net/mac80211/scan.c

   1 /*
   2  * Scanning implementation
   3  *
   4  * Copyright 2003, Jouni Malinen <[email protected]>
   5  * Copyright 2004, Instant802 Networks, Inc.
   6  * Copyright 2005, Devicescape Software, Inc.
   7  * Copyright 2006-2007  Jiri Benc <[email protected]>
   8  * Copyright 2007, Michael Wu <[email protected]>
   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         if (beacon) {
 144                 struct ieee80211_supported_band *sband =
 145                         local->hw.wiphy->bands[rx_status->band];
 146                 if (!(rx_status->flag & RX_FLAG_HT) &&
 147                     !(rx_status->flag & RX_FLAG_VHT))
 148                         bss->beacon_rate =
 149                                 &sband->bitrates[rx_status->rate_idx];
 150         }
 151
 152         return bss;
 153 }
 154
 155 void ieee80211_scan_rx(struct ieee80211_local *local, struct sk_buff *skb)
 156 {
 157         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
 158         struct ieee80211_sub_if_data *sdata1, *sdata2;
 159         struct ieee80211_mgmt *mgmt = (void *)skb->data;
 160         struct ieee80211_bss *bss;
 161         u8 *elements;
 162         struct ieee80211_channel *channel;
 163         size_t baselen;
 164         struct ieee802_11_elems elems;
 165
 166         if (skb->len < 24 ||
 167             (!ieee80211_is_probe_resp(mgmt->frame_control) &&
 168              !ieee80211_is_beacon(mgmt->frame_control)))
 169                 return;
 170
 171         sdata1 = rcu_dereference(local->scan_sdata);
 172         sdata2 = rcu_dereference(local->sched_scan_sdata);
 173
 174         if (likely(!sdata1 && !sdata2))
 175                 return;
 176
 177         if (ieee80211_is_probe_resp(mgmt->frame_control)) {
 178                 /* ignore ProbeResp to foreign address */
 179                 if ((!sdata1 || !ether_addr_equal(mgmt->da, sdata1->vif.addr)) &&
 180                     (!sdata2 || !ether_addr_equal(mgmt->da, sdata2->vif.addr)))
 181                         return;
 182
 183                 elements = mgmt->u.probe_resp.variable;
 184                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 185         } else {
 186                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 187                 elements = mgmt->u.beacon.variable;
 188         }
 189
 190         if (baselen > skb->len)
 191                 return;
 192
 193         ieee802_11_parse_elems(elements, skb->len - baselen, false, &elems);
 194
 195         channel = ieee80211_get_channel(local->hw.wiphy, rx_status->freq);
 196
 197         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 198                 return;
 199
 200         bss = ieee80211_bss_info_update(local, rx_status,
 201                                         mgmt, skb->len, &elems,
 202                                         channel);
 203         if (bss)
 204                 ieee80211_rx_bss_put(local, bss);
 205 }
 206
 207 /* return false if no more work */
 208 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 209 {
 210         struct cfg80211_scan_request *req = local->scan_req;
 211         enum ieee80211_band band;
 212         int i, ielen, n_chans;
 213
 214         do {
 215                 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
 216                         return false;
 217
 218                 band = local->hw_scan_band;
 219                 n_chans = 0;
 220                 for (i = 0; i < req->n_channels; i++) {
 221                         if (req->channels[i]->band == band) {
 222                                 local->hw_scan_req->channels[n_chans] =
 223                                                         req->channels[i];
 224                                 n_chans++;
 225                         }
 226                 }
 227
 228                 local->hw_scan_band++;
 229         } while (!n_chans);
 230
 231         local->hw_scan_req->n_channels = n_chans;
 232
 233         ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
 234                                          local->hw_scan_ies_bufsize,
 235                                          req->ie, req->ie_len, band,
 236                                          req->rates[band], 0);
 237         local->hw_scan_req->ie_len = ielen;
 238         local->hw_scan_req->no_cck = req->no_cck;
 239
 240         return true;
 241 }
 242
 243 static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted,
 244                                        bool was_hw_scan)
 245 {
 246         struct ieee80211_local *local = hw_to_local(hw);
 247
 248         lockdep_assert_held(&local->mtx);
 249
 250         /*
 251          * It's ok to abort a not-yet-running scan (that
 252          * we have one at all will be verified by checking
 253          * local->scan_req next), but not to complete it
 254          * successfully.
