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/etherdevice.h>
  17 #include <linux/rtnetlink.h>
  18 #include <linux/pm_qos.h>
  19 #include <net/sch_generic.h>
  20 #include <linux/slab.h>
  21 #include <linux/export.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 struct ieee80211_bss *
  59 ieee80211_bss_info_update(struct ieee80211_local *local,
  60                           struct ieee80211_rx_status *rx_status,
  61                           struct ieee80211_mgmt *mgmt, size_t len,
  62                           struct ieee802_11_elems *elems,
  63                           struct ieee80211_channel *channel)
  64 {
  65         bool beacon = ieee80211_is_beacon(mgmt->frame_control);
  66         struct cfg80211_bss *cbss;
  67         struct ieee80211_bss *bss;
  68         int clen, srlen;
  69         s32 signal = 0;
  70
  71         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
  72                 signal = rx_status->signal * 100;
  73         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
  74                 signal = (rx_status->signal * 100) / local->hw.max_signal;
  75
  76         cbss = cfg80211_inform_bss_frame(local->hw.wiphy, channel,
  77                                          mgmt, len, signal, GFP_ATOMIC);
  78         if (!cbss)
  79                 return NULL;
  80
  81         bss = (void *)cbss->priv;
  82
  83         if (beacon)
  84                 bss->device_ts_beacon = rx_status->device_timestamp;
  85         else
  86                 bss->device_ts_presp = rx_status->device_timestamp;
  87
  88         if (elems->parse_error) {
  89                 if (beacon)
  90                         bss->corrupt_data |= IEEE80211_BSS_CORRUPT_BEACON;
  91                 else
  92                         bss->corrupt_data |= IEEE80211_BSS_CORRUPT_PROBE_RESP;
  93         } else {
  94                 if (beacon)
  95                         bss->corrupt_data &= ~IEEE80211_BSS_CORRUPT_BEACON;
  96                 else
  97                         bss->corrupt_data &= ~IEEE80211_BSS_CORRUPT_PROBE_RESP;
  98         }
  99
 100         /* save the ERP value so that it is available at association time */
 101         if (elems->erp_info && elems->erp_info_len >= 1 &&
 102                         (!elems->parse_error ||
 103                          !(bss->valid_data & IEEE80211_BSS_VALID_ERP))) {
 104                 bss->erp_value = elems->erp_info[0];
 105                 bss->has_erp_value = true;
 106                 if (!elems->parse_error)
 107                         bss->valid_data |= IEEE80211_BSS_VALID_ERP;
 108         }
 109
 110         /* replace old supported rates if we get new values */
 111         if (!elems->parse_error ||
 112             !(bss->valid_data & IEEE80211_BSS_VALID_RATES)) {
 113                 srlen = 0;
 114                 if (elems->supp_rates) {
 115                         clen = IEEE80211_MAX_SUPP_RATES;
 116                         if (clen > elems->supp_rates_len)
 117                                 clen = elems->supp_rates_len;
 118                         memcpy(bss->supp_rates, elems->supp_rates, clen);
 119                         srlen += clen;
 120                 }
 121                 if (elems->ext_supp_rates) {
 122                         clen = IEEE80211_MAX_SUPP_RATES - srlen;
 123                         if (clen > elems->ext_supp_rates_len)
 124                                 clen = elems->ext_supp_rates_len;
 125                         memcpy(bss->supp_rates + srlen, elems->ext_supp_rates,
 126                                clen);
 127                         srlen += clen;
 128                 }
 129                 if (srlen) {
 130                         bss->supp_rates_len = srlen;
 131                         if (!elems->parse_error)
 132                                 bss->valid_data |= IEEE80211_BSS_VALID_RATES;
 133                 }
 134         }
 135
 136         if (!elems->parse_error ||
 137             !(bss->valid_data & IEEE80211_BSS_VALID_WMM)) {
 138                 bss->wmm_used = elems->wmm_param || elems->wmm_info;
 139                 bss->uapsd_supported = is_uapsd_supported(elems);
