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->parse_error ||
 102                                 !(bss->valid_data & IEEE80211_BSS_VALID_ERP))) {
 103                 bss->erp_value = elems->erp_info[0];
 104                 bss->has_erp_value = true;
 105                 if (!elems->parse_error)
 106                         bss->valid_data |= IEEE80211_BSS_VALID_ERP;
 107         }
 108
 109         /* replace old supported rates if we get new values */
 110         if (!elems->parse_error ||
 111             !(bss->valid_data & IEEE80211_BSS_VALID_RATES)) {
 112                 srlen = 0;
 113                 if (elems->supp_rates) {
 114                         clen = IEEE80211_MAX_SUPP_RATES;
 115                         if (clen > elems->supp_rates_len)
 116                                 clen = elems->supp_rates_len;
 117                         memcpy(bss->supp_rates, elems->supp_rates, clen);
 118                         srlen += clen;
 119                 }
 120                 if (elems->ext_supp_rates) {
 121                         clen = IEEE80211_MAX_SUPP_RATES - srlen;
 122                         if (clen > elems->ext_supp_rates_len)
 123                                 clen = elems->ext_supp_rates_len;
 124                         memcpy(bss->supp_rates + srlen, elems->ext_supp_rates,
 125                                clen);
 126                         srlen += clen;
 127                 }
 128                 if (srlen) {
 129                         bss->supp_rates_len = srlen;
 130                         if (!elems->parse_error)
 131                                 bss->valid_data |= IEEE80211_BSS_VALID_RATES;
 132                 }
 133         }
 134
 135         if (!elems->parse_error ||
 136             !(bss->valid_data & IEEE80211_BSS_VALID_WMM)) {
 137                 bss->wmm_used = elems->wmm_param || elems->wmm_info;
 138                 bss->uapsd_supported = is_uapsd_supported(elems);
 139                 if (!elems->parse_error)
 140                         bss->valid_data |= IEEE80211_BSS_VALID_WMM;
 141         }
 142
 143         return bss;
 144 }
 145
 146 void ieee80211_scan_rx(struct ieee80211_local *local, struct sk_buff *skb)
 147 {
 148         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
 149         struct ieee80211_sub_if_data *sdata1, *sdata2;
 150         struct ieee80211_mgmt *mgmt = (void *)skb->data;
 151         struct ieee80211_bss *bss;
 152         u8 *elements;
 153         struct ieee80211_channel *channel;
 154         size_t baselen;
 155         struct ieee802_11_elems elems;
 156
 157         if (skb->len < 24 ||
 158             (!ieee80211_is_probe_resp(mgmt->frame_control) &&
 159              !ieee80211_is_beacon(mgmt->frame_control)))
 160                 return;
 161
 162         sdata1 = rcu_dereference(local->scan_sdata);
 163         sdata2 = rcu_dereference(local->sched_scan_sdata);
 164
 165         if (likely(!sdata1 && !sdata2))
 166                 return;
 167
 168         if (ieee80211_is_probe_resp(mgmt->frame_control)) {
 169                 /* ignore ProbeResp to foreign address */
 170                 if ((!sdata1 || !ether_addr_equal(mgmt->da, sdata1->vif.addr)) &&
 171                     (!sdata2 || !ether_addr_equal(mgmt->da, sdata2->vif.addr)))
 172                         return;
 173
 174                 elements = mgmt->u.probe_resp.variable;
 175                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 176         } else {
 177                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 178                 elements = mgmt->u.beacon.variable;
 179         }
 180
 181         if (baselen > skb->len)
 182                 return;
 183
 184         ieee802_11_parse_elems(elements, skb->len - baselen, false, &elems);
 185
 186         channel = ieee80211_get_channel(local->hw.wiphy, rx_status->freq);
 187
 188         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 189                 return;
 190
 191         bss = ieee80211_bss_info_update(local, rx_status,
 192                                         mgmt, skb->len, &elems,
 193                                         channel);
 194         if (bss)
 195                 ieee80211_rx_bss_put(local, bss);
 196 }
 197
 198 /* return false if no more work */
 199 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 200 {
 201         struct cfg80211_scan_request *req = local->scan_req;
 202         enum ieee80211_band band;
 203         int i, ielen, n_chans;
 204
 205         do {
