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 / 8)
  31
  32 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
  33 {
  34         struct ieee80211_bss *bss = (void *)cbss->priv;
  35
  36         kfree(bss_mesh_id(bss));
  37         kfree(bss_mesh_cfg(bss));
  38 }
  39
  40 void ieee80211_rx_bss_put(struct ieee80211_local *local,
  41                           struct ieee80211_bss *bss)
  42 {
  43         if (!bss)
  44                 return;
  45         cfg80211_put_bss(container_of((void *)bss, struct cfg80211_bss, priv));
  46 }
  47
  48 static bool is_uapsd_supported(struct ieee802_11_elems *elems)
  49 {
  50         u8 qos_info;
  51
  52         if (elems->wmm_info && elems->wmm_info_len == 7
  53             && elems->wmm_info[5] == 1)
  54                 qos_info = elems->wmm_info[6];
  55         else if (elems->wmm_param && elems->wmm_param_len == 24
  56                  && elems->wmm_param[5] == 1)
  57                 qos_info = elems->wmm_param[6];
  58         else
  59                 /* no valid wmm information or parameter element found */
  60                 return false;
  61
  62         return qos_info & IEEE80211_WMM_IE_AP_QOSINFO_UAPSD;
  63 }
  64
  65 struct ieee80211_bss *
  66 ieee80211_bss_info_update(struct ieee80211_local *local,
  67                           struct ieee80211_rx_status *rx_status,
  68                           struct ieee80211_mgmt *mgmt,
  69                           size_t len,
  70                           struct ieee802_11_elems *elems,
  71                           struct ieee80211_channel *channel,
  72                           bool beacon)
  73 {
  74         struct cfg80211_bss *cbss;
  75         struct ieee80211_bss *bss;
  76         int clen, srlen;
  77         s32 signal = 0;
  78
  79         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
  80                 signal = rx_status->signal * 100;
  81         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
  82                 signal = (rx_status->signal * 100) / local->hw.max_signal;
  83
  84         cbss = cfg80211_inform_bss_frame(local->hw.wiphy, channel,
  85                                          mgmt, len, signal, GFP_ATOMIC);
  86         if (!cbss)
  87                 return NULL;
  88
  89         cbss->free_priv = ieee80211_rx_bss_free;
  90         bss = (void *)cbss->priv;
  91
  92         bss->device_ts = rx_status->device_timestamp;
  93
  94         if (elems->parse_error) {
  95                 if (beacon)
  96                         bss->corrupt_data |= IEEE80211_BSS_CORRUPT_BEACON;
  97                 else
  98                         bss->corrupt_data |= IEEE80211_BSS_CORRUPT_PROBE_RESP;
  99         } else {
 100                 if (beacon)
 101                         bss->corrupt_data &= ~IEEE80211_BSS_CORRUPT_BEACON;
 102                 else
 103                         bss->corrupt_data &= ~IEEE80211_BSS_CORRUPT_PROBE_RESP;
 104         }
 105
 106         /* save the ERP value so that it is available at association time */
 107         if (elems->erp_info && elems->erp_info_len >= 1 &&
 108                         (!elems->parse_error ||
 109                          !(bss->valid_data & IEEE80211_BSS_VALID_ERP))) {
 110                 bss->erp_value = elems->erp_info[0];
 111                 bss->has_erp_value = true;
 112                 if (!elems->parse_error)
 113                         bss->valid_data |= IEEE80211_BSS_VALID_ERP;
 114         }
 115
 116         if (elems->tim && (!elems->parse_error ||
 117                            !(bss->valid_data & IEEE80211_BSS_VALID_DTIM))) {
 118                 struct ieee80211_tim_ie *tim_ie = elems->tim;
 119                 bss->dtim_period = tim_ie->dtim_period;
 120                 if (!elems->parse_error)
 121                                 bss->valid_data |= IEEE80211_BSS_VALID_DTIM;
 122         }
 123
 124         /* If the beacon had no TIM IE, or it was invalid, use 1 */
 125         if (beacon && !bss->dtim_period)
 126                 bss->dtim_period = 1;
 127
 128         /* replace old supported rates if we get new values */
 129         if (!elems->parse_error ||
 130             !(bss->valid_data & IEEE80211_BSS_VALID_RATES)) {
 131                 srlen = 0;
 132                 if (elems->supp_rates) {
 133                         clen = IEEE80211_MAX_SUPP_RATES;
 134                         if (clen > elems->supp_rates_len)
 135                                 clen = elems->supp_rates_len;
 136                         memcpy(bss->supp_rates, elems->supp_rates, clen);
 137                         srlen += clen;
 138                 }
 139                 if (elems->ext_supp_rates) {
 140                         clen = IEEE80211_MAX_SUPP_RATES - srlen;
 141                         if (clen > elems->ext_supp_rates_len)
 142                                 clen = elems->ext_supp_rates_len;
 143                         memcpy(bss->supp_rates + srlen, elems->ext_supp_rates,
 144                                clen);
 145                         srlen += clen;
 146                 }
 147                 if (srlen) {
