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 <net/mac80211.h>
  20
  21 #include "ieee80211_i.h"
  22 #include "driver-ops.h"
  23 #include "mesh.h"
  24
  25 #define IEEE80211_PROBE_DELAY (HZ / 33)
  26 #define IEEE80211_CHANNEL_TIME (HZ / 33)
  27 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
  28
  29 struct ieee80211_bss *
  30 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
  31                      u8 *ssid, u8 ssid_len)
  32 {
  33         struct cfg80211_bss *cbss;
  34
  35         cbss = cfg80211_get_bss(local->hw.wiphy,
  36                                 ieee80211_get_channel(local->hw.wiphy, freq),
  37                                 bssid, ssid, ssid_len, 0, 0);
  38         if (!cbss)
  39                 return NULL;
  40         return (void *)cbss->priv;
  41 }
  42
  43 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
  44 {
  45         struct ieee80211_bss *bss = (void *)cbss->priv;
  46
  47         kfree(bss_mesh_id(bss));
  48         kfree(bss_mesh_cfg(bss));
  49 }
  50
  51 void ieee80211_rx_bss_put(struct ieee80211_local *local,
  52                           struct ieee80211_bss *bss)
  53 {
  54         if (!bss)
  55                 return;
  56         cfg80211_put_bss(container_of((void *)bss, struct cfg80211_bss, priv));
  57 }
  58
  59 static bool is_uapsd_supported(struct ieee802_11_elems *elems)
  60 {
  61         u8 qos_info;
  62
  63         if (elems->wmm_info && elems->wmm_info_len == 7
  64             && elems->wmm_info[5] == 1)
  65                 qos_info = elems->wmm_info[6];
  66         else if (elems->wmm_param && elems->wmm_param_len == 24
  67                  && elems->wmm_param[5] == 1)
  68                 qos_info = elems->wmm_param[6];
  69         else
  70                 /* no valid wmm information or parameter element found */
  71                 return false;
  72
  73         return qos_info & IEEE80211_WMM_IE_AP_QOSINFO_UAPSD;
  74 }
  75
  76 struct ieee80211_bss *
  77 ieee80211_bss_info_update(struct ieee80211_local *local,
  78                           struct ieee80211_rx_status *rx_status,
  79                           struct ieee80211_mgmt *mgmt,
  80                           size_t len,
  81                           struct ieee802_11_elems *elems,
  82                           struct ieee80211_channel *channel,
  83                           bool beacon)
  84 {
  85         struct cfg80211_bss *cbss;
  86         struct ieee80211_bss *bss;
  87         int clen;
  88         s32 signal = 0;
  89
  90         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
  91                 signal = rx_status->signal * 100;
  92         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
  93                 signal = (rx_status->signal * 100) / local->hw.max_signal;
  94
  95         cbss = cfg80211_inform_bss_frame(local->hw.wiphy, channel,
  96                                          mgmt, len, signal, GFP_ATOMIC);
  97
  98         if (!cbss)
  99                 return NULL;
 100
 101         cbss->free_priv = ieee80211_rx_bss_free;
 102         bss = (void *)cbss->priv;
 103
 104         /* save the ERP value so that it is available at association time */
 105         if (elems->erp_info && elems->erp_info_len >= 1) {
 106                 bss->erp_value = elems->erp_info[0];
 107                 bss->has_erp_value = 1;
 108         }
 109
 110         if (elems->tim) {
 111                 struct ieee80211_tim_ie *tim_ie =
 112                         (struct ieee80211_tim_ie *)elems->tim;
 113                 bss->dtim_period = tim_ie->dtim_period;
 114         }
 115
 116         bss->supp_rates_len = 0;
 117         if (elems->supp_rates) {
 118                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 119                 if (clen > elems->supp_rates_len)
 120                         clen = elems->supp_rates_len;
 121                 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
 122                        clen);
 123                 bss->supp_rates_len += clen;
 124         }
 125         if (elems->ext_supp_rates) {
 126                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 127                 if (clen > elems->ext_supp_rates_len)
 128                         clen = elems->ext_supp_rates_len;
 129                 memcpy(&bss->supp_rates[bss->supp_rates_len],
 130                        elems->ext_supp_rates, clen);
 131                 bss->supp_rates_len += clen;
 132         }
