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                                                       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         dev_kfree_skb(skb);
 216         return RX_QUEUED;
 217 }
 218
 219 /* return false if no more work */
 220 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 221 {
 222         struct cfg80211_scan_request *req = local->scan_req;
 223         enum ieee80211_band band;
 224         int i, ielen, n_chans;
 225
 226         do {
 227                 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
 228                         return false;
 229
 230                 band = local->hw_scan_band;
 231                 n_chans = 0;
 232                 for (i = 0; i < req->n_channels; i++) {
 233                         if (req->channels[i]->band == band) {
 234                                 local->hw_scan_req->channels[n_chans] =
 235                                                         req->channels[i];
 236                                 n_chans++;
 237                         }
 238                 }
 239
 240                 local->hw_scan_band++;
 241         } while (!n_chans);
 242
 243         local->hw_scan_req->n_channels = n_chans;
 244
 245         ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
 246                                          req->ie, req->ie_len, band, (u32) -1,
 247                                          0);
 248         local->hw_scan_req->ie_len = ielen;
 249
 250         return true;
 251 }
 252
 253 static bool __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted,
 254                                        bool was_hw_scan)
 255 {
 256         struct ieee80211_local *local = hw_to_local(hw);
 257
 258         lockdep_assert_held(&local->mtx);
 259
 260         /*
 261          * It's ok to abort a not-yet-running scan (that
 262          * we have one at all will be verified by checking
 263          * local->scan_req next), but not to complete it
 264          * successfully.
 265          */
 266         if (WARN_ON(!local->scanning && !aborted))
 267                 aborted = true;
 268
 269         if (WARN_ON(!local->scan_req))
 270                 return false;
 271
 272         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 273                 int rc = drv_hw_scan(local, local->scan_sdata, local->hw_scan_req);
 274                 if (rc == 0)
 275                         return false;
 276         }
 277
 278         kfree(local->hw_scan_req);
 279         local->hw_scan_req = NULL;
 280
 281         if (local->scan_req != local->int_scan_req)
 282                 cfg80211_scan_done(local->scan_req, aborted);
 283         local->scan_req = NULL;
 284         local->scan_sdata = NULL;
 285
 286         local->scanning = 0;
 287         local->scan_channel = NULL;
 288
 289         return true;
 290 }
 291
 292 static void __ieee80211_scan_completed_finish(struct ieee80211_hw *hw,
 293                                               bool was_hw_scan)
 294 {
 295         struct ieee80211_local *local = hw_to_local(hw);
 296
 297         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 298         if (!was_hw_scan) {
 299                 ieee80211_configure_filter(local);
 300                 drv_sw_scan_complete(local);
 301                 ieee80211_offchannel_return(local, true);
 302         }
 303
 304         mutex_lock(&local->mtx);
 305         ieee80211_recalc_idle(local);
 306         mutex_unlock(&local->mtx);
 307
 308         ieee80211_mlme_notify_scan_completed(local);
 309         ieee80211_ibss_notify_scan_completed(local);
 310         ieee80211_mesh_notify_scan_completed(local);
 311         ieee80211_queue_work(&local->hw, &local->work_work);
 312 }
 313
 314 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 315 {
 316         struct ieee80211_local *local = hw_to_local(hw);
 317
 318         trace_api_scan_completed(local, aborted);
 319
 320         set_bit(SCAN_COMPLETED, &local->scanning);
 321         if (aborted)
 322                 set_bit(SCAN_ABORTED, &local->scanning);
 323         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, 0);
 324 }
 325 EXPORT_SYMBOL(ieee80211_scan_completed);
 326
 327 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 328 {
 329         /*
 330          * Hardware/driver doesn't support hw_scan, so use software
 331          * scanning instead. First send a nullfunc frame with power save
 332          * bit on so that AP will buffer the frames for us while we are not
 333          * listening, then send probe requests to each channel and wait for
 334          * the responses. After all channels are scanned, tune back to the
 335          * original channel and send a nullfunc frame with power save bit
 336          * off to trigger the AP to send us all the buffered frames.
