SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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;
  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         bss->supp_rates_len = 0;
 118         if (elems->supp_rates) {
 119                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 120                 if (clen > elems->supp_rates_len)
 121                         clen = elems->supp_rates_len;
 122                 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
 123                        clen);
 124                 bss->supp_rates_len += clen;
 125         }
 126         if (elems->ext_supp_rates) {
 127                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 128                 if (clen > elems->ext_supp_rates_len)
 129                         clen = elems->ext_supp_rates_len;
 130                 memcpy(&bss->supp_rates[bss->supp_rates_len],
 131                        elems->ext_supp_rates, clen);
 132                 bss->supp_rates_len += clen;
 133         }
 134
 135         bss->wmm_used = elems->wmm_param || elems->wmm_info;
 136         bss->uapsd_supported = is_uapsd_supported(elems);
 137
 138         if (!beacon)
 139                 bss->last_probe_resp = jiffies;
 140
 141         return bss;
 142 }
 143
 144 ieee80211_rx_result
 145 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
 146 {
 147         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
 148         struct ieee80211_mgmt *mgmt;
 149         struct ieee80211_bss *bss;
 150         u8 *elements;
 151         struct ieee80211_channel *channel;
 152         size_t baselen;
 153         int freq;
 154         __le16 fc;
 155         bool presp, beacon = false;
 156         struct ieee802_11_elems elems;
 157
 158         if (skb->len < 2)
 159                 return RX_DROP_UNUSABLE;
 160
 161         mgmt = (struct ieee80211_mgmt *) skb->data;
 162         fc = mgmt->frame_control;
 163
 164         if (ieee80211_is_ctl(fc))
 165                 return RX_CONTINUE;
 166
 167         if (skb->len < 24)
 168                 return RX_DROP_MONITOR;
 169
 170         presp = ieee80211_is_probe_resp(fc);
 171         if (presp) {
 172                 /* ignore ProbeResp to foreign address */
 173                 if (memcmp(mgmt->da, sdata->vif.addr, ETH_ALEN))
 174                         return RX_DROP_MONITOR;
 175
 176                 presp = true;
 177                 elements = mgmt->u.probe_resp.variable;
 178                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 179         } else {
 180                 beacon = ieee80211_is_beacon(fc);
 181                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 182                 elements = mgmt->u.beacon.variable;
 183         }
 184
 185         if (!presp && !beacon)
 186                 return RX_CONTINUE;
 187
 188         if (baselen > skb->len)
 189                 return RX_DROP_MONITOR;
 190
 191         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
 192
 193         if (elems.ds_params && elems.ds_params_len == 1)
 194                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
 195         else
 196                 freq = rx_status->freq;
 197
 198         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
 199
 200         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 201                 return RX_DROP_MONITOR;
 202
 203         bss = ieee80211_bss_info_update(sdata->local, rx_status,
 204                                         mgmt, skb->len, &elems,
 205                                         channel, beacon);
 206         if (bss)
 207                 ieee80211_rx_bss_put(sdata->local, bss);
 208
 209         dev_kfree_skb(skb);
 210         return RX_QUEUED;
 211 }
 212
 213 /* return false if no more work */
 214 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 215 {
 216         struct cfg80211_scan_request *req = local->scan_req;
 217         enum ieee80211_band band;
 218         int i, ielen, n_chans;
 219
 220         do {
 221                 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
 222                         return false;
 223
 224                 band = local->hw_scan_band;
 225                 n_chans = 0;
 226                 for (i = 0; i < req->n_channels; i++) {
 227                         if (req->channels[i]->band == band) {
 228                                 local->hw_scan_req->channels[n_chans] =
 229                                                         req->channels[i];
 230                                 n_chans++;
 231                         }
 232                 }
 233
 234                 local->hw_scan_band++;
 235         } while (!n_chans);
 236
 237         local->hw_scan_req->n_channels = n_chans;
 238
 239         ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
 240                                          req->ie, req->ie_len, band);
 241         local->hw_scan_req->ie_len = ielen;
 242
 243         return true;
 244 }
 245
 246 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 247 {
 248         struct ieee80211_local *local = hw_to_local(hw);
 249         bool was_hw_scan;
 250
 251         mutex_lock(&local->scan_mtx);
 252
 253         /*
 254          * It's ok to abort a not-yet-running scan (that
 255          * we have one at all will be verified by checking
 256          * local->scan_req next), but not to complete it
 257          * successfully.