 140                 if (!elems->parse_error)
 141                         bss->valid_data |= IEEE80211_BSS_VALID_WMM;
 142         }
 143
 144         return bss;
 145 }
 146
 147 void ieee80211_scan_rx(struct ieee80211_local *local, struct sk_buff *skb)
 148 {
 149         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
 150         struct ieee80211_sub_if_data *sdata1, *sdata2;
 151         struct ieee80211_mgmt *mgmt = (void *)skb->data;
 152         struct ieee80211_bss *bss;
 153         u8 *elements;
 154         struct ieee80211_channel *channel;
 155         size_t baselen;
 156         struct ieee802_11_elems elems;
 157
 158         if (skb->len < 24 ||
 159             (!ieee80211_is_probe_resp(mgmt->frame_control) &&
 160              !ieee80211_is_beacon(mgmt->frame_control)))
 161                 return;
 162
 163         sdata1 = rcu_dereference(local->scan_sdata);
 164         sdata2 = rcu_dereference(local->sched_scan_sdata);
 165
 166         if (likely(!sdata1 && !sdata2))
 167                 return;
 168
 169         if (ieee80211_is_probe_resp(mgmt->frame_control)) {
 170                 /* ignore ProbeResp to foreign address */
 171                 if ((!sdata1 || !ether_addr_equal(mgmt->da, sdata1->vif.addr)) &&
 172                     (!sdata2 || !ether_addr_equal(mgmt->da, sdata2->vif.addr)))
 173                         return;
 174
 175                 elements = mgmt->u.probe_resp.variable;
 176                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 177         } else {
 178                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 179                 elements = mgmt->u.beacon.variable;
 180         }
 181
 182         if (baselen > skb->len)
 183                 return;
 184
 185         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
 186
 187         channel = ieee80211_get_channel(local->hw.wiphy, rx_status->freq);
 188
 189         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 190                 return;
 191
 192         bss = ieee80211_bss_info_update(local, rx_status,
 193                                         mgmt, skb->len, &elems,
 194                                         channel);
 195         if (bss)
 196                 ieee80211_rx_bss_put(local, bss);
 197 }
 198
 199 /* return false if no more work */
 200 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 201 {
 202         struct cfg80211_scan_request *req = local->scan_req;
 203         enum ieee80211_band band;
 204         int i, ielen, n_chans;
 205
 206         do {
 207                 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
 208                         return false;
 209
 210                 band = local->hw_scan_band;
 211                 n_chans = 0;
 212                 for (i = 0; i < req->n_channels; i++) {
 213                         if (req->channels[i]->band == band) {
 214                                 local->hw_scan_req->channels[n_chans] =
 215                                                         req->channels[i];
 216                                 n_chans++;
 217                         }
 218                 }
 219
 220                 local->hw_scan_band++;
 221         } while (!n_chans);
 222
 223         local->hw_scan_req->n_channels = n_chans;
 224
 225         ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
 226                                          local->hw_scan_ies_bufsize,
 227                                          req->ie, req->ie_len, band,
 228                                          req->rates[band], 0);
 229         local->hw_scan_req->ie_len = ielen;
 230         local->hw_scan_req->no_cck = req->no_cck;
 231
 232         return true;
 233 }
 234
 235 static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted,
 236                                        bool was_hw_scan)
 237 {
 238         struct ieee80211_local *local = hw_to_local(hw);
 239
 240         lockdep_assert_held(&local->mtx);
 241
 242         /*
 243          * It's ok to abort a not-yet-running scan (that
 244          * we have one at all will be verified by checking
 245          * local->scan_req next), but not to complete it
 246          * successfully.
