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
 231         local->scan_ps_enabled = false;
 232
 233         /* FIXME: what to do when local->pspolling is true? */
 234
 235         del_timer_sync(&local->dynamic_ps_timer);
 236         cancel_work_sync(&local->dynamic_ps_enable_work);
 237
 238         if (local->hw.conf.flags & IEEE80211_CONF_PS) {
 239                 local->scan_ps_enabled = true;
 240                 local->hw.conf.flags &= ~IEEE80211_CONF_PS;
 241                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
 242         }
 243
 244         if (!(local->scan_ps_enabled) ||
 245             !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
 246                 /*
 247                  * If power save was enabled, no need to send a nullfunc
 248                  * frame because AP knows that we are sleeping. But if the
 249                  * hardware is creating the nullfunc frame for power save
 250                  * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
 251                  * enabled) and power save was enabled, the firmware just
 252                  * sent a null frame with power save disabled. So we need
 253                  * to send a new nullfunc frame to inform the AP that we
 254                  * are again sleeping.
 255                  */
 256                 ieee80211_send_nullfunc(local, sdata, 1);
 257 }
 258
 259 /* inform AP that we are awake again, unless power save is enabled */
 260 static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
 261 {
 262         struct ieee80211_local *local = sdata->local;
 263
 264         if (!local->ps_sdata)
 265                 ieee80211_send_nullfunc(local, sdata, 0);
 266         else if (local->scan_ps_enabled) {
 267                 /*
 268                  * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
 269                  * will send a nullfunc frame with the powersave bit set
 270                  * even though the AP already knows that we are sleeping.
 271                  * This could be avoided by sending a null frame with power
 272                  * save bit disabled before enabling the power save, but
 273                  * this doesn't gain anything.
 274                  *
 275                  * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
 276                  * to send a nullfunc frame because AP already knows that
 277                  * we are sleeping, let's just enable power save mode in
 278                  * hardware.
 279                  */
 280                 local->hw.conf.flags |= IEEE80211_CONF_PS;
 281                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
 282         } else if (local->hw.conf.dynamic_ps_timeout > 0) {
 283                 /*
 284                  * If IEEE80211_CONF_PS was not set and the dynamic_ps_timer
 285                  * had been running before leaving the operating channel,
 286                  * restart the timer now and send a nullfunc frame to inform
 287                  * the AP that we are awake.
 288                  */
 289                 ieee80211_send_nullfunc(local, sdata, 0);
 290                 mod_timer(&local->dynamic_ps_timer, jiffies +
 291                           msecs_to_jiffies(local->hw.conf.dynamic_ps_timeout));
 292         }
 293 }
 294
 295 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 296 {
 297         struct ieee80211_local *local = hw_to_local(hw);
 298         struct ieee80211_sub_if_data *sdata;
 299         bool was_hw_scan;
 300
 301         mutex_lock(&local->scan_mtx);
 302
 303         /*
 304          * It's ok to abort a not-yet-running scan (that
 305          * we have one at all will be verified by checking
 306          * local->scan_req next), but not to complete it
 307          * successfully.
 308          */
 309         if (WARN_ON(!local->scanning && !aborted))
 310                 aborted = true;
 311
 312         if (WARN_ON(!local->scan_req)) {
 313                 mutex_unlock(&local->scan_mtx);
 314                 return;
 315         }
 316
 317         was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 318         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 319                 ieee80211_queue_delayed_work(&local->hw,
 320                                              &local->scan_work, 0);
 321                 mutex_unlock(&local->scan_mtx);
 322                 return;
 323         }
 324
 325         kfree(local->hw_scan_req);
 326         local->hw_scan_req = NULL;
 327
 328         if (local->scan_req != local->int_scan_req)
 329                 cfg80211_scan_done(local->scan_req, aborted);
 330         local->scan_req = NULL;
 331         local->scan_sdata = NULL;
 332
 333         local->scanning = 0;
 334         local->scan_channel = NULL;
 335
 336         /* we only have to protect scan_req and hw/sw scan */
 337         mutex_unlock(&local->scan_mtx);
 338
 339         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 340         if (was_hw_scan)
 341                 goto done;
 342
 343         ieee80211_configure_filter(local);
 344
 345         drv_sw_scan_complete(local);
 346
 347         mutex_lock(&local->iflist_mtx);
 348         list_for_each_entry(sdata, &local->interfaces, list) {
 349                 if (!ieee80211_sdata_running(sdata))
 350                         continue;
 351
 352                 /* Tell AP we're back */
 353                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 354                         if (sdata->u.mgd.associated) {
 355                                 ieee80211_scan_ps_disable(sdata);
 356                                 netif_wake_queue(sdata->dev);
 357                         }
 358                 } else
 359                         netif_wake_queue(sdata->dev);
 360
 361                 /* re-enable 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         mutex_unlock(&local->iflist_mtx);
 369
 370  done:
 371         ieee80211_recalc_idle(local);
 372         ieee80211_mlme_notify_scan_completed(local);
 373         ieee80211_ibss_notify_scan_completed(local);
 374         ieee80211_mesh_notify_scan_completed(local);
 375 }
 376 EXPORT_SYMBOL(ieee80211_scan_completed);
 377
 378 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 379 {
 380         struct ieee80211_sub_if_data *sdata;
 381
 382         /*
 383          * Hardware/driver doesn't support hw_scan, so use software
 384          * scanning instead. First send a nullfunc frame with power save
 385          * bit on so that AP will buffer the frames for us while we are not
 386          * listening, then send probe requests to each channel and wait for
 387          * the responses. After all channels are scanned, tune back to the
 388          * original channel and send a nullfunc frame with power save bit
 389          * off to trigger the AP to send us all the buffered frames.