 255          */
 256         if (WARN_ON(!local->scanning && !aborted))
 257                 aborted = true;
 258
 259         if (WARN_ON(!local->scan_req))
 260                 return;
 261
 262         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 263                 int rc;
 264
 265                 rc = drv_hw_scan(local,
 266                         rcu_dereference_protected(local->scan_sdata,
 267                                                   lockdep_is_held(&local->mtx)),
 268                         local->hw_scan_req);
 269
 270                 if (rc == 0)
 271                         return;
 272         }
 273
 274         kfree(local->hw_scan_req);
 275         local->hw_scan_req = NULL;
 276
 277         if (local->scan_req != local->int_scan_req)
 278                 cfg80211_scan_done(local->scan_req, aborted);
 279         local->scan_req = NULL;
 280         rcu_assign_pointer(local->scan_sdata, NULL);
 281
 282         local->scanning = 0;
 283         local->scan_channel = NULL;
 284
 285         /* Set power back to normal operating levels. */
 286         ieee80211_hw_config(local, 0);
 287
 288         if (!was_hw_scan) {
 289                 ieee80211_configure_filter(local);
 290                 drv_sw_scan_complete(local);
 291                 ieee80211_offchannel_return(local);
 292         }
 293
 294         ieee80211_recalc_idle(local);
 295
 296         ieee80211_mlme_notify_scan_completed(local);
 297         ieee80211_ibss_notify_scan_completed(local);
 298         ieee80211_mesh_notify_scan_completed(local);
 299         ieee80211_start_next_roc(local);
 300 }
 301
 302 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 303 {
 304         struct ieee80211_local *local = hw_to_local(hw);
 305
 306         trace_api_scan_completed(local, aborted);
 307
 308         set_bit(SCAN_COMPLETED, &local->scanning);
 309         if (aborted)
 310                 set_bit(SCAN_ABORTED, &local->scanning);
 311         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, 0);
 312 }
 313 EXPORT_SYMBOL(ieee80211_scan_completed);
 314
 315 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 316 {
 317         /* Software scan is not supported in multi-channel cases */
 318         if (local->use_chanctx)
 319                 return -EOPNOTSUPP;
 320
 321         /*
 322          * Hardware/driver doesn't support hw_scan, so use software
 323          * scanning instead. First send a nullfunc frame with power save
 324          * bit on so that AP will buffer the frames for us while we are not
 325          * listening, then send probe requests to each channel and wait for
 326          * the responses. After all channels are scanned, tune back to the
 327          * original channel and send a nullfunc frame with power save bit
 328          * off to trigger the AP to send us all the buffered frames.
 329          *
 330          * Note that while local->sw_scanning is true everything else but
 331          * nullfunc frames and probe requests will be dropped in
 332          * ieee80211_tx_h_check_assoc().