 247          */
 248         if (WARN_ON(!local->scanning && !aborted))
 249                 aborted = true;
 250
 251         if (WARN_ON(!local->scan_req))
 252                 return;
 253
 254         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 255                 int rc;
 256
 257                 rc = drv_hw_scan(local,
 258                         rcu_dereference_protected(local->scan_sdata,
 259                                                   lockdep_is_held(&local->mtx)),
 260                         local->hw_scan_req);
 261
 262                 if (rc == 0)
 263                         return;
 264         }
 265
 266         kfree(local->hw_scan_req);
 267         local->hw_scan_req = NULL;
 268
 269         if (local->scan_req != local->int_scan_req)
 270                 cfg80211_scan_done(local->scan_req, aborted);
 271         local->scan_req = NULL;
 272         rcu_assign_pointer(local->scan_sdata, NULL);
 273
 274         local->scanning = 0;
 275         local->scan_channel = NULL;
 276
 277         /* Set power back to normal operating levels. */
 278         ieee80211_hw_config(local, 0);
 279
 280         if (!was_hw_scan) {
 281                 ieee80211_configure_filter(local);
 282                 drv_sw_scan_complete(local);
 283                 ieee80211_offchannel_return(local);
 284         }
 285
 286         ieee80211_recalc_idle(local);
 287
 288         ieee80211_mlme_notify_scan_completed(local);
 289         ieee80211_ibss_notify_scan_completed(local);
 290         ieee80211_mesh_notify_scan_completed(local);
 291         ieee80211_start_next_roc(local);
 292 }
 293
 294 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 295 {
 296         struct ieee80211_local *local = hw_to_local(hw);
 297
 298         trace_api_scan_completed(local, aborted);
 299
 300         set_bit(SCAN_COMPLETED, &local->scanning);
 301         if (aborted)
 302                 set_bit(SCAN_ABORTED, &local->scanning);
 303         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, 0);
 304 }
 305 EXPORT_SYMBOL(ieee80211_scan_completed);
 306
 307 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 308 {
 309         /* Software scan is not supported in multi-channel cases */
 310         if (local->use_chanctx)
 311                 return -EOPNOTSUPP;
 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         local->leave_oper_channel_time = jiffies;
 329         local->next_scan_state = SCAN_DECISION;
 330         local->scan_channel_idx = 0;
 331
 332         ieee80211_offchannel_stop_vifs(local);
 333
 334         /* ensure nullfunc is transmitted before leaving operating channel */
 335         ieee80211_flush_queues(local, NULL);
 336
 337         ieee80211_configure_filter(local);
 338
 339         /* We need to set power level at maximum rate for scanning. */
 340         ieee80211_hw_config(local, 0);
 341
 342         ieee80211_queue_delayed_work(&local->hw,
 343                                      &local->scan_work, 0);
 344
 345         return 0;
 346 }
 347
 348 static bool ieee80211_can_scan(struct ieee80211_local *local,
 349                                struct ieee80211_sub_if_data *sdata)
 350 {
 351         if (local->radar_detect_enabled)
 352                 return false;
 353
 354         if (!list_empty(&local->roc_list))
 355                 return false;
 356
 357         if (sdata->vif.type == NL80211_IFTYPE_STATION &&
 358             sdata->u.mgd.flags & (IEEE80211_STA_BEACON_POLL |
 359                                   IEEE80211_STA_CONNECTION_POLL))
 360                 return false;
 361
 362         return true;
 363 }
 364
 365 void ieee80211_run_deferred_scan(struct ieee80211_local *local)
 366 {
 367         lockdep_assert_held(&local->mtx);
 368
 369         if (!local->scan_req || local->scanning)
 370                 return;
 371
 372         if (!ieee80211_can_scan(local,
 373                                 rcu_dereference_protected(
 374                                         local->scan_sdata,
 375                                         lockdep_is_held(&local->mtx))))
 376                 return;
 377
 378         ieee80211_queue_delayed_work(&local->hw, &local->scan_work,
 379                                      round_jiffies_relative(0));
 380 }
 381
 382 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 383                                             unsigned long *next_delay)
 384 {
 385         int i;
 386         struct ieee80211_sub_if_data *sdata;
 387         enum ieee80211_band band = local->hw.conf.channel->band;
 388         u32 tx_flags;
 389
 390         tx_flags = IEEE80211_TX_INTFL_OFFCHAN_TX_OK;
 391         if (local->scan_req->no_cck)
 392                 tx_flags |= IEEE80211_TX_CTL_NO_CCK_RATE;
 393
 394         sdata = rcu_dereference_protected(local->scan_sdata,
 395                                           lockdep_is_held(&local->mtx));
 396
 397         for (i = 0; i < local->scan_req->n_ssids; i++)
 398                 ieee80211_send_probe_req(
 399                         sdata, NULL,
 400                         local->scan_req->ssids[i].ssid,
 401                         local->scan_req->ssids[i].ssid_len,
 402                         local->scan_req->ie, local->scan_req->ie_len,
 403                         local->scan_req->rates[band], false,
 404                         tx_flags, local->hw.conf.channel, true);
 405
 406         /*
 407          * After sending probe requests, wait for probe responses
 408          * on the channel.
