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/wireless.h>
  16 #include <linux/if_arp.h>
  17 #include <linux/rtnetlink.h>
  18 #include <net/mac80211.h>
  19
  20 #include "ieee80211_i.h"
  21 #include "driver-ops.h"
  22 #include "mesh.h"
  23
  24 #define IEEE80211_PROBE_DELAY (HZ / 33)
  25 #define IEEE80211_CHANNEL_TIME (HZ / 33)
  26 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
  27
  28 struct ieee80211_bss *
  29 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
  30                      u8 *ssid, u8 ssid_len)
  31 {
  32         return (void *)cfg80211_get_bss(local->hw.wiphy,
  33                                         ieee80211_get_channel(local->hw.wiphy,
  34                                                               freq),
  35                                         bssid, ssid, ssid_len,
  36                                         0, 0);
  37 }
  38
  39 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
  40 {
  41         struct ieee80211_bss *bss = (void *)cbss;
  42
  43         kfree(bss_mesh_id(bss));
  44         kfree(bss_mesh_cfg(bss));
  45 }
  46
  47 void ieee80211_rx_bss_put(struct ieee80211_local *local,
  48                           struct ieee80211_bss *bss)
  49 {
  50         cfg80211_put_bss((struct cfg80211_bss *)bss);
  51 }
  52
  53 struct ieee80211_bss *
  54 ieee80211_bss_info_update(struct ieee80211_local *local,
  55                           struct ieee80211_rx_status *rx_status,
  56                           struct ieee80211_mgmt *mgmt,
  57                           size_t len,
  58                           struct ieee802_11_elems *elems,
  59                           struct ieee80211_channel *channel,
  60                           bool beacon)
  61 {
  62         struct ieee80211_bss *bss;
  63         int clen;
  64         s32 signal = 0;
  65
  66         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
  67                 signal = rx_status->signal * 100;
  68         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
  69                 signal = (rx_status->signal * 100) / local->hw.max_signal;
  70
  71         bss = (void *)cfg80211_inform_bss_frame(local->hw.wiphy, channel,
  72                                                 mgmt, len, signal, GFP_ATOMIC);
  73
  74         if (!bss)
  75                 return NULL;
  76
  77         bss->cbss.free_priv = ieee80211_rx_bss_free;
  78
  79         /* save the ERP value so that it is available at association time */
  80         if (elems->erp_info && elems->erp_info_len >= 1) {
  81                 bss->erp_value = elems->erp_info[0];
  82                 bss->has_erp_value = 1;
  83         }
  84
  85         if (elems->tim) {
  86                 struct ieee80211_tim_ie *tim_ie =
  87                         (struct ieee80211_tim_ie *)elems->tim;
  88                 bss->dtim_period = tim_ie->dtim_period;
  89         }
  90
  91         /* set default value for buggy AP/no TIM element */
  92         if (bss->dtim_period == 0)
  93                 bss->dtim_period = 1;
  94
  95         bss->supp_rates_len = 0;
  96         if (elems->supp_rates) {
  97                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
  98                 if (clen > elems->supp_rates_len)
  99                         clen = elems->supp_rates_len;
 100                 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
 101                        clen);
 102                 bss->supp_rates_len += clen;
 103         }
 104         if (elems->ext_supp_rates) {
 105                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 106                 if (clen > elems->ext_supp_rates_len)
 107                         clen = elems->ext_supp_rates_len;
 108                 memcpy(&bss->supp_rates[bss->supp_rates_len],
 109                        elems->ext_supp_rates, clen);
 110                 bss->supp_rates_len += clen;
 111         }
 112
 113         bss->wmm_used = elems->wmm_param || elems->wmm_info;
 114
 115         if (!beacon)
 116                 bss->last_probe_resp = jiffies;
 117
 118         return bss;
 119 }
 120
 121 ieee80211_rx_result
 122 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
 123 {
 124         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
 125         struct ieee80211_mgmt *mgmt;
 126         struct ieee80211_bss *bss;
 127         u8 *elements;
 128         struct ieee80211_channel *channel;
 129         size_t baselen;
 130         int freq;
 131         __le16 fc;
 132         bool presp, beacon = false;
 133         struct ieee802_11_elems elems;
 134
 135         if (skb->len < 2)
 136                 return RX_DROP_UNUSABLE;
 137
 138         mgmt = (struct ieee80211_mgmt *) skb->data;
 139         fc = mgmt->frame_control;
 140
 141         if (ieee80211_is_ctl(fc))
 142                 return RX_CONTINUE;
 143
 144         if (skb->len < 24)
 145                 return RX_DROP_MONITOR;
 146