 206                 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
 207                         return false;
 208
 209                 band = local->hw_scan_band;
 210                 n_chans = 0;
 211                 for (i = 0; i < req->n_channels; i++) {
 212                         if (req->channels[i]->band == band) {
 213                                 local->hw_scan_req->channels[n_chans] =
 214                                                         req->channels[i];
 215                                 n_chans++;
 216                         }
 217                 }
 218
 219                 local->hw_scan_band++;
 220         } while (!n_chans);
 221
 222         local->hw_scan_req->n_channels = n_chans;
 223
 224         ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
 225                                          local->hw_scan_ies_bufsize,
 226                                          req->ie, req->ie_len, band,
 227                                          req->rates[band], 0);
 228         local->hw_scan_req->ie_len = ielen;
 229         local->hw_scan_req->no_cck = req->no_cck;
 230
 231         return true;
 232 }
 233
 234 static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted,
 235                                        bool was_hw_scan)
 236 {
 237         struct ieee80211_local *local = hw_to_local(hw);
 238
 239         lockdep_assert_held(&local->mtx);
 240
 241         /*
 242          * It's ok to abort a not-yet-running scan (that
 243          * we have one at all will be verified by checking
 244          * local->scan_req next), but not to complete it
 245          * successfully.
 246          */
 247         if (WARN_ON(!local->scanning && !aborted))
 248                 aborted = true;
 249
 250         if (WARN_ON(!local->scan_req))
 251                 return;
 252
 253         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 254                 int rc;
 255
 256                 rc = drv_hw_scan(local,
 257                         rcu_dereference_protected(local->scan_sdata,
 258                                                   lockdep_is_held(&local->mtx)),
 259                         local->hw_scan_req);
 260
 261                 if (rc == 0)
 262                         return;
 263         }
 264
 265         kfree(local->hw_scan_req);
 266         local->hw_scan_req = NULL;
 267
 268         if (local->scan_req != local->int_scan_req)
 269                 cfg80211_scan_done(local->scan_req, aborted);
 270         local->scan_req = NULL;
 271         rcu_assign_pointer(local->scan_sdata, NULL);
 272
 273         local->scanning = 0;
 274         local->scan_channel = NULL;
 275
 276         /* Set power back to normal operating levels. */
 277         ieee80211_hw_config(local, 0);
 278
 279         if (!was_hw_scan) {
 280                 ieee80211_configure_filter(local);
 281                 drv_sw_scan_complete(local);
 282                 ieee80211_offchannel_return(local);
 283         }
 284
 285         ieee80211_recalc_idle(local);
 286
 287         ieee80211_mlme_notify_scan_completed(local);
 288         ieee80211_ibss_notify_scan_completed(local);
 289         ieee80211_mesh_notify_scan_completed(local);
 290         ieee80211_start_next_roc(local);
 291 }
 292
 293 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 294 {
 295         struct ieee80211_local *local = hw_to_local(hw);
 296
 297         trace_api_scan_completed(local, aborted);
 298
 299         set_bit(SCAN_COMPLETED, &local->scanning);
 300         if (aborted)
 301                 set_bit(SCAN_ABORTED, &local->scanning);
 302         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, 0);
 303 }
 304 EXPORT_SYMBOL(ieee80211_scan_completed);
 305
 306 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 307 {
 308         /* Software scan is not supported in multi-channel cases */
 309         if (local->use_chanctx)
 310                 return -EOPNOTSUPP;
 311
 312         /*
 313          * Hardware/driver doesn't support hw_scan, so use software
 314          * scanning instead. First send a nullfunc frame with power save
 315          * bit on so that AP will buffer the frames for us while we are not
 316          * listening, then send probe requests to each channel and wait for
 317          * the responses. After all channels are scanned, tune back to the
 318          * original channel and send a nullfunc frame with power save bit
 319          * off to trigger the AP to send us all the buffered frames.