 333          */
 334         drv_sw_scan_start(local);
 335
 336         local->leave_oper_channel_time = jiffies;
 337         local->next_scan_state = SCAN_DECISION;
 338         local->scan_channel_idx = 0;
 339
 340         ieee80211_offchannel_stop_vifs(local);
 341
 342         /* ensure nullfunc is transmitted before leaving operating channel */
 343         ieee80211_flush_queues(local, NULL);
 344
 345         ieee80211_configure_filter(local);
 346
 347         /* We need to set power level at maximum rate for scanning. */
 348         ieee80211_hw_config(local, 0);
 349
 350         ieee80211_queue_delayed_work(&local->hw,
 351                                      &local->scan_work, 0);
 352
 353         return 0;
 354 }
 355
 356 static bool ieee80211_can_scan(struct ieee80211_local *local,
 357                                struct ieee80211_sub_if_data *sdata)
 358 {
 359         if (local->radar_detect_enabled)
 360                 return false;
 361
 362         if (!list_empty(&local->roc_list))
 363                 return false;
 364
 365         if (sdata->vif.type == NL80211_IFTYPE_STATION &&
 366             sdata->u.mgd.flags & (IEEE80211_STA_BEACON_POLL |
 367                                   IEEE80211_STA_CONNECTION_POLL))
 368                 return false;
 369
 370         return true;
 371 }
 372
 373 void ieee80211_run_deferred_scan(struct ieee80211_local *local)
 374 {
 375         lockdep_assert_held(&local->mtx);
 376
 377         if (!local->scan_req || local->scanning)
 378                 return;
 379
 380         if (!ieee80211_can_scan(local,
 381                                 rcu_dereference_protected(
 382                                         local->scan_sdata,
 383                                         lockdep_is_held(&local->mtx))))
 384                 return;
 385
 386         ieee80211_queue_delayed_work(&local->hw, &local->scan_work,
 387                                      round_jiffies_relative(0));
 388 }
 389
 390 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 391                                             unsigned long *next_delay)
 392 {
 393         int i;
 394         struct ieee80211_sub_if_data *sdata;
 395         enum ieee80211_band band = local->hw.conf.chandef.chan->band;
 396         u32 tx_flags;
 397
 398         tx_flags = IEEE80211_TX_INTFL_OFFCHAN_TX_OK;
 399         if (local->scan_req->no_cck)
 400                 tx_flags |= IEEE80211_TX_CTL_NO_CCK_RATE;
 401
 402         sdata = rcu_dereference_protected(local->scan_sdata,
 403                                           lockdep_is_held(&local->mtx));
 404
 405         for (i = 0; i < local->scan_req->n_ssids; i++)
 406                 ieee80211_send_probe_req(
 407                         sdata, NULL,
 408                         local->scan_req->ssids[i].ssid,
 409                         local->scan_req->ssids[i].ssid_len,
 410                         local->scan_req->ie, local->scan_req->ie_len,
 411                         local->scan_req->rates[band], false,
 412                         tx_flags, local->hw.conf.chandef.chan, true);
 413
 414         /*
 415          * After sending probe requests, wait for probe responses
 416          * on the channel.
 417          */
 418         *next_delay = IEEE80211_CHANNEL_TIME;
 419         local->next_scan_state = SCAN_DECISION;
 420 }
 421
 422 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 423                                   struct cfg80211_scan_request *req)
 424 {
 425         struct ieee80211_local *local = sdata->local;
 426         int rc;
 427
 428         lockdep_assert_held(&local->mtx);
 429
 430         if (local->scan_req)
 431                 return -EBUSY;
 432
 433         if (!ieee80211_can_scan(local, sdata)) {
 434                 /* wait for the work to finish/time out */
 435                 local->scan_req = req;
 436                 rcu_assign_pointer(local->scan_sdata, sdata);
 437                 return 0;
 438         }
 439
 440         if (local->ops->hw_scan) {
 441                 u8 *ies;
 442
 443                 local->hw_scan_ies_bufsize = 2 + IEEE80211_MAX_SSID_LEN +
 444                                              local->scan_ies_len +
 445                                              req->ie_len;
 446                 local->hw_scan_req = kmalloc(
 447                                 sizeof(*local->hw_scan_req) +
 448                                 req->n_channels * sizeof(req->channels[0]) +
 449                                 local->hw_scan_ies_bufsize, GFP_KERNEL);
 450                 if (!local->hw_scan_req)
 451                         return -ENOMEM;
 452
 453                 local->hw_scan_req->ssids = req->ssids;
 454                 local->hw_scan_req->n_ssids = req->n_ssids;
 455                 ies = (u8 *)local->hw_scan_req +
 456                         sizeof(*local->hw_scan_req) +
 457                         req->n_channels * sizeof(req->channels[0]);
 458                 local->hw_scan_req->ie = ies;
 459                 local->hw_scan_req->flags = req->flags;
 460
 461                 local->hw_scan_band = 0;
 462
 463                 /*
 464                  * After allocating local->hw_scan_req, we must
 465                  * go through until ieee80211_prep_hw_scan(), so
 466                  * anything that might be changed here and leave
 467                  * this function early must not go after this
 468                  * allocation.
