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 /* TODO: figure out how to avoid that the "current BSS" expires */
  16
  17 #include <linux/wireless.h>
  18 #include <linux/if_arp.h>
  19 #include <linux/rtnetlink.h>
  20 #include <net/mac80211.h>
  21 #include <net/iw_handler.h>
  22
  23 #include "ieee80211_i.h"
  24 #include "driver-ops.h"
  25 #include "mesh.h"
  26
  27 #define IEEE80211_PROBE_DELAY (HZ / 33)
  28 #define IEEE80211_CHANNEL_TIME (HZ / 33)
  29 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
  30
  31 struct ieee80211_bss *
  32 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
  33                      u8 *ssid, u8 ssid_len)
  34 {
  35         return (void *)cfg80211_get_bss(local->hw.wiphy,
  36                                         ieee80211_get_channel(local->hw.wiphy,
  37                                                               freq),
  38                                         bssid, ssid, ssid_len,
  39                                         0, 0);
  40 }
  41
  42 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
  43 {
  44         struct ieee80211_bss *bss = (void *)cbss;
  45
  46         kfree(bss_mesh_id(bss));
  47         kfree(bss_mesh_cfg(bss));
  48 }
  49
  50 void ieee80211_rx_bss_put(struct ieee80211_local *local,
  51                           struct ieee80211_bss *bss)
  52 {
  53         cfg80211_put_bss((struct cfg80211_bss *)bss);
  54 }
  55
  56 struct ieee80211_bss *
  57 ieee80211_bss_info_update(struct ieee80211_local *local,
  58                           struct ieee80211_rx_status *rx_status,
  59                           struct ieee80211_mgmt *mgmt,
  60                           size_t len,
  61                           struct ieee802_11_elems *elems,
  62                           struct ieee80211_channel *channel,
  63                           bool beacon)
  64 {
  65         struct ieee80211_bss *bss;
  66         int clen;
  67         s32 signal = 0;
  68
  69         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
  70                 signal = rx_status->signal * 100;
  71         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
  72                 signal = (rx_status->signal * 100) / local->hw.max_signal;
  73
  74         bss = (void *)cfg80211_inform_bss_frame(local->hw.wiphy, channel,
  75                                                 mgmt, len, signal, GFP_ATOMIC);
  76
  77         if (!bss)
  78                 return NULL;
  79
  80         bss->cbss.free_priv = ieee80211_rx_bss_free;
  81
  82         /* save the ERP value so that it is available at association time */
  83         if (elems->erp_info && elems->erp_info_len >= 1) {
  84                 bss->erp_value = elems->erp_info[0];
  85                 bss->has_erp_value = 1;
  86         }
  87
  88         if (elems->tim) {
  89                 struct ieee80211_tim_ie *tim_ie =
  90                         (struct ieee80211_tim_ie *)elems->tim;
  91                 bss->dtim_period = tim_ie->dtim_period;
  92         }
  93
  94         /* set default value for buggy APs */
  95         if (!elems->tim || bss->dtim_period == 0)
  96                 bss->dtim_period = 1;
  97
  98         bss->supp_rates_len = 0;
  99         if (elems->supp_rates) {
 100                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 101                 if (clen > elems->supp_rates_len)
 102                         clen = elems->supp_rates_len;
 103                 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
 104                        clen);
 105                 bss->supp_rates_len += clen;
 106         }
 107         if (elems->ext_supp_rates) {
 108                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 109                 if (clen > elems->ext_supp_rates_len)
 110                         clen = elems->ext_supp_rates_len;
 111                 memcpy(&bss->supp_rates[bss->supp_rates_len],
 112                        elems->ext_supp_rates, clen);
 113                 bss->supp_rates_len += clen;
 114         }
 115
 116         bss->wmm_used = elems->wmm_param || elems->wmm_info;
 117
 118         if (!beacon)
 119                 bss->last_probe_resp = jiffies;
 120
 121         return bss;
 122 }
 123
 124 ieee80211_rx_result
 125 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
 126 {
 127         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
 128         struct ieee80211_mgmt *mgmt;
 129         struct ieee80211_bss *bss;
 130         u8 *elements;
 131         struct ieee80211_channel *channel;
 132         size_t baselen;
 133         int freq;
 134         __le16 fc;
 135         bool presp, beacon = false;