 409          */
 410         *next_delay = IEEE80211_CHANNEL_TIME;
 411         local->next_scan_state = SCAN_DECISION;
 412 }
 413
 414 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 415                                   struct cfg80211_scan_request *req)
 416 {
 417         struct ieee80211_local *local = sdata->local;
 418         int rc;
 419
 420         lockdep_assert_held(&local->mtx);
 421
 422         if (local->scan_req)
 423                 return -EBUSY;
 424
 425         if (!ieee80211_can_scan(local, sdata)) {
 426                 /* wait for the work to finish/time out */
 427                 local->scan_req = req;
 428                 rcu_assign_pointer(local->scan_sdata, sdata);
 429                 return 0;
 430         }
 431
 432         if (local->ops->hw_scan) {
 433                 u8 *ies;
 434
 435                 local->hw_scan_ies_bufsize = 2 + IEEE80211_MAX_SSID_LEN +
 436                                              local->scan_ies_len +
 437                                              req->ie_len;
 438                 local->hw_scan_req = kmalloc(
 439                                 sizeof(*local->hw_scan_req) +
 440                                 req->n_channels * sizeof(req->channels[0]) +
 441                                 local->hw_scan_ies_bufsize, GFP_KERNEL);
 442                 if (!local->hw_scan_req)
 443                         return -ENOMEM;
 444
 445                 local->hw_scan_req->ssids = req->ssids;
 446                 local->hw_scan_req->n_ssids = req->n_ssids;
 447                 ies = (u8 *)local->hw_scan_req +
 448                         sizeof(*local->hw_scan_req) +
 449                         req->n_channels * sizeof(req->channels[0]);
 450                 local->hw_scan_req->ie = ies;
 451                 local->hw_scan_req->flags = req->flags;
 452
 453                 local->hw_scan_band = 0;
 454
 455                 /*
 456                  * After allocating local->hw_scan_req, we must
 457                  * go through until ieee80211_prep_hw_scan(), so
 458                  * anything that might be changed here and leave
 459                  * this function early must not go after this
 460                  * allocation.
 461                  */
 462         }
 463
 464         local->scan_req = req;
 465         rcu_assign_pointer(local->scan_sdata, sdata);
 466
 467         if (local->ops->hw_scan) {
 468                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 469         } else if ((req->n_channels == 1) &&
 470                    (req->channels[0] == local->_oper_channel)) {
 471                 /*
 472                  * If we are scanning only on the operating channel
 473                  * then we do not need to stop normal activities
 474                  */
 475                 unsigned long next_delay;
 476
 477                 __set_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning);
 478
 479                 ieee80211_recalc_idle(local);
 480
 481                 /* Notify driver scan is starting, keep order of operations
 482                  * same as normal software scan, in case that matters. */
 483                 drv_sw_scan_start(local);
 484
 485                 ieee80211_configure_filter(local); /* accept probe-responses */
 486
 487                 /* We need to ensure power level is at max for scanning. */
 488                 ieee80211_hw_config(local, 0);
 489
 490                 if ((req->channels[0]->flags &
 491                      IEEE80211_CHAN_PASSIVE_SCAN) ||
 492                     !local->scan_req->n_ssids) {
 493                         next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 494                 } else {
 495                         ieee80211_scan_state_send_probe(local, &next_delay);
 496                         next_delay = IEEE80211_CHANNEL_TIME;
 497                 }
 498
 499                 /* Now, just wait a bit and we are all done! */
 500                 ieee80211_queue_delayed_work(&local->hw, &local->scan_work,
 501                                              next_delay);
 502                 return 0;
 503         } else {
 504                 /* Do normal software scan */
 505                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 506         }
 507
 508         ieee80211_recalc_idle(local);
 509
 510         if (local->ops->hw_scan) {
 511                 WARN_ON(!ieee80211_prep_hw_scan(local));
 512                 rc = drv_hw_scan(local, sdata, local->hw_scan_req);
 513         } else
 514                 rc = ieee80211_start_sw_scan(local);
 515
 516         if (rc) {
 517                 kfree(local->hw_scan_req);
