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