 258          */
 259         if (WARN_ON(!local->scanning && !aborted))
 260                 aborted = true;
 261
 262         if (WARN_ON(!local->scan_req)) {
 263                 mutex_unlock(&local->scan_mtx);
 264                 return;
 265         }
 266
 267         was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 268         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 269                 ieee80211_queue_delayed_work(&local->hw,
 270                                              &local->scan_work, 0);
 271                 mutex_unlock(&local->scan_mtx);
 272                 return;
 273         }
 274
 275         kfree(local->hw_scan_req);
 276         local->hw_scan_req = NULL;
 277
 278         if (local->scan_req != local->int_scan_req)
 279                 cfg80211_scan_done(local->scan_req, aborted);
 280         local->scan_req = NULL;
 281         local->scan_sdata = NULL;
 282
 283         local->scanning = 0;
 284         local->scan_channel = NULL;
 285
 286         /* we only have to protect scan_req and hw/sw scan */
 287         mutex_unlock(&local->scan_mtx);
 288
 289         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 290         if (was_hw_scan)
 291                 goto done;
 292
 293         ieee80211_configure_filter(local);
 294
 295         drv_sw_scan_complete(local);
 296
 297         ieee80211_offchannel_return(local, true);
 298
 299  done:
 300         ieee80211_recalc_idle(local);
 301         ieee80211_mlme_notify_scan_completed(local);
 302         ieee80211_ibss_notify_scan_completed(local);
 303         ieee80211_mesh_notify_scan_completed(local);
 304         ieee80211_queue_work(&local->hw, &local->work_work);
 305 }
 306 EXPORT_SYMBOL(ieee80211_scan_completed);
 307
 308 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 309 {
 310         /*
 311          * Hardware/driver doesn't support hw_scan, so use software
 312          * scanning instead. First send a nullfunc frame with power save
 313          * bit on so that AP will buffer the frames for us while we are not
 314          * listening, then send probe requests to each channel and wait for
 315          * the responses. After all channels are scanned, tune back to the
 316          * original channel and send a nullfunc frame with power save bit
 317          * off to trigger the AP to send us all the buffered frames.
 318          *
 319          * Note that while local->sw_scanning is true everything else but
 320          * nullfunc frames and probe requests will be dropped in
 321          * ieee80211_tx_h_check_assoc().
 322          */
 323         drv_sw_scan_start(local);
 324
 325         ieee80211_offchannel_stop_beaconing(local);
 326
 327         local->leave_oper_channel_time = 0;
 328         local->next_scan_state = SCAN_DECISION;
 329         local->scan_channel_idx = 0;
 330
 331         drv_flush(local, false);
 332
 333         ieee80211_configure_filter(local);
 334
 335         ieee80211_queue_delayed_work(&local->hw,
 336                                      &local->scan_work,
 337                                      IEEE80211_CHANNEL_TIME);
 338
 339         return 0;
 340 }
 341
 342
 343 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 344                                   struct cfg80211_scan_request *req)
 345 {
 346         struct ieee80211_local *local = sdata->local;
 347         int rc;
 348
 349         if (local->scan_req)
 350                 return -EBUSY;
 351
 352         if (!list_empty(&local->work_list)) {
 353                 /* wait for the work to finish/time out */
 354                 local->scan_req = req;
 355                 local->scan_sdata = sdata;
 356                 return 0;
 357         }
 358
 359         if (local->ops->hw_scan) {
 360                 u8 *ies;
 361
 362                 local->hw_scan_req = kmalloc(
 363                                 sizeof(*local->hw_scan_req) +
 364                                 req->n_channels * sizeof(req->channels[0]) +
 365                                 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
 366                                 req->ie_len, GFP_KERNEL);
 367                 if (!local->hw_scan_req)
 368                         return -ENOMEM;
 369
 370                 local->hw_scan_req->ssids = req->ssids;
 371                 local->hw_scan_req->n_ssids = req->n_ssids;
 372                 ies = (u8 *)local->hw_scan_req +
 373                         sizeof(*local->hw_scan_req) +
 374                         req->n_channels * sizeof(req->channels[0]);
 375                 local->hw_scan_req->ie = ies;
 376
 377                 local->hw_scan_band = 0;
 378
 379                 /*
 380                  * After allocating local->hw_scan_req, we must
 381                  * go through until ieee80211_prep_hw_scan(), so
 382                  * anything that might be changed here and leave
 383                  * this function early must not go after this
 384                  * allocation.
 385                  */
 386         }
 387
 388         local->scan_req = req;
 389         local->scan_sdata = sdata;
 390
 391         if (local->ops->hw_scan)
 392                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 393         else
 394                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 395
 396         /*
 397          * Kicking off the scan need not be protected,
 398          * only the scan variable stuff, since now
 399          * local->scan_req is assigned and other callers
 400          * will abort their scan attempts.
 401          *
 402          * This avoids too many locking dependencies
 403          * so that the scan completed calls have more
 404          * locking freedom.