 518                 local->hw_scan_req = NULL;
 519                 local->scanning = 0;
 520
 521                 ieee80211_recalc_idle(local);
 522
 523                 local->scan_req = NULL;
 524                 rcu_assign_pointer(local->scan_sdata, NULL);
 525         }
 526
 527         return rc;
 528 }
 529
 530 static unsigned long
 531 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
 532 {
 533         /*
 534          * TODO: channel switching also consumes quite some time,
 535          * add that delay as well to get a better estimation
 536          */
 537         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN)
 538                 return IEEE80211_PASSIVE_CHANNEL_TIME;
 539         return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
 540 }
 541
 542 static void ieee80211_scan_state_decision(struct ieee80211_local *local,
 543                                           unsigned long *next_delay)
 544 {
 545         bool associated = false;
 546         bool tx_empty = true;
 547         bool bad_latency;
 548         struct ieee80211_sub_if_data *sdata;
 549         struct ieee80211_channel *next_chan;
 550         enum mac80211_scan_state next_scan_state;
 551
 552         /*
 553          * check if at least one STA interface is associated,
 554          * check if at least one STA interface has pending tx frames
 555          * and grab the lowest used beacon interval
 556          */
 557         mutex_lock(&local->iflist_mtx);
 558         list_for_each_entry(sdata, &local->interfaces, list) {
 559                 if (!ieee80211_sdata_running(sdata))
 560                         continue;
 561
 562                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 563                         if (sdata->u.mgd.associated) {
 564                                 associated = true;
 565
 566                                 if (!qdisc_all_tx_empty(sdata->dev)) {
 567                                         tx_empty = false;
 568                                         break;
 569                                 }
 570                         }
 571                 }
 572         }
 573         mutex_unlock(&local->iflist_mtx);
 574
 575         next_chan = local->scan_req->channels[local->scan_channel_idx];
 576
 577         /*
 578          * we're currently scanning a different channel, let's
 579          * see if we can scan another channel without interfering
 580          * with the current traffic situation.
 581          *
 582          * Keep good latency, do not stay off-channel more than 125 ms.
 583          */
 584
 585         bad_latency = time_after(jiffies +
 586                                  ieee80211_scan_get_channel_time(next_chan),
 587                                  local->leave_oper_channel_time + HZ / 8);
 588
 589         if (associated && !tx_empty) {
 590                 if (local->scan_req->flags & NL80211_SCAN_FLAG_LOW_PRIORITY)
 591                         next_scan_state = SCAN_ABORT;
 592                 else
 593                         next_scan_state = SCAN_SUSPEND;
 594         } else if (associated && bad_latency) {
 595                 next_scan_state = SCAN_SUSPEND;
 596         } else {
 597                 next_scan_state = SCAN_SET_CHANNEL;
 598         }
 599
 600         local->next_scan_state = next_scan_state;
 601
 602         *next_delay = 0;
 603 }
 604
 605 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 606                                              unsigned long *next_delay)
 607 {
 608         int skip;
 609         struct ieee80211_channel *chan;
 610
 611         skip = 0;
 612         chan = local->scan_req->channels[local->scan_channel_idx];
 613
 614         local->scan_channel = chan;
 615
 616         if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 617                 skip = 1;
 618
 619         /* advance state machine to next channel/band */
 620         local->scan_channel_idx++;
 621
 622         if (skip) {
 623                 /* if we skip this channel return to the decision state */
 624                 local->next_scan_state = SCAN_DECISION;
 625                 return;
 626         }
 627
 628         /*
 629          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 630          * (which unfortunately doesn't say _why_ step a) is done,
 631          * but it waits for the probe delay or until a frame is
 632          * received - and the received frame would update the NAV).
 633          * For now, we do not support waiting until a frame is
 634          * received.
 635          *
 636          * In any case, it is not necessary for a passive scan.