 390          *
 391          * Note that while local->sw_scanning is true everything else but
 392          * nullfunc frames and probe requests will be dropped in
 393          * ieee80211_tx_h_check_assoc().
 394          */
 395         drv_sw_scan_start(local);
 396
 397         mutex_lock(&local->iflist_mtx);
 398         list_for_each_entry(sdata, &local->interfaces, list) {
 399                 if (!ieee80211_sdata_running(sdata))
 400                         continue;
 401
 402                 /* disable beaconing */
 403                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
 404                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
 405                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 406                         ieee80211_bss_info_change_notify(
 407                                 sdata, BSS_CHANGED_BEACON_ENABLED);
 408
 409                 /*
 410                  * only handle non-STA interfaces here, STA interfaces
 411                  * are handled in the scan state machine
 412                  */
 413                 if (sdata->vif.type != NL80211_IFTYPE_STATION)
 414                         netif_stop_queue(sdata->dev);
 415         }
 416         mutex_unlock(&local->iflist_mtx);
 417
 418         local->next_scan_state = SCAN_DECISION;
 419         local->scan_channel_idx = 0;
 420
 421         drv_flush(local, false);
 422
 423         ieee80211_configure_filter(local);
 424
 425         ieee80211_queue_delayed_work(&local->hw,
 426                                      &local->scan_work,
 427                                      IEEE80211_CHANNEL_TIME);
 428
 429         return 0;
 430 }
 431
 432
 433 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 434                                   struct cfg80211_scan_request *req)
 435 {
 436         struct ieee80211_local *local = sdata->local;
 437         int rc;
 438
 439         if (local->scan_req)
 440                 return -EBUSY;
 441
 442         if (local->ops->hw_scan) {
 443                 u8 *ies;
 444
 445                 local->hw_scan_req = kmalloc(
 446                                 sizeof(*local->hw_scan_req) +
 447                                 req->n_channels * sizeof(req->channels[0]) +
 448                                 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
 449                                 req->ie_len, GFP_KERNEL);
 450                 if (!local->hw_scan_req)
 451                         return -ENOMEM;
 452
 453                 local->hw_scan_req->ssids = req->ssids;
 454                 local->hw_scan_req->n_ssids = req->n_ssids;
 455                 ies = (u8 *)local->hw_scan_req +
 456                         sizeof(*local->hw_scan_req) +
 457                         req->n_channels * sizeof(req->channels[0]);
 458                 local->hw_scan_req->ie = ies;
 459
 460                 local->hw_scan_band = 0;
 461         }
 462
 463         local->scan_req = req;
 464         local->scan_sdata = sdata;
 465
 466         if (!list_empty(&local->work_list)) {
 467                 /* wait for the work to finish/time out */
 468                 return 0;
 469         }
 470
 471         if (local->ops->hw_scan)
 472                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 473         else
 474                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 475         /*
 476          * Kicking off the scan need not be protected,
 477          * only the scan variable stuff, since now
 478          * local->scan_req is assigned and other callers
 479          * will abort their scan attempts.
 480          *
 481          * This avoids getting a scan_mtx -> iflist_mtx
 482          * dependency, so that the scan completed calls
 483          * have more locking freedom.