 469                  */
 470         }
 471
 472         local->scan_req = req;
 473         rcu_assign_pointer(local->scan_sdata, sdata);
 474
 475         if (local->ops->hw_scan) {
 476                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 477         } else if ((req->n_channels == 1) &&
 478                    (req->channels[0] == local->_oper_chandef.chan)) {
 479                 /*
 480                  * If we are scanning only on the operating channel
 481                  * then we do not need to stop normal activities
 482                  */
 483                 unsigned long next_delay;
 484
 485                 __set_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning);
 486
 487                 ieee80211_recalc_idle(local);
 488
 489                 /* Notify driver scan is starting, keep order of operations
 490                  * same as normal software scan, in case that matters. */
 491                 drv_sw_scan_start(local);
 492
 493                 ieee80211_configure_filter(local); /* accept probe-responses */
 494
 495                 /* We need to ensure power level is at max for scanning. */
 496                 ieee80211_hw_config(local, 0);
 497
 498                 if ((req->channels[0]->flags &
 499                      IEEE80211_CHAN_PASSIVE_SCAN) ||
 500                     !local->scan_req->n_ssids) {
 501                         next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 502                 } else {
 503                         ieee80211_scan_state_send_probe(local, &next_delay);
 504                         next_delay = IEEE80211_CHANNEL_TIME;
 505                 }
 506
 507                 /* Now, just wait a bit and we are all done! */
 508                 ieee80211_queue_delayed_work(&local->hw, &local->scan_work,
 509                                              next_delay);
 510                 return 0;
 511         } else {
 512                 /* Do normal software scan */
 513                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 514         }
 515
 516         ieee80211_recalc_idle(local);
 517
 518         if (local->ops->hw_scan) {
 519                 WARN_ON(!ieee80211_prep_hw_scan(local));
 520                 rc = drv_hw_scan(local, sdata, local->hw_scan_req);
 521         } else
 522                 rc = ieee80211_start_sw_scan(local);
 523
 524         if (rc) {
 525                 kfree(local->hw_scan_req);
 526                 local->hw_scan_req = NULL;
 527                 local->scanning = 0;
 528
 529                 ieee80211_recalc_idle(local);
 530
 531                 local->scan_req = NULL;
 532                 rcu_assign_pointer(local->scan_sdata, NULL);
 533         }
 534
 535         return rc;
 536 }
 537
 538 static unsigned long
 539 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
 540 {
 541         /*
 542          * TODO: channel switching also consumes quite some time,
 543          * add that delay as well to get a better estimation
 544          */
 545         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN)
 546                 return IEEE80211_PASSIVE_CHANNEL_TIME;
 547         return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
 548 }
 549
 550 static void ieee80211_scan_state_decision(struct ieee80211_local *local,
 551                                           unsigned long *next_delay)
 552 {
 553         bool associated = false;
 554         bool tx_empty = true;
 555         bool bad_latency;
 556         struct ieee80211_sub_if_data *sdata;
 557         struct ieee80211_channel *next_chan;
 558         enum mac80211_scan_state next_scan_state;
 559
 560         /*
 561          * check if at least one STA interface is associated,
 562          * check if at least one STA interface has pending tx frames
 563          * and grab the lowest used beacon interval
 564          */
 565         mutex_lock(&local->iflist_mtx);
 566         list_for_each_entry(sdata, &local->interfaces, list) {
 567                 if (!ieee80211_sdata_running(sdata))
 568                         continue;
 569
 570                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 571                         if (sdata->u.mgd.associated) {
 572                                 associated = true;
 573
 574                                 if (!qdisc_all_tx_empty(sdata->dev)) {
 575                                         tx_empty = false;
 576                                         break;
 577                                 }
 578                         }
 579                 }
 580         }
 581         mutex_unlock(&local->iflist_mtx);
 582
 583         next_chan = local->scan_req->channels[local->scan_channel_idx];
 584
 585         /*
 586          * we're currently scanning a different channel, let's
 587          * see if we can scan another channel without interfering
 588          * with the current traffic situation.
