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