 148                         bss->supp_rates_len = srlen;
 149                         if (!elems->parse_error)
 150                                 bss->valid_data |= IEEE80211_BSS_VALID_RATES;
 151                 }
 152         }
 153
 154         if (!elems->parse_error ||
 155             !(bss->valid_data & IEEE80211_BSS_VALID_WMM)) {
 156                 bss->wmm_used = elems->wmm_param || elems->wmm_info;
 157                 bss->uapsd_supported = is_uapsd_supported(elems);
 158                 if (!elems->parse_error)
 159                         bss->valid_data |= IEEE80211_BSS_VALID_WMM;
 160         }
 161
 162         if (!beacon)
 163                 bss->last_probe_resp = jiffies;
 164
 165         return bss;
 166 }
 167
 168 void ieee80211_scan_rx(struct ieee80211_local *local, struct sk_buff *skb)
 169 {
 170         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
 171         struct ieee80211_sub_if_data *sdata1, *sdata2;
 172         struct ieee80211_mgmt *mgmt = (void *)skb->data;
 173         struct ieee80211_bss *bss;
 174         u8 *elements;
 175         struct ieee80211_channel *channel;
 176         size_t baselen;
 177         int freq;
 178         bool beacon;
 179         struct ieee802_11_elems elems;
 180
 181         if (skb->len < 24 ||
 182             (!ieee80211_is_probe_resp(mgmt->frame_control) &&
 183              !ieee80211_is_beacon(mgmt->frame_control)))
 184                 return;
 185
 186         sdata1 = rcu_dereference(local->scan_sdata);
 187         sdata2 = rcu_dereference(local->sched_scan_sdata);
 188
 189         if (likely(!sdata1 && !sdata2))
 190                 return;
 191
 192         if (ieee80211_is_probe_resp(mgmt->frame_control)) {
 193                 /* ignore ProbeResp to foreign address */
 194                 if ((!sdata1 || !ether_addr_equal(mgmt->da, sdata1->vif.addr)) &&
 195                     (!sdata2 || !ether_addr_equal(mgmt->da, sdata2->vif.addr)))
 196                         return;
 197
 198                 elements = mgmt->u.probe_resp.variable;
 199                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 200                 beacon = false;
 201         } else {
 202                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 203                 elements = mgmt->u.beacon.variable;
 204                 beacon = true;
 205         }
 206
 207         if (baselen > skb->len)
 208                 return;
 209
 210         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
 211
 212         if (elems.ds_params && elems.ds_params_len == 1)
 213                 freq = ieee80211_channel_to_frequency(elems.ds_params[0],
 214                                                       rx_status->band);
 215         else
 216                 freq = rx_status->freq;
 217
 218         channel = ieee80211_get_channel(local->hw.wiphy, freq);
 219
 220         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 221                 return;
 222
 223         bss = ieee80211_bss_info_update(local, rx_status,
 224                                         mgmt, skb->len, &elems,
 225                                         channel, beacon);
 226         if (bss)
 227                 ieee80211_rx_bss_put(local, bss);
 228 }
 229
 230 /* return false if no more work */
 231 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 232 {
 233         struct cfg80211_scan_request *req = local->scan_req;
 234         enum ieee80211_band band;
 235         int i, ielen, n_chans;
 236
 237         do {
 238                 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
 239                         return false;
 240
 241                 band = local->hw_scan_band;
 242                 n_chans = 0;
 243                 for (i = 0; i < req->n_channels; i++) {
 244                         if (req->channels[i]->band == band) {
 245                                 local->hw_scan_req->channels[n_chans] =
 246                                                         req->channels[i];
 247                                 n_chans++;
 248                         }
 249                 }
 250
 251                 local->hw_scan_band++;
 252         } while (!n_chans);
 253
 254         local->hw_scan_req->n_channels = n_chans;
 255
 256         ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
 257                                          req->ie, req->ie_len, band,
 258                                          req->rates[band], 0);
 259         local->hw_scan_req->ie_len = ielen;
 260         local->hw_scan_req->no_cck = req->no_cck;
 261
 262         return true;
 263 }
 264
 265 static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted,
 266                                        bool was_hw_scan)
 267 {
 268         struct ieee80211_local *local = hw_to_local(hw);
 269
 270         lockdep_assert_held(&local->mtx);
 271
 272         /*
 273          * It's ok to abort a not-yet-running scan (that
 274          * we have one at all will be verified by checking
 275          * local->scan_req next), but not to complete it
 276          * successfully.
