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_params.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_DROP_MONITOR;
 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         else
 201                 freq = rx_status->freq;
 202
 203         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
 204
 205         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 206                 return RX_DROP_MONITOR;
 207
 208         bss = ieee80211_bss_info_update(sdata->local, rx_status,
 209                                         mgmt, skb->len, &elems,
 210                                         channel, beacon);
 211         if (bss)
 212                 ieee80211_rx_bss_put(sdata->local, bss);
 213
 214         dev_kfree_skb(skb);
 215         return RX_QUEUED;
 216 }
 217
 218 /* return false if no more work */
 219 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 220 {
 221         struct cfg80211_scan_request *req = local->scan_req;
 222         enum ieee80211_band band;
 223         int i, ielen, n_chans;
 224
 225         do {
 226                 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
 227                         return false;
 228
 229                 band = local->hw_scan_band;
 230                 n_chans = 0;
 231                 for (i = 0; i < req->n_channels; i++) {
 232                         if (req->channels[i]->band == band) {
 233                                 local->hw_scan_req->channels[n_chans] =
 234                                                         req->channels[i];
 235                                 n_chans++;
 236                         }
 237                 }
 238
 239                 local->hw_scan_band++;
 240         } while (!n_chans);
 241
 242         local->hw_scan_req->n_channels = n_chans;
 243
 244         ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
 245                                          req->ie, req->ie_len, band, (u32) -1,
 246                                          0);
 247         local->hw_scan_req->ie_len = ielen;
 248
 249         return true;
 250 }
 251
 252 static bool __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted,
 253                                        bool was_hw_scan)
 254 {
 255         struct ieee80211_local *local = hw_to_local(hw);
 256
 257         lockdep_assert_held(&local->mtx);
 258
 259         /*
 260          * It's ok to abort a not-yet-running scan (that
 261          * we have one at all will be verified by checking
 262          * local->scan_req next), but not to complete it
 263          * successfully.
 264          */
 265         if (WARN_ON(!local->scanning && !aborted))
 266                 aborted = true;
 267
 268         if (WARN_ON(!local->scan_req))
 269                 return false;
 270
 271         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 272                 int rc = drv_hw_scan(local, local->scan_sdata, local->hw_scan_req);
 273                 if (rc == 0)
 274                         return false;
 275         }
 276
 277         kfree(local->hw_scan_req);
 278         local->hw_scan_req = NULL;
 279
 280         if (local->scan_req != local->int_scan_req)
 281                 cfg80211_scan_done(local->scan_req, aborted);
 282         local->scan_req = NULL;
 283         local->scan_sdata = NULL;
 284
 285         local->scanning = 0;
 286         local->scan_channel = NULL;
 287
 288         return true;
 289 }
 290
 291 static void __ieee80211_scan_completed_finish(struct ieee80211_hw *hw,
 292                                               bool was_hw_scan)
 293 {
 294         struct ieee80211_local *local = hw_to_local(hw);
 295
 296         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 297         if (!was_hw_scan) {
 298                 ieee80211_configure_filter(local);
 299                 drv_sw_scan_complete(local);
 300                 ieee80211_offchannel_return(local, true);
 301         }
 302
 303         mutex_lock(&local->mtx);
 304         ieee80211_recalc_idle(local);
 305         mutex_unlock(&local->mtx);
 306
 307         ieee80211_mlme_notify_scan_completed(local);
 308         ieee80211_ibss_notify_scan_completed(local);
 309         ieee80211_mesh_notify_scan_completed(local);
 310         ieee80211_queue_work(&local->hw, &local->work_work);
 311 }
 312
 313 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 314 {
 315         struct ieee80211_local *local = hw_to_local(hw);
 316
 317         trace_api_scan_completed(local, aborted);
 318
 319         set_bit(SCAN_COMPLETED, &local->scanning);
 320         if (aborted)
 321                 set_bit(SCAN_ABORTED, &local->scanning);
 322         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, 0);
 323 }
 324 EXPORT_SYMBOL(ieee80211_scan_completed);
 325
 326 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 327 {
 328         /*
 329          * Hardware/driver doesn't support hw_scan, so use software
 330          * scanning instead. First send a nullfunc frame with power save
 331          * bit on so that AP will buffer the frames for us while we are not
 332          * listening, then send probe requests to each channel and wait for
 333          * the responses. After all channels are scanned, tune back to the
 334          * original channel and send a nullfunc frame with power save bit
 335          * off to trigger the AP to send us all the buffered frames.
