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         struct cfg80211_bss *cbss;
  33
  34         cbss = cfg80211_get_bss(local->hw.wiphy,
  35                                 ieee80211_get_channel(local->hw.wiphy, freq),
  36                                 bssid, ssid, ssid_len, 0, 0);
  37         if (!cbss)
  38                 return NULL;
  39         return (void *)cbss->priv;
  40 }
  41
  42 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
  43 {
  44         struct ieee80211_bss *bss = (void *)cbss->priv;
  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         if (!bss)
  54                 return;
  55         cfg80211_put_bss(container_of((void *)bss, struct cfg80211_bss, priv));
  56 }
  57
  58 struct ieee80211_bss *
  59 ieee80211_bss_info_update(struct ieee80211_local *local,
  60                           struct ieee80211_rx_status *rx_status,
  61                           struct ieee80211_mgmt *mgmt,
  62                           size_t len,
  63                           struct ieee802_11_elems *elems,
  64                           struct ieee80211_channel *channel,
  65                           bool beacon)
  66 {
  67         struct cfg80211_bss *cbss;
  68         struct ieee80211_bss *bss;
  69         int clen;
  70         s32 signal = 0;
  71
  72         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
  73                 signal = rx_status->signal * 100;
  74         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
  75                 signal = (rx_status->signal * 100) / local->hw.max_signal;
  76
  77         cbss = cfg80211_inform_bss_frame(local->hw.wiphy, channel,
  78                                          mgmt, len, signal, GFP_ATOMIC);
  79
  80         if (!cbss)
  81                 return NULL;
  82
  83         cbss->free_priv = ieee80211_rx_bss_free;
  84         bss = (void *)cbss->priv;
  85
  86         /* save the ERP value so that it is available at association time */
  87         if (elems->erp_info && elems->erp_info_len >= 1) {
  88                 bss->erp_value = elems->erp_info[0];
  89                 bss->has_erp_value = 1;
  90         }
  91
  92         if (elems->tim) {
  93                 struct ieee80211_tim_ie *tim_ie =
  94                         (struct ieee80211_tim_ie *)elems->tim;
  95                 bss->dtim_period = tim_ie->dtim_period;
  96         }
  97
  98         /* set default value for buggy AP/no TIM element */
  99         if (bss->dtim_period == 0)
 100                 bss->dtim_period = 1;
 101
 102         bss->supp_rates_len = 0;
 103         if (elems->supp_rates) {
 104                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 105                 if (clen > elems->supp_rates_len)
 106                         clen = elems->supp_rates_len;
 107                 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
 108                        clen);
 109                 bss->supp_rates_len += clen;
 110         }
 111         if (elems->ext_supp_rates) {
 112                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 113                 if (clen > elems->ext_supp_rates_len)
 114                         clen = elems->ext_supp_rates_len;
 115                 memcpy(&bss->supp_rates[bss->supp_rates_len],
 116                        elems->ext_supp_rates, clen);
 117                 bss->supp_rates_len += clen;
 118         }
 119
 120         bss->wmm_used = elems->wmm_param || elems->wmm_info;
 121
 122         if (!beacon)
 123                 bss->last_probe_resp = jiffies;
 124
 125         return bss;
 126 }
 127
 128 ieee80211_rx_result
 129 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
 130 {
 131         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
 132         struct ieee80211_mgmt *mgmt;
 133         struct ieee80211_bss *bss;
 134         u8 *elements;
 135         struct ieee80211_channel *channel;
 136         size_t baselen;
 137         int freq;
 138         __le16 fc;
 139         bool presp, beacon = false;
 140         struct ieee802_11_elems elems;
 141
 142         if (skb->len < 2)
 143                 return RX_DROP_UNUSABLE;
 144
 145         mgmt = (struct ieee80211_mgmt *) skb->data;
 146         fc = mgmt->frame_control;
 147
 148         if (ieee80211_is_ctl(fc))
 149                 return RX_CONTINUE;
 150
 151         if (skb->len < 24)
 152                 return RX_DROP_MONITOR;
 153
 154         presp = ieee80211_is_probe_resp(fc);
 155         if (presp) {
 156                 /* ignore ProbeResp to foreign address */
 157                 if (memcmp(mgmt->da, sdata->vif.addr, ETH_ALEN))
 158                         return RX_DROP_MONITOR;
 159
 160                 presp = true;
 161                 elements = mgmt->u.probe_resp.variable;