 277          */
 278         if (WARN_ON(!local->scanning && !aborted))
 279                 aborted = true;
 280
 281         if (WARN_ON(!local->scan_req))
 282                 return;
 283
 284         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 285                 int rc;
 286
 287                 rc = drv_hw_scan(local,
 288                         rcu_dereference_protected(local->scan_sdata,
 289                                                   lockdep_is_held(&local->mtx)),
 290                         local->hw_scan_req);
 291
 292                 if (rc == 0)
 293                         return;
 294         }
 295
 296         kfree(local->hw_scan_req);
 297         local->hw_scan_req = NULL;
 298
 299         if (local->scan_req != local->int_scan_req)
 300                 cfg80211_scan_done(local->scan_req, aborted);
 301         local->scan_req = NULL;
 302         rcu_assign_pointer(local->scan_sdata, NULL);
 303
 304         local->scanning = 0;
 305         local->scan_channel = NULL;
 306
 307         /* Set power back to normal operating levels. */
 308         ieee80211_hw_config(local, 0);
 309
 310         if (!was_hw_scan) {
 311                 ieee80211_configure_filter(local);
 312                 drv_sw_scan_complete(local);
 313                 ieee80211_offchannel_return(local, true);
 314         }
 315
 316         ieee80211_recalc_idle(local);
 317
 318         ieee80211_mlme_notify_scan_completed(local);
 319         ieee80211_ibss_notify_scan_completed(local);
 320         ieee80211_mesh_notify_scan_completed(local);
 321         ieee80211_start_next_roc(local);
 322 }
 323
 324 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 325 {
 326         struct ieee80211_local *local = hw_to_local(hw);
 327
 328         trace_api_scan_completed(local, aborted);
 329
 330         set_bit(SCAN_COMPLETED, &local->scanning);
 331         if (aborted)
 332                 set_bit(SCAN_ABORTED, &local->scanning);
 333         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, 0);
 334 }
 335 EXPORT_SYMBOL(ieee80211_scan_completed);
 336
 337 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 338 {
 339         /* Software scan is not supported in multi-channel cases */
 340         if (local->use_chanctx)
 341                 return -EOPNOTSUPP;
 342
 343         /*
 344          * Hardware/driver doesn't support hw_scan, so use software
 345          * scanning instead. First send a nullfunc frame with power save
 346          * bit on so that AP will buffer the frames for us while we are not
 347          * listening, then send probe requests to each channel and wait for
 348          * the responses. After all channels are scanned, tune back to the
 349          * original channel and send a nullfunc frame with power save bit
 350          * off to trigger the AP to send us all the buffered frames.
 351          *
 352          * Note that while local->sw_scanning is true everything else but
 353          * nullfunc frames and probe requests will be dropped in
 354          * ieee80211_tx_h_check_assoc().