 637          */
 638         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 639             !local->scan_req->n_ssids) {
 640                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 641                 local->next_scan_state = SCAN_DECISION;
 642                 return;
 643         }
 644
 645         /* active scan, send probes */
 646         *next_delay = IEEE80211_PROBE_DELAY;
 647         local->next_scan_state = SCAN_SEND_PROBE;
 648 }
 649
 650 static void ieee80211_scan_state_suspend(struct ieee80211_local *local,
 651                                          unsigned long *next_delay)
 652 {
 653         /* switch back to the operating channel */
 654         local->scan_channel = NULL;
 655         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 656
 657         /* disable PS */
 658         ieee80211_offchannel_return(local);
 659
 660         *next_delay = HZ / 5;
 661         /* afterwards, resume scan & go to next channel */
 662         local->next_scan_state = SCAN_RESUME;
 663 }
 664
 665 static void ieee80211_scan_state_resume(struct ieee80211_local *local,
 666                                         unsigned long *next_delay)
 667 {
 668         ieee80211_offchannel_stop_vifs(local);
 669
 670         if (local->ops->flush) {
 671                 ieee80211_flush_queues(local, NULL);
 672                 *next_delay = 0;
 673         } else
 674                 *next_delay = HZ / 10;
 675
 676         /* remember when we left the operating channel */
 677         local->leave_oper_channel_time = jiffies;
 678
 679         /* advance to the next channel to be scanned */
 680         local->next_scan_state = SCAN_SET_CHANNEL;
 681 }
 682
 683 void ieee80211_scan_work(struct work_struct *work)
 684 {
 685         struct ieee80211_local *local =
 686                 container_of(work, struct ieee80211_local, scan_work.work);
 687         struct ieee80211_sub_if_data *sdata;
 688         unsigned long next_delay = 0;
 689         bool aborted, hw_scan;
 690
 691         mutex_lock(&local->mtx);
 692
 693         sdata = rcu_dereference_protected(local->scan_sdata,
 694                                           lockdep_is_held(&local->mtx));
 695
 696         /* When scanning on-channel, the first-callback means completed. */
 697         if (test_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning)) {
 698                 aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
 699                 goto out_complete;
 700         }
 701
 702         if (test_and_clear_bit(SCAN_COMPLETED, &local->scanning)) {
 703                 aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
 704                 goto out_complete;
 705         }
 706
 707         if (!sdata || !local->scan_req)
 708                 goto out;
 709
 710         if (local->scan_req && !local->scanning) {
 711                 struct cfg80211_scan_request *req = local->scan_req;
 712                 int rc;
 713
 714                 local->scan_req = NULL;
 715                 rcu_assign_pointer(local->scan_sdata, NULL);
 716
 717                 rc = __ieee80211_start_scan(sdata, req);
 718                 if (rc) {
 719                         /* need to complete scan in cfg80211 */
 720                         local->scan_req = req;
 721                         aborted = true;
 722                         goto out_complete;
 723                 } else
 724                         goto out;
 725         }
 726
 727         /*
 728          * Avoid re-scheduling when the sdata is going away.
 729          */
 730         if (!ieee80211_sdata_running(sdata)) {
 731                 aborted = true;
 732                 goto out_complete;
 733         }
 734
 735         /*
 736          * as long as no delay is required advance immediately
 737          * without scheduling a new work
 738          */
 739         do {
 740                 if (!ieee80211_sdata_running(sdata)) {
 741                         aborted = true;
 742                         goto out_complete;
 743                 }
 744
 745                 switch (local->next_scan_state) {
 746                 case SCAN_DECISION:
 747                         /* if no more bands/channels left, complete scan */
 748                         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 749                                 aborted = false;
 750                                 goto out_complete;
 751                         }
 752                         ieee80211_scan_state_decision(local, &next_delay);
 753                         break;
 754                 case SCAN_SET_CHANNEL:
 755                         ieee80211_scan_state_set_channel(local, &next_delay);
 756                         break;
 757                 case SCAN_SEND_PROBE:
 758                         ieee80211_scan_state_send_probe(local, &next_delay);
 759                         break;
 760                 case SCAN_SUSPEND:
 761                         ieee80211_scan_state_suspend(local, &next_delay);
 762                         break;
 763                 case SCAN_RESUME:
 764                         ieee80211_scan_state_resume(local, &next_delay);
