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/rtnetlink.h>
  17 #include <linux/pm_qos.h>
  18 #include <net/sch_generic.h>
  19 #include <linux/slab.h>
  20 #include <net/mac80211.h>
  21
  22 #include "ieee80211_i.h"
  23 #include "driver-ops.h"
  24 #include "mesh.h"
  25
  26 #define IEEE80211_PROBE_DELAY (HZ / 33)
  27 #define IEEE80211_CHANNEL_TIME (HZ / 33)
  28 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
  29
  30 struct ieee80211_bss *
  31 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
  32                      u8 *ssid, u8 ssid_len)
  33 {
  34         struct cfg80211_bss *cbss;
  35
  36         cbss = cfg80211_get_bss(local->hw.wiphy,
  37                                 ieee80211_get_channel(local->hw.wiphy, freq),
  38                                 bssid, ssid, ssid_len, 0, 0);
  39         if (!cbss)
  40                 return NULL;
  41         return (void *)cbss->priv;
  42 }
  43
  44 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
  45 {
  46         struct ieee80211_bss *bss = (void *)cbss->priv;
  47
  48         kfree(bss_mesh_id(bss));
  49         kfree(bss_mesh_cfg(bss));
  50 }
  51
  52 void ieee80211_rx_bss_put(struct ieee80211_local *local,
  53                           struct ieee80211_bss *bss)
  54 {
  55         if (!bss)
  56                 return;
  57         cfg80211_put_bss(container_of((void *)bss, struct cfg80211_bss, priv));
  58 }
  59
  60 static bool is_uapsd_supported(struct ieee802_11_elems *elems)
  61 {
  62         u8 qos_info;
  63
  64         if (elems->wmm_info && elems->wmm_info_len == 7
  65             && elems->wmm_info[5] == 1)
  66                 qos_info = elems->wmm_info[6];
  67         else if (elems->wmm_param && elems->wmm_param_len == 24
  68                  && elems->wmm_param[5] == 1)
  69                 qos_info = elems->wmm_param[6];
  70         else
  71                 /* no valid wmm information or parameter element found */
  72                 return false;
  73
  74         return qos_info & IEEE80211_WMM_IE_AP_QOSINFO_UAPSD;
  75 }
  76
  77 struct ieee80211_bss *
  78 ieee80211_bss_info_update(struct ieee80211_local *local,
  79                           struct ieee80211_rx_status *rx_status,
  80                           struct ieee80211_mgmt *mgmt,
  81                           size_t len,
  82                           struct ieee802_11_elems *elems,
  83                           struct ieee80211_channel *channel,
  84                           bool beacon)
  85 {
  86         struct cfg80211_bss *cbss;
  87         struct ieee80211_bss *bss;
  88         int clen, srlen;
  89         s32 signal = 0;
  90
  91         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
  92                 signal = rx_status->signal * 100;
  93         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
  94                 signal = (rx_status->signal * 100) / local->hw.max_signal;
  95
  96         cbss = cfg80211_inform_bss_frame(local->hw.wiphy, channel,
  97                                          mgmt, len, signal, GFP_ATOMIC);
  98
  99         if (!cbss)
 100                 return NULL;
 101
 102         cbss->free_priv = ieee80211_rx_bss_free;
 103         bss = (void *)cbss->priv;
 104
 105         /* save the ERP value so that it is available at association time */
 106         if (elems->erp_info && elems->erp_info_len >= 1) {
 107                 bss->erp_value = elems->erp_info[0];
 108                 bss->has_erp_value = 1;
 109         }
 110
 111         if (elems->tim) {
 112                 struct ieee80211_tim_ie *tim_ie =
 113                         (struct ieee80211_tim_ie *)elems->tim;
 114                 bss->dtim_period = tim_ie->dtim_period;
 115         }
 116
 117         /* If the beacon had no TIM IE, or it was invalid, use 1 */
 118         if (beacon && !bss->dtim_period)
 119                 bss->dtim_period = 1;
 120
 121         /* replace old supported rates if we get new values */
 122         srlen = 0;
 123         if (elems->supp_rates) {
 124                 clen = IEEE80211_MAX_SUPP_RATES;
 125                 if (clen > elems->supp_rates_len)
 126                         clen = elems->supp_rates_len;
 127                 memcpy(bss->supp_rates, elems->supp_rates, clen);
 128                 srlen += clen;
 129         }
 130         if (elems->ext_supp_rates) {
 131                 clen = IEEE80211_MAX_SUPP_RATES - srlen;
 132                 if (clen > elems->ext_supp_rates_len)
 133                         clen = elems->ext_supp_rates_len;
 134                 memcpy(bss->supp_rates + srlen, elems->ext_supp_rates, clen);
 135                 srlen += clen;
 136         }
 137         if (srlen)
 138                 bss->supp_rates_len = srlen;