 355          */
 356         drv_sw_scan_start(local);
 357
 358         local->leave_oper_channel_time = jiffies;
 359         local->next_scan_state = SCAN_DECISION;
 360         local->scan_channel_idx = 0;
 361
 362         ieee80211_offchannel_stop_vifs(local, true);
 363
 364         ieee80211_configure_filter(local);
 365
 366         /* We need to set power level at maximum rate for scanning. */
 367         ieee80211_hw_config(local, 0);
 368
 369         ieee80211_queue_delayed_work(&local->hw,
 370                                      &local->scan_work, 0);
 371
 372         return 0;
 373 }
 374
 375 static bool ieee80211_can_scan(struct ieee80211_local *local,
 376                                struct ieee80211_sub_if_data *sdata)
 377 {
 378         if (!list_empty(&local->roc_list))
 379                 return false;
 380
 381         if (sdata->vif.type == NL80211_IFTYPE_STATION &&
 382             sdata->u.mgd.flags & (IEEE80211_STA_BEACON_POLL |
 383                                   IEEE80211_STA_CONNECTION_POLL))
 384                 return false;
 385
 386         return true;
 387 }
 388
 389 void ieee80211_run_deferred_scan(struct ieee80211_local *local)
 390 {
 391         lockdep_assert_held(&local->mtx);
 392
 393         if (!local->scan_req || local->scanning)
 394                 return;
 395
 396         if (!ieee80211_can_scan(local,
 397                                 rcu_dereference_protected(
 398                                         local->scan_sdata,
 399                                         lockdep_is_held(&local->mtx))))
 400                 return;
 401
 402         ieee80211_queue_delayed_work(&local->hw, &local->scan_work,
 403                                      round_jiffies_relative(0));
 404 }
 405
 406 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 407                                             unsigned long *next_delay)
 408 {
 409         int i;
 410         struct ieee80211_sub_if_data *sdata;
 411         enum ieee80211_band band = local->hw.conf.channel->band;
 412
 413         sdata = rcu_dereference_protected(local->scan_sdata,
 414                                           lockdep_is_held(&local->mtx));
 415
 416         for (i = 0; i < local->scan_req->n_ssids; i++)
 417                 ieee80211_send_probe_req(
 418                         sdata, NULL,
 419                         local->scan_req->ssids[i].ssid,
 420                         local->scan_req->ssids[i].ssid_len,
 421                         local->scan_req->ie, local->scan_req->ie_len,
 422                         local->scan_req->rates[band], false,
 423                         local->scan_req->no_cck,
 424                         local->hw.conf.channel, true);
 425
 426         /*
 427          * After sending probe requests, wait for probe responses
 428          * on the channel.
 429          */
 430         *next_delay = IEEE80211_CHANNEL_TIME;
 431         local->next_scan_state = SCAN_DECISION;
 432 }
 433
 434 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 435                                   struct cfg80211_scan_request *req)
 436 {
 437         struct ieee80211_local *local = sdata->local;
 438         int rc;
 439
 440         lockdep_assert_held(&local->mtx);
 441
 442         if (local->scan_req)
 443                 return -EBUSY;
 444
 445         if (!ieee80211_can_scan(local, sdata)) {
 446                 /* wait for the work to finish/time out */
 447                 local->scan_req = req;
 448                 rcu_assign_pointer(local->scan_sdata, sdata);
 449                 return 0;
 450         }
 451
 452         if (local->ops->hw_scan) {
 453                 u8 *ies;
 454
 455                 local->hw_scan_req = kmalloc(
 456                                 sizeof(*local->hw_scan_req) +
 457                                 req->n_channels * sizeof(req->channels[0]) +
 458                                 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
 459                                 req->ie_len, GFP_KERNEL);
 460                 if (!local->hw_scan_req)
 461                         return -ENOMEM;
 462
 463                 local->hw_scan_req->ssids = req->ssids;
 464                 local->hw_scan_req->n_ssids = req->n_ssids;
 465                 ies = (u8 *)local->hw_scan_req +
 466                         sizeof(*local->hw_scan_req) +
 467                         req->n_channels * sizeof(req->channels[0]);
 468                 local->hw_scan_req->ie = ies;
 469                 local->hw_scan_req->flags = req->flags;
 470
 471                 local->hw_scan_band = 0;
 472
 473                 /*
 474                  * After allocating local->hw_scan_req, we must
 475                  * go through until ieee80211_prep_hw_scan(), so
 476                  * anything that might be changed here and leave
 477                  * this function early must not go after this
 478                  * allocation.