 337          *
 338          * Note that while local->sw_scanning is true everything else but
 339          * nullfunc frames and probe requests will be dropped in
 340          * ieee80211_tx_h_check_assoc().
 341          */
 342         drv_sw_scan_start(local);
 343
 344         ieee80211_offchannel_stop_beaconing(local);
 345
 346         local->leave_oper_channel_time = 0;
 347         local->next_scan_state = SCAN_DECISION;
 348         local->scan_channel_idx = 0;
 349
 350         drv_flush(local, false);
 351
 352         ieee80211_configure_filter(local);
 353
 354         ieee80211_queue_delayed_work(&local->hw,
 355                                      &local->scan_work,
 356                                      IEEE80211_CHANNEL_TIME);
 357
 358         return 0;
 359 }
 360
 361
 362 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 363                                   struct cfg80211_scan_request *req)
 364 {
 365         struct ieee80211_local *local = sdata->local;
 366         int rc;
 367
 368         lockdep_assert_held(&local->mtx);
 369
 370         if (local->scan_req)
 371                 return -EBUSY;
 372
 373         if (!list_empty(&local->work_list)) {
 374                 /* wait for the work to finish/time out */
 375                 local->scan_req = req;
 376                 local->scan_sdata = sdata;
 377                 return 0;
 378         }
 379
 380         if (local->ops->hw_scan) {
 381                 u8 *ies;
 382
 383                 local->hw_scan_req = kmalloc(
 384                                 sizeof(*local->hw_scan_req) +
 385                                 req->n_channels * sizeof(req->channels[0]) +
 386                                 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
 387                                 req->ie_len, GFP_KERNEL);
 388                 if (!local->hw_scan_req)
 389                         return -ENOMEM;
 390
 391                 local->hw_scan_req->ssids = req->ssids;
 392                 local->hw_scan_req->n_ssids = req->n_ssids;
 393                 ies = (u8 *)local->hw_scan_req +
 394                         sizeof(*local->hw_scan_req) +
 395                         req->n_channels * sizeof(req->channels[0]);
 396                 local->hw_scan_req->ie = ies;
 397
 398                 local->hw_scan_band = 0;
 399
 400                 /*
 401                  * After allocating local->hw_scan_req, we must
 402                  * go through until ieee80211_prep_hw_scan(), so
 403                  * anything that might be changed here and leave
 404                  * this function early must not go after this
 405                  * allocation.
 406                  */
 407         }
 408
 409         local->scan_req = req;
 410         local->scan_sdata = sdata;
 411
 412         if (local->ops->hw_scan)
 413                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 414         else
 415                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 416
 417         ieee80211_recalc_idle(local);
 418
 419         if (local->ops->hw_scan) {
 420                 WARN_ON(!ieee80211_prep_hw_scan(local));
 421                 rc = drv_hw_scan(local, sdata, local->hw_scan_req);
 422         } else
 423                 rc = ieee80211_start_sw_scan(local);
 424
 425         if (rc) {
 426                 kfree(local->hw_scan_req);
 427                 local->hw_scan_req = NULL;
 428                 local->scanning = 0;
 429
 430                 ieee80211_recalc_idle(local);
 431
 432                 local->scan_req = NULL;
 433                 local->scan_sdata = NULL;
 434         }
 435
 436         return rc;
 437 }
 438
 439 static unsigned long
 440 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
 441 {
 442         /*
 443          * TODO: channel switching also consumes quite some time,
 444          * add that delay as well to get a better estimation
 445          */
 446         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN)
 447                 return IEEE80211_PASSIVE_CHANNEL_TIME;
 448         return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
 449 }
 450
 451 static void ieee80211_scan_state_decision(struct ieee80211_local *local,
 452                                           unsigned long *next_delay)
 453 {
 454         bool associated = false;
 455         bool tx_empty = true;
 456         bool bad_latency;
 457         bool listen_int_exceeded;
 458         unsigned long min_beacon_int = 0;
 459         struct ieee80211_sub_if_data *sdata;
 460         struct ieee80211_channel *next_chan;
 461
 462         /*
 463          * check if at least one STA interface is associated,
 464          * check if at least one STA interface has pending tx frames
 465          * and grab the lowest used beacon interval
 466          */
 467         mutex_lock(&local->iflist_mtx);
 468         list_for_each_entry(sdata, &local->interfaces, list) {
 469                 if (!ieee80211_sdata_running(sdata))
 470                         continue;
 471
 472                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 473                         if (sdata->u.mgd.associated) {
 474                                 associated = true;
 475
 476                                 if (sdata->vif.bss_conf.beacon_int <
 477                                     min_beacon_int || min_beacon_int == 0)
 478                                         min_beacon_int =
 479                                                 sdata->vif.bss_conf.beacon_int;
 480
 481                                 if (!qdisc_all_tx_empty(sdata->dev)) {
 482                                         tx_empty = false;
 483                                         break;
 484                                 }
 485                         }
 486                 }
 487         }
 488         mutex_unlock(&local->iflist_mtx);
 489
 490         if (local->scan_channel) {
 491                 /*
 492                  * we're currently scanning a different channel, let's
 493                  * see if we can scan another channel without interfering
 494                  * with the current traffic situation.