 320          *
 321          * Note that while local->sw_scanning is true everything else but
 322          * nullfunc frames and probe requests will be dropped in
 323          * ieee80211_tx_h_check_assoc().
 324          */
 325         drv_sw_scan_start(local);
 326
 327         local->leave_oper_channel_time = jiffies;
 328         local->next_scan_state = SCAN_DECISION;
 329         local->scan_channel_idx = 0;
 330
 331         ieee80211_offchannel_stop_vifs(local);
 332
 333         /* ensure nullfunc is transmitted before leaving operating channel */
 334         ieee80211_flush_queues(local, NULL);
 335
 336         ieee80211_configure_filter(local);
 337
 338         /* We need to set power level at maximum rate for scanning. */
 339         ieee80211_hw_config(local, 0);
 340
 341         ieee80211_queue_delayed_work(&local->hw,
 342                                      &local->scan_work, 0);
 343
 344         return 0;
 345 }
 346
 347 static bool ieee80211_can_scan(struct ieee80211_local *local,
 348                                struct ieee80211_sub_if_data *sdata)
 349 {
 350         if (local->radar_detect_enabled)
 351                 return false;
 352
 353         if (!list_empty(&local->roc_list))
 354                 return false;
 355
 356         if (sdata->vif.type == NL80211_IFTYPE_STATION &&
 357             sdata->u.mgd.flags & (IEEE80211_STA_BEACON_POLL |
 358                                   IEEE80211_STA_CONNECTION_POLL))
 359                 return false;
 360
 361         return true;
 362 }
 363
 364 void ieee80211_run_deferred_scan(struct ieee80211_local *local)
 365 {
 366         lockdep_assert_held(&local->mtx);
 367
 368         if (!local->scan_req || local->scanning)
 369                 return;
 370
 371         if (!ieee80211_can_scan(local,
 372                                 rcu_dereference_protected(
 373                                         local->scan_sdata,
 374                                         lockdep_is_held(&local->mtx))))
 375                 return;
 376
 377         ieee80211_queue_delayed_work(&local->hw, &local->scan_work,
 378                                      round_jiffies_relative(0));
 379 }
 380
 381 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 382                                             unsigned long *next_delay)
 383 {
 384         int i;
 385         struct ieee80211_sub_if_data *sdata;
 386         enum ieee80211_band band = local->hw.conf.chandef.chan->band;
 387         u32 tx_flags;
 388
 389         tx_flags = IEEE80211_TX_INTFL_OFFCHAN_TX_OK;
 390         if (local->scan_req->no_cck)
 391                 tx_flags |= IEEE80211_TX_CTL_NO_CCK_RATE;
 392
 393         sdata = rcu_dereference_protected(local->scan_sdata,
 394                                           lockdep_is_held(&local->mtx));
 395
 396         for (i = 0; i < local->scan_req->n_ssids; i++)
 397                 ieee80211_send_probe_req(
 398                         sdata, NULL,
 399                         local->scan_req->ssids[i].ssid,
 400                         local->scan_req->ssids[i].ssid_len,
 401                         local->scan_req->ie, local->scan_req->ie_len,
 402                         local->scan_req->rates[band], false,
 403                         tx_flags, local->hw.conf.chandef.chan, true);
 404
 405         /*
 406          * After sending probe requests, wait for probe responses
 407          * on the channel.