 484          */
 485
 486         ieee80211_recalc_idle(local);
 487         mutex_unlock(&local->scan_mtx);
 488
 489         if (local->ops->hw_scan) {
 490                 WARN_ON(!ieee80211_prep_hw_scan(local));
 491                 rc = drv_hw_scan(local, local->hw_scan_req);
 492         } else
 493                 rc = ieee80211_start_sw_scan(local);
 494
 495         mutex_lock(&local->scan_mtx);
 496
 497         if (rc) {
 498                 kfree(local->hw_scan_req);
 499                 local->hw_scan_req = NULL;
 500                 local->scanning = 0;
 501
 502                 ieee80211_recalc_idle(local);
 503
 504                 local->scan_req = NULL;
 505                 local->scan_sdata = NULL;
 506         }
 507
 508         return rc;
 509 }
 510
 511 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
 512                                          unsigned long *next_delay)
 513 {
 514         bool associated = false;
 515         struct ieee80211_sub_if_data *sdata;
 516
 517         /* if no more bands/channels left, complete scan and advance to the idle state */
 518         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 519                 ieee80211_scan_completed(&local->hw, false);
 520                 return 1;
 521         }
 522
 523         /* check if at least one STA interface is associated */
 524         mutex_lock(&local->iflist_mtx);
 525         list_for_each_entry(sdata, &local->interfaces, list) {
 526                 if (!ieee80211_sdata_running(sdata))
 527                         continue;
 528
 529                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 530                         if (sdata->u.mgd.associated) {
 531                                 associated = true;
 532                                 break;
 533                         }
 534                 }
 535         }
 536         mutex_unlock(&local->iflist_mtx);
 537
 538         if (local->scan_channel) {
 539                 /*
 540                  * we're currently scanning a different channel, let's
 541                  * switch back to the operating channel now if at least
 542                  * one interface is associated. Otherwise just scan the
 543                  * next channel
 544                  */
 545                 if (associated)
 546                         local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
 547                 else
 548                         local->next_scan_state = SCAN_SET_CHANNEL;
 549         } else {
 550                 /*
 551                  * we're on the operating channel currently, let's
 552                  * leave that channel now to scan another one
 553                  */
 554                 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
 555         }
 556
 557         *next_delay = 0;
 558         return 0;
 559 }
 560
 561 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
 562                                                     unsigned long *next_delay)
 563 {
 564         struct ieee80211_sub_if_data *sdata;
 565
 566         /*
 567          * notify the AP about us leaving the channel and stop all STA interfaces
 568          */
 569         mutex_lock(&local->iflist_mtx);
 570         list_for_each_entry(sdata, &local->interfaces, list) {
 571                 if (!ieee80211_sdata_running(sdata))
 572                         continue;
 573
 574                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 575                         netif_stop_queue(sdata->dev);
 576                         if (sdata->u.mgd.associated)
 577                                 ieee80211_scan_ps_enable(sdata);
 578                 }
 579         }
 580         mutex_unlock(&local->iflist_mtx);
 581
 582         __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
 583
 584         /*
 585          * What if the nullfunc frames didn't arrive?
 586          */
 587         drv_flush(local, false);
 588         if (local->ops->flush)
 589                 *next_delay = 0;
 590         else
 591                 *next_delay = HZ / 10;
 592
 593         /* advance to the next channel to be scanned */
 594         local->next_scan_state = SCAN_SET_CHANNEL;
 595 }
 596
 597 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
 598                                                     unsigned long *next_delay)
 599 {
 600         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 601
 602         /* switch back to the operating channel */
 603         local->scan_channel = NULL;
 604         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 605
 606         /*
 607          * notify the AP about us being back and restart all STA interfaces
 608          */
 609         mutex_lock(&local->iflist_mtx);
 610         list_for_each_entry(sdata, &local->interfaces, list) {
 611                 if (!ieee80211_sdata_running(sdata))
 612                         continue;
 613
 614                 /* Tell AP we're back */
 615                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 616                         if (sdata->u.mgd.associated)
 617                                 ieee80211_scan_ps_disable(sdata);
 618                         netif_wake_queue(sdata->dev);
 619                 }
 620         }
 621         mutex_unlock(&local->iflist_mtx);
 622
 623         __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
 624
 625         *next_delay = HZ / 5;
 626         local->next_scan_state = SCAN_DECISION;
 627 }
 628
 629 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 630                                              unsigned long *next_delay)
 631 {
 632         int skip;
 633         struct ieee80211_channel *chan;
 634
 635         skip = 0;
 636         chan = local->scan_req->channels[local->scan_channel_idx];
 637
 638         local->scan_channel = chan;
 639         if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 640                 skip = 1;
 641
 642         /* advance state machine to next channel/band */
 643         local->scan_channel_idx++;
 644
 645         if (skip) {
 646                 /* if we skip this channel return to the decision state */
 647                 local->next_scan_state = SCAN_DECISION;
 648                 return;
 649         }
 650
 651         /*
 652          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 653          * (which unfortunately doesn't say _why_ step a) is done,
 654          * but it waits for the probe delay or until a frame is
 655          * received - and the received frame would update the NAV).
 656          * For now, we do not support waiting until a frame is
 657          * received.
 658          *
 659          * In any case, it is not necessary for a passive scan.