 495                  *
 496                  * Since we don't know if the AP has pending frames for us
 497                  * we can only check for our tx queues and use the current
 498                  * pm_qos requirements for rx. Hence, if no tx traffic occurs
 499                  * at all we will scan as many channels in a row as the pm_qos
 500                  * latency allows us to. Additionally we also check for the
 501                  * currently negotiated listen interval to prevent losing
 502                  * frames unnecessarily.
 503                  *
 504                  * Otherwise switch back to the operating channel.
 505                  */
 506                 next_chan = local->scan_req->channels[local->scan_channel_idx];
 507
 508                 bad_latency = time_after(jiffies +
 509                                 ieee80211_scan_get_channel_time(next_chan),
 510                                 local->leave_oper_channel_time +
 511                                 usecs_to_jiffies(pm_qos_request(PM_QOS_NETWORK_LATENCY)));
 512
 513                 listen_int_exceeded = time_after(jiffies +
 514                                 ieee80211_scan_get_channel_time(next_chan),
 515                                 local->leave_oper_channel_time +
 516                                 usecs_to_jiffies(min_beacon_int * 1024) *
 517                                 local->hw.conf.listen_interval);
 518
 519                 if (associated && ( !tx_empty || bad_latency ||
 520                     listen_int_exceeded))
 521                         local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
 522                 else
 523                         local->next_scan_state = SCAN_SET_CHANNEL;
 524         } else {
 525                 /*
 526                  * we're on the operating channel currently, let's
 527                  * leave that channel now to scan another one
 528                  */
 529                 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
 530         }
 531
 532         *next_delay = 0;
 533 }
 534
 535 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
 536                                                     unsigned long *next_delay)
 537 {
 538         ieee80211_offchannel_stop_station(local);
 539
 540         __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
 541
 542         /*
 543          * What if the nullfunc frames didn't arrive?
 544          */
 545         drv_flush(local, false);
 546         if (local->ops->flush)
 547                 *next_delay = 0;
 548         else
 549                 *next_delay = HZ / 10;
 550
 551         /* remember when we left the operating channel */
 552         local->leave_oper_channel_time = jiffies;
 553
 554         /* advance to the next channel to be scanned */
 555         local->next_scan_state = SCAN_SET_CHANNEL;
 556 }
 557
 558 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
 559                                                     unsigned long *next_delay)
 560 {
 561         /* switch back to the operating channel */
 562         local->scan_channel = NULL;
 563         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 564
 565         /*
 566          * Only re-enable station mode interface now; beaconing will be
 567          * re-enabled once the full scan has been completed.