 147         presp = ieee80211_is_probe_resp(fc);
 148         if (presp) {
 149                 /* ignore ProbeResp to foreign address */
 150                 if (memcmp(mgmt->da, sdata->vif.addr, ETH_ALEN))
 151                         return RX_DROP_MONITOR;
 152
 153                 presp = true;
 154                 elements = mgmt->u.probe_resp.variable;
 155                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 156         } else {
 157                 beacon = ieee80211_is_beacon(fc);
 158                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 159                 elements = mgmt->u.beacon.variable;
 160         }
 161
 162         if (!presp && !beacon)
 163                 return RX_CONTINUE;
 164
 165         if (baselen > skb->len)
 166                 return RX_DROP_MONITOR;
 167
 168         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
 169
 170         if (elems.ds_params && elems.ds_params_len == 1)
 171                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
 172         else
 173                 freq = rx_status->freq;
 174
 175         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
 176
 177         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 178                 return RX_DROP_MONITOR;
 179
 180         bss = ieee80211_bss_info_update(sdata->local, rx_status,
 181                                         mgmt, skb->len, &elems,
 182                                         channel, beacon);
 183         if (bss)
 184                 ieee80211_rx_bss_put(sdata->local, bss);
 185
 186         dev_kfree_skb(skb);
 187         return RX_QUEUED;
 188 }
 189
 190 /* return false if no more work */
 191 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 192 {
 193         struct cfg80211_scan_request *req = local->scan_req;
 194         enum ieee80211_band band;
 195         int i, ielen, n_chans;
 196
 197         do {
 198                 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
 199                         return false;
 200
 201                 band = local->hw_scan_band;
 202                 n_chans = 0;
 203                 for (i = 0; i < req->n_channels; i++) {
 204                         if (req->channels[i]->band == band) {
 205                                 local->hw_scan_req->channels[n_chans] =
 206                                                         req->channels[i];
 207                                 n_chans++;
 208                         }
 209                 }
 210
 211                 local->hw_scan_band++;
 212         } while (!n_chans);
 213
 214         local->hw_scan_req->n_channels = n_chans;
 215
 216         ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
 217                                          req->ie, req->ie_len, band);
 218         local->hw_scan_req->ie_len = ielen;
 219
 220         return true;
 221 }
 222
 223 /*
 224  * inform AP that we will go to sleep so that it will buffer the frames
 225  * while we scan
 226  */
 227 static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
 228 {
 229         struct ieee80211_local *local = sdata->local;
 230         bool ps = false;
 231
 232         /* FIXME: what to do when local->pspolling is true? */
 233
 234         del_timer_sync(&local->dynamic_ps_timer);
 235         cancel_work_sync(&local->dynamic_ps_enable_work);
 236
 237         if (local->hw.conf.flags & IEEE80211_CONF_PS) {
 238                 ps = true;
 239                 local->hw.conf.flags &= ~IEEE80211_CONF_PS;
 240                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
 241         }
 242
 243         if (!ps || !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
 244                 /*
 245                  * If power save was enabled, no need to send a nullfunc
 246                  * frame because AP knows that we are sleeping. But if the
 247                  * hardware is creating the nullfunc frame for power save
 248                  * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
 249                  * enabled) and power save was enabled, the firmware just
 250                  * sent a null frame with power save disabled. So we need
 251                  * to send a new nullfunc frame to inform the AP that we
 252                  * are again sleeping.
 253                  */
 254                 ieee80211_send_nullfunc(local, sdata, 1);
 255 }
 256
 257 /* inform AP that we are awake again, unless power save is enabled */
 258 static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
 259 {
 260         struct ieee80211_local *local = sdata->local;
 261
 262         if (!local->ps_sdata)
 263                 ieee80211_send_nullfunc(local, sdata, 0);
 264         else {
 265                 /*
 266                  * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
 267                  * will send a nullfunc frame with the powersave bit set
 268                  * even though the AP already knows that we are sleeping.