 479                  */
 480         }
 481
 482         local->scan_req = req;
 483         rcu_assign_pointer(local->scan_sdata, sdata);
 484
 485         if (local->ops->hw_scan) {
 486                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 487         } else if ((req->n_channels == 1) &&
 488                    (req->channels[0] == local->_oper_channel)) {
 489                 /*
 490                  * If we are scanning only on the operating channel
 491                  * then we do not need to stop normal activities
 492                  */
 493                 unsigned long next_delay;
 494
 495                 __set_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning);
 496
 497                 ieee80211_recalc_idle(local);
 498
 499                 /* Notify driver scan is starting, keep order of operations
 500                  * same as normal software scan, in case that matters. */
 501                 drv_sw_scan_start(local);
 502
 503                 ieee80211_configure_filter(local); /* accept probe-responses */
 504
 505                 /* We need to ensure power level is at max for scanning. */
 506                 ieee80211_hw_config(local, 0);
 507
 508                 if ((req->channels[0]->flags &
 509                      IEEE80211_CHAN_PASSIVE_SCAN) ||
 510                     !local->scan_req->n_ssids) {
 511                         next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 512                 } else {
 513                         ieee80211_scan_state_send_probe(local, &next_delay);
 514                         next_delay = IEEE80211_CHANNEL_TIME;
 515                 }
 516
 517                 /* Now, just wait a bit and we are all done! */
 518                 ieee80211_queue_delayed_work(&local->hw, &local->scan_work,
 519                                              next_delay);
 520                 return 0;
 521         } else {
 522                 /* Do normal software scan */
 523                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 524         }
 525
 526         ieee80211_recalc_idle(local);
 527
 528         if (local->ops->hw_scan) {
 529                 WARN_ON(!ieee80211_prep_hw_scan(local));
 530                 rc = drv_hw_scan(local, sdata, local->hw_scan_req);
 531         } else
 532                 rc = ieee80211_start_sw_scan(local);
 533
 534         if (rc) {
 535                 kfree(local->hw_scan_req);
 536                 local->hw_scan_req = NULL;
 537                 local->scanning = 0;
 538
 539                 ieee80211_recalc_idle(local);
 540
 541                 local->scan_req = NULL;
 542                 rcu_assign_pointer(local->scan_sdata, NULL);
 543         }
 544
 545         return rc;
 546 }
 547
 548 static unsigned long
 549 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
 550 {
 551         /*
 552          * TODO: channel switching also consumes quite some time,
 553          * add that delay as well to get a better estimation
 554          */
 555         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN)
 556                 return IEEE80211_PASSIVE_CHANNEL_TIME;
 557         return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
 558 }
 559
 560 static void ieee80211_scan_state_decision(struct ieee80211_local *local,
 561                                           unsigned long *next_delay)
 562 {
 563         bool associated = false;
 564         bool tx_empty = true;
 565         bool bad_latency;
 566         bool listen_int_exceeded;
 567         unsigned long min_beacon_int = 0;
 568         struct ieee80211_sub_if_data *sdata;
 569         struct ieee80211_channel *next_chan;
 570         enum mac80211_scan_state next_scan_state;
 571
 572         /*
 573          * check if at least one STA interface is associated,
 574          * check if at least one STA interface has pending tx frames
 575          * and grab the lowest used beacon interval
 576          */
 577         mutex_lock(&local->iflist_mtx);
 578         list_for_each_entry(sdata, &local->interfaces, list) {
 579                 if (!ieee80211_sdata_running(sdata))
 580                         continue;
 581
 582                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 583                         if (sdata->u.mgd.associated) {
 584                                 associated = true;
 585
 586                                 if (sdata->vif.bss_conf.beacon_int <
 587                                     min_beacon_int || min_beacon_int == 0)
 588                                         min_beacon_int =
 589                                                 sdata->vif.bss_conf.beacon_int;
 590
 591                                 if (!qdisc_all_tx_empty(sdata->dev)) {
 592                                         tx_empty = false;
 593                                         break;
 594                                 }
 595                         }
 596                 }
 597         }
 598         mutex_unlock(&local->iflist_mtx);
 599
 600         next_chan = local->scan_req->channels[local->scan_channel_idx];
 601
 602         /*
 603          * we're currently scanning a different channel, let's
 604          * see if we can scan another channel without interfering
 605          * with the current traffic situation.
 606          *
 607          * Since we don't know if the AP has pending frames for us
 608          * we can only check for our tx queues and use the current
 609          * pm_qos requirements for rx. Hence, if no tx traffic occurs
 610          * at all we will scan as many channels in a row as the pm_qos
 611          * latency allows us to. Additionally we also check for the
 612          * currently negotiated listen interval to prevent losing
 613          * frames unnecessarily.
 614          *
 615          * Otherwise switch back to the operating channel.
 616          */
 617
 618         bad_latency = time_after(jiffies +
 619                         ieee80211_scan_get_channel_time(next_chan),
 620                         local->leave_oper_channel_time +
 621                         usecs_to_jiffies(pm_qos_request(PM_QOS_NETWORK_LATENCY)));
 622
 623         listen_int_exceeded = time_after(jiffies +
 624                         ieee80211_scan_get_channel_time(next_chan),
 625                         local->leave_oper_channel_time +
 626                         usecs_to_jiffies(min_beacon_int * 1024) *
 627                         local->hw.conf.listen_interval);
 628
 629         if (associated && !tx_empty) {
 630                 if (local->scan_req->flags & NL80211_SCAN_FLAG_LOW_PRIORITY)
 631                         next_scan_state = SCAN_ABORT;
 632                 else
 633                         next_scan_state = SCAN_SUSPEND;
 634         } else if (associated && (bad_latency || listen_int_exceeded)) {
 635                 next_scan_state = SCAN_SUSPEND;
 636         } else {
 637                 next_scan_state = SCAN_SET_CHANNEL;
 638         }
 639
 640         local->next_scan_state = next_scan_state;
 641
 642         *next_delay = 0;
 643 }
 644
 645 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 646                                              unsigned long *next_delay)
 647 {
 648         int skip;
 649         struct ieee80211_channel *chan;
 650
 651         skip = 0;
 652         chan = local->scan_req->channels[local->scan_channel_idx];
 653
 654         local->scan_channel = chan;
 655
 656         if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 657                 skip = 1;
 658
 659         /* advance state machine to next channel/band */
 660         local->scan_channel_idx++;
 661
 662         if (skip) {
 663                 /* if we skip this channel return to the decision state */
 664                 local->next_scan_state = SCAN_DECISION;
 665                 return;
 666         }
 667
 668         /*
 669          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 670          * (which unfortunately doesn't say _why_ step a) is done,
 671          * but it waits for the probe delay or until a frame is
 672          * received - and the received frame would update the NAV).