 568          */
 569         ieee80211_offchannel_return(local, false);
 570
 571         __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
 572
 573         *next_delay = HZ / 5;
 574         local->next_scan_state = SCAN_DECISION;
 575 }
 576
 577 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 578                                              unsigned long *next_delay)
 579 {
 580         int skip;
 581         struct ieee80211_channel *chan;
 582
 583         skip = 0;
 584         chan = local->scan_req->channels[local->scan_channel_idx];
 585
 586         local->scan_channel = chan;
 587         if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 588                 skip = 1;
 589
 590         /* advance state machine to next channel/band */
 591         local->scan_channel_idx++;
 592
 593         if (skip) {
 594                 /* if we skip this channel return to the decision state */
 595                 local->next_scan_state = SCAN_DECISION;
 596                 return;
 597         }
 598
 599         /*
 600          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 601          * (which unfortunately doesn't say _why_ step a) is done,
 602          * but it waits for the probe delay or until a frame is
 603          * received - and the received frame would update the NAV).
 604          * For now, we do not support waiting until a frame is
 605          * received.
 606          *
 607          * In any case, it is not necessary for a passive scan.
 608          */
 609         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 610             !local->scan_req->n_ssids) {
 611                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 612                 local->next_scan_state = SCAN_DECISION;
 613                 return;
 614         }
 615
 616         /* active scan, send probes */
 617         *next_delay = IEEE80211_PROBE_DELAY;
 618         local->next_scan_state = SCAN_SEND_PROBE;
 619 }
 620
 621 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 622                                             unsigned long *next_delay)
 623 {
 624         int i;
 625         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 626
 627         for (i = 0; i < local->scan_req->n_ssids; i++)
 628                 ieee80211_send_probe_req(
 629                         sdata, NULL,
 630                         local->scan_req->ssids[i].ssid,
 631                         local->scan_req->ssids[i].ssid_len,
 632                         local->scan_req->ie, local->scan_req->ie_len);
 633
 634         /*
 635          * After sending probe requests, wait for probe responses
 636          * on the channel.
 637          */
 638         *next_delay = IEEE80211_CHANNEL_TIME;
 639         local->next_scan_state = SCAN_DECISION;
 640 }
 641
 642 void ieee80211_scan_work(struct work_struct *work)
 643 {
 644         struct ieee80211_local *local =
 645                 container_of(work, struct ieee80211_local, scan_work.work);
 646         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 647         unsigned long next_delay = 0;
 648         bool aborted, hw_scan, finish;
 649
 650         mutex_lock(&local->mtx);
 651
 652         if (test_and_clear_bit(SCAN_COMPLETED, &local->scanning)) {
 653                 aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
 654                 goto out_complete;
 655         }
 656
 657         if (!sdata || !local->scan_req)
 658                 goto out;
 659
 660         if (local->scan_req && !local->scanning) {
 661                 struct cfg80211_scan_request *req = local->scan_req;
 662                 int rc;
 663
 664                 local->scan_req = NULL;
 665                 local->scan_sdata = NULL;
 666
 667                 rc = __ieee80211_start_scan(sdata, req);
 668                 if (rc) {
 669                         /* need to complete scan in cfg80211 */
 670                         local->scan_req = req;
 671                         aborted = true;
 672                         goto out_complete;
 673                 } else
 674                         goto out;
 675         }
 676
 677         /*
 678          * Avoid re-scheduling when the sdata is going away.