 136         struct ieee802_11_elems elems;
 137
 138         if (skb->len < 2)
 139                 return RX_DROP_UNUSABLE;
 140
 141         mgmt = (struct ieee80211_mgmt *) skb->data;
 142         fc = mgmt->frame_control;
 143
 144         if (ieee80211_is_ctl(fc))
 145                 return RX_CONTINUE;
 146
 147         if (skb->len < 24)
 148                 return RX_DROP_MONITOR;
 149
 150         presp = ieee80211_is_probe_resp(fc);
 151         if (presp) {
 152                 /* ignore ProbeResp to foreign address */
 153                 if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
 154                         return RX_DROP_MONITOR;
 155
 156                 presp = true;
 157                 elements = mgmt->u.probe_resp.variable;
 158                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 159         } else {
 160                 beacon = ieee80211_is_beacon(fc);
 161                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 162                 elements = mgmt->u.beacon.variable;
 163         }
 164
 165         if (!presp && !beacon)
 166                 return RX_CONTINUE;
 167
 168         if (baselen > skb->len)
 169                 return RX_DROP_MONITOR;
 170
 171         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
 172
 173         if (elems.ds_params && elems.ds_params_len == 1)
 174                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
 175         else
 176                 freq = rx_status->freq;
 177
 178         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
 179
 180         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 181                 return RX_DROP_MONITOR;
 182
 183         bss = ieee80211_bss_info_update(sdata->local, rx_status,
 184                                         mgmt, skb->len, &elems,
 185                                         channel, beacon);
 186         if (bss)
 187                 ieee80211_rx_bss_put(sdata->local, bss);
 188
 189         dev_kfree_skb(skb);
 190         return RX_QUEUED;
 191 }
 192
 193 /*
 194  * inform AP that we will go to sleep so that it will buffer the frames
 195  * while we scan
 196  */
 197 static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
 198 {
 199         struct ieee80211_local *local = sdata->local;
 200         bool ps = false;
 201
 202         /* FIXME: what to do when local->pspolling is true? */
 203
 204         del_timer_sync(&local->dynamic_ps_timer);
 205         cancel_work_sync(&local->dynamic_ps_enable_work);
 206
 207         if (local->hw.conf.flags & IEEE80211_CONF_PS) {
 208                 ps = true;
 209                 local->hw.conf.flags &= ~IEEE80211_CONF_PS;
 210                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
 211         }
 212
 213         if (!ps || !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
 214                 /*
 215                  * If power save was enabled, no need to send a nullfunc
 216                  * frame because AP knows that we are sleeping. But if the
 217                  * hardware is creating the nullfunc frame for power save
 218                  * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
 219                  * enabled) and power save was enabled, the firmware just
 220                  * sent a null frame with power save disabled. So we need
 221                  * to send a new nullfunc frame to inform the AP that we
 222                  * are again sleeping.
 223                  */
 224                 ieee80211_send_nullfunc(local, sdata, 1);
 225 }
 226
 227 /* inform AP that we are awake again, unless power save is enabled */
 228 static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
 229 {
 230         struct ieee80211_local *local = sdata->local;
 231
 232         if (!local->ps_sdata)
 233                 ieee80211_send_nullfunc(local, sdata, 0);
 234         else {
 235                 /*
 236                  * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
 237                  * will send a nullfunc frame with the powersave bit set
 238                  * even though the AP already knows that we are sleeping.
 239                  * This could be avoided by sending a null frame with power
 240                  * save bit disabled before enabling the power save, but
 241                  * this doesn't gain anything.
 242                  *
 243                  * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
 244                  * to send a nullfunc frame because AP already knows that
 245                  * we are sleeping, let's just enable power save mode in
 246                  * hardware.