 336          *
 337          * Note that while local->sw_scanning is true everything else but
 338          * nullfunc frames and probe requests will be dropped in
 339          * ieee80211_tx_h_check_assoc().
 340          */
 341         drv_sw_scan_start(local);
 342
 343         ieee80211_offchannel_stop_beaconing(local);
 344
 345         local->leave_oper_channel_time = 0;
 346         local->next_scan_state = SCAN_DECISION;
 347         local->scan_channel_idx = 0;
 348
 349         drv_flush(local, false);
 350
 351         ieee80211_configure_filter(local);
 352
 353         ieee80211_queue_delayed_work(&local->hw,
 354                                      &local->scan_work,
 355                                      IEEE80211_CHANNEL_TIME);
 356
 357         return 0;
 358 }
 359
 360
 361 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 362                                   struct cfg80211_scan_request *req)
 363 {
 364         struct ieee80211_local *local = sdata->local;
 365         int rc;
 366
 367         lockdep_assert_held(&local->mtx);
 368
 369         if (local->scan_req)
 370                 return -EBUSY;
 371
 372         if (!list_empty(&local->work_list)) {
 373                 /* wait for the work to finish/time out */
 374                 local->scan_req = req;
 375                 local->scan_sdata = sdata;
 376                 return 0;
 377         }
 378
 379         if (local->ops->hw_scan) {
 380                 u8 *ies;
 381
 382                 local->hw_scan_req = kmalloc(
 383                                 sizeof(*local->hw_scan_req) +
 384                                 req->n_channels * sizeof(req->channels[0]) +
 385                                 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
 386                                 req->ie_len, GFP_KERNEL);
 387                 if (!local->hw_scan_req)
 388                         return -ENOMEM;
 389
 390                 local->hw_scan_req->ssids = req->ssids;
 391                 local->hw_scan_req->n_ssids = req->n_ssids;
 392                 ies = (u8 *)local->hw_scan_req +
 393                         sizeof(*local->hw_scan_req) +
 394                         req->n_channels * sizeof(req->channels[0]);
 395                 local->hw_scan_req->ie = ies;
 396
 397                 local->hw_scan_band = 0;
 398
 399                 /*
 400                  * After allocating local->hw_scan_req, we must
 401                  * go through until ieee80211_prep_hw_scan(), so
 402                  * anything that might be changed here and leave
 403                  * this function early must not go after this
 404                  * allocation.
 405                  */
 406         }
 407
 408         local->scan_req = req;
 409         local->scan_sdata = sdata;
 410
 411         if (local->ops->hw_scan)
 412                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 413         else
 414                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 415
 416         ieee80211_recalc_idle(local);
 417
 418         if (local->ops->hw_scan) {
 419                 WARN_ON(!ieee80211_prep_hw_scan(local));
 420                 rc = drv_hw_scan(local, sdata, local->hw_scan_req);
 421         } else
 422                 rc = ieee80211_start_sw_scan(local);
 423
 424         if (rc) {
 425                 kfree(local->hw_scan_req);
 426                 local->hw_scan_req = NULL;
 427                 local->scanning = 0;
 428
 429                 ieee80211_recalc_idle(local);
 430
 431                 local->scan_req = NULL;
 432                 local->scan_sdata = NULL;
 433         }
 434
 435         return rc;
 436 }
 437
 438 static unsigned long
 439 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
 440 {
 441         /*
 442          * TODO: channel switching also consumes quite some time,
 443          * add that delay as well to get a better estimation
 444          */
 445         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN)
 446                 return IEEE80211_PASSIVE_CHANNEL_TIME;
 447         return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
 448 }
 449
 450 static void ieee80211_scan_state_decision(struct ieee80211_local *local,
 451                                           unsigned long *next_delay)
 452 {
 453         bool associated = false;
 454         bool tx_empty = true;
 455         bool bad_latency;
 456         bool listen_int_exceeded;
 457         unsigned long min_beacon_int = 0;
 458         struct ieee80211_sub_if_data *sdata;
 459         struct ieee80211_channel *next_chan;
 460
 461         /*
 462          * check if at least one STA interface is associated,
 463          * check if at least one STA interface has pending tx frames
