_width = scan_width;
1198         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
1199         local->int_scan_req->ssids[0].ssid_len = ssid_len;
1200
1201         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
1202  unlock:
1203         mutex_unlock(&local->mtx);
1204         return ret;
1205 }
1206
1207 /*
1208  * Only call this function when a scan can't be queued -- under RTNL.
1209  */
1210 void ieee80211_scan_cancel(struct ieee80211_local *local)
1211 {
1212         /*
1213          * We are canceling software scan, or deferred scan that was not
1214          * yet really started (see __ieee80211_start_scan ).
1215          *
1216          * Regarding hardware scan:
1217          * - we can not call  __ieee80211_scan_completed() as when
1218          *   SCAN_HW_SCANNING bit is set this function change
1219          *   local->hw_scan_req to operate on 5G band, what race with
1220          *   driver which can use local->hw_scan_req
1221          *
1222          * - we can not cancel scan_work since driver can schedule it
1223          *   by ieee80211_scan_completed(..., true) to finish scan
1224          *
1225          * Hence we only call the cancel_hw_scan() callback, but the low-level
1226          * driver is still responsible for calling ieee80211_scan_completed()
1227          * after the scan was completed/aborted.
1228          */
1229
1230         mutex_lock(&local->mtx);
1231         if (!local->scan_req)
1232                 goto out;
1233
1234         /*
1235          * We have a scan running and the driver already reported completion,
1236          * but the worker hasn't run yet or is stuck on the mutex - mark it as
1237          * cancelled.
1238          */
1239         if (test_bit(SCAN_HW_SCANNING, &local->scanning) &&
1240             test_bit(SCAN_COMPLETED, &local->scanning)) {
1241                 set_bit(SCAN_HW_CANCELLED, &local->scanning);
1242                 goto out;
1243         }
1244
1245         if (test_bit(SCAN_HW_SCANNING, &local->scanning)) {
1246                 /*
1247                  * Make sure that __ieee80211_scan_completed doesn't trigger a
1248                  * scan on another band.
1249                  */
1250                 set_bit(SCAN_HW_CANCELLED, &local->scanning);
1251                 if (local->ops->cancel_hw_scan)
1252                         drv_cancel_hw_scan(local,
1253                                 rcu_dereference_protected(local->scan_sdata,
1254                                                 lockdep_is_held(&local->mtx)));
1255                 goto out;
1256         }
1257
1258         /*
1259          * If the work is currently running, it must be blocked on
1260          * the mutex, but we'll set scan_sdata = NULL and it'll
1261          * simply exit once it acquires the mutex.
1262          */
1263         cancel_delayed_work(&local->scan_work);
1264         /* and clean up */
1265         memset(&local->scan_info, 0, sizeof(local->scan_info));
1266         __ieee80211_scan_completed(&local->hw, true);
1267 out:
1268         mutex_unlock(&local->mtx);
1269 }
1270
1271 int __ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
1272                                         struct cfg80211_sched_scan_request *req)
1273 {
1274         struct ieee80211_local *local = sdata->local;
1275         struct ieee80211_scan_ies sched_scan_ies = {};
1276         struct cfg80211_chan_def chandef;
1277         int ret, i, iebufsz, num_bands = 0;
1278         u32 rate_masks[NUM_NL80211_BANDS] = {};
1279         u8 bands_used = 0;
1280         u8 *ie;
1281         u32 flags = 0;
1282
1283         iebufsz = local->scan_ies_len + req->ie_len;
1284
1285         lockdep_assert_held(&local->mtx);
1286
1287         if (!local->ops->sched_scan_start)
1288                 return -ENOTSUPP;
1289
1290         for (i = 0; i < NUM_NL80211_BANDS; i++) {
1291                 if (local->hw.wiphy->bands[i]) {
1292                         bands_used |= BIT(i);
1293                         rate_masks[i] = (u32) -1;
1294                         num_bands++;
1295                 }
1296         }
1297
1298         if (req->flags & NL80211_SCAN_FLAG_MIN_PREQ_CONTENT)
1299                 flags |= IEEE80211_PROBE_FLAG_MIN_CONTENT;
1300
1301         ie = kcalloc(iebufsz, num_bands, GFP_KERNEL);
1302         if (!ie) {
1303                 ret = -ENOMEM;