 247                  */
 248                 local->hw.conf.flags |= IEEE80211_CONF_PS;
 249                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
 250         }
 251 }
 252
 253 static void ieee80211_restore_scan_ies(struct ieee80211_local *local)
 254 {
 255         kfree(local->scan_req->ie);
 256         local->scan_req->ie = local->orig_ies;
 257         local->scan_req->ie_len = local->orig_ies_len;
 258 }
 259
 260 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 261 {
 262         struct ieee80211_local *local = hw_to_local(hw);
 263         struct ieee80211_sub_if_data *sdata;
 264         bool was_hw_scan;
 265
 266         mutex_lock(&local->scan_mtx);
 267
 268         if (WARN_ON(!local->scanning)) {
 269                 mutex_unlock(&local->scan_mtx);
 270                 return;
 271         }
 272
 273         if (WARN_ON(!local->scan_req)) {
 274                 mutex_unlock(&local->scan_mtx);
 275                 return;
 276         }
 277
 278         if (test_bit(SCAN_HW_SCANNING, &local->scanning))
 279                 ieee80211_restore_scan_ies(local);
 280
 281         if (local->scan_req != &local->int_scan_req)
 282                 cfg80211_scan_done(local->scan_req, aborted);
 283         local->scan_req = NULL;
 284
 285         was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 286         local->scanning = 0;
 287         local->scan_channel = NULL;
 288
 289         /* we only have to protect scan_req and hw/sw scan */
 290         mutex_unlock(&local->scan_mtx);
 291
 292         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 293         if (was_hw_scan)
 294                 goto done;
 295
 296         spin_lock_bh(&local->filter_lock);
 297         local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
 298         drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
 299                              &local->filter_flags,
 300                              local->mc_count,
 301                              local->mc_list);
 302         spin_unlock_bh(&local->filter_lock);
 303
 304         drv_sw_scan_complete(local);
 305
 306         mutex_lock(&local->iflist_mtx);
 307         list_for_each_entry(sdata, &local->interfaces, list) {
 308                 if (!netif_running(sdata->dev))
 309                         continue;
 310
 311                 /* Tell AP we're back */
 312                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 313                         if (sdata->u.mgd.associated) {
 314                                 ieee80211_scan_ps_disable(sdata);
 315                                 netif_tx_wake_all_queues(sdata->dev);
 316                         }
 317                 } else
 318                         netif_tx_wake_all_queues(sdata->dev);
 319
 320                 /* re-enable beaconing */
 321                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
 322                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
 323                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 324                         ieee80211_bss_info_change_notify(
 325                                 sdata, BSS_CHANGED_BEACON_ENABLED);
 326         }
 327         mutex_unlock(&local->iflist_mtx);
 328
 329  done:
 330         ieee80211_recalc_idle(local);
 331         ieee80211_mlme_notify_scan_completed(local);
 332         ieee80211_ibss_notify_scan_completed(local);
 333         ieee80211_mesh_notify_scan_completed(local);
 334 }
 335 EXPORT_SYMBOL(ieee80211_scan_completed);
 336
 337 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 338 {
 339         struct ieee80211_sub_if_data *sdata;
 340
 341         /*
 342          * Hardware/driver doesn't support hw_scan, so use software
 343          * scanning instead. First send a nullfunc frame with power save
 344          * bit on so that AP will buffer the frames for us while we are not
 345          * listening, then send probe requests to each channel and wait for
 346          * the responses. After all channels are scanned, tune back to the
 347          * original channel and send a nullfunc frame with power save bit
 348          * off to trigger the AP to send us all the buffered frames.
 349          *
 350          * Note that while local->sw_scanning is true everything else but
 351          * nullfunc frames and probe requests will be dropped in
 352          * ieee80211_tx_h_check_assoc().