 269                  * This could be avoided by sending a null frame with power
 270                  * save bit disabled before enabling the power save, but
 271                  * this doesn't gain anything.
 272                  *
 273                  * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
 274                  * to send a nullfunc frame because AP already knows that
 275                  * we are sleeping, let's just enable power save mode in
 276                  * hardware.
 277                  */
 278                 local->hw.conf.flags |= IEEE80211_CONF_PS;
 279                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
 280         }
 281 }
 282
 283 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 284 {
 285         struct ieee80211_local *local = hw_to_local(hw);
 286         struct ieee80211_sub_if_data *sdata;
 287         bool was_hw_scan;
 288
 289         mutex_lock(&local->scan_mtx);
 290
 291         /*
 292          * It's ok to abort a not-yet-running scan (that
 293          * we have one at all will be verified by checking
 294          * local->scan_req next), but not to complete it
 295          * successfully.
 296          */
 297         if (WARN_ON(!local->scanning && !aborted))
 298                 aborted = true;
 299
 300         if (WARN_ON(!local->scan_req)) {
 301                 mutex_unlock(&local->scan_mtx);
 302                 return;
 303         }
 304
 305         was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 306         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 307                 ieee80211_queue_delayed_work(&local->hw,
 308                                              &local->scan_work, 0);
 309                 mutex_unlock(&local->scan_mtx);
 310                 return;
 311         }
 312
 313         kfree(local->hw_scan_req);
 314         local->hw_scan_req = NULL;
 315
 316         if (local->scan_req != local->int_scan_req)
 317                 cfg80211_scan_done(local->scan_req, aborted);
 318         local->scan_req = NULL;
 319         local->scan_sdata = NULL;
 320
 321         local->scanning = 0;
 322         local->scan_channel = NULL;
 323
 324         /* we only have to protect scan_req and hw/sw scan */
 325         mutex_unlock(&local->scan_mtx);
 326
 327         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 328         if (was_hw_scan)
 329                 goto done;
 330
 331         ieee80211_configure_filter(local);
 332
 333         drv_sw_scan_complete(local);
 334
 335         mutex_lock(&local->iflist_mtx);
 336         list_for_each_entry(sdata, &local->interfaces, list) {
 337                 if (!netif_running(sdata->dev))
 338                         continue;
 339
 340                 /* Tell AP we're back */
 341                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 342                         if (sdata->u.mgd.associated) {
 343                                 ieee80211_scan_ps_disable(sdata);
 344                                 netif_wake_queue(sdata->dev);
 345                         }
 346                 } else
 347                         netif_wake_queue(sdata->dev);
 348
 349                 /* re-enable beaconing */
 350                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
 351                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
 352                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 353                         ieee80211_bss_info_change_notify(
 354                                 sdata, BSS_CHANGED_BEACON_ENABLED);
 355         }
 356         mutex_unlock(&local->iflist_mtx);
 357
 358  done:
 359         ieee80211_recalc_idle(local);
 360         ieee80211_mlme_notify_scan_completed(local);
 361         ieee80211_ibss_notify_scan_completed(local);
 362         ieee80211_mesh_notify_scan_completed(local);
 363 }
 364 EXPORT_SYMBOL(ieee80211_scan_completed);
 365
 366 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 367 {
 368         struct ieee80211_sub_if_data *sdata;
 369
 370         /*
 371          * Hardware/driver doesn't support hw_scan, so use software
 372          * scanning instead. First send a nullfunc frame with power save
 373          * bit on so that AP will buffer the frames for us while we are not
 374          * listening, then send probe requests to each channel and wait for
 375          * the responses. After all channels are scanned, tune back to the
 376          * original channel and send a nullfunc frame with power save bit
 377          * off to trigger the AP to send us all the buffered frames.
 378          *
 379          * Note that while local->sw_scanning is true everything else but
 380          * nullfunc frames and probe requests will be dropped in
 381          * ieee80211_tx_h_check_assoc().