 162                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 163         } else {
 164                 beacon = ieee80211_is_beacon(fc);
 165                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 166                 elements = mgmt->u.beacon.variable;
 167         }
 168
 169         if (!presp && !beacon)
 170                 return RX_CONTINUE;
 171
 172         if (baselen > skb->len)
 173                 return RX_DROP_MONITOR;
 174
 175         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
 176
 177         if (elems.ds_params && elems.ds_params_len == 1)
 178                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
 179         else
 180                 freq = rx_status->freq;
 181
 182         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
 183
 184         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 185                 return RX_DROP_MONITOR;
 186
 187         bss = ieee80211_bss_info_update(sdata->local, rx_status,
 188                                         mgmt, skb->len, &elems,
 189                                         channel, beacon);
 190         if (bss)
 191                 ieee80211_rx_bss_put(sdata->local, bss);
 192
 193         dev_kfree_skb(skb);
 194         return RX_QUEUED;
 195 }
 196
 197 /* return false if no more work */
 198 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 199 {
 200         struct cfg80211_scan_request *req = local->scan_req;
 201         enum ieee80211_band band;
 202         int i, ielen, n_chans;
 203
 204         do {
 205                 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
 206                         return false;
 207
 208                 band = local->hw_scan_band;
 209                 n_chans = 0;
 210                 for (i = 0; i < req->n_channels; i++) {
 211                         if (req->channels[i]->band == band) {
 212                                 local->hw_scan_req->channels[n_chans] =
 213                                                         req->channels[i];
 214                                 n_chans++;
 215                         }
 216                 }
 217
 218                 local->hw_scan_band++;
 219         } while (!n_chans);
 220
 221         local->hw_scan_req->n_channels = n_chans;
 222
 223         ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
 224                                          req->ie, req->ie_len, band);
 225         local->hw_scan_req->ie_len = ielen;
 226
 227         return true;
 228 }
 229
 230 /*
 231  * inform AP that we will go to sleep so that it will buffer the frames
 232  * while we scan
 233  */
 234 static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
 235 {
 236         struct ieee80211_local *local = sdata->local;
 237
 238         local->scan_ps_enabled = false;
 239
 240         /* FIXME: what to do when local->pspolling is true? */
 241
 242         del_timer_sync(&local->dynamic_ps_timer);
 243         cancel_work_sync(&local->dynamic_ps_enable_work);
 244
 245         if (local->hw.conf.flags & IEEE80211_CONF_PS) {
 246                 local->scan_ps_enabled = true;
 247                 local->hw.conf.flags &= ~IEEE80211_CONF_PS;
 248                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
 249         }
 250
 251         if (!(local->scan_ps_enabled) ||
 252             !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
 253                 /*
 254                  * If power save was enabled, no need to send a nullfunc
 255                  * frame because AP knows that we are sleeping. But if the
 256                  * hardware is creating the nullfunc frame for power save
 257                  * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
 258                  * enabled) and power save was enabled, the firmware just
 259                  * sent a null frame with power save disabled. So we need
 260                  * to send a new nullfunc frame to inform the AP that we
 261                  * are again sleeping.
 262                  */
 263                 ieee80211_send_nullfunc(local, sdata, 1);
 264 }
 265
 266 /* inform AP that we are awake again, unless power save is enabled */
 267 static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
 268 {
 269         struct ieee80211_local *local = sdata->local;
 270
 271         if (!local->ps_sdata)
 272                 ieee80211_send_nullfunc(local, sdata, 0);
 273         else if (local->scan_ps_enabled) {
 274                 /*
 275                  * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
 276                  * will send a nullfunc frame with the powersave bit set
 277                  * even though the AP already knows that we are sleeping.
 278                  * This could be avoided