 589          *
 590          * Keep good latency, do not stay off-channel more than 125 ms.
 591          */
 592
 593         bad_latency = time_after(jiffies +
 594                                  ieee80211_scan_get_channel_time(next_chan),
 595                                  local->leave_oper_channel_time + HZ / 8);
 596
 597         if (associated && !tx_empty) {
 598                 if (local->scan_req->flags & NL80211_SCAN_FLAG_LOW_PRIORITY)
 599                         next_scan_state = SCAN_ABORT;
 600                 else
 601                         next_scan_state = SCAN_SUSPEND;
 602         } else if (associated && bad_latency) {
 603                 next_scan_state = SCAN_SUSPEND;
 604         } else {
 605                 next_scan_state = SCAN_SET_CHANNEL;
 606         }
 607
 608         local->next_scan_state = next_scan_state;
 609
 610         *next_delay = 0;
 611 }
 612
 613 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 614                                              unsigned long *next_delay)
 615 {
 616         int skip;
 617         struct ieee80211_channel *chan;
 618
 619         skip = 0;
 620         chan = local->scan_req->channels[local->scan_channel_idx];
 621
 622         local->scan_channel = chan;
 623
 624         if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 625                 skip = 1;
 626
 627         /* advance state machine to next channel/band */
 628         local->scan_channel_idx++;
 629
 630         if (skip) {
 631                 /* if we skip this channel return to the decision state */
 632                 local->next_scan_state = SCAN_DECISION;
 633                 return;
 634         }
 635
 636         /*
 637          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 638          * (which unfortunately doesn't say _why_ step a) is done,
 639          * but it waits for the probe delay or until a frame is
 640          * received - and the received frame would update the NAV).
 641          * For now, we do not support waiting until a frame is
 642          * received.
 643          *
 644          * In any case, it is not necessary for a passive scan.
 645          */
 646         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 647             !local->scan_req->n_ssids) {
 648                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 649                 local->next_scan_state = SCAN_DECISION;
 650                 return;
 651         }
 652
 653         /* active scan, send probes */
 654         *next_delay = IEEE80211_PROBE_DELAY;
 655         local->next_scan_state = SCAN_SEND_PROBE;
 656 }
 657
 658 static void ieee80211_scan_state_suspend(struct ieee80211_local *local,
 659                                          unsigned long *next_delay)
 660 {
 661         /* switch back to the operating channel */
 662         local->scan_channel = NULL;
 663         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 664
 665         /* disable PS */
 666         ieee80211_offchannel_return(local);
 667
 668         *next_delay = HZ / 5;
 669         /* afterwards, resume scan & go to next channel */
 670         local->next_scan_state = SCAN_RESUME;
 671 }
 672
 673 static void ieee80211_scan_state_resume(struct ieee80211_local *local,
 674                                         unsigned long *next_delay)
 675 {
 676         ieee80211_offchannel_stop_vifs(local);
 677
 678         if (local->ops->flush) {
 679                 ieee80211_flush_queues(local, NULL);
 680                 *next_delay = 0;
 681         } else
 682                 *next_delay = HZ / 10;
 683
 684         /* remember when we left the operating channel */
 685         local->leave_oper_channel_time = jiffies;
 686
 687         /* advance to the next channel to be scanned */
 688         local->next_scan_state = SCAN_SET_CHANNEL;
 689 }
 690
 691 void ieee80211_scan_work(struct work_struct *work)
 692 {
 693         struct ieee80211_local *local =
 694                 container_of(work, struct ieee80211_local, scan_work.work);
 695         struct ieee80211_sub_if_data *sdata;
 696         unsigned long next_delay = 0;