 382          */
 383         drv_sw_scan_start(local);
 384
 385         mutex_lock(&local->iflist_mtx);
 386         list_for_each_entry(sdata, &local->interfaces, list) {
 387                 if (!netif_running(sdata->dev))
 388                         continue;
 389
 390                 /* disable beaconing */
 391                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
 392                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
 393                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 394                         ieee80211_bss_info_change_notify(
 395                                 sdata, BSS_CHANGED_BEACON_ENABLED);
 396
 397                 /*
 398                  * only handle non-STA interfaces here, STA interfaces
 399                  * are handled in the scan state machine
 400                  */
 401                 if (sdata->vif.type != NL80211_IFTYPE_STATION)
 402                         netif_stop_queue(sdata->dev);
 403         }
 404         mutex_unlock(&local->iflist_mtx);
 405
 406         local->next_scan_state = SCAN_DECISION;
 407         local->scan_channel_idx = 0;
 408
 409         ieee80211_configure_filter(local);
 410
 411         /* TODO: start scan as soon as all nullfunc frames are ACKed */
 412         ieee80211_queue_delayed_work(&local->hw,
 413                                      &local->scan_work,
 414                                      IEEE80211_CHANNEL_TIME);
 415
 416         return 0;
 417 }
 418
 419
 420 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 421                                   struct cfg80211_scan_request *req)
 422 {
 423         struct ieee80211_local *local = sdata->local;
 424         struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
 425         int rc;
 426
 427         if (local->scan_req)
 428                 return -EBUSY;
 429
 430         if (local->ops->hw_scan) {
 431                 u8 *ies;
 432
 433                 local->hw_scan_req = kmalloc(
 434                                 sizeof(*local->hw_scan_req) +
 435                                 req->n_channels * sizeof(req->channels[0]) +
 436                                 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
 437                                 req->ie_len, GFP_KERNEL);
 438                 if (!local->hw_scan_req)
 439                         return -ENOMEM;
 440
 441                 local->hw_scan_req->ssids = req->ssids;
 442                 local->hw_scan_req->n_ssids = req->n_ssids;
 443                 ies = (u8 *)local->hw_scan_req +
 444                         sizeof(*local->hw_scan_req) +
 445                         req->n_channels * sizeof(req->channels[0]);
 446                 local->hw_scan_req->ie = ies;
 447
 448                 local->hw_scan_band = 0;
 449         }
 450
 451         local->scan_req = req;
 452         local->scan_sdata = sdata;
 453
 454         if (req != local->int_scan_req &&
 455             sdata->vif.type == NL80211_IFTYPE_STATION &&
 456             !list_empty(&ifmgd->work_list)) {
 457                 /* actually wait for the work it's doing to finish/time out */
 458                 set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
 459                 return 0;
 460         }
 461
 462         if (local->ops->hw_scan)
 463                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 464         else
 465                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 466         /*
 467          * Kicking off the scan need not be protected,
 468          * only the scan variable stuff, since now
 469          * local->scan_req is assigned and other callers
 470          * will abort their scan attempts.
 471          *
 472          * This avoids getting a scan_mtx -> iflist_mtx
 473          * dependency, so that the scan completed calls
 474          * have more locking freedom.
 475          */
 476
 477         ieee80211_recalc_idle(local);
 478         mutex_unlock(&local->scan_mtx);
 479
 480         if (local->ops->hw_scan) {
 481                 WARN_ON(!ieee80211_prep_hw_scan(local));
 482                 rc = drv_hw_scan(local, local->hw_scan_req);
 483         } else
 484                 rc = ieee80211_start_sw_scan(local);
 485
 486         mutex_lock(&local->scan_mtx);
 487
 488         if (rc) {
 489                 kfree(local->hw_scan_req);
 490                 local->hw_scan_req = NULL;
 491                 local->scanning = 0;
 492
 493                 ieee80211_recalc_idle(local);
 494
 495                 local->scan_req = NULL;
 496                 local->scan_sdata = NULL;
 497         }
 498
 499         return rc;
 500 }
 501
 502 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
 503                                          unsigned long *next_delay)
 504 {
 505         bool associated = false;
 506         struct ieee80211_sub_if_data *sdata;
 507
 508         /* if no more bands/channels left, complete scan and advance to the idle state */
 509         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 510                 ieee80211_scan_completed(&local->hw, false);
 511                 return 1;
 512         }
 513
 514         /* check if at least one STA interface is associated */
 515         mutex_lock(&local->iflist_mtx);
 516         list_for_each_entry(sdata, &local->interfaces, list) {
 517                 if (!netif_running(sdata->dev))
 518                         continue;
 519
 520                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 521                         if (sdata->u.mgd.associated) {
 522                                 associated = true;
 523                                 break;
 524                         }
 525                 }
 526         }
 527         mutex_unlock(&local->iflist_mtx);