 765                         break;
 766                 case SCAN_ABORT:
 767                         aborted = true;
 768                         goto out_complete;
 769                 }
 770         } while (next_delay == 0);
 771
 772         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
 773         goto out;
 774
 775 out_complete:
 776         hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 777         __ieee80211_scan_completed(&local->hw, aborted, hw_scan);
 778 out:
 779         mutex_unlock(&local->mtx);
 780 }
 781
 782 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 783                            struct cfg80211_scan_request *req)
 784 {
 785         int res;
 786
 787         mutex_lock(&sdata->local->mtx);
 788         res = __ieee80211_start_scan(sdata, req);
 789         mutex_unlock(&sdata->local->mtx);
 790
 791         return res;
 792 }
 793
 794 int ieee80211_request_ibss_scan(struct ieee80211_sub_if_data *sdata,
 795                                 const u8 *ssid, u8 ssid_len,
 796                                 struct ieee80211_channel *chan)
 797 {
 798         struct ieee80211_local *local = sdata->local;
 799         int ret = -EBUSY;
 800         enum ieee80211_band band;
 801
 802         mutex_lock(&local->mtx);
 803
 804         /* busy scanning */
 805         if (local->scan_req)
 806                 goto unlock;
 807
 808         /* fill internal scan request */
 809         if (!chan) {
 810                 int i, max_n;
 811                 int n_ch = 0;
 812
 813                 for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
 814                         if (!local->hw.wiphy->bands[band])
 815                                 continue;
 816
 817                         max_n = local->hw.wiphy->bands[band]->n_channels;
 818                         for (i = 0; i < max_n; i++) {
 819                                 struct ieee80211_channel *tmp_ch =
 820                                     &local->hw.wiphy->bands[band]->channels[i];
 821
 822                                 if (tmp_ch->flags & (IEEE80211_CHAN_NO_IBSS |
 823                                                      IEEE80211_CHAN_DISABLED))
 824                                         continue;
 825
 826                                 local->int_scan_req->channels[n_ch] = tmp_ch;
 827                                 n_ch++;
 828                         }
 829                 }
 830
 831                 if (WARN_ON_ONCE(n_ch == 0))
 832                         goto unlock;
 833
 834                 local->int_scan_req->n_channels = n_ch;
 835         } else {
 836                 if (WARN_ON_ONCE(chan->flags & (IEEE80211_CHAN_NO_IBSS |
 837                                                 IEEE80211_CHAN_DISABLED)))
 838                         goto unlock;
 839
 840                 local->int_scan_req->channels[0] = chan;
 841                 local->int_scan_req->n_channels = 1;
 842         }
 843
 844         local->int_scan_req->ssids = &local->scan_ssid;
 845         local->int_scan_req->n_ssids = 1;
 846         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 847         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 848
 849         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 850  unlock:
 851         mutex_unlock(&local->mtx);
 852         return ret;
 853 }
 854
 855 /*
 856  * Only call this function when a scan can't be queued -- under RTNL.
 857  */
 858 void ieee80211_scan_cancel(struct ieee80211_local *local)
 859 {
 860         /*
 861          * We are canceling software scan, or deferred scan that was not
 862          * yet really started (see __ieee80211_start_scan ).
 863          *
 864          * Regarding hardware scan:
 865          * - we can not call  __ieee80211_scan_completed() as when
 866          *   SCAN_HW_SCANNING bit is set this function change
 867          *   local->hw_scan_req to operate on 5G band, what race with
 868          *   driver which can use local->hw_scan_req
 869          *
 870          * - we can not cancel scan_work since driver can schedule it
 871          *   by ieee80211_scan_completed(..., true) to finish scan
 872          *
 873          * Hence we only call the cancel_hw_scan() callback, but the low-level
 874          * driver is still responsible for calling ieee80211_scan_completed()
 875          * after the scan was completed/aborted.
 876          */
 877
 878         mutex_lock(&local->mtx);
 879         if (!local->scan_req)
 880                 goto out;
 881
 882         if (test_bit(SCAN_HW_SCANNING, &local->scanning)) {
 883                 if (local->ops->cancel_hw_scan)
 884                         drv_cancel_hw_scan(local,
 885                                 rcu_dereference_protected(local->scan_sdata,
 886                                                 lockdep_is_held(&local->mtx)));
 887                 goto out;
 888         }
 889
 890         /*
 891          * If the work is currently running, it must be blocked on
 892          * the mutex, but we'll set scan_sdata = NULL and it'll
 893          * simply exit once it acquires the mutex.