 679          */
 680         if (!ieee80211_sdata_running(sdata)) {
 681                 aborted = true;
 682                 goto out_complete;
 683         }
 684
 685         /*
 686          * as long as no delay is required advance immediately
 687          * without scheduling a new work
 688          */
 689         do {
 690                 switch (local->next_scan_state) {
 691                 case SCAN_DECISION:
 692                         /* if no more bands/channels left, complete scan */
 693                         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 694                                 aborted = false;
 695                                 goto out_complete;
 696                         }
 697                         ieee80211_scan_state_decision(local, &next_delay);
 698                         break;
 699                 case SCAN_SET_CHANNEL:
 700                         ieee80211_scan_state_set_channel(local, &next_delay);
 701                         break;
 702                 case SCAN_SEND_PROBE:
 703                         ieee80211_scan_state_send_probe(local, &next_delay);
 704                         break;
 705                 case SCAN_LEAVE_OPER_CHANNEL:
 706                         ieee80211_scan_state_leave_oper_channel(local, &next_delay);
 707                         break;
 708                 case SCAN_ENTER_OPER_CHANNEL:
 709                         ieee80211_scan_state_enter_oper_channel(local, &next_delay);
 710                         break;
 711                 }
 712         } while (next_delay == 0);
 713
 714         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
 715         mutex_unlock(&local->mtx);
 716         return;
 717
 718 out_complete:
 719         hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 720         finish = __ieee80211_scan_completed(&local->hw, aborted, hw_scan);
 721         mutex_unlock(&local->mtx);
 722         if (finish)
 723                 __ieee80211_scan_completed_finish(&local->hw, hw_scan);
 724         return;
 725
 726 out:
 727         mutex_unlock(&local->mtx);
 728 }
 729
 730 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 731                            struct cfg80211_scan_request *req)
 732 {
 733         int res;
 734
 735         mutex_lock(&sdata->local->mtx);
 736         res = __ieee80211_start_scan(sdata, req);
 737         mutex_unlock(&sdata->local->mtx);
 738
 739         return res;
 740 }
 741
 742 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 743                                     const u8 *ssid, u8 ssid_len,
 744                                     struct ieee80211_channel *chan)
 745 {
 746         struct ieee80211_local *local = sdata->local;
 747         int ret = -EBUSY;
 748         enum ieee80211_band band;
 749
 750         mutex_lock(&local->mtx);
 751
 752         /* busy scanning */
 753         if (local->scan_req)
 754                 goto unlock;
 755
 756         /* fill internal scan request */
 757         if (!chan) {
 758                 int i, nchan = 0;
 759
 760                 for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
 761                         if (!local->hw.wiphy->bands[band])
 762                                 continue;
 763                         for (i = 0;
 764                              i < local->hw.wiphy->bands[band]->n_channels;
 765                              i++) {
 766                                 local->int_scan_req->channels[nchan] =
 767                                     &local->hw.wiphy->bands[band]->channels[i];
 768                                 nchan++;
 769                         }
 770                 }
 771
 772                 local->int_scan_req->n_channels = nchan;
 773         } else {
 774                 local->int_scan_req->channels[0] = chan;
 775                 local->int_scan_req->n_channels = 1;
 776         }
 777
 778         local->int_scan_req->ssids = &local->scan_ssid;
 779         local->int_scan_req->n_ssids = 1;
 780         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 781         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 782
 783         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 784  unlock:
 785         mutex_unlock(&local->mtx);
 786         return ret;
 787 }
 788
 789 /*
 790  * Only call this function when a scan can't be queued -- under RTNL.
 791  */
 792 void ieee80211_scan_cancel(struct ieee80211_local *local)
 793 {
 794         bool abortscan;
 795         bool finish = false;
 796
 797         /*
 798          * We are only canceling software scan, or deferred scan that was not
 799          * yet really started (see __ieee80211_start_scan ).
 800          *
 801          * Regarding hardware scan:
 802          * - we can not call  __ieee80211_scan_completed() as when
 803          *   SCAN_HW_SCANNING bit is set this function change
 804          *   local->hw_scan_req to operate on 5G band, what race with
 805          *   driver which can use local->hw_scan_req
 806          *
 807          * - we can not cancel scan_work since driver can schedule it
 808          *   by ieee80211_scan_completed(..., true) to finish scan
 809          *
 810          * Hence low lever driver is responsible for canceling HW scan.
 811          */
 812
 813         mutex_lock(&local->mtx);
 814         abortscan = local->scan_req && !test_bit(SCAN_HW_SCANNING, &local->scanning);
 815         if (abortscan)
 816                 finish = __ieee80211_scan_completed(&local->hw, true, false);
 817         mutex_unlock(&local->mtx);
 818
 819         if (abortscan) {
 820                 /* The scan is canceled, but stop work from being pending */
 821                 cancel_delayed_work_sync(&local->scan_work);
 822         }
 823         if (finish)
 824                 __ieee80211_scan_completed_finish(&local->hw, false);
 825 }