 133
 134         bss->wmm_used = elems->wmm_param || elems->wmm_info;
 135         bss->uapsd_supported = is_uapsd_supported(elems);
 136
 137         if (!beacon)
 138                 bss->last_probe_resp = jiffies;
 139
 140         return bss;
 141 }
 142
 143 ieee80211_rx_result
 144 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
 145 {
 146         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
 147         struct ieee80211_mgmt *mgmt;
 148         struct ieee80211_bss *bss;
 149         u8 *elements;
 150         struct ieee80211_channel *channel;
 151         size_t baselen;
 152         int freq;
 153         __le16 fc;
 154         bool presp, beacon = false;
 155         struct ieee802_11_elems elems;
 156
 157         if (skb->len < 2)
 158                 return RX_DROP_UNUSABLE;
 159
 160         mgmt = (struct ieee80211_mgmt *) skb->data;
 161         fc = mgmt->frame_control;
 162
 163         if (ieee80211_is_ctl(fc))
 164                 return RX_CONTINUE;
 165
 166         if (skb->len < 24)
 167                 return RX_DROP_MONITOR;
 168
 169         presp = ieee80211_is_probe_resp(fc);
 170         if (presp) {
 171                 /* ignore ProbeResp to foreign address */
 172                 if (memcmp(mgmt->da, sdata->vif.addr, ETH_ALEN))
 173                         return RX_DROP_MONITOR;
 174
 175                 presp = true;
 176                 elements = mgmt->u.probe_resp.variable;
 177                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 178         } else {
 179                 beacon = ieee80211_is_beacon(fc);
 180                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 181                 elements = mgmt->u.beacon.variable;
 182         }
 183
 184         if (!presp && !beacon)
 185                 return RX_CONTINUE;
 186
 187         if (baselen > skb->len)
 188                 return RX_DROP_MONITOR;
 189
 190         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
 191
 192         if (elems.ds_params && elems.ds_params_len == 1)
 193                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
 194         else
 195                 freq = rx_status->freq;
 196
 197         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
 198
 199         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 200                 return RX_DROP_MONITOR;
 201
 202         bss = ieee80211_bss_info_update(sdata->local, rx_status,
 203                                         mgmt, skb->len, &elems,
 204                                         channel, beacon);
 205         if (bss)
 206                 ieee80211_rx_bss_put(sdata->local, bss);
 207
 208         dev_kfree_skb(skb);
 209         return RX_QUEUED;
 210 }
 211
 212 /* return false if no more work */
 213 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 214 {
 215         struct cfg80211_scan_request *req = local->scan_req;
 216         enum ieee80211_band band;
 217         int i, ielen, n_chans;
 218
 219         do {
 220                 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
 221                         return false;
 222
 223                 band = local->hw_scan_band;
 224                 n_chans = 0;
 225                 for (i = 0; i < req->n_channels; i++) {
 226                         if (req->channels[i]->band == band) {
 227                                 local->hw_scan_req->channels[n_chans] =
 228                                                         req->channels[i];
 229                                 n_chans++;
 230                         }
 231                 }
 232
 233                 local->hw_scan_band++;
 234         } while (!n_chans);
 235
 236         local->hw_scan_req->n_channels = n_chans;
 237
 238         ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
 239                                          req->ie, req->ie_len, band);
 240         local->hw_scan_req->ie_len = ielen;
 241
 242         return true;
 243 }
 244
 245 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 246 {
 247         struct ieee80211_local *local = hw_to_local(hw);
 248         bool was_hw_scan;
 249
 250         trace_api_scan_completed(local, aborted);
 251
 252         mutex_lock(&local->scan_mtx);
 253
 254         /*
 255          * It's ok to abort a not-yet-running scan (that
 256          * we have one at all will be verified by checking
 257          * local->scan_req next), but not to complete it
 258          * successfully.