 353          */
 354         drv_sw_scan_start(local);
 355
 356         mutex_lock(&local->iflist_mtx);
 357         list_for_each_entry(sdata, &local->interfaces, list) {
 358                 if (!netif_running(sdata->dev))
 359                         continue;
 360
 361                 /* disable beaconing */
 362                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
 363                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
 364                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 365                         ieee80211_bss_info_change_notify(
 366                                 sdata, BSS_CHANGED_BEACON_ENABLED);
 367
 368                 /*
 369                  * only handle non-STA interfaces here, STA interfaces
 370                  * are handled in the scan state machine
 371                  */
 372                 if (sdata->vif.type != NL80211_IFTYPE_STATION)
 373                         netif_tx_stop_all_queues(sdata->dev);
 374         }
 375         mutex_unlock(&local->iflist_mtx);
 376
 377         local->next_scan_state = SCAN_DECISION;
 378         local->scan_channel_idx = 0;
 379
 380         spin_lock_bh(&local->filter_lock);
 381         local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
 382         drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
 383                              &local->filter_flags,
 384                              local->mc_count,
 385                              local->mc_list);
 386         spin_unlock_bh(&local->filter_lock);
 387
 388         /* TODO: start scan as soon as all nullfunc frames are ACKed */
 389         queue_delayed_work(local->hw.workqueue, &local->scan_work,
 390                            IEEE80211_CHANNEL_TIME);
 391
 392         return 0;
 393 }
 394
 395
 396 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 397                                   struct cfg80211_scan_request *req)
 398 {
 399         struct ieee80211_local *local = sdata->local;
 400         struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
 401         int rc;
 402
 403         if (local->scan_req)
 404                 return -EBUSY;
 405
 406         if (local->ops->hw_scan) {
 407                 u8 *ies;
 408                 int ielen;
 409
 410                 ies = kmalloc(2 + IEEE80211_MAX_SSID_LEN +
 411                               local->scan_ies_len + req->ie_len, GFP_KERNEL);
 412                 if (!ies)
 413                         return -ENOMEM;
 414
 415                 ielen = ieee80211_build_preq_ies(local, ies,
 416                                                  req->ie, req->ie_len);
 417                 local->orig_ies = req->ie;
 418                 local->orig_ies_len = req->ie_len;
 419                 req->ie = ies;
 420                 req->ie_len = ielen;
 421         }
 422
 423         local->scan_req = req;
 424         local->scan_sdata = sdata;
 425
 426         if (req != &local->int_scan_req &&
 427             sdata->vif.type == NL80211_IFTYPE_STATION &&
 428             !list_empty(&ifmgd->work_list)) {
 429                 /* actually wait for the work it's doing to finish/time out */
 430                 set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
 431                 return 0;
 432         }
 433
 434         if (local->ops->hw_scan)
 435                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 436         else
 437                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 438         /*
 439          * Kicking off the scan need not be protected,
 440          * only the scan variable stuff, since now
 441          * local->scan_req is assigned and other callers
 442          * will abort their scan attempts.
 443          *
 444          * This avoids getting a scan_mtx -> iflist_mtx
 445          * dependency, so that the scan completed calls
 446          * have more locking freedom.
 447          */
 448
 449         ieee80211_recalc_idle(local);
 450         mutex_unlock(&local->scan_mtx);
 451
 452         if (local->ops->hw_scan)
 453                 rc = drv_hw_scan(local, local->scan_req);
 454         else
 455                 rc = ieee80211_start_sw_scan(local);
 456
 457         mutex_lock(&local->scan_mtx);
 458
 459         if (rc) {
 460                 if (local->ops->hw_scan)
 461                         ieee80211_restore_scan_ies(local);
 462                 local->scanning = 0;
 463
 464                 ieee80211_recalc_idle(local);
 465
 466                 local->scan_req = NULL;
 467                 local->scan_sdata = NULL;
 468         }
 469
 470         return rc;
 471 }
 472
 473 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
 474                                          unsigned long *next_delay)
 475 {
 476         bool associated = false;
 477         struct ieee80211_sub_if_data *sdata;
 478
 479         /* if no more bands/channels left, complete scan and advance to the idle state */
 480         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 481                 ieee80211_scan_completed(&local->hw, false);
 482                 return 1;
 483         }
 484
 485         /* check if at least one STA interface is associated */
 486         mutex_lock(&local->iflist_mtx);
 487         list_for_each_entry(sdata, &local->interfaces, list) {
 488                 if (!netif_running(sdata->dev))
 489                         continue;
 490
 491                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 492                         if (sdata->u.mgd.associated) {
 493                                 associated = true;
 494                                 break;
 495                         }
 496                 }
 497         }
 498         mutex_unlock(&local->iflist_mtx);
 499
 500         if (local->scan_channel) {
 501                 /*
 502                  * we're currently scanning a different channel, let's
 503                  * switch back to the operating channel now if at least