 528
 529         if (local->scan_channel) {
 530                 /*
 531                  * we're currently scanning a different channel, let's
 532                  * switch back to the operating channel now if at least
 533                  * one interface is associated. Otherwise just scan the
 534                  * next channel
 535                  */
 536                 if (associated)
 537                         local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
 538                 else
 539                         local->next_scan_state = SCAN_SET_CHANNEL;
 540         } else {
 541                 /*
 542                  * we're on the operating channel currently, let's
 543                  * leave that channel now to scan another one
 544                  */
 545                 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
 546         }
 547
 548         *next_delay = 0;
 549         return 0;
 550 }
 551
 552 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
 553                                                     unsigned long *next_delay)
 554 {
 555         struct ieee80211_sub_if_data *sdata;
 556
 557         /*
 558          * notify the AP about us leaving the channel and stop all STA interfaces
 559          */
 560         mutex_lock(&local->iflist_mtx);
 561         list_for_each_entry(sdata, &local->interfaces, list) {
 562                 if (!netif_running(sdata->dev))
 563                         continue;
 564
 565                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 566                         netif_stop_queue(sdata->dev);
 567                         if (sdata->u.mgd.associated)
 568                                 ieee80211_scan_ps_enable(sdata);
 569                 }
 570         }
 571         mutex_unlock(&local->iflist_mtx);
 572
 573         __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
 574
 575         /* advance to the next channel to be scanned */
 576         *next_delay = HZ / 10;
 577         local->next_scan_state = SCAN_SET_CHANNEL;
 578 }
 579
 580 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
 581                                                     unsigned long *next_delay)
 582 {
 583         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 584
 585         /* switch back to the operating channel */
 586         local->scan_channel = NULL;
 587         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 588
 589         /*
 590          * notify the AP about us being back and restart all STA interfaces
 591          */
 592         mutex_lock(&local->iflist_mtx);
 593         list_for_each_entry(sdata, &local->interfaces, list) {
 594                 if (!netif_running(sdata->dev))
 595                         continue;
 596
 597                 /* Tell AP we're back */
 598                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 599                         if (sdata->u.mgd.associated)
 600                                 ieee80211_scan_ps_disable(sdata);
 601                         netif_wake_queue(sdata->dev);
 602                 }
 603         }
 604         mutex_unlock(&local->iflist_mtx);
 605
 606         __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
 607
 608         *next_delay = HZ / 5;
 609         local->next_scan_state = SCAN_DECISION;
 610 }
 611
 612 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 613                                              unsigned long *next_delay)
 614 {
 615         int skip;
 616         struct ieee80211_channel *chan;
 617
 618         skip = 0;
 619         chan = local->scan_req->channels[local->scan_channel_idx];
 620
 621         local->scan_channel = chan;
 622         if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 623                 skip = 1;
 624
 625         /* advance state machine to next channel/band */
 626         local->scan_channel_idx++;
 627
 628         if (skip) {
 629                 /* if we skip this channel return to the decision state */
 630                 local->next_scan_state = SCAN_DECISION;
 631                 return;
 632         }
 633
 634         /*
 635          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 636          * (which unfortunately doesn't say _why_ step a) is done,
 637          * but it waits for the probe delay or until a frame is
 638          * received - and the received frame would update the NAV).
 639          * For now, we do not support waiting until a frame is
 640          * received.
 641          *
 642          * In any case, it is not necessary for a passive scan.
 643          */
 644         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 645             !local->scan_req->n_ssids) {
 646                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 647                 local->next_scan_state = SCAN_DECISION;
 648                 return;
 649         }
 650
 651         /* active scan, send probes */
 652         *next_delay = IEEE80211_PROBE_DELAY;
 653         local->next_scan_state = SCAN_SEND_PROBE;
 654 }
 655
 656 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 657                                             unsigned long *next_delay)
 658 {
 659         int i;
 660         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 661
 662         for (i = 0; i < local->scan_req->n_ssids; i++)
 663                 ieee80211_send_probe_req(
 664                         sdata, NULL,
 665                         local->scan_req->ssids[i].ssid,
 666                         local->scan_req->ssids[i].ssid_len,
 667                         local->scan_req->ie, local->scan_req->ie_len);
 668
 669         /*
 670          * After sending probe requests, wait for probe responses
 671          * on the channel.