 259          */
 260         if (WARN_ON(!local->scanning && !aborted))
 261                 aborted = true;
 262
 263         if (WARN_ON(!local->scan_req)) {
 264                 mutex_unlock(&local->scan_mtx);
 265                 return;
 266         }
 267
 268         was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 269         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 270                 ieee80211_queue_delayed_work(&local->hw,
 271                                              &local->scan_work, 0);
 272                 mutex_unlock(&local->scan_mtx);
 273                 return;
 274         }
 275
 276         kfree(local->hw_scan_req);
 277         local->hw_scan_req = NULL;
 278
 279         if (local->scan_req != local->int_scan_req)
 280                 cfg80211_scan_done(local->scan_req, aborted);
 281         local->scan_req = NULL;
 282         local->scan_sdata = NULL;
 283
 284         local->scanning = 0;
 285         local->scan_channel = NULL;
 286
 287         /* we only have to protect scan_req and hw/sw scan */
 288         mutex_unlock(&local->scan_mtx);
 289
 290         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 291         if (was_hw_scan)
 292                 goto done;
 293
 294         ieee80211_configure_filter(local);
 295
 296         drv_sw_scan_complete(local);
 297
 298         ieee80211_offchannel_return(local, true);
 299
 300  done:
 301         ieee80211_recalc_idle(local);
 302         ieee80211_mlme_notify_scan_completed(local);
 303         ieee80211_ibss_notify_scan_completed(local);
 304         ieee80211_mesh_notify_scan_completed(local);
 305         ieee80211_queue_work(&local->hw, &local->work_work);
 306 }
 307 EXPORT_SYMBOL(ieee80211_scan_completed);
 308
 309 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 310 {
 311         /*
 312          * Hardware/driver doesn't support hw_scan, so use software
 313          * scanning instead. First send a nullfunc frame with power save
 314          * bit on so that AP will buffer the frames for us while we are not
 315          * listening, then send probe requests to each channel and wait for
 316          * the responses. After all channels are scanned, tune back to the
 317          * original channel and send a nullfunc frame with power save bit
 318          * off to trigger the AP to send us all the buffered frames.
 319          *
 320          * Note that while local->sw_scanning is true everything else but
 321          * nullfunc frames and probe requests will be dropped in
 322          * ieee80211_tx_h_check_assoc().
 323          */
 324         drv_sw_scan_start(local);
 325
 326         ieee80211_offchannel_stop_beaconing(local);
 327
 328         local->leave_oper_channel_time = 0;
 329         local->next_scan_state = SCAN_DECISION;
 330         local->scan_channel_idx = 0;
 331
 332         drv_flush(local, false);
 333
 334         ieee80211_configure_filter(local);
 335
 336         ieee80211_queue_delayed_work(&local->hw,
 337                                      &local->scan_work,
 338                                      IEEE80211_CHANNEL_TIME);
 339
 340         return 0;
 341 }
 342
 343
 344 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 345                                   struct cfg80211_scan_request *req)
 346 {
 347         struct ieee80211_local *local = sdata->local;
 348         int rc;
 349
 350         if (local->scan_req)
 351                 return -EBUSY;
 352
 353         if (!list_empty(&local->work_list)) {
 354                 /* wait for the work to finish/time out */
 355                 local->scan_req = req;
 356                 local->scan_sdata = sdata;
 357                 return 0;
 358         }
 359
 360         if (local->ops->hw_scan) {
 361                 u8 *ies;
 362
 363                 local->hw_scan_req = kmalloc(
 364                                 sizeof(*local->hw_scan_req) +
 365                                 req->n_channels * sizeof(req->channels[0]) +
 366                                 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
 367                                 req->ie_len, GFP_KERNEL);
 368                 if (!local->hw_scan_req)
 369                         return -ENOMEM;
 370
 371                 local->hw_scan_req->ssids = req->ssids;
 372                 local->hw_scan_req->n_ssids = req->n_ssids;
 373                 ies = (u8 *)local->hw_scan_req +
 374                         sizeof(*local->hw_scan_req) +
 375                         req->n_channels * sizeof(req->channels[0]);
 376                 local->hw_scan_req->ie = ies;
 377
 378                 local->hw_scan_band = 0;
 379
 380                 /*
 381                  * After allocating local->hw_scan_req, we must
 382                  * go through until ieee80211_prep_hw_scan(), so
 383                  * anything that might be changed here and leave
 384                  * this function early must not go after this
 385                  * allocation.
 386                  */
 387         }
 388
 389         local->scan_req = req;
 390         local->scan_sdata = sdata;
 391
 392         if (local->ops->hw_scan)
 393                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 394         else
 395                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 396
 397         /*
 398          * Kicking off the scan need not be protected,
 399          * only the scan variable stuff, since now
 400          * local->scan_req is assigned and other callers
 401          * will abort their scan attempts.