 408          */
 409         *next_delay = IEEE80211_CHANNEL_TIME;
 410         local->next_scan_state = SCAN_DECISION;
 411 }
 412
 413 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 414                                   struct cfg80211_scan_request *req)
 415 {
 416         struct ieee80211_local *local = sdata->local;
 417         int rc;
 418
 419         lockdep_assert_held(&local->mtx);
 420
 421         if (local->scan_req)
 422                 return -EBUSY;
 423
 424         if (!ieee80211_can_scan(local, sdata)) {
 425                 /* wait for the work to finish/time out */
 426                 local->scan_req = req;
 427                 rcu_assign_pointer(local->scan_sdata, sdata);
 428                 return 0;
 429         }
 430
 431         if (local->ops->hw_scan) {
 432                 u8 *ies;
 433
 434                 local->hw_scan_ies_bufsize = 2 + IEEE80211_MAX_SSID_LEN +
 435                                              local->scan_ies_len +
 436                                              req->ie_len;
 437                 local->hw_scan_req = kmalloc(
 438                                 sizeof(*local->hw_scan_req) +
 439                                 req->n_channels * sizeof(req->channels[0]) +
 440                                 local->hw_scan_ies_bufsize, GFP_KERNEL);
 441                 if (!local->hw_scan_req)
 442                         return -ENOMEM;
 443
 444                 local->hw_scan_req->ssids = req->ssids;
 445                 local->hw_scan_req->n_ssids = req->n_ssids;
 446                 ies = (u8 *)local->hw_scan_req +
 447                         sizeof(*local->hw_scan_req) +
 448                         req->n_channels * sizeof(req->channels[0]);
 449                 local->hw_scan_req->ie = ies;
 450                 local->hw_scan_req->flags = req->flags;
 451
 452                 local->hw_scan_band = 0;
 453
 454                 /*
 455                  * After allocating local->hw_scan_req, we must
 456                  * go through until ieee80211_prep_hw_scan(), so
 457                  * anything that might be changed here and leave
 458                  * this function early must not go after this
 459                  * allocation.
 460                  */
 461         }
 462
 463         local->scan_req = req;
 464         rcu_assign_pointer(local->scan_sdata, sdata);
 465
 466         if (local->ops->hw_scan) {
 467                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 468         } else if ((req->n_channels == 1) &&
 469                    (req->channels[0] == local->_oper_chandef.chan)) {
 470                 /*
 471                  * If we are scanning only on the operating channel
 472                  * then we do not need to stop normal activities
 473                  */
 474                 unsigned long next_delay;
 475
 476                 __set_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning);
 477
 478                 ieee80211_recalc_idle(local);
 479
 480                 /* Notify driver scan is starting, keep order of operations
 481                  * same as normal software scan, in case that matters. */
 482                 drv_sw_scan_start(local);
 483
 484                 ieee80211_configure_filter(local); /* accept probe-responses */
 485
 486                 /* We need to ensure power level is at max for scanning. */
 487                 ieee80211_hw_config(local, 0);
 488
 489                 if ((req->channels[0]->flags &
 490                      IEEE80211_CHAN_PASSIVE_SCAN) ||
 491                     !local->scan_req->n_ssids) {
 492                         next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 493                 } else {
 494                         ieee80211_scan_state_send_probe(local, &next_delay);
 495                         next_delay = IEEE80211_CHANNEL_TIME;
 496                 }
 497
 498                 /* Now, just wait a bit and we are all done! */
 499                 ieee80211_queue_delayed_work(&local->hw, &local->scan_work,
 500                                              next_delay);
 501                 return 0;
 502         } else {
 503                 /* Do normal software scan */
 504                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 505         }
 506
 507         ieee80211_recalc_idle(local);
 508
 509         if (local->ops->hw_scan) {
 510                 WARN_ON(!ieee80211_prep_hw_scan(local));
 511                 rc = drv_hw_scan(local, sdata, local->hw_scan_req);
 512         } else
 513                 rc = ieee80211_start_sw_scan(local);
 514
 515         if (rc) {
 516                 kfree(local->hw_scan_req);