 504                  * one interface is associated. Otherwise just scan the
 505                  * next channel
 506                  */
 507                 if (associated)
 508                         local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
 509                 else
 510                         local->next_scan_state = SCAN_SET_CHANNEL;
 511         } else {
 512                 /*
 513                  * we're on the operating channel currently, let's
 514                  * leave that channel now to scan another one
 515                  */
 516                 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
 517         }
 518
 519         *next_delay = 0;
 520         return 0;
 521 }
 522
 523 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
 524                                                     unsigned long *next_delay)
 525 {
 526         struct ieee80211_sub_if_data *sdata;
 527
 528         /*
 529          * notify the AP about us leaving the channel and stop all STA interfaces
 530          */
 531         mutex_lock(&local->iflist_mtx);
 532         list_for_each_entry(sdata, &local->interfaces, list) {
 533                 if (!netif_running(sdata->dev))
 534                         continue;
 535
 536                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 537                         netif_tx_stop_all_queues(sdata->dev);
 538                         if (sdata->u.mgd.associated)
 539                                 ieee80211_scan_ps_enable(sdata);
 540                 }
 541         }
 542         mutex_unlock(&local->iflist_mtx);
 543
 544         __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
 545
 546         /* advance to the next channel to be scanned */
 547         *next_delay = HZ / 10;
 548         local->next_scan_state = SCAN_SET_CHANNEL;
 549 }
 550
 551 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
 552                                                     unsigned long *next_delay)
 553 {
 554         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 555
 556         /* switch back to the operating channel */
 557         local->scan_channel = NULL;
 558         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 559
 560         /*
 561          * notify the AP about us being back and restart all STA interfaces
 562          */
 563         mutex_lock(&local->iflist_mtx);
 564         list_for_each_entry(sdata, &local->interfaces, list) {
 565                 if (!netif_running(sdata->dev))
 566                         continue;
 567
 568                 /* Tell AP we're back */
 569                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 570                         if (sdata->u.mgd.associated)
 571                                 ieee80211_scan_ps_disable(sdata);
 572                         netif_tx_wake_all_queues(sdata->dev);
 573                 }
 574         }
 575         mutex_unlock(&local->iflist_mtx);
 576
 577         __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
 578
 579         *next_delay = HZ / 5;
 580         local->next_scan_state = SCAN_DECISION;
 581 }
 582
 583 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 584                                              unsigned long *next_delay)
 585 {
 586         int skip;
 587         struct ieee80211_channel *chan;
 588         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 589
 590         skip = 0;
 591         chan = local->scan_req->channels[local->scan_channel_idx];
 592
 593         if (chan->flags & IEEE80211_CHAN_DISABLED ||
 594             (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
 595              chan->flags & IEEE80211_CHAN_NO_IBSS))
 596                 skip = 1;
 597
 598         if (!skip) {
 599                 local->scan_channel = chan;
 600                 if (ieee80211_hw_config(local,
 601                                         IEEE80211_CONF_CHANGE_CHANNEL))
 602                         skip = 1;
 603         }
 604
 605         /* advance state machine to next channel/band */
 606         local->scan_channel_idx++;
 607
 608         if (skip) {
 609                 /* if we skip this channel return to the decision state */
 610                 local->next_scan_state = SCAN_DECISION;
 611                 return;
 612         }
 613
 614         /*
 615          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 616          * (which unfortunately doesn't say _why_ step a) is done,
 617          * but it waits for the probe delay or until a frame is
 618          * received - and the received frame would update the NAV).
 619          * For now, we do not support waiting until a frame is
 620          * received.
 621          *
 622          * In any case, it is not necessary for a passive scan.
 623          */
 624         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 625             !local->scan_req->n_ssids) {
 626                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 627                 local->next_scan_state = SCAN_DECISION;
 628                 return;
 629         }
 630
 631         /* active scan, send probes */
 632         *next_delay = IEEE80211_PROBE_DELAY;
 633         local->next_scan_state = SCAN_SEND_PROBE;
 634 }
 635
 636 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 637                                             unsigned long *next_delay)
 638 {
 639         int i;
 640         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 641
 642         for (i = 0; i < local->scan_req->n_ssids; i++)
 643                 ieee80211_send_probe_req(
 644                         sdata, NULL,
 645                         local->scan_req->ssids[i].ssid,
 646                         local->scan_req->ssids[i].ssid_len,
 647                         local->scan_req->ie, local->scan_req->ie_len);
 648
 649         /*
 650          * After sending probe requests, wait for probe responses
 651          * on the channel.