 405          */
 406
 407         ieee80211_recalc_idle(local);
 408         mutex_unlock(&local->scan_mtx);
 409
 410         if (local->ops->hw_scan) {
 411                 WARN_ON(!ieee80211_prep_hw_scan(local));
 412                 rc = drv_hw_scan(local, local->hw_scan_req);
 413         } else
 414                 rc = ieee80211_start_sw_scan(local);
 415
 416         mutex_lock(&local->scan_mtx);
 417
 418         if (rc) {
 419                 kfree(local->hw_scan_req);
 420                 local->hw_scan_req = NULL;
 421                 local->scanning = 0;
 422
 423                 ieee80211_recalc_idle(local);
 424
 425                 local->scan_req = NULL;
 426                 local->scan_sdata = NULL;
 427         }
 428
 429         return rc;
 430 }
 431
 432 static unsigned long
 433 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
 434 {
 435         /*
 436          * TODO: channel switching also consumes quite some time,
 437          * add that delay as well to get a better estimation
 438          */
 439         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN)
 440                 return IEEE80211_PASSIVE_CHANNEL_TIME;
 441         return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
 442 }
 443
 444 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
 445                                          unsigned long *next_delay)
 446 {
 447         bool associated = false;
 448         bool tx_empty = true;
 449         bool bad_latency;
 450         bool listen_int_exceeded;
 451         unsigned long min_beacon_int = 0;
 452         struct ieee80211_sub_if_data *sdata;
 453         struct ieee80211_channel *next_chan;
 454
 455         /* if no more bands/channels left, complete scan and advance to the idle state */
 456         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 457                 ieee80211_scan_completed(&local->hw, false);
 458                 return 1;
 459         }
 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_requirement(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         return 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
 649         mutex_lock(&local->scan_mtx);
 650         if (!sdata || !local->scan_req) {
 651                 mutex_unlock(&local->scan_mtx);
 652                 return;
 653         }
 654
 655         if (local->hw_scan_req) {
 656                 int rc = drv_hw_scan(local, local->hw_scan_req);
 657                 mutex_unlock(&local->scan_mtx);
 658                 if (rc)
 659                         ieee80211_scan_completed(&local->hw, true);
 660                 return;
 661         }
 662
 663         if (local->scan_req && !local->scanning) {
 664                 struct cfg80211_scan_request *req = local->scan_req;
 665                 int rc;
 666
 667                 local->scan_req = NULL;
 668                 local->scan_sdata = NULL;
 669
 670                 rc = __ieee80211_start_scan(sdata, req);
 671                 mutex_unlock(&local->scan_mtx);
 672
 673                 if (rc)
 674                         ieee80211_scan_completed(&local->hw, true);
 675                 return;
 676         }
 677
 678         mutex_unlock(&local->scan_mtx);
 679
 680         /*
 681          * Avoid re-scheduling when the sdata is going away.
 682          */
 683         if (!ieee80211_sdata_running(sdata)) {
 684                 ieee80211_scan_completed(&local->hw, true);
 685                 return;
 686         }
 687
 688         /*
 689          * as long as no delay is required advance immediately
 690          * without scheduling a new work
 691          */
 692         do {
 693                 switch (local->next_scan_state) {
 694                 case SCAN_DECISION:
 695                         if (ieee80211_scan_state_decision(local, &next_delay))
 696                                 return;
 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 }
 715
 716 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 717                            struct cfg80211_scan_request *req)
 718 {
 719         int res;
 720
 721         mutex_lock(&sdata->local->scan_mtx);
 722         res = __ieee80211_start_scan(sdata, req);
 723         mutex_unlock(&sdata->local->scan_mtx);
 724
 725         return res;
 726 }
 727
 728 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 729                                     const u8 *ssid, u8 ssid_len)
 730 {
 731         struct ieee80211_local *local = sdata->local;
 732         int ret = -EBUSY;
 733
 734         mutex_lock(&local->scan_mtx);
 735
 736         /* busy scanning */
 737         if (local->scan_req)
 738                 goto unlock;
 739
 740         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 741         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 742
 743         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 744  unlock:
 745         mutex_unlock(&local->scan_mtx);
 746         return ret;
 747 }
 748
 749 void ieee80211_scan_cancel(struct ieee80211_local *local)
 750 {
 751         bool abortscan;
 752
 753         cancel_delayed_work_sync(&local->scan_work);
 754
 755         /*
 756          * Only call this function when a scan can't be
 757          * queued -- mostly at suspend under RTNL.
 758          */
 759         mutex_lock(&local->scan_mtx);
 760         abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
 761                     (!local->scanning && local->scan_req);
 762         mutex_unlock(&local->scan_mtx);
 763
 764         if (abortscan)
 765                 ieee80211_scan_completed(&local->hw, true);
 766 }