 660          */
 661         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 662             !local->scan_req->n_ssids) {
 663                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 664                 local->next_scan_state = SCAN_DECISION;
 665                 return;
 666         }
 667
 668         /* active scan, send probes */
 669         *next_delay = IEEE80211_PROBE_DELAY;
 670         local->next_scan_state = SCAN_SEND_PROBE;
 671 }
 672
 673 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 674                                             unsigned long *next_delay)
 675 {
 676         int i;
 677         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 678
 679         for (i = 0; i < local->scan_req->n_ssids; i++)
 680                 ieee80211_send_probe_req(
 681                         sdata, NULL,
 682                         local->scan_req->ssids[i].ssid,
 683                         local->scan_req->ssids[i].ssid_len,
 684                         local->scan_req->ie, local->scan_req->ie_len);
 685
 686         /*
 687          * After sending probe requests, wait for probe responses
 688          * on the channel.
 689          */
 690         *next_delay = IEEE80211_CHANNEL_TIME;
 691         local->next_scan_state = SCAN_DECISION;
 692 }
 693
 694 void ieee80211_scan_work(struct work_struct *work)
 695 {
 696         struct ieee80211_local *local =
 697                 container_of(work, struct ieee80211_local, scan_work.work);
 698         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 699         unsigned long next_delay = 0;
 700
 701         mutex_lock(&local->scan_mtx);
 702         if (!sdata || !local->scan_req) {
 703                 mutex_unlock(&local->scan_mtx);
 704                 return;
 705         }
 706
 707         if (local->hw_scan_req) {
 708                 int rc = drv_hw_scan(local, local->hw_scan_req);
 709                 mutex_unlock(&local->scan_mtx);
 710                 if (rc)
 711                         ieee80211_scan_completed(&local->hw, true);
 712                 return;
 713         }
 714
 715         if (local->scan_req && !local->scanning) {
 716                 struct cfg80211_scan_request *req = local->scan_req;
 717                 int rc;
 718
 719                 local->scan_req = NULL;
 720                 local->scan_sdata = NULL;
 721
 722                 rc = __ieee80211_start_scan(sdata, req);
 723                 mutex_unlock(&local->scan_mtx);
 724
 725                 if (rc)
 726                         ieee80211_scan_completed(&local->hw, true);
 727                 return;
 728         }
 729
 730         mutex_unlock(&local->scan_mtx);
 731
 732         /*
 733          * Avoid re-scheduling when the sdata is going away.
 734          */
 735         if (!ieee80211_sdata_running(sdata)) {
 736                 ieee80211_scan_completed(&local->hw, true);
 737                 return;
 738         }
 739
 740         /*
 741          * as long as no delay is required advance immediately
 742          * without scheduling a new work
 743          */
 744         do {
 745                 switch (local->next_scan_state) {
 746                 case SCAN_DECISION:
 747                         if (ieee80211_scan_state_decision(local, &next_delay))
 748                                 return;
 749                         break;
 750                 case SCAN_SET_CHANNEL:
 751                         ieee80211_scan_state_set_channel(local, &next_delay);
 752                         break;
 753                 case SCAN_SEND_PROBE:
 754                         ieee80211_scan_state_send_probe(local, &next_delay);
 755                         break;
 756                 case SCAN_LEAVE_OPER_CHANNEL:
 757                         ieee80211_scan_state_leave_oper_channel(local, &next_delay);
 758                         break;
 759                 case SCAN_ENTER_OPER_CHANNEL:
 760                         ieee80211_scan_state_enter_oper_channel(local, &next_delay);
 761                         break;
 762                 }
 763         } while (next_delay == 0);
 764
 765         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
 766 }
 767
 768 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 769                            struct cfg80211_scan_request *req)
 770 {
 771         int res;
 772
 773         mutex_lock(&sdata->local->scan_mtx);
 774         res = __ieee80211_start_scan(sdata, req);
 775         mutex_unlock(&sdata->local->scan_mtx);
 776
 777         return res;
 778 }
 779
 780 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 781                                     const u8 *ssid, u8 ssid_len)
 782 {
 783         struct ieee80211_local *local = sdata->local;
 784         int ret = -EBUSY;
 785
 786         mutex_lock(&local->scan_mtx);
 787
 788         /* busy scanning */
 789         if (local->scan_req)
 790                 goto unlock;
 791
 792         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 793         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 794
 795         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 796  unlock:
 797         mutex_unlock(&local->scan_mtx);
 798         return ret;
 799 }
 800
 801 void ieee80211_scan_cancel(struct ieee80211_local *local)
 802 {
 803         bool abortscan;
 804
 805         cancel_delayed_work_sync(&local->scan_work);
 806
 807         /*
 808          * Only call this function when a scan can't be
 809          * queued -- mostly at suspend under RTNL.
 810          */
 811         mutex_lock(&local->scan_mtx);
 812         abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
 813                     (!local->scanning && local->scan_req);
 814         mutex_unlock(&local->scan_mtx);
 815
 816         if (abortscan)
 817                 ieee80211_scan_completed(&local->hw, true);
 818 }