 464          * and grab the lowest used beacon interval
 465          */
 466         mutex_lock(&local->iflist_mtx);
 467         list_for_each_entry(sdata, &local->interfaces, list) {
 468                 if (!ieee80211_sdata_running(sdata))
 469                         continue;
 470
 471                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 472                         if (sdata->u.mgd.associated) {
 473                                 associated = true;
 474
 475                                 if (sdata->vif.bss_conf.beacon_int <
 476                                     min_beacon_int || min_beacon_int == 0)
 477                                         min_beacon_int =
 478                                                 sdata->vif.bss_conf.beacon_int;
 479
 480                                 if (!qdisc_all_tx_empty(sdata->dev)) {
 481                                         tx_empty = false;
 482                                         break;
 483                                 }
 484                         }
 485                 }
 486         }
 487         mutex_unlock(&local->iflist_mtx);
 488
 489         if (local->scan_channel) {
 490                 /*
 491                  * we're currently scanning a different channel, let's
 492                  * see if we can scan another channel without interfering
 493                  * with the current traffic situation.
 494                  *
 495                  * Since we don't know if the AP has pending frames for us
 496                  * we can only check for our tx queues and use the current
 497                  * pm_qos requirements for rx. Hence, if no tx traffic occurs
 498                  * at all we will scan as many channels in a row as the pm_qos
 499                  * latency allows us to. Additionally we also check for the
 500                  * currently negotiated listen interval to prevent losing
 501                  * frames unnecessarily.
 502                  *
 503                  * Otherwise switch back to the operating channel.
 504                  */
 505                 next_chan = local->scan_req->channels[local->scan_channel_idx];
 506
 507                 bad_latency = time_after(jiffies +
 508                                 ieee80211_scan_get_channel_time(next_chan),
 509                                 local->leave_oper_channel_time +
 510                                 usecs_to_jiffies(pm_qos_request(PM_QOS_NETWORK_LATENCY)));
 511
 512                 listen_int_exceeded = time_after(jiffies +
 513                                 ieee80211_scan_get_channel_time(next_chan),
 514                                 local->leave_oper_channel_time +
 515                                 usecs_to_jiffies(min_beacon_int * 1024) *
 516                                 local->hw.conf.listen_interval);
 517
 518                 if (associated && ( !tx_empty || bad_latency ||
 519                     listen_int_exceeded))
 520                         local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
 521                 else
 522                         local->next_scan_state = SCAN_SET_CHANNEL;
 523         } else {
 524                 /*
 525                  * we're on the operating channel currently, let's
 526                  * leave that channel now to scan another one
 527                  */
 528                 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
 529         }
 530
 531         *next_delay = 0;
 532 }
 533
 534 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
 535                                                     unsigned long *next_delay)
 536 {
 537         ieee80211_offchannel_stop_station(local);
 538
 539         __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
 540
 541         /*
 542          * What if the nullfunc frames didn't arrive?
 543          */
 544         drv_flush(local, false);
 545         if (local->ops->flush)
 546                 *next_delay = 0;
 547         else
 548                 *next_delay = HZ / 10;
 549
 550         /* remember when we left the operating channel */
 551         local->leave_oper_channel_time = jiffies;
 552
 553         /* advance to the next channel to be scanned */
 554         local->next_scan_state = SCAN_SET_CHANNEL;
 555 }
 556
 557 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
 558                                                     unsigned long *next_delay)
 559 {
 560         /* switch back to the operating channel */
 561         local->scan_channel = NULL;
 562         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 563
 564         /*
 565          * Only re-enable station mode interface now; beaconing will be
 566          * re-enabled once the full scan has been completed.