 517                 local->hw_scan_req = NULL;
 518                 local->scanning = 0;
 519
 520                 ieee80211_recalc_idle(local);
 521
 522                 local->scan_req = NULL;
 523                 rcu_assign_pointer(local->scan_sdata, NULL);
 524         }
 525
 526         return rc;
 527 }
 528
 529 static unsigned long
 530 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
 531 {
 532         /*
 533          * TODO: channel switching also consumes quite some time,
 534          * add that delay as well to get a better estimation
 535          */
 536         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN)
 537                 return IEEE80211_PASSIVE_CHANNEL_TIME;
 538         return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
 539 }
 540
 541 static void ieee80211_scan_state_decision(struct ieee80211_local *local,
 542                                           unsigned long *next_delay)
 543 {
 544         bool associated = false;
 545         bool tx_empty = true;
 546         bool bad_latency;
 547         struct ieee80211_sub_if_data *sdata;
 548         struct ieee80211_channel *next_chan;
 549         enum mac80211_scan_state next_scan_state;
 550
 551         /*
 552          * check if at least one STA interface is associated,
 553          * check if at least one STA interface has pending tx frames
 554          * and grab the lowest used beacon interval
 555          */
 556         mutex_lock(&local->iflist_mtx);
 557         list_for_each_entry(sdata, &local->interfaces, list) {
 558                 if (!ieee80211_sdata_running(sdata))
 559                         continue;
 560
 561                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 562                         if (sdata->u.mgd.associated) {
 563                                 associated = true;
 564
 565                                 if (!qdisc_all_tx_empty(sdata->dev)) {
 566                                         tx_empty = false;
 567                                         break;
 568                                 }
 569                         }
 570                 }
 571         }
 572         mutex_unlock(&local->iflist_mtx);
 573
 574         next_chan = local->scan_req->channels[local->scan_channel_idx];
 575
 576         /*
 577          * we're currently scanning a different channel, let's
 578          * see if we can scan another channel without interfering
 579          * with the current traffic situation.
 580          *
 581          * Keep good latency, do not stay off-channel more than 125 ms.
 582          */
 583
 584         bad_latency = time_after(jiffies +
 585                                  ieee80211_scan_get_channel_time(next_chan),
 586                                  local->leave_oper_channel_time + HZ / 8);
 587
 588         if (associated && !tx_empty) {
 589                 if (local->scan_req->flags & NL80211_SCAN_FLAG_LOW_PRIORITY)
 590                         next_scan_state = SCAN_ABORT;
 591                 else
 592                         next_scan_state = SCAN_SUSPEND;
 593         } else if (associated && bad_latency) {
 594                 next_scan_state = SCAN_SUSPEND;
 595         } else {
 596                 next_scan_state = SCAN_SET_CHANNEL;
 597         }
 598
 599         local->next_scan_state = next_scan_state;
 600
 601         *next_delay = 0;
 602 }
 603
 604 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 605                                              unsigned long *next_delay)
 606 {
 607         int skip;
 608         struct ieee80211_channel *chan;
 609
 610         skip = 0;
 611         chan = local->scan_req->channels[local->scan_channel_idx];
 612
 613         local->scan_channel = chan;
 614
 615         if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 616                 skip = 1;
 617
 618         /* advance state machine to next channel/band */
 619         local->scan_channel_idx++;
 620
 621         if (skip) {
 622                 /* if we skip this channel return to the decision state */
 623                 local->next_scan_state = SCAN_DECISION;
 624                 return;
 625         }
 626
 627         /*
 628          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 629          * (which unfortunately doesn't say _why_ step a) is done,
 630          * but it waits for the probe delay or until a frame is
 631          * received - and the received frame would update the NAV).
 632          * For now, we do not support waiting until a frame is
 633          * received.
 634          *
 635          * In any case, it is not necessary for a passive scan.