 697         bool aborted, hw_scan;
 698
 699         mutex_lock(&local->mtx);
 700
 701         sdata = rcu_dereference_protected(local->scan_sdata,
 702                                           lockdep_is_held(&local->mtx));
 703
 704         /* When scanning on-channel, the first-callback means completed. */
 705         if (test_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning)) {
 706                 aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
 707                 goto out_complete;
 708         }
 709
 710         if (test_and_clear_bit(SCAN_COMPLETED, &local->scanning)) {
 711                 aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
 712                 goto out_complete;
 713         }
 714
 715         if (!sdata || !local->scan_req)
 716                 goto out;
 717
 718         if (local->scan_req && !local->scanning) {
 719                 struct cfg80211_scan_request *req = local->scan_req;
 720                 int rc;
 721
 722                 local->scan_req = NULL;
 723                 rcu_assign_pointer(local->scan_sdata, NULL);
 724
 725                 rc = __ieee80211_start_scan(sdata, req);
 726                 if (rc) {
 727                         /* need to complete scan in cfg80211 */
 728                         local->scan_req = req;
 729                         aborted = true;
 730                         goto out_complete;
 731                 } else
 732                         goto out;
 733         }
 734
 735         /*
 736          * Avoid re-scheduling when the sdata is going away.
 737          */
 738         if (!ieee80211_sdata_running(sdata)) {
 739                 aborted = true;
 740                 goto out_complete;
 741         }
 742
 743         /*
 744          * as long as no delay is required advance immediately
 745          * without scheduling a new work
 746          */
 747         do {
 748                 if (!ieee80211_sdata_running(sdata)) {
 749                         aborted = true;
 750                         goto out_complete;
 751                 }
 752
 753                 switch (local->next_scan_state) {
 754                 case SCAN_DECISION:
 755                         /* if no more bands/channels left, complete scan */
 756                         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 757                                 aborted = false;
 758                                 goto out_complete;
 759                         }
 760                         ieee80211_scan_state_decision(local, &next_delay);
 761                         break;
 762                 case SCAN_SET_CHANNEL:
 763                         ieee80211_scan_state_set_channel(local, &next_delay);
 764                         break;
 765                 case SCAN_SEND_PROBE:
 766                         ieee80211_scan_state_send_probe(local, &next_delay);
 767                         break;
 768                 case SCAN_SUSPEND:
 769                         ieee80211_scan_state_suspend(local, &next_delay);
 770                         break;
 771                 case SCAN_RESUME:
 772                         ieee80211_scan_state_resume(local, &next_delay);
 773                         break;
 774                 case SCAN_ABORT:
 775                         aborted = true;
 776                         goto out_complete;
 777                 }
 778         } while (next_delay == 0);
 779
 780         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
 781         goto out;
 782
 783 out_complete:
 784         hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 785         __ieee80211_scan_completed(&local->hw, aborted, hw_scan);
 786 out:
 787         mutex_unlock(&local->mtx);
 788 }
 789
 790 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 791                            struct cfg80211_scan_request *req)
 792 {
 793         int res;
 794
 795         mutex_lock(&sdata->local->mtx);
 796         res = __ieee80211_start_scan(sdata, req);
 797         mutex_unlock(&sdata->local->mtx);
 798
 799         return res;
 800 }
 801
 802 int ieee80211_request_ibss_scan(struct ieee80211_sub_if_data *sdata,