1304                 goto out;
1305         }
1306
1307         ieee80211_prepare_scan_chandef(&chandef, req->scan_width);
1308
1309         ieee80211_build_preq_ies(sdata, ie, num_bands * iebufsz,
1310                                  &sched_scan_ies, req->ie,
1311                                  req->ie_len, bands_used, rate_masks, &chandef,
1312                                  flags);
1313
1314         ret = drv_sched_scan_start(local, sdata, req, &sched_scan_ies);
1315         if (ret == 0) {
1316                 rcu_assign_pointer(local->sched_scan_sdata, sdata);
1317                 rcu_assign_pointer(local->sched_scan_req, req);
1318         }
1319
1320         kfree(ie);
1321
1322 out:
1323         if (ret) {
1324                 /* Clean in case of failure after HW restart or upon resume. */
1325                 RCU_INIT_POINTER(local->sched_scan_sdata, NULL);
1326                 RCU_INIT_POINTER(local->sched_scan_req, NULL);
1327         }
1328
1329         return ret;
1330 }
1331
1332 int ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
1333                                        struct cfg80211_sched_scan_request *req)
1334 {
1335         struct ieee80211_local *local = sdata->local;
1336         int ret;
1337
1338         mutex_lock(&local->mtx);
1339
1340         if (rcu_access_pointer(local->sched_scan_sdata)) {
1341                 mutex_unlock(&local->mtx);
1342                 return -EBUSY;
1343         }
1344
1345         ret = __ieee80211_request_sched_scan_start(sdata, req);
1346
1347         mutex_unlock(&local->mtx);
1348         return ret;
1349 }
1350
1351 int ieee80211_request_sched_scan_stop(struct ieee80211_local *local)
1352 {
1353         struct ieee80211_sub_if_data *sched_scan_sdata;
1354         int ret = -ENOENT;
1355
1356         mutex_lock(&local->mtx);
1357
1358         if (!local->ops->sched_scan_stop) {
1359                 ret = -ENOTSUPP;
1360                 goto out;
1361         }
1362
1363         /* We don't want to restart sched scan anymore. */
1364         RCU_INIT_POINTER(local->sched_scan_req, NULL);
1365
1366         sched_scan_sdata = rcu_dereference_protected(local->sched_scan_sdata,
1367                                                 lockdep_is_held(&local->mtx));
1368         if (sched_scan_sdata) {
1369                 ret = drv_sched_scan_stop(local, sched_scan_sdata);
1370                 if (!ret)
1371                         RCU_INIT_POINTER(local->sched_scan_sdata, NULL);
1372         }
1373 out:
1374         mutex_unlock(&local->mtx);
1375
1376         return ret;
1377 }
1378
1379 void ieee80211_sched_scan_results(struct ieee80211_hw *hw)
1380 {
1381         struct ieee80211_local *local = hw_to_local(hw);
1382
1383         trace_api_sched_scan_results(local);
1384
1385         cfg80211_sched_scan_results(hw->wiphy, 0);
1386 }
1387 EXPORT_SYMBOL(ieee80211_sched_scan_results);
1388
1389 void ieee80211_sched_scan_end(struct ieee80211_local *local)
1390 {
1391         mutex_lock(&local->mtx);
1392
1393         if (!rcu_access_pointer(local->sched_scan_sdata)) {
1394                 mutex_unlock(&local->mtx);
1395                 return;
1396         }
1397
1398         RCU_INIT_POINTER(local->sched_scan_sdata, NULL);
1399
1400         /* If sched scan was aborted by the driver. */
1401         RCU_INIT_POINTER(local->sched_scan_req, NULL);
1402
1403         mutex_unlock(&local->mtx);
1404
1405         cfg80211_sched_scan_stopped(local->hw.wiphy, 0);
1406 }
1407
1408 void ieee80211_sched_scan_stopped_work(struct work_struct *work)
1409 {
1410         struct ieee80211_local *local =
1411                 container_of(work, struct ieee80211_local,
1412                              sched_scan_stopped_work);
1413
1414         ieee80211_sched_scan_end(local);
1415 }
1416
1417 void ieee80211_sched_scan_stopped(struct ieee80211_hw *hw)
1418 {
1419         struct ieee80211_local *local = hw_to_local(hw);
1420
1421         trace_api_sched_scan_stopped(local);
1422
1423         /*
1424          * this shouldn't really happen, so for simplicity
1425          * simply ignore it, and let mac80211 reconfigure
1426          * the sched scan later on.
1427          */
1428         if (local->in_reconfig)
1429                 return;
1430
1431         schedule_work(&local->sched_scan_stopped_work);
1432 }
1433 EXPORT_SYMBOL(ieee80211_sched_scan_stopped);