 636          */
 637         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 638             !local->scan_req->n_ssids) {
 639                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 640                 local->next_scan_state = SCAN_DECISION;
 641                 return;
 642         }
 643
 644         /* active scan, send probes */
 645         *next_delay = IEEE80211_PROBE_DELAY;
 646         local->next_scan_state = SCAN_SEND_PROBE;
 647 }
 648
 649 static void ieee80211_scan_state_suspend(struct ieee80211_local *local,
 650                                          unsigned long *next_delay)
 651 {
 652         /* switch back to the operating channel */
 653         local->scan_channel = NULL;
 654         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 655
 656         /* disable PS */
 657         ieee80211_offchannel_return(local);
 658
 659         *next_delay = HZ / 5;
 660         /* afterwards, resume scan & go to next channel */
 661         local->next_scan_state = SCAN_RESUME;
 662 }
 663
 664 static void ieee80211_scan_state_resume(struct ieee80211_local *local,
 665                                         unsigned long *next_delay)
 666 {
 667         ieee80211_offchannel_stop_vifs(local);
 668
 669         if (local->ops->flush) {
 670                 ieee80211_flush_queues(local, NULL);
 671                 *next_delay = 0;
 672         } else
 673                 *next_delay = HZ / 10;
 674
 675         /* remember when we left the operating channel */
 676         local->leave_oper_channel_time = jiffies;
 677
 678         /* advance to the next channel to be scanned */
 679         local->next_scan_state = SCAN_SET_CHANNEL;
 680 }
 681
 682 void ieee80211_scan_work(struct work_struct *work)
 683 {
 684         struct ieee80211_local *local =
 685                 container_of(work, struct ieee80211_local, scan_work.work);
 686         struct ieee80211_sub_if_data *sdata;
 687         unsigned long next_delay = 0;
 688         bool aborted, hw_scan;
 689
 690         mutex_lock(&local->mtx);
 691
 692         sdata = rcu_dereference_protected(local->scan_sdata,
 693                                           lockdep_is_held(&local->mtx));
 694
 695         /* When scanning on-channel, the first-callback means completed. */
 696         if (test_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning)) {
 697                 aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
 698                 goto out_complete;
 699         }
 700
 701         if (test_and_clear_bit(SCAN_COMPLETED, &local->scanning)) {
 702                 aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
 703                 goto out_complete;
 704         }
 705
 706         if (!sdata || !local->scan_req)
 707                 goto out;
 708
 709         if (local->scan_req && !local->scanning) {
 710                 struct cfg80211_scan_request *req = local->scan_req;
 711                 int rc;
 712
 713                 local->scan_req = NULL;
 714                 rcu_assign_pointer(local->scan_sdata, NULL);
 715
 716                 rc = __ieee80211_start_scan(sdata, req);
 717                 if (rc) {
 718                         /* need to complete scan in cfg80211 */
 719                         local->scan_req = req;
 720                         aborted = true;
 721                         goto out_complete;
 722                 } else
 723                         goto out;
 724         }
 725
 726         /*
 727          * Avoid re-scheduling when the sdata is going away.
 728          */
 729         if (!ieee80211_sdata_running(sdata)) {
 730                 aborted = true;
 731                 goto out_complete;
 732         }
 733
 734         /*
 735          * as long as no delay is required advance immediately
 736          * without scheduling a new work
 737          */
 738         do {
 739                 if (!ieee80211_sdata_running(sdata)) {
 740                         aborted = true;
 741                         goto out_complete;
 742                 }
 743
 744                 switch (local->next_scan_state) {
 745                 case SCAN_DECISION:
 746                         /* if no more bands/channels left, complete scan */
 747                         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 748                                 aborted = false;
 749                                 goto out_complete;
 750                         }
 751                         ieee80211_scan_state_decision(local, &next_delay);
 752                         break;
 753                 case SCAN_SET_CHANNEL:
 754                         ieee80211_scan_state_set_channel(local, &next_delay);
 755                         break;
 756                 case SCAN_SEND_PROBE:
 757                         ieee80211_scan_state_send_probe(local, &next_delay);
 758                         break;
 759                 case SCAN_SUSPEND:
 760                         ieee80211_scan_state_suspend(local, &next_delay);
 761                         break;
 762                 case SCAN_RESUME:
 763                         ieee80211_scan_state_resume(local, &next_delay);