 673          * For now, we do not support waiting until a frame is
 674          * received.
 675          *
 676          * In any case, it is not necessary for a passive scan.
 677          */
 678         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 679             !local->scan_req->n_ssids) {
 680                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 681                 local->next_scan_state = SCAN_DECISION;
 682                 return;
 683         }
 684
 685         /* active scan, send probes */
 686         *next_delay = IEEE80211_PROBE_DELAY;
 687         local->next_scan_state = SCAN_SEND_PROBE;
 688 }
 689
 690 static void ieee80211_scan_state_suspend(struct ieee80211_local *local,
 691                                          unsigned long *next_delay)
 692 {
 693         /* switch back to the operating channel */
 694         local->scan_channel = NULL;
 695         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 696
 697         /*
 698          * Re-enable vifs and beaconing.  Leave PS
 699          * in off-channel state..will put that back
 700          * on-channel at the end of scanning.
 701          */
 702         ieee80211_offchannel_return(local, false);
 703
 704         *next_delay = HZ / 5;
 705         /* afterwards, resume scan & go to next channel */
 706         local->next_scan_state = SCAN_RESUME;
 707 }
 708
 709 static void ieee80211_scan_state_resume(struct ieee80211_local *local,
 710                                         unsigned long *next_delay)
 711 {
 712         /* PS already is in off-channel mode */
 713         ieee80211_offchannel_stop_vifs(local, false);
 714
 715         if (local->ops->flush) {
 716                 drv_flush(local, false);
 717                 *next_delay = 0;
 718         } else
 719                 *next_delay = HZ / 10;
 720
 721         /* remember when we left the operating channel */
 722         local->leave_oper_channel_time = jiffies;
 723
 724         /* advance to the next channel to be scanned */
 725         local->next_scan_state = SCAN_SET_CHANNEL;
 726 }
 727
 728 void ieee80211_scan_work(struct work_struct *work)
 729 {
 730         struct ieee80211_local *local =
 731                 container_of(work, struct ieee80211_local, scan_work.work);
 732         struct ieee80211_sub_if_data *sdata;
 733         unsigned long next_delay = 0;
 734         bool aborted, hw_scan;
 735
 736         mutex_lock(&local->mtx);
 737
 738         sdata = rcu_dereference_protected(local->scan_sdata,
 739                                           lockdep_is_held(&local->mtx));
 740
 741         /* When scanning on-channel, the first-callback means completed. */
 742         if (test_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning)) {
 743                 aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
 744                 goto out_complete;
 745         }
 746
 747         if (test_and_clear_bit(SCAN_COMPLETED, &local->scanning)) {
 748                 aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
 749                 goto out_complete;
 750         }
 751
 752         if (!sdata || !local->scan_req)
 753                 goto out;
 754
 755         if (local->scan_req && !local->scanning) {
 756                 struct cfg80211_scan_request *req = local->scan_req;
 757                 int rc;
 758
 759                 local->scan_req = NULL;
 760                 rcu_assign_pointer(local->scan_sdata, NULL);
 761
 762                 rc = __ieee80211_start_scan(sdata, req);
 763                 if (rc) {
 764                         /* need to complete scan in cfg80211 */
 765                         local->scan_req = req;
 766                         aborted = true;
 767                         goto out_complete;
 768                 } else
 769                         goto out;
 770         }
 771
 772         /*
 773          * Avoid re-scheduling when the sdata is going away.