 567          */
 568         ieee80211_offchannel_return(local, false);
 569
 570         __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
 571
 572         *next_delay = HZ / 5;
 573         local->next_scan_state = SCAN_DECISION;
 574 }
 575
 576 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 577                                              unsigned long *next_delay)
 578 {
 579         int skip;
 580         struct ieee80211_channel *chan;
 581
 582         skip = 0;
 583         chan = local->scan_req->channels[local->scan_channel_idx];
 584
 585         local->scan_channel = chan;
 586         if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 587                 skip = 1;
 588
 589         /* advance state machine to next channel/band */
 590         local->scan_channel_idx++;
 591
 592         if (skip) {
 593                 /* if we skip this channel return to the decision state */
 594                 local->next_scan_state = SCAN_DECISION;
 595                 return;
 596         }
 597
 598         /*
 599          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 600          * (which unfortunately doesn't say _why_ step a) is done,
 601          * but it waits for the probe delay or until a frame is
 602          * received - and the received frame would update the NAV).
 603          * For now, we do not support waiting until a frame is
 604          * received.
 605          *
 606          * In any case, it is not necessary for a passive scan.
 607          */
 608         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 609             !local->scan_req->n_ssids) {
 610                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 611                 local->next_scan_state = SCAN_DECISION;
 612                 return;
 613         }
 614
 615         /* active scan, send probes */
 616         *next_delay = IEEE80211_PROBE_DELAY;
 617         local->next_scan_state = SCAN_SEND_PROBE;
 618 }
 619
 620 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 621                                             unsigned long *next_delay)
 622 {
 623         int i;
 624         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 625
 626         for (i = 0; i < local->scan_req->n_ssids; i++)
 627                 ieee80211_send_probe_req(
 628                         sdata, NULL,
 629                         local->scan_req->ssids[i].ssid,
 630                         local->scan_req->ssids[i].ssid_len,
 631                         local->scan_req->ie, local->scan_req->ie_len);
 632
 633         /*
 634          * After sending probe requests, wait for probe responses
 635          * on the channel.
 636          */
 637         *next_delay = IEEE80211_CHANNEL_TIME;
 638         local->next_scan_state = SCAN_DECISION;
 639 }
 640
 641 void ieee80211_scan_work(struct work_struct *work)
 642 {
 643         struct ieee80211_local *local =
 644                 container_of(work, struct ieee80211_local, scan_work.work);
 645         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 646         unsigned long next_delay = 0;
 647         bool aborted, hw_scan, finish;
 648
 649         mutex_lock(&local->mtx);
 650
 651         if (test_and_clear_bit(SCAN_COMPLETED, &local->scanning)) {
 652                 aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
 653                 goto out_complete;
 654         }
 655
 656         if (!sdata || !local->scan_req)
 657                 goto out;
 658
 659         if (local->scan_req && !local->scanning) {
 660                 struct cfg80211_scan_request *req = local->scan_req;
 661                 int rc;
 662
 663                 local->scan_req = NULL;
 664                 local->scan_sdata = NULL;
 665
 666                 rc = __ieee80211_start_scan(sdata, req);
 667                 if (rc) {
 668                         /* need to complete scan in cfg80211 */
 669                         local->scan_req = req;
 670                         aborted = true;
 671                         goto out_complete;
 672                 } else
 673                         goto out;
 674         }
 675
 676         /*
 677          * Avoid re-scheduling when the sdata is going away.