 139
 140         bss->wmm_used = elems->wmm_param || elems->wmm_info;
 141         bss->uapsd_supported = is_uapsd_supported(elems);
 142
 143         if (!beacon)
 144                 bss->last_probe_resp = jiffies;
 145
 146         return bss;
 147 }
 148
 149 ieee80211_rx_result
 150 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
 151 {
 152         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
 153         struct ieee80211_mgmt *mgmt;
 154         struct ieee80211_bss *bss;
 155         u8 *elements;
 156         struct ieee80211_channel *channel;
 157         size_t baselen;
 158         int freq;
 159         __le16 fc;
 160         bool presp, beacon = false;
 161         struct ieee802_11_elems elems;
 162
 163         if (skb->len < 2)
 164                 return RX_DROP_UNUSABLE;
 165
 166         mgmt = (struct ieee80211_mgmt *) skb->data;
 167         fc = mgmt->frame_control;
 168
 169         if (ieee80211_is_ctl(fc))
 170                 return RX_CONTINUE;
 171
 172         if (skb->len < 24)
 173                 return RX_CONTINUE;
 174
 175         presp = ieee80211_is_probe_resp(fc);
 176         if (presp) {
 177                 /* ignore ProbeResp to foreign address */
 178                 if (memcmp(mgmt->da, sdata->vif.addr, ETH_ALEN))
 179                         return RX_DROP_MONITOR;
 180
 181                 presp = true;
 182                 elements = mgmt->u.probe_resp.variable;
 183                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 184         } else {
 185                 beacon = ieee80211_is_beacon(fc);
 186                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 187                 elements = mgmt->u.beacon.variable;
 188         }
 189
 190         if (!presp && !beacon)
 191                 return RX_CONTINUE;
 192
 193         if (baselen > skb->len)
 194                 return RX_DROP_MONITOR;
 195
 196         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
 197
 198         if (elems.ds_params && elems.ds_params_len == 1)
 199                 freq = ieee80211_channel_to_frequency(elems.ds_params[0],
 200                                                       rx_status->band);
 201         else
 202                 freq = rx_status->freq;
 203
 204         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
 205
 206         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 207                 return RX_DROP_MONITOR;
 208
 209         bss = ieee80211_bss_info_update(sdata->local, rx_status,
 210                                         mgmt, skb->len, &elems,
 211                                         channel, beacon);
 212         if (bss)
 213                 ieee80211_rx_bss_put(sdata->local, bss);
 214
 215         if (channel == sdata->local->oper_channel)
 216                 return RX_CONTINUE;
 217
 218         dev_kfree_skb(skb);
 219         return RX_QUEUED;
 220 }
 221
 222 /* return false if no more work */
 223 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 224 {
 225         struct cfg80211_scan_request *req = local->scan_req;
 226         enum ieee80211_band band;
 227         int i, ielen, n_chans;
 228
 229         do {
 230                 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
 231                         return false;
 232
 233                 band = local->hw_scan_band;
 234                 n_chans = 0;
 235                 for (i = 0; i < req->n_channels; i++) {
 236                         if (req->channels[i]->band == band) {
 237                                 local->hw_scan_req->channels[n_chans] =
 238                                                         req->channels[i];
 239                                 n_chans++;
 240                         }
 241                 }
 242
 243                 local->hw_scan_band++;
 244         } while (!n_chans);
 245
 246         local->hw_scan_req->n_channels = n_chans;
 247
 248         ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
 249                                          req->ie, req->ie_len, band,
 250                                          req->rates[band], 0);
 251         local->hw_scan_req->ie_len = ielen;
 252         local->hw_scan_req->no_cck = req->no_cck;
 253
 254         return true;
 255 }
 256
 257 static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted,
 258                                        bool was_hw_scan)
 259 {
 260         struct ieee80211_local *local = hw_to_local(hw);
 261
 262         lockdep_assert_held(&local->mtx);
 263
 264         /*
 265          * It's ok to abort a not-yet-running scan (that
 266          * we have one at all will be verified by checking
 267          * local->scan_req next), but not to complete it
 268          * successfully.
