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