 774          */
 775         if (!ieee80211_sdata_running(sdata)) {
 776                 aborted = true;
 777                 goto out_complete;
 778         }
 779
 780         /*
 781          * as long as no delay is required advance immediately
 782          * without scheduling a new work
 783          */
 784         do {
 785                 if (!ieee80211_sdata_running(sdata)) {
 786                         aborted = true;
 787                         goto out_complete;
 788                 }
 789
 790                 switch (local->next_scan_state) {
 791                 case SCAN_DECISION:
 792                         /* if no more bands/channels left, complete scan */
 793                         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 794                                 aborted = false;
 795                                 goto out_complete;
 796                         }
 797                         ieee80211_scan_state_decision(local, &next_delay);
 798                         break;
 799                 case SCAN_SET_CHANNEL:
 800                         ieee80211_scan_state_set_channel(local, &next_delay);
 801                         break;
 802                 case SCAN_SEND_PROBE:
 803                         ieee80211_scan_state_send_probe(local, &next_delay);
 804                         break;
 805                 case SCAN_SUSPEND:
 806                         ieee80211_scan_state_suspend(local, &next_delay);
 807                         break;
 808                 case SCAN_RESUME:
 809                         ieee80211_scan_state_resume(local, &next_delay);
 810                         break;
 811                 case SCAN_ABORT:
 812                         aborted = true;
 813                         goto out_complete;
 814                 }
 815         } while (next_delay == 0);
 816
 817         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
 818         goto out;
 819
 820 out_complete:
 821         hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 822         __ieee80211_scan_completed(&local->hw, aborted, hw_scan);
 823 out:
 824         mutex_unlock(&local->mtx);
 825 }
 826
 827 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 828                            struct cfg80211_scan_request *req)
 829 {
 830         int res;
 831
 832         mutex_lock(&sdata->local->mtx);
 833         res = __ieee80211_start_scan(sdata, req);
 834         mutex_unlock(&sdata->local->mtx);
 835
 836         return res;
 837 }
 838
 839 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 840                                     const u8 *ssid, u8 ssid_len,
 841                                     struct ieee80211_channel *chan)
 842 {
 843         struct ieee80211_local *local = sdata->local;
 844         int ret = -EBUSY;
 845         enum ieee80211_band band;
 846
 847         mutex_lock(&local->mtx);
 848
 849         /* busy scanning */
 850         if (local->scan_req)
 851                 goto unlock;
 852
 853         /* fill internal scan request */
 854         if (!chan) {
 855                 int i, nchan = 0;
 856
 857                 for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
 858                         if (!local->hw.wiphy->bands[band])
 859                                 continue;
 860                         for (i = 0;
 861                              i < local->hw.wiphy->bands[band]->n_channels;
 862                              i++) {
 863                                 local->int_scan_req->channels[nchan] =
 864                                     &local->hw.wiphy->bands[band]->channels[i];
 865                                 nchan++;
 866                         }
 867                 }
 868
 869                 local->int_scan_req->n_channels = nchan;
 870         } else {
 871                 local->int_scan_req->channels[0] = chan;
 872                 local->int_scan_req->n_channels = 1;
 873         }
 874
 875         local->int_scan_req->ssids = &local->scan_ssid;
 876         local->int_scan_req->n_ssids = 1;
 877         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 878         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 879
 880         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 881  unlock:
 882         mutex_unlock(&local->mtx);
 883         return ret;
 884 }
 885
 886 /*
 887  * Only call this function when a scan can't be queued -- under RTNL.
 888  */
 889 void ieee80211_scan_cancel(struct ieee80211_local *local)
 890 {
 891         /*
 892          * We are canceling software scan, or deferred scan that was not
 893          * yet really started (see __ieee80211_start_scan ).
 894          *
 895          * Regarding hardware scan:
 896          * - we can not call  __ieee80211_scan_completed() as when
 897          *   SCAN_HW_SCANNING bit is set this function change
 898          *   local->hw_scan_req to operate on 5G band, what race with
 899          *   driver which can use local->hw_scan_req
 900          *
 901          * - we can not cancel scan_work since driver can schedule it
 902          *   by ieee80211_scan_completed(..., true) to finish scan
 903          *
 904          * Hence we only call the cancel_hw_scan() callback, but the low-level
 905          * driver is still responsible for calling ieee80211_scan_completed()
 906          * after the scan was completed/aborted.