 269          */
 270         if (WARN_ON(!local->scanning && !aborted))
 271                 aborted = true;
 272
 273         if (WARN_ON(!local->scan_req))
 274                 return;
 275
 276         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 277                 int rc = drv_hw_scan(local, local->scan_sdata, local->hw_scan_req);
 278                 if (rc == 0)
 279                         return;
 280         }
 281
 282         kfree(local->hw_scan_req);
 283         local->hw_scan_req = NULL;
 284
 285         if (local->scan_req != local->int_scan_req)
 286                 cfg80211_scan_done(local->scan_req, aborted);
 287         local->scan_req = NULL;
 288         local->scan_sdata = NULL;
 289
 290         local->scanning = 0;
 291         local->scan_channel = NULL;
 292
 293         /* Set power back to normal operating levels. */
 294         ieee80211_hw_config(local, 0);
 295
 296         if (!was_hw_scan) {
 297                 ieee80211_configure_filter(local);
 298                 drv_sw_scan_complete(local);
 299                 ieee80211_offchannel_return(local, true, true);
 300         }
 301
 302         ieee80211_recalc_idle(local);
 303
 304         ieee80211_mlme_notify_scan_completed(local);
 305         ieee80211_ibss_notify_scan_completed(local);
 306         ieee80211_mesh_notify_scan_completed(local);
 307         ieee80211_queue_work(&local->hw, &local->work_work);
 308 }
 309
 310 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 311 {
 312         struct ieee80211_local *local = hw_to_local(hw);
 313
 314         trace_api_scan_completed(local, aborted);
 315
 316         set_bit(SCAN_COMPLETED, &local->scanning);
 317         if (aborted)
 318                 set_bit(SCAN_ABORTED, &local->scanning);
 319         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, 0);
 320 }
 321 EXPORT_SYMBOL(ieee80211_scan_completed);
 322
 323 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 324 {
 325         /*
 326          * Hardware/driver doesn't support hw_scan, so use software
 327          * scanning instead. First send a nullfunc frame with power save
 328          * bit on so that AP will buffer the frames for us while we are not
 329          * listening, then send probe requests to each channel and wait for
 330          * the responses. After all channels are scanned, tune back to the
 331          * original channel and send a nullfunc frame with power save bit
 332          * off to trigger the AP to send us all the buffered frames.
 333          *
 334          * Note that while local->sw_scanning is true everything else but
 335          * nullfunc frames and probe requests will be dropped in
 336          * ieee80211_tx_h_check_assoc().