 803                                 const u8 *ssid, u8 ssid_len,
 804                                 struct ieee80211_channel *chan)
 805 {
 806         struct ieee80211_local *local = sdata->local;
 807         int ret = -EBUSY;
 808         enum ieee80211_band band;
 809
 810         mutex_lock(&local->mtx);
 811
 812         /* busy scanning */
 813         if (local->scan_req)
 814                 goto unlock;
 815
 816         /* fill internal scan request */
 817         if (!chan) {
 818                 int i, max_n;
 819                 int n_ch = 0;
 820
 821                 for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
 822                         if (!local->hw.wiphy->bands[band])
 823                                 continue;
 824
 825                         max_n = local->hw.wiphy->bands[band]->n_channels;
 826                         for (i = 0; i < max_n; i++) {
 827                                 struct ieee80211_channel *tmp_ch =
 828                                     &local->hw.wiphy->bands[band]->channels[i];
 829
 830                                 if (tmp_ch->flags & (IEEE80211_CHAN_NO_IBSS |
 831                                                      IEEE80211_CHAN_DISABLED))
 832                                         continue;
 833
 834                                 local->int_scan_req->channels[n_ch] = tmp_ch;
 835                                 n_ch++;
 836                         }
 837                 }
 838
 839                 if (WARN_ON_ONCE(n_ch == 0))
 840                         goto unlock;
 841
 842                 local->int_scan_req->n_channels = n_ch;
 843         } else {
 844                 if (WARN_ON_ONCE(chan->flags & (IEEE80211_CHAN_NO_IBSS |
 845                                                 IEEE80211_CHAN_DISABLED)))
 846                         goto unlock;
 847
 848                 local->int_scan_req->channels[0] = chan;
 849                 local->int_scan_req->n_channels = 1;
 850         }
 851
 852         local->int_scan_req->ssids = &local->scan_ssid;
 853         local->int_scan_req->n_ssids = 1;
 854         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 855         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 856
 857         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 858  unlock:
 859         mutex_unlock(&local->mtx);
 860         return ret;
 861 }
 862
 863 /*
 864  * Only call this function when a scan can't be queued -- under RTNL.
 865  */
 866 void ieee80211_scan_cancel(struct ieee80211_local *local)
 867 {
 868         /*
 869          * We are canceling software scan, or deferred scan that was not
 870          * yet really started (see __ieee80211_start_scan ).
 871          *
 872          * Regarding hardware scan:
 873          * - we can not call  __ieee80211_scan_completed() as when
 874          *   SCAN_HW_SCANNING bit is set this function change
 875          *   local->hw_scan_req to operate on 5G band, what race with
 876          *   driver which can use local->hw_scan_req
 877          *
 878          * - we can not cancel scan_work since driver can schedule it
 879          *   by ieee80211_scan_completed(..., true) to finish scan
 880          *
 881          * Hence we only call the cancel_hw_scan() callback, but the low-level
 882          * driver is still responsible for calling ieee80211_scan_completed()
 883          * after the scan was completed/aborted.
 884          */
 885
 886         mutex_lock(&local->mtx);
 887         if (!local->scan_req)
 888                 goto out;
 889
 890         if (test_bit(SCAN_HW_SCANNING, &local->scanning)) {
 891                 if (local->ops->cancel_hw_scan)
 892                         drv_cancel_hw_scan(local,
 893                                 rcu_dereference_protected(local->scan_sdata,
 894                                                 lockdep_is_held(&local->mtx)));
 895                 goto out;
 896         }
 897
 898         /*
 899          * If the work is currently running, it must be blocked on
 900          * the mutex, but we'll set scan_sdata = NULL and it'll
 901          * simply exit once it acquires the mutex.