 652          */
 653         *next_delay = IEEE80211_CHANNEL_TIME;
 654         local->next_scan_state = SCAN_DECISION;
 655 }
 656
 657 void ieee80211_scan_work(struct work_struct *work)
 658 {
 659         struct ieee80211_local *local =
 660                 container_of(work, struct ieee80211_local, scan_work.work);
 661         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 662         unsigned long next_delay = 0;
 663
 664         mutex_lock(&local->scan_mtx);
 665         if (!sdata || !local->scan_req) {
 666                 mutex_unlock(&local->scan_mtx);
 667                 return;
 668         }
 669
 670         if (local->scan_req && !local->scanning) {
 671                 struct cfg80211_scan_request *req = local->scan_req;
 672                 int rc;
 673
 674                 local->scan_req = NULL;
 675
 676                 rc = __ieee80211_start_scan(sdata, req);
 677                 mutex_unlock(&local->scan_mtx);
 678
 679                 if (rc)
 680                         ieee80211_scan_completed(&local->hw, true);
 681                 return;
 682         }
 683
 684         mutex_unlock(&local->scan_mtx);
 685
 686         /*
 687          * Avoid re-scheduling when the sdata is going away.
 688          */
 689         if (!netif_running(sdata->dev)) {
 690                 ieee80211_scan_completed(&local->hw, true);
 691                 return;
 692         }
 693
 694         /*
 695          * as long as no delay is required advance immediately
 696          * without scheduling a new work
 697          */
 698         do {
 699                 switch (local->next_scan_state) {
 700                 case SCAN_DECISION:
 701                         if (ieee80211_scan_state_decision(local, &next_delay))
 702                                 return;
 703                         break;
 704                 case SCAN_SET_CHANNEL:
 705                         ieee80211_scan_state_set_channel(local, &next_delay);
 706                         break;
 707                 case SCAN_SEND_PROBE:
 708                         ieee80211_scan_state_send_probe(local, &next_delay);
 709                         break;
 710                 case SCAN_LEAVE_OPER_CHANNEL:
 711                         ieee80211_scan_state_leave_oper_channel(local, &next_delay);
 712                         break;
 713                 case SCAN_ENTER_OPER_CHANNEL:
 714                         ieee80211_scan_state_enter_oper_channel(local, &next_delay);
 715                         break;
 716                 }
 717         } while (next_delay == 0);
 718
 719         queue_delayed_work(local->hw.workqueue, &local->scan_work,
 720                            next_delay);
 721 }
 722
 723 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 724                            struct cfg80211_scan_request *req)
 725 {
 726         int res;
 727
 728         mutex_lock(&sdata->local->scan_mtx);
 729         res = __ieee80211_start_scan(sdata, req);
 730         mutex_unlock(&sdata->local->scan_mtx);
 731
 732         return res;
 733 }
 734
 735 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 736                                     const u8 *ssid, u8 ssid_len)
 737 {
 738         struct ieee80211_local *local = sdata->local;
 739         int ret = -EBUSY;
 740
 741         mutex_lock(&local->scan_mtx);
 742
 743         /* busy scanning */
 744         if (local->scan_req)
 745                 goto unlock;
 746
 747         memcpy(local->int_scan_req.ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 748         local->int_scan_req.ssids[0].ssid_len = ssid_len;
 749
 750         ret = __ieee80211_start_scan(sdata, &sdata->local->int_scan_req);
 751  unlock:
 752         mutex_unlock(&local->scan_mtx);
 753         return ret;
 754 }
 755
 756 void ieee80211_scan_cancel(struct ieee80211_local *local)
 757 {
 758         bool swscan;
 759
 760         cancel_delayed_work_sync(&local->scan_work);
 761
 762         /*
 763          * Only call this function when a scan can't be
 764          * queued -- mostly at suspend under RTNL.
 765          */
 766         mutex_lock(&local->scan_mtx);
 767         swscan = test_bit(SCAN_SW_SCANNING, &local->scanning);
 768         mutex_unlock(&local->scan_mtx);
 769
 770         if (swscan)
 771                 ieee80211_scan_completed(&local->hw, true);
 772 }