 337          */
 338         drv_sw_scan_start(local);
 339
 340         local->leave_oper_channel_time = 0;
 341         local->next_scan_state = SCAN_DECISION;
 342         local->scan_channel_idx = 0;
 343
 344         ieee80211_offchannel_stop_vifs(local, true);
 345
 346         ieee80211_configure_filter(local);
 347
 348         /* We need to set power level at maximum rate for scanning. */
 349         ieee80211_hw_config(local, 0);
 350
 351         ieee80211_queue_delayed_work(&local->hw,
 352                                      &local->scan_work, 0);
 353
 354         return 0;
 355 }
 356
 357
 358 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 359                                   struct cfg80211_scan_request *req)
 360 {
 361         struct ieee80211_local *local = sdata->local;
 362         int rc;
 363
 364         lockdep_assert_held(&local->mtx);
 365
 366         if (local->scan_req)
 367                 return -EBUSY;
 368
 369         if (!list_empty(&local->work_list)) {
 370                 /* wait for the work to finish/time out */
 371                 local->scan_req = req;
 372                 local->scan_sdata = sdata;
 373                 return 0;
 374         }
 375
 376         if (local->ops->hw_scan) {
 377                 u8 *ies;
 378
 379                 local->hw_scan_req = kmalloc(
 380                                 sizeof(*local->hw_scan_req) +
 381                                 req->n_channels * sizeof(req->channels[0]) +
 382                                 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
 383                                 req->ie_len, GFP_KERNEL);
 384                 if (!local->hw_scan_req)
 385                         return -ENOMEM;
 386
 387                 local->hw_scan_req->ssids = req->ssids;
 388                 local->hw_scan_req->n_ssids = req->n_ssids;
 389                 ies = (u8 *)local->hw_scan_req +
 390                         sizeof(*local->hw_scan_req) +
 391                         req->n_channels * sizeof(req->channels[0]);
 392                 local->hw_scan_req->ie = ies;
 393
 394                 local->hw_scan_band = 0;
 395
 396                 /*
 397                  * After allocating local->hw_scan_req, we must
 398                  * go through until ieee80211_prep_hw_scan(), so
 399                  * anything that might be changed here and leave
 400                  * this function early must not go after this
 401                  * allocation.
 402                  */
 403         }
 404
 405         local->scan_req = req;
 406         local->scan_sdata = sdata;
 407
 408         if (local->ops->hw_scan)
 409                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 410         else
 411                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 412
 413         ieee80211_recalc_idle(local);
 414
 415         if (local->ops->hw_scan) {
 416                 WARN_ON(!ieee80211_prep_hw_scan(local));
 417                 rc = drv_hw_scan(local, sdata, local->hw_scan_req);
 418         } else
 419                 rc = ieee80211_start_sw_scan(local);
 420
 421         if (rc) {
 422                 kfree(local->hw_scan_req);
 423                 local->hw_scan_req = NULL;
 424                 local->scanning = 0;
 425
 426                 ieee80211_recalc_idle(local);
 427
 428                 local->scan_req = NULL;
 429                 local->scan_sdata = NULL;
 430         }
 431
 432         return rc;
 433 }
 434
 435 static unsigned long
 436 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
 437 {
 438         /*
 439          * TODO: channel switching also consumes quite some time,
 440          * add that delay as well to get a better estimation
 441          */
 442         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN)
 443                 return IEEE80211_PASSIVE_CHANNEL_TIME;
 444         return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
 445 }
 446
 447 static void ieee80211_scan_state_decision(struct ieee80211_local *local,
 448                                           unsigned long *next_delay)
 449 {
 450         bool associated = false;
 451         bool tx_empty = true;
 452         bool bad_latency;
 453         bool listen_int_exceeded;
 454         unsigned long min_beacon_int = 0;
 455         struct ieee80211_sub_if_data *sdata;
 456         struct ieee80211_channel *next_chan;
 457
 458         /*
 459          * check if at least one STA interface is associated,
 460          * check if at least one STA interface has pending tx frames
 461          * and grab the lowest used beacon interval
 462          */
 463         mutex_lock(&local->iflist_mtx);
 464         list_for_each_entry(sdata, &local->interfaces, list) {
 465                 if (!ieee80211_sdata_running(sdata))
 466                         continue;
 467
 468                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 469                         if (sdata->u.mgd.associated) {
 470                                 associated = true;
 471
 472                                 if (sdata->vif.bss_conf.beacon_int <
 473                                     min_beacon_int || min_beacon_int == 0)
 474                                         min_beacon_int =
 475                                                 sdata->vif.bss_conf.beacon_int;
 476
 477                                 if (!qdisc_all_tx_empty(sdata->dev)) {
 478                                         tx_empty = false;
 479                                         break;
 480                                 }
 481                         }
 482                 }
 483         }
 484         mutex_unlock(&local->iflist_mtx);
 485
 486         next_chan = local->scan_req->channels[local->scan_channel_idx];
 487
 488         /*
 489          * we're currently scanning a different channel, let's
 490          * see if we can scan another channel without interfering
 491          * with the current traffic situation.