 894          */
 895         cancel_delayed_work(&local->scan_work);
 896         /* and clean up */
 897         __ieee80211_scan_completed(&local->hw, true, false);
 898 out:
 899         mutex_unlock(&local->mtx);
 900 }
 901
 902 int ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
 903                                        struct cfg80211_sched_scan_request *req)
 904 {
 905         struct ieee80211_local *local = sdata->local;
 906         struct ieee80211_sched_scan_ies sched_scan_ies = {};
 907         int ret, i, iebufsz;
 908
 909         iebufsz = 2 + IEEE80211_MAX_SSID_LEN +
 910                   local->scan_ies_len + req->ie_len;
 911
 912         mutex_lock(&local->mtx);
 913
 914         if (rcu_access_pointer(local->sched_scan_sdata)) {
 915                 ret = -EBUSY;
 916                 goto out;
 917         }
 918
 919         if (!local->ops->sched_scan_start) {
 920                 ret = -ENOTSUPP;
 921                 goto out;
 922         }
 923
 924         for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
 925                 if (!local->hw.wiphy->bands[i])
 926                         continue;
 927
 928                 sched_scan_ies.ie[i] = kzalloc(iebufsz, GFP_KERNEL);
 929                 if (!sched_scan_ies.ie[i]) {
 930                         ret = -ENOMEM;
 931                         goto out_free;
 932                 }
 933
 934                 sched_scan_ies.len[i] =
 935                         ieee80211_build_preq_ies(local, sched_scan_ies.ie[i],
 936                                                  iebufsz, req->ie, req->ie_len,
 937                                                  i, (u32) -1, 0);
 938         }
 939
 940         ret = drv_sched_scan_start(local, sdata, req, &sched_scan_ies);
 941         if (ret == 0)
 942                 rcu_assign_pointer(local->sched_scan_sdata, sdata);
 943
 944 out_free:
 945         while (i > 0)
 946                 kfree(sched_scan_ies.ie[--i]);
 947 out:
 948         mutex_unlock(&local->mtx);
 949         return ret;
 950 }
 951
 952 int ieee80211_request_sched_scan_stop(struct ieee80211_sub_if_data *sdata)
 953 {
 954         struct ieee80211_local *local = sdata->local;
 955         int ret = 0;
 956
 957         mutex_lock(&local->mtx);
 958
 959         if (!local->ops->sched_scan_stop) {
 960                 ret = -ENOTSUPP;
 961                 goto out;
 962         }
 963
 964         if (rcu_access_pointer(local->sched_scan_sdata))
 965                 drv_sched_scan_stop(local, sdata);
 966
 967 out:
 968         mutex_unlock(&local->mtx);
 969
 970         return ret;
 971 }
 972
 973 void ieee80211_sched_scan_results(struct ieee80211_hw *hw)
 974 {
 975         struct ieee80211_local *local = hw_to_local(hw);
 976
 977         trace_api_sched_scan_results(local);
 978
 979         cfg80211_sched_scan_results(hw->wiphy);
 980 }
 981 EXPORT_SYMBOL(ieee80211_sched_scan_results);
 982
 983 void ieee80211_sched_scan_stopped_work(struct work_struct *work)
 984 {
 985         struct ieee80211_local *local =
 986                 container_of(work, struct ieee80211_local,
 987                              sched_scan_stopped_work);
 988
 989         mutex_lock(&local->mtx);
 990
 991         if (!rcu_access_pointer(local->sched_scan_sdata)) {
 992                 mutex_unlock(&local->mtx);
 993                 return;
 994         }
 995
 996         rcu_assign_pointer(local->sched_scan_sdata, NULL);
 997
 998         mutex_unlock(&local->mtx);
 999
1000         cfg80211_sched_scan_stopped(local->hw.wiphy);
1001 }
1002
1003 void ieee80211_sched_scan_stopped(struct ieee80211_hw *hw)
1004 {
1005         struct ieee80211_local *local = hw_to_local(hw);
1006
1007         trace_api_sched_scan_stopped(local);
1008
1009         ieee80211_queue_work(&local->hw, &local->sched_scan_stopped_work);
1010 }
1011 EXPORT_SYMBOL(ieee80211_sched_scan_stopped);