 402          *
 403          * This avoids too many locking dependencies
 404          * so that the scan completed calls have more
 405          * locking freedom.
 406          */
 407
 408         ieee80211_recalc_idle(local);
 409         mutex_unlock(&local->scan_mtx);
 410
 411         if (local->ops->hw_scan) {
 412                 WARN_ON(!ieee80211_prep_hw_scan(local));
 413                 rc = drv_hw_scan(local, local->hw_scan_req);
 414         } else
 415                 rc = ieee80211_start_sw_scan(local);
 416
 417         mutex_lock(&local->scan_mtx);
 418
 419         if (rc) {
 420                 kfree(local->hw_scan_req);
 421                 local->hw_scan_req = NULL;
 422                 local->scanning = 0;
 423
 424                 ieee80211_recalc_idle(local);
 425
 426                 local->scan_req = NULL;
 427                 local->scan_sdata = NULL;
 428         }
 429
 430         return rc;
 431 }
 432
 433 static unsigned long
 434 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
 435 {
 436         /*
 437          * TODO: channel switching also consumes quite some time,
 438          * add that delay as well to get a better estimation
 439          */
 440         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN)
 441                 return IEEE80211_PASSIVE_CHANNEL_TIME;
 442         return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
 443 }
 444
 445 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
 446                                          unsigned long *next_delay)
 447 {
 448         bool associated = false;
 449         bool tx_empty = true;
 450         bool bad_latency;
 451         bool listen_int_exceeded;
 452         unsigned long min_beacon_int = 0;
 453         struct ieee80211_sub_if_data *sdata;
 454         struct ieee80211_channel *next_chan;
 455
 456         /* if no more bands/channels left, complete scan and advance to the idle state */
 457         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 458                 ieee80211_scan_completed(&local->hw, false);
 459                 return 1;
 460         }
 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_requirement(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         return 0;
 534 }
 535
 536 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
 537                                                     unsigned long *next_delay)
 538 {
 539         ieee80211_offchannel_stop_station(local);
 540
 541         __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
 542
 543         /*
 544          * What if the nullfunc frames didn't arrive?
 545          */
 546         drv_flush(local, false);
 547         if (local->ops->flush)
 548                 *next_delay = 0;
 549         else
 550                 *next_delay = HZ / 10;
 551
 552         /* remember when we left the operating channel */
 553         local->leave_oper_channel_time = jiffies;
 554
 555         /* advance to the next channel to be scanned */
 556         local->next_scan_state = SCAN_SET_CHANNEL;
 557 }
 558
 559 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
 560                                                     unsigned long *next_delay)
 561 {
 562         /* switch back to the operating channel */
 563         local->scan_channel = NULL;
 564         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 565
 566         /*
 567          * Only re-enable station mode interface now; beaconing will be
 568          * re-enabled once the full scan has been completed.
 569          */
 570         ieee80211_offchannel_return(local, false);
 571
 572         __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
 573
 574         *next_delay = HZ / 5;
 575         local->next_scan_state = SCAN_DECISION;
 576 }
 577
 578 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 579                                              unsigned long *next_delay)
 580 {
 581         int skip;
 582         struct ieee80211_channel *chan;
 583
 584         skip = 0;
 585         chan = local->scan_req->channels[local->scan_channel_idx];
 586
 587         local->scan_channel = chan;
 588         if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 589                 skip = 1;
 590
 591         /* advance state machine to next channel/band */
 592         local->scan_channel_idx++;
 593
 594         if (skip) {
 595                 /* if we skip this channel return to the decision state */
 596                 local->next_scan_state = SCAN_DECISION;
 597                 return;
 598         }
 599
 600         /*
 601          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 602          * (which unfortunately doesn't say _why_ step a) is done,
 603          * but it waits for the probe delay or until a frame is
 604          * received - and the received frame would update the NAV).
 605          * For now, we do not support waiting until a frame is
 606          * received.
 607          *
 608          * In any case, it is not necessary for a passive scan.