 492          *
 493          * Since we don't know if the AP has pending frames for us
 494          * we can only check for our tx queues and use the current
 495          * pm_qos requirements for rx. Hence, if no tx traffic occurs
 496          * at all we will scan as many channels in a row as the pm_qos
 497          * latency allows us to. Additionally we also check for the
 498          * currently negotiated listen interval to prevent losing
 499          * frames unnecessarily.
 500          *
 501          * Otherwise switch back to the operating channel.
 502          */
 503
 504         bad_latency = time_after(jiffies +
 505                         ieee80211_scan_get_channel_time(next_chan),
 506                         local->leave_oper_channel_time +
 507                         usecs_to_jiffies(pm_qos_request(PM_QOS_NETWORK_LATENCY)));
 508
 509         listen_int_exceeded = time_after(jiffies +
 510                         ieee80211_scan_get_channel_time(next_chan),
 511                         local->leave_oper_channel_time +
 512                         usecs_to_jiffies(min_beacon_int * 1024) *
 513                         local->hw.conf.listen_interval);
 514
 515         if (associated && (!tx_empty || bad_latency || listen_int_exceeded))
 516                 local->next_scan_state = SCAN_SUSPEND;
 517         else
 518                 local->next_scan_state = SCAN_SET_CHANNEL;
 519
 520         *next_delay = 0;
 521 }
 522
 523 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 524                                              unsigned long *next_delay)
 525 {
 526         int skip;
 527         struct ieee80211_channel *chan;
 528
 529         skip = 0;
 530         chan = local->scan_req->channels[local->scan_channel_idx];
 531
 532         local->scan_channel = chan;
 533
 534         if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 535                 skip = 1;
 536
 537         /* advance state machine to next channel/band */
 538         local->scan_channel_idx++;
 539
 540         if (skip) {
 541                 /* if we skip this channel return to the decision state */
 542                 local->next_scan_state = SCAN_DECISION;
 543                 return;
 544         }
 545
 546         /*
 547          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 548          * (which unfortunately doesn't say _why_ step a) is done,
 549          * but it waits for the probe delay or until a frame is
 550          * received - and the received frame would update the NAV).
 551          * For now, we do not support waiting until a frame is
 552          * received.
 553          *
 554          * In any case, it is not necessary for a passive scan.
 555          */
 556         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 557             !local->scan_req->n_ssids) {
 558                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 559                 local->next_scan_state = SCAN_DECISION;
 560                 return;
 561         }
 562
 563         /* active scan, send probes */
 564         *next_delay = IEEE80211_PROBE_DELAY;
 565         local->next_scan_state = SCAN_SEND_PROBE;
 566 }
 567
 568 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 569                                             unsigned long *next_delay)
 570 {
 571         int i;
 572         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 573         enum ieee80211_band band = local->hw.conf.channel->band;
 574
 575         for (i = 0; i < local->scan_req->n_ssids; i++)
 576                 ieee80211_send_probe_req(
 577                         sdata, NULL,
 578                         local->scan_req->ssids[i].ssid,
 579                         local->scan_req->ssids[i].ssid_len,
 580                         local->scan_req->ie, local->scan_req->ie_len,
 581                         local->scan_req->rates[band], false,
 582                         local->scan_req->no_cck);
 583
 584         /*
 585          * After sending probe requests, wait for probe responses
 586          * on the channel.