 672          */
 673         *next_delay = IEEE80211_CHANNEL_TIME;
 674         local->next_scan_state = SCAN_DECISION;
 675 }
 676
 677 void ieee80211_scan_work(struct work_struct *work)
 678 {
 679         struct ieee80211_local *local =
 680                 container_of(work, struct ieee80211_local, scan_work.work);
 681         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 682         unsigned long next_delay = 0;
 683
 684         mutex_lock(&local->scan_mtx);
 685         if (!sdata || !local->scan_req) {
 686                 mutex_unlock(&local->scan_mtx);
 687                 return;
 688         }
 689
 690         if (local->hw_scan_req) {
 691                 int rc = drv_hw_scan(local, local->hw_scan_req);
 692                 mutex_unlock(&local->scan_mtx);
 693                 if (rc)
 694                         ieee80211_scan_completed(&local->hw, true);
 695                 return;
 696         }
 697
 698         if (local->scan_req && !local->scanning) {
 699                 struct cfg80211_scan_request *req = local->scan_req;
 700                 int rc;
 701
 702                 local->scan_req = NULL;
 703                 local->scan_sdata = NULL;
 704
 705                 rc = __ieee80211_start_scan(sdata, req);
 706                 mutex_unlock(&local->scan_mtx);
 707
 708                 if (rc)
 709                         ieee80211_scan_completed(&local->hw, true);
 710                 return;
 711         }
 712
 713         mutex_unlock(&local->scan_mtx);
 714
 715         /*
 716          * Avoid re-scheduling when the sdata is going away.
 717          */
 718         if (!netif_running(sdata->dev)) {
 719                 ieee80211_scan_completed(&local->hw, true);
 720                 return;
 721         }
 722
 723         /*
 724          * as long as no delay is required advance immediately
 725          * without scheduling a new work
 726          */
 727         do {
 728                 switch (local->next_scan_state) {
 729                 case SCAN_DECISION:
 730                         if (ieee80211_scan_state_decision(local, &next_delay))
 731                                 return;
 732                         break;
 733                 case SCAN_SET_CHANNEL:
 734                         ieee80211_scan_state_set_channel(local, &next_delay);
 735                         break;
 736                 case SCAN_SEND_PROBE:
 737                         ieee80211_scan_state_send_probe(local, &next_delay);
 738                         break;
 739                 case SCAN_LEAVE_OPER_CHANNEL:
 740                         ieee80211_scan_state_leave_oper_channel(local, &next_delay);
 741                         break;
 742                 case SCAN_ENTER_OPER_CHANNEL:
 743                         ieee80211_scan_state_enter_oper_channel(local, &next_delay);
 744                         break;
 745                 }
 746         } while (next_delay == 0);
 747
 748         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
 749 }
 750
 751 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 752                            struct cfg80211_scan_request *req)
 753 {
 754         int res;
 755
 756         mutex_lock(&sdata->local->scan_mtx);
 757         res = __ieee80211_start_scan(sdata, req);
 758         mutex_unlock(&sdata->local->scan_mtx);
 759
 760         return res;
 761 }
 762
 763 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 764                                     const u8 *ssid, u8 ssid_len)
 765 {
 766         struct ieee80211_local *local = sdata->local;
 767         int ret = -EBUSY;
 768
 769         mutex_lock(&local->scan_mtx);
 770
 771         /* busy scanning */
 772         if (local->scan_req)
 773                 goto unlock;
 774
 775         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 776         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 777
 778         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 779  unlock:
 780         mutex_unlock(&local->scan_mtx);
 781         return ret;
 782 }
 783
 784 void ieee80211_scan_cancel(struct ieee80211_local *local)
 785 {
 786         bool abortscan;
 787
 788         cancel_delayed_work_sync(&local->scan_work);
 789
 790         /*
 791          * Only call this function when a scan can't be
 792          * queued -- mostly at suspend under RTNL.
 793          */
 794         mutex_lock(&local->scan_mtx);
 795         abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
 796                     (!local->scanning && local->scan_req);
 797         mutex_unlock(&local->scan_mtx);
 798
 799         if (abortscan)
 800                 ieee80211_scan_completed(&local->hw, true);
 801 }