 609          */
 610         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 611             !local->scan_req->n_ssids) {
 612                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 613                 local->next_scan_state = SCAN_DECISION;
 614                 return;
 615         }
 616
 617         /* active scan, send probes */
 618         *next_delay = IEEE80211_PROBE_DELAY;
 619         local->next_scan_state = SCAN_SEND_PROBE;
 620 }
 621
 622 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 623                                             unsigned long *next_delay)
 624 {
 625         int i;
 626         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 627
 628         for (i = 0; i < local->scan_req->n_ssids; i++)
 629                 ieee80211_send_probe_req(
 630                         sdata, NULL,
 631                         local->scan_req->ssids[i].ssid,
 632                         local->scan_req->ssids[i].ssid_len,
 633                         local->scan_req->ie, local->scan_req->ie_len);
 634
 635         /*
 636          * After sending probe requests, wait for probe responses
 637          * on the channel.
 638          */
 639         *next_delay = IEEE80211_CHANNEL_TIME;
 640         local->next_scan_state = SCAN_DECISION;
 641 }
 642
 643 void ieee80211_scan_work(struct work_struct *work)
 644 {
 645         struct ieee80211_local *local =
 646                 container_of(work, struct ieee80211_local, scan_work.work);
 647         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 648         unsigned long next_delay = 0;
 649
 650         mutex_lock(&local->scan_mtx);
 651         if (!sdata || !local->scan_req) {
 652                 mutex_unlock(&local->scan_mtx);
 653                 return;
 654         }
 655
 656         if (local->hw_scan_req) {
 657                 int rc = drv_hw_scan(local, local->hw_scan_req);
 658                 mutex_unlock(&local->scan_mtx);
 659                 if (rc)
 660                         ieee80211_scan_completed(&local->hw, true);
 661                 return;
 662         }
 663
 664         if (local->scan_req && !local->scanning) {
 665                 struct cfg80211_scan_request *req = local->scan_req;
 666                 int rc;
 667
 668                 local->scan_req = NULL;
 669                 local->scan_sdata = NULL;
 670
 671                 rc = __ieee80211_start_scan(sdata, req);
 672                 mutex_unlock(&local->scan_mtx);
 673
 674                 if (rc)
 675                         ieee80211_scan_completed(&local->hw, true);
 676                 return;
 677         }
 678
 679         mutex_unlock(&local->scan_mtx);
 680
 681         /*
 682          * Avoid re-scheduling when the sdata is going away.
 683          */
 684         if (!ieee80211_sdata_running(sdata)) {
 685                 ieee80211_scan_completed(&local->hw, true);
 686                 return;
 687         }
 688
 689         /*
 690          * as long as no delay is required advance immediately
 691          * without scheduling a new work
 692          */
 693         do {
 694                 switch (local->next_scan_state) {
 695                 case SCAN_DECISION:
 696                         if (ieee80211_scan_state_decision(local, &next_delay))
 697                                 return;
 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 }
 716
 717 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 718                            struct cfg80211_scan_request *req)
 719 {
 720         int res;
 721
 722         mutex_lock(&sdata->local->scan_mtx);
 723         res = __ieee80211_start_scan(sdata, req);
 724         mutex_unlock(&sdata->local->scan_mtx);
 725
 726         return res;
 727 }
 728
 729 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 730                                     const u8 *ssid, u8 ssid_len)
 731 {
 732         struct ieee80211_local *local = sdata->local;
 733         int ret = -EBUSY;
 734
 735         mutex_lock(&local->scan_mtx);
 736
 737         /* busy scanning */
 738         if (local->scan_req)
 739                 goto unlock;
 740
 741         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 742         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 743
 744         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 745  unlock:
 746         mutex_unlock(&local->scan_mtx);
 747         return ret;
 748 }
 749
 750 void ieee80211_scan_cancel(struct ieee80211_local *local)
 751 {
 752         bool abortscan;
 753
 754         cancel_delayed_work_sync(&local->scan_work);
 755
 756         /*
 757          * Only call this function when a scan can't be
 758          * queued -- mostly at suspend under RTNL.
 759          */
 760         mutex_lock(&local->scan_mtx);
 761         abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
 762                     (!local->scanning && local->scan_req);
 763         mutex_unlock(&local->scan_mtx);
 764
 765         if (abortscan)
 766                 ieee80211_scan_completed(&local->hw, true);
 767 }