 587          */
 588         *next_delay = IEEE80211_CHANNEL_TIME;
 589         local->next_scan_state = SCAN_DECISION;
 590 }
 591
 592 static void ieee80211_scan_state_suspend(struct ieee80211_local *local,
 593                                          unsigned long *next_delay)
 594 {
 595         /* switch back to the operating channel */
 596         local->scan_channel = NULL;
 597         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 598
 599         /*
 600          * Re-enable vifs and beaconing.  Leave PS
 601          * in off-channel state..will put that back
 602          * on-channel at the end of scanning.
 603          */
 604         ieee80211_offchannel_return(local, true, false);
 605
 606         *next_delay = HZ / 5;
 607         /* afterwards, resume scan & go to next channel */
 608         local->next_scan_state = SCAN_RESUME;
 609 }
 610
 611 static void ieee80211_scan_state_resume(struct ieee80211_local *local,
 612                                         unsigned long *next_delay)
 613 {
 614         /* PS already is in off-channel mode */
 615         ieee80211_offchannel_stop_vifs(local, false);
 616
 617         if (local->ops->flush) {
 618                 drv_flush(local, false);
 619                 *next_delay = 0;
 620         } else
 621                 *next_delay = HZ / 10;
 622
 623         /* remember when we left the operating channel */
 624         local->leave_oper_channel_time = jiffies;
 625
 626         /* advance to the next channel to be scanned */
 627         local->next_scan_state = SCAN_DECISION;
 628 }
 629
 630 void ieee80211_scan_work(struct work_struct *work)
 631 {
 632         struct ieee80211_local *local =
 633                 container_of(work, struct ieee80211_local, scan_work.work);
 634         struct ieee80211_sub_if_data *sdata;
 635         unsigned long next_delay = 0;
 636         bool aborted, hw_scan;
 637
 638         mutex_lock(&local->mtx);
 639
 640         sdata = local->scan_sdata;
 641
 642         if (test_and_clear_bit(SCAN_COMPLETED, &local->scanning)) {
 643                 aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
 644                 goto out_complete;
 645         }
 646
 647         if (!sdata || !local->scan_req)
 648                 goto out;
 649
 650         if (local->scan_req && !local->scanning) {
 651                 struct cfg80211_scan_request *req = local->scan_req;
 652                 int rc;
 653
 654                 local->scan_req = NULL;
 655                 local->scan_sdata = NULL;
 656
 657                 rc = __ieee80211_start_scan(sdata, req);
 658                 if (rc) {
 659                         /* need to complete scan in cfg80211 */
 660                         local->scan_req = req;
 661                         aborted = true;
 662                         goto out_complete;
 663                 } else
 664                         goto out;
 665         }
 666
 667         /*
 668          * Avoid re-scheduling when the sdata is going away.
 669          */
 670         if (!ieee80211_sdata_running(sdata)) {
 671                 aborted = true;
 672                 goto out_complete;
 673         }
 674
 675         /*
 676          * as long as no delay is required advance immediately
 677          * without scheduling a new work
 678          */
 679         do {
 680                 if (!ieee80211_sdata_running(sdata)) {
 681                         aborted = true;
 682                         goto out_complete;
 683                 }
 684
 685                 switch (local->next_scan_state) {
 686                 case SCAN_DECISION:
 687                         /* if no more bands/channels left, complete scan */
 688                         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 689                                 aborted = false;
 690                                 goto out_complete;
 691                         }
 692                         ieee80211_scan_state_decision(local, &next_delay);
 693                         break;
 694                 case SCAN_SET_CHANNEL:
 695                         ieee80211_scan_state_set_channel(local, &next_delay);
 696                         break;
 697                 case SCAN_SEND_PROBE:
 698                         ieee80211_scan_state_send_probe(local, &next_delay);
 699                         break;
 700                 case SCAN_SUSPEND:
 701                         ieee80211_scan_state_suspend(local, &next_delay);
 702                         break;
 703                 case SCAN_RESUME:
 704                         ieee80211_scan_state_resume(local, &next_delay);
 705                         break;
 706                 }
 707         } while (next_delay == 0);
 708
 709         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
 710         goto out;
 711
 712 out_complete:
 713         hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 714         __ieee80211_scan_completed(&local->hw, aborted, hw_scan);
 715 out:
 716         mutex_unlock(&local->mtx);
 717 }
 718
 719 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 720                            struct cfg80211_scan_request *req)
 721 {
 722         int res;
 723
 724         mutex_lock(&sdata->local->mtx);
 725         res = __ieee80211_start_scan(sdata, req);
 726         mutex_unlock(&sdata->local->mtx);
 727
 728         return res;
 729 }
 730
 731 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 732                                     const u8 *ssid, u8 ssid_len,
 733                                     struct ieee80211_channel *chan)
 734 {
 735         struct ieee80211_local *local = sdata->local;
 736         int ret = -EBUSY;
 737         enum ieee80211_band band;
 738
 739         mutex_lock(&local->mtx);
 740
 741         /* busy scanning */
 742         if (local->scan_req)
 743                 goto unlock;
 744
 745         /* fill internal scan request */
 746         if (!chan) {
 747                 int i, nchan = 0;
 748
 749                 for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
 750                         if (!local->hw.wiphy->bands[band])
 751                                 continue;
 752                         for (i = 0;
 753                              i < local->hw.wiphy->bands[band]->n_channels;
 754                              i++) {
 755                                 local->int_scan_req->channels[nchan] =
 756                                     &local->hw.wiphy->bands[band]->channels[i];
 757                                 nchan++;
 758                         }
 759                 }
 760
 761                 local->int_scan_req->n_channels = nchan;
 762         } else {
 763                 local->int_scan_req->channels[0] = chan;
 764                 local->int_scan_req->n_channels = 1;
 765         }
 766
 767         local->int_scan_req->ssids = &local->scan_ssid;
 768         local->int_scan_req->n_ssids = 1;
 769         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 770         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 771
 772         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 773  unlock:
 774         mutex_unlock(&local->mtx);
 775         return ret;
 776 }
 777
 778 /*
 779  * Only call this function when a scan can't be queued -- under RTNL.
 780  */
 781 void ieee80211_scan_cancel(struct ieee80211_local *local)
 782 {
 783         /*
 784          * We are canceling software scan, or deferred scan that was not
 785          * yet really started (see __ieee80211_start_scan ).
 786          *
 787          * Regarding hardware scan:
 788          * - we can not call  __ieee80211_scan_completed() as when
 789          *   SCAN_HW_SCANNING bit is set this function change
 790          *   local->hw_scan_req to operate on 5G band, what race with
 791          *   driver which can use local->hw_scan_req
 792          *
 793          * - we can not cancel scan_work since driver can schedule it
 794          *   by ieee80211_scan_completed(..., true) to finish scan
 795          *
 796          * Hence we only call the cancel_hw_scan() callback, but the low-level
 797          * driver is still responsible for calling ieee80211_scan_completed()
 798          * after the scan was completed/aborted.
 799          */
 800
 801         mutex_lock(&local->mtx);
 802         if (!local->scan_req)
 803                 goto out;
 804
 805         if (test_bit(SCAN_HW_SCANNING, &local->scanning)) {
 806                 if (local->ops->cancel_hw_scan)
 807                         drv_cancel_hw_scan(local, local->scan_sdata);
 808                 goto out;
 809         }
 810
 811         /*
 812          * If the work is currently running, it must be blocked on
 813          * the mutex, but we'll set scan_sdata = NULL and it'll
 814          * simply exit once it acquires the mutex.