 764                         break;
 765                 case SCAN_ABORT:
 766                         aborted = true;
 767                         goto out_complete;
 768                 }
 769         } while (next_delay == 0);
 770
 771         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
 772         goto out;
 773
 774 out_complete:
 775         hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 776         __ieee80211_scan_completed(&local->hw, aborted, hw_scan);
 777 out:
 778         mutex_unlock(&local->mtx);
 779 }
 780
 781 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 782                            struct cfg80211_scan_request *req)
 783 {
 784         int res;
 785
 786         mutex_lock(&sdata->local->mtx);
 787         res = __ieee80211_start_scan(sdata, req);
 788         mutex_unlock(&sdata->local->mtx);
 789
 790         return res;
 791 }
 792
 793 int ieee80211_request_ibss_scan(struct ieee80211_sub_if_data *sdata,
 794                                 const u8 *ssid, u8 ssid_len,
 795                                 struct ieee80211_channel *chan)
 796 {
 797         struct ieee80211_local *local = sdata->local;
 798         int ret = -EBUSY;
 799         enum ieee80211_band band;
 800
 801         mutex_lock(&local->mtx);
 802
 803         /* busy scanning */
 804         if (local->scan_req)
 805                 goto unlock;
 806
 807         /* fill internal scan request */
 808         if (!chan) {
 809                 int i, max_n;
 810                 int n_ch = 0;
 811
 812                 for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
 813                         if (!local->hw.wiphy->bands[band])
 814                                 continue;
 815
 816                         max_n = local->hw.wiphy->bands[band]->n_channels;
 817                         for (i = 0; i < max_n; i++) {
 818                                 struct ieee80211_channel *tmp_ch =
 819                                     &local->hw.wiphy->bands[band]->channels[i];
 820
 821                                 if (tmp_ch->flags & (IEEE80211_CHAN_NO_IBSS |
 822                                                      IEEE80211_CHAN_DISABLED))
 823                                         continue;
 824
 825                                 local->int_scan_req->channels[n_ch] = tmp_ch;
 826                                 n_ch++;
 827                         }
 828                 }
 829
 830                 if (WARN_ON_ONCE(n_ch == 0))
 831                         goto unlock;
 832
 833                 local->int_scan_req->n_channels = n_ch;
 834         } else {
 835                 if (WARN_ON_ONCE(chan->flags & (IEEE80211_CHAN_NO_IBSS |
 836                                                 IEEE80211_CHAN_DISABLED)))
 837                         goto unlock;
 838
 839                 local->int_scan_req->channels[0] = chan;
 840                 local->int_scan_req->n_channels = 1;
 841         }
 842
 843         local->int_scan_req->ssids = &local->scan_ssid;
 844         local->int_scan_req->n_ssids = 1;
 845         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 846         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 847
 848         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 849  unlock:
 850         mutex_unlock(&local->mtx);
 851         return ret;
 852 }
 853
 854 /*
 855  * Only call this function when a scan can't be queued -- under RTNL.
 856  */
 857 void ieee80211_scan_cancel(struct ieee80211_local *local)
 858 {
 859         /*
 860          * We are canceling software scan, or deferred scan that was not
 861          * yet really started (see __ieee80211_start_scan ).
 862          *
 863          * Regarding hardware scan:
 864          * - we can not call  __ieee80211_scan_completed() as when
 865          *   SCAN_HW_SCANNING bit is set this function change
 866          *   local->hw_scan_req to operate on 5G band, what race with
 867          *   driver which can use local->hw_scan_req
 868          *
 869          * - we can not cancel scan_work since driver can schedule it
 870          *   by ieee80211_scan_completed(..., true) to finish scan
 871          *
 872          * Hence we only call the cancel_hw_scan() callback, but the low-level
 873          * driver is still responsible for calling ieee80211_scan_completed()
 874          * after the scan was completed/aborted.
 875          */
 876
 877         mutex_lock(&local->mtx);
 878         if (!local->scan_req)
 879                 goto out;
 880
 881         if (test_bit(SCAN_HW_SCANNING, &local->scanning)) {
 882                 if (local->ops->cancel_hw_scan)
 883                         drv_cancel_hw_scan(local,
 884                                 rcu_dereference_protected(local->scan_sdata,
 885                                                 lockdep_is_held(&local->mtx)));
 886                 goto out;
 887         }
 888
 889         /*
 890          * If the work is currently running, it must be blocked on
 891          * the mutex, but we'll set scan_sdata = NULL and it'll
 892          * simply exit once it acquires the mutex.