 907          */
 908
 909         mutex_lock(&local->mtx);
 910         if (!local->scan_req)
 911                 goto out;
 912
 913         if (test_bit(SCAN_HW_SCANNING, &local->scanning)) {
 914                 if (local->ops->cancel_hw_scan)
 915                         drv_cancel_hw_scan(local,
 916                                 rcu_dereference_protected(local->scan_sdata,
 917                                                 lockdep_is_held(&local->mtx)));
 918                 goto out;
 919         }
 920
 921         /*
 922          * If the work is currently running, it must be blocked on
 923          * the mutex, but we'll set scan_sdata = NULL and it'll
 924          * simply exit once it acquires the mutex.
 925          */
 926         cancel_delayed_work(&local->scan_work);
 927         /* and clean up */
 928         __ieee80211_scan_completed(&local->hw, true, false);
 929 out:
 930         mutex_unlock(&local->mtx);
 931 }
 932
 933 int ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
 934                                        struct cfg80211_sched_scan_request *req)
 935 {
 936         struct ieee80211_local *local = sdata->local;
 937         struct ieee80211_sched_scan_ies sched_scan_ies = {};
 938         int ret, i;
 939
 940         mutex_lock(&local->mtx);
 941
 942         if (rcu_access_pointer(local->sched_scan_sdata)) {
 943                 ret = -EBUSY;
 944                 goto out;
 945         }
 946
 947         if (!local->ops->sched_scan_start) {
 948                 ret = -ENOTSUPP;
 949                 goto out;
 950         }
 951
 952         for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
 953                 if (!local->hw.wiphy->bands[i])
 954                         continue;
 955
 956                 sched_scan_ies.ie[i] = kzalloc(2 + IEEE80211_MAX_SSID_LEN +
 957                                                local->scan_ies_len +
 958                                                req->ie_len,
 959                                                GFP_KERNEL);
 960                 if (!sched_scan_ies.ie[i]) {
 961                         ret = -ENOMEM;
 962                         goto out_free;
 963                 }
 964
 965                 sched_scan_ies.len[i] =
 966                         ieee80211_build_preq_ies(local, sched_scan_ies.ie[i],
 967                                                  req->ie, req->ie_len, i,
 968                                                  (u32) -1, 0);
 969         }
 970
 971         ret = drv_sched_scan_start(local, sdata, req, &sched_scan_ies);
 972         if (ret == 0)
 973                 rcu_assign_pointer(local->sched_scan_sdata, sdata);
 974
 975 out_free:
 976         while (i > 0)
 977                 kfree(sched_scan_ies.ie[--i]);
 978 out:
 979         mutex_unlock(&local->mtx);
 980         return ret;
 981 }
 982
 983 int ieee80211_request_sched_scan_stop(struct ieee80211_sub_if_data *sdata)
 984 {
 985         struct ieee80211_local *local = sdata->local;
 986         int ret = 0;
 987
 988         mutex_lock(&local->mtx);
 989
 990         if (!local->ops->sched_scan_stop) {
 991                 ret = -ENOTSUPP;
 992                 goto out;
 993         }
 994
 995         if (rcu_access_pointer(local->sched_scan_sdata))
 996                 drv_sched_scan_stop(local, sdata);
 997
 998 out:
 999         mutex_unlock(&local->mtx);
1000
1001         return ret;
1002 }
1003
1004 void ieee80211_sched_scan_results(struct ieee80211_hw *hw)
1005 {
1006         struct ieee80211_local *local = hw_to_local(hw);
1007
1008         trace_api_sched_scan_results(local);
1009
1010         cfg80211_sched_scan_results(hw->wiphy);
1011 }
1012 EXPORT_SYMBOL(ieee80211_sched_scan_results);
1013
1014 void ieee80211_sched_scan_stopped_work(struct work_struct *work)
1015 {
1016         struct ieee80211_local *local =
1017                 container_of(work, struct ieee80211_local,
1018                              sched_scan_stopped_work);
1019
1020         mutex_lock(&local->mtx);
1021
1022         if (!rcu_access_pointer(local->sched_scan_sdata)) {
1023                 mutex_unlock(&local->mtx);
1024                 return;
1025         }
1026
1027         rcu_assign_pointer(local->sched_scan_sdata, NULL);
1028
1029         mutex_unlock(&local->mtx);
1030
1031         cfg80211_sched_scan_stopped(local->hw.wiphy);
1032 }
1033
1034 void ieee80211_sched_scan_stopped(struct ieee80211_hw *hw)
1035 {
1036         struct ieee80211_local *local = hw_to_local(hw);
1037
1038         trace_api_sched_scan_stopped(local);
1039
1040         ieee80211_queue_work(&local->hw, &local->sched_scan_stopped_work);
1041 }
1042 EXPORT_SYMBOL(ieee80211_sched_scan_stopped);