 815          */
 816         cancel_delayed_work(&local->scan_work);
 817         /* and clean up */
 818         __ieee80211_scan_completed(&local->hw, true, false);
 819 out:
 820         mutex_unlock(&local->mtx);
 821 }
 822
 823 int ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
 824                                        struct cfg80211_sched_scan_request *req)
 825 {
 826         struct ieee80211_local *local = sdata->local;
 827         int ret, i;
 828
 829         mutex_lock(&sdata->local->mtx);
 830
 831         if (local->sched_scanning) {
 832                 ret = -EBUSY;
 833                 goto out;
 834         }
 835
 836         if (!local->ops->sched_scan_start) {
 837                 ret = -ENOTSUPP;
 838                 goto out;
 839         }
 840
 841         for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
 842                 local->sched_scan_ies.ie[i] = kzalloc(2 +
 843                                                       IEEE80211_MAX_SSID_LEN +
 844                                                       local->scan_ies_len +
 845                                                       req->ie_len,
 846                                                       GFP_KERNEL);
 847                 if (!local->sched_scan_ies.ie[i]) {
 848                         ret = -ENOMEM;
 849                         goto out_free;
 850                 }
 851
 852                 local->sched_scan_ies.len[i] =
 853                         ieee80211_build_preq_ies(local,
 854                                                  local->sched_scan_ies.ie[i],
 855                                                  req->ie, req->ie_len, i,
 856                                                  (u32) -1, 0);
 857         }
 858
 859         ret = drv_sched_scan_start(local, sdata, req,
 860                                    &local->sched_scan_ies);
 861         if (ret == 0) {
 862                 local->sched_scanning = true;
 863                 goto out;
 864         }
 865
 866 out_free:
 867         while (i > 0)
 868                 kfree(local->sched_scan_ies.ie[--i]);
 869 out:
 870         mutex_unlock(&sdata->local->mtx);
 871         return ret;
 872 }
 873
 874 int ieee80211_request_sched_scan_stop(struct ieee80211_sub_if_data *sdata)
 875 {
 876         struct ieee80211_local *local = sdata->local;
 877         int ret = 0, i;
 878
 879         mutex_lock(&sdata->local->mtx);
 880
 881         if (!local->ops->sched_scan_stop) {
 882                 ret = -ENOTSUPP;
 883                 goto out;
 884         }
 885
 886         if (local->sched_scanning) {
 887                 for (i = 0; i < IEEE80211_NUM_BANDS; i++)
 888                         kfree(local->sched_scan_ies.ie[i]);
 889
 890                 drv_sched_scan_stop(local, sdata);
 891                 local->sched_scanning = false;
 892         }
 893 out:
 894         mutex_unlock(&sdata->local->mtx);
 895
 896         return ret;
 897 }
 898
 899 void ieee80211_sched_scan_results(struct ieee80211_hw *hw)
 900 {
 901         struct ieee80211_local *local = hw_to_local(hw);
 902
 903         trace_api_sched_scan_results(local);
 904
 905         cfg80211_sched_scan_results(hw->wiphy);
 906 }
 907 EXPORT_SYMBOL(ieee80211_sched_scan_results);
 908
 909 void ieee80211_sched_scan_stopped_work(struct work_struct *work)
 910 {
 911         struct ieee80211_local *local =
 912                 container_of(work, struct ieee80211_local,
 913                              sched_scan_stopped_work);
 914         int i;
 915
 916         mutex_lock(&local->mtx);
 917
 918         if (!local->sched_scanning) {
 919                 mutex_unlock(&local->mtx);
 920                 return;
 921         }
 922
 923         for (i = 0; i < IEEE80211_NUM_BANDS; i++)
 924                 kfree(local->sched_scan_ies.ie[i]);
 925
 926         local->sched_scanning = false;
 927
 928         mutex_unlock(&local->mtx);
 929
 930         cfg80211_sched_scan_stopped(local->hw.wiphy);
 931 }
 932
 933 void ieee80211_sched_scan_stopped(struct ieee80211_hw *hw)
 934 {
 935         struct ieee80211_local *local = hw_to_local(hw);
 936
 937         trace_api_sched_scan_stopped(local);
 938
 939         ieee80211_queue_work(&local->hw, &local->sched_scan_stopped_work);
 940 }
 941 EXPORT_SYMBOL(ieee80211_sched_scan_stopped);