 893          */
 894         cancel_delayed_work(&local->scan_work);
 895         /* and clean up */
 896         __ieee80211_scan_completed(&local->hw, true, false);
 897 out:
 898         mutex_unlock(&local->mtx);
 899 }
 900
 901 int ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
 902                                        struct cfg80211_sched_scan_request *req)
 903 {
 904         struct ieee80211_local *local = sdata->local;
 905         struct ieee80211_sched_scan_ies sched_scan_ies = {};
 906         int ret, i, iebufsz;
 907
 908         iebufsz = 2 + IEEE80211_MAX_SSID_LEN +
 909                   local->scan_ies_len + req->ie_len;
 910
 911         mutex_lock(&local->mtx);
 912
 913         if (rcu_access_pointer(local->sched_scan_sdata)) {
 914                 ret = -EBUSY;
 915                 goto out;
 916         }
 917
 918         if (!local->ops->sched_scan_start) {
 919                 ret = -ENOTSUPP;
 920                 goto out;
 921         }
 922
 923         for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
 924                 if (!local->hw.wiphy->bands[i])
 925                         continue;
 926
 927                 sched_scan_ies.ie[i] = kzalloc(iebufsz, GFP_KERNEL);
 928                 if (!sched_scan_ies.ie[i]) {
 929                         ret = -ENOMEM;
 930                         goto out_free;
 931                 }
 932
 933                 sched_scan_ies.len[i] =
 934                         ieee80211_build_preq_ies(local, sched_scan_ies.ie[i],
 935                                                  iebufsz, req->ie, req->ie_len,
 936                                                  i, (u32) -1, 0);
 937         }
 938
 939         ret = drv_sched_scan_start(local, sdata, req, &sched_scan_ies);
 940         if (ret == 0)
 941                 rcu_assign_pointer(local->sched_scan_sdata, sdata);
 942
 943 out_free:
 944         while (i > 0)
 945                 kfree(sched_scan_ies.ie[--i]);
 946 out:
 947         mutex_unlock(&local->mtx);
 948         return ret;
 949 }
 950
 951 int ieee80211_request_sched_scan_stop(struct ieee80211_sub_if_data *sdata)
 952 {
 953         struct ieee80211_local *local = sdata->local;
 954         int ret = 0;
 955
 956         mutex_lock(&local->mtx);
 957
 958         if (!local->ops->sched_scan_stop) {
 959                 ret = -ENOTSUPP;
 960                 goto out;
 961         }
 962
 963         if (rcu_access_pointer(local->sched_scan_sdata))
 964                 drv_sched_scan_stop(local, sdata);
 965
 966 out:
 967         mutex_unlock(&local->mtx);
 968
 969         return ret;
 970 }
 971
 972 void ieee80211_sched_scan_results(struct ieee80211_hw *hw)
 973 {
 974         struct ieee80211_local *local = hw_to_local(hw);
 975
 976         trace_api_sched_scan_results(local);
 977
 978         cfg80211_sched_scan_results(hw->wiphy);
 979 }
 980 EXPORT_SYMBOL(ieee80211_sched_scan_results);
 981
 982 void ieee80211_sched_scan_stopped_work(struct work_struct *work)
 983 {
 984         struct ieee80211_local *local =
 985                 container_of(work, struct ieee80211_local,
 986                              sched_scan_stopped_work);
 987
 988         mutex_lock(&local->mtx);
 989
 990         if (!rcu_access_pointer(local->sched_scan_sdata)) {
 991                 mutex_unlock(&local->mtx);
 992                 return;
 993         }
 994
 995         rcu_assign_pointer(local->sched_scan_sdata, NULL);
 996
 997         mutex_unlock(&local->mtx);
 998
 999         cfg80211_sched_scan_stopped(local->hw.wiphy);
1000 }
1001
1002 void ieee80211_sched_scan_stopped(struct ieee80211_hw *hw)
1003 {
1004         struct ieee80211_local *local = hw_to_local(hw);
1005
1006         trace_api_sched_scan_stopped(local);
1007
1008         ieee80211_queue_work(&local->hw, &local->sched_scan_stopped_work);
1009 }
1010 EXPORT_SYMBOL(ieee80211_sched_scan_stopped);