 902          */
 903         cancel_delayed_work(&local->scan_work);
 904         /* and clean up */
 905         __ieee80211_scan_completed(&local->hw, true, false);
 906 out:
 907         mutex_unlock(&local->mtx);
 908 }
 909
 910 int ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
 911                                        struct cfg80211_sched_scan_request *req)
 912 {
 913         struct ieee80211_local *local = sdata->local;
 914         struct ieee80211_sched_scan_ies sched_scan_ies = {};
 915         int ret, i, iebufsz;
 916
 917         iebufsz = 2 + IEEE80211_MAX_SSID_LEN +
 918                   local->scan_ies_len + req->ie_len;
 919
 920         mutex_lock(&local->mtx);
 921
 922         if (rcu_access_pointer(local->sched_scan_sdata)) {
 923                 ret = -EBUSY;
 924                 goto out;
 925         }
 926
 927         if (!local->ops->sched_scan_start) {
 928                 ret = -ENOTSUPP;
 929                 goto out;
 930         }
 931
 932         for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
 933                 if (!local->hw.wiphy->bands[i])
 934                         continue;
 935
 936                 sched_scan_ies.ie[i] = kzalloc(iebufsz, GFP_KERNEL);
 937                 if (!sched_scan_ies.ie[i]) {
 938                         ret = -ENOMEM;
 939                         goto out_free;
 940                 }
 941
 942                 sched_scan_ies.len[i] =
 943                         ieee80211_build_preq_ies(local, sched_scan_ies.ie[i],
 944                                                  iebufsz, req->ie, req->ie_len,
 945                                                  i, (u32) -1, 0);
 946         }
 947
 948         ret = drv_sched_scan_start(local, sdata, req, &sched_scan_ies);
 949         if (ret == 0)
 950                 rcu_assign_pointer(local->sched_scan_sdata, sdata);
 951
 952 out_free:
 953         while (i > 0)
 954                 kfree(sched_scan_ies.ie[--i]);
 955 out:
 956         mutex_unlock(&local->mtx);
 957         return ret;
 958 }
 959
 960 int ieee80211_request_sched_scan_stop(struct ieee80211_sub_if_data *sdata)
 961 {
 962         struct ieee80211_local *local = sdata->local;
 963         int ret = 0;
 964
 965         mutex_lock(&local->mtx);
 966
 967         if (!local->ops->sched_scan_stop) {
 968                 ret = -ENOTSUPP;
 969                 goto out;
 970         }
 971
 972         if (rcu_access_pointer(local->sched_scan_sdata))
 973                 drv_sched_scan_stop(local, sdata);
 974
 975 out:
 976         mutex_unlock(&local->mtx);
 977
 978         return ret;
 979 }
 980
 981 void ieee80211_sched_scan_results(struct ieee80211_hw *hw)
 982 {
 983         struct ieee80211_local *local = hw_to_local(hw);
 984
 985         trace_api_sched_scan_results(local);
 986
 987         cfg80211_sched_scan_results(hw->wiphy);
 988 }
 989 EXPORT_SYMBOL(ieee80211_sched_scan_results);
 990
 991 void ieee80211_sched_scan_stopped_work(struct work_struct *work)
 992 {
 993         struct ieee80211_local *local =
 994                 container_of(work, struct ieee80211_local,
 995                              sched_scan_stopped_work);
 996
 997         mutex_lock(&local->mtx);
 998
 999         if (!rcu_access_pointer(local->sched_scan_sdata)) {
1000                 mutex_unlock(&local->mtx);
1001                 return;
1002         }
1003
1004         rcu_assign_pointer(local->sched_scan_sdata, NULL);
1005
1006         mutex_unlock(&local->mtx);
1007
1008         cfg80211_sched_scan_stopped(local->hw.wiphy);
1009 }
1010
1011 void ieee80211_sched_scan_stopped(struct ieee80211_hw *hw)
1012 {
1013         struct ieee80211_local *local = hw_to_local(hw);
1014
1015         trace_api_sched_scan_stopped(local);
1016
1017         ieee80211_queue_work(&local->hw, &local->sched_scan_stopped_work);
1018 }
1019 EXPORT_SYMBOL(ieee80211_sched_scan_stopped);