 678          */
 679         if (!ieee80211_sdata_running(sdata)) {
 680                 aborted = true;
 681                 goto out_complete;
 682         }
 683
 684         /*
 685          * as long as no delay is required advance immediately
 686          * without scheduling a new work
 687          */
 688         do {
 689                 switch (local->next_scan_state) {
 690                 case SCAN_DECISION:
 691                         /* if no more bands/channels left, complete scan */
 692                         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 693                                 aborted = false;
 694                                 goto out_complete;
 695                         }
 696                         ieee80211_scan_state_decision(local, &next_delay);
 697                         break;
 698                 case SCAN_SET_CHANNEL:
 699                         ieee80211_scan_state_set_channel(local, &next_delay);
 700                         break;
 701                 case SCAN_SEND_PROBE:
 702                         ieee80211_scan_state_send_probe(local, &next_delay);
 703                         break;
 704                 case SCAN_LEAVE_OPER_CHANNEL:
 705                         ieee80211_scan_state_leave_oper_channel(local, &next_delay);
 706                         break;
 707                 case SCAN_ENTER_OPER_CHANNEL:
 708                         ieee80211_scan_state_enter_oper_channel(local, &next_delay);
 709                         break;
 710                 }
 711         } while (next_delay == 0);
 712
 713         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
 714         mutex_unlock(&local->mtx);
 715         return;
 716
 717 out_complete:
 718         hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 719         finish = __ieee80211_scan_completed(&local->hw, aborted, hw_scan);
 720         mutex_unlock(&local->mtx);
 721         if (finish)
 722                 __ieee80211_scan_completed_finish(&local->hw, hw_scan);
 723         return;
 724
 725 out:
 726         mutex_unlock(&local->mtx);
 727 }
 728
 729 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 730                            struct cfg80211_scan_request *req)
 731 {
 732         int res;
 733
 734         mutex_lock(&sdata->local->mtx);
 735         res = __ieee80211_start_scan(sdata, req);
 736         mutex_unlock(&sdata->local->mtx);
 737
 738         return res;
 739 }
 740
 741 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 742                                     const u8 *ssid, u8 ssid_len,
 743                                     struct ieee80211_channel *chan)
 744 {
 745         struct ieee80211_local *local = sdata->local;
 746         int ret = -EBUSY;
 747         enum ieee80211_band band;
 748
 749         mutex_lock(&local->mtx);
 750
 751         /* busy scanning */
 752         if (local->scan_req)
 753                 goto unlock;
 754
 755         /* fill internal scan request */
 756         if (!chan) {
 757                 int i, nchan = 0;
 758
 759                 for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
 760                         if (!local->hw.wiphy->bands[band])
 761                                 continue;
 762                         for (i = 0;
 763                              i < local->hw.wiphy->bands[band]->n_channels;
 764                              i++) {
 765                                 local->int_scan_req->channels[nchan] =
 766                                     &local->hw.wiphy->bands[band]->channels[i];
 767                                 nchan++;
 768                         }
 769                 }
 770
 771                 local->int_scan_req->n_channels = nchan;
 772         } else {
 773                 local->int_scan_req->channels[0] = chan;
 774                 local->int_scan_req->n_channels = 1;
 775         }
 776
 777         local->int_scan_req->ssids = &local->scan_ssid;
 778         local->int_scan_req->n_ssids = 1;
 779         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 780         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 781
 782         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 783  unlock:
 784         mutex_unlock(&local->mtx);
 785         return ret;
 786 }
 787
 788 /*
 789  * Only call this function when a scan can't be queued -- under RTNL.
 790  */
 791 void ieee80211_scan_cancel(struct ieee80211_local *local)
 792 {
 793         bool abortscan;
 794         bool finish = false;
 795
 796         /*
 797          * We are only canceling software scan, or deferred scan that was not
 798          * yet really started (see __ieee80211_start_scan ).
 799          *
 800          * Regarding hardware scan:
 801          * - we can not call  __ieee80211_scan_completed() as when
 802          *   SCAN_HW_SCANNING bit is set this function change
 803          *   local->hw_scan_req to operate on 5G band, what race with
 804          *   driver which can use local->hw_scan_req
 805          *
 806          * - we can not cancel scan_work since driver can schedule it
 807          *   by ieee80211_scan_completed(..., true) to finish scan
 808          *
 809          * Hence low lever driver is responsible for canceling HW scan.
 810          */
 811
 812         mutex_lock(&local->mtx);
 813         abortscan = local->scan_req && !test_bit(SCAN_HW_SCANNING, &local->scanning);
 814         if (abortscan)
 815                 finish = __ieee80211_scan_completed(&local->hw, true, false);
 816         mutex_unlock(&local->mtx);
 817
 818         if (abortscan) {
 819                 /* The scan is canceled, but stop work from being pending */
 820                 cancel_delayed_work_sync(&local->scan_work);
 821         }
 822         if (finish)
 823                 __ieee80211_scan_completed_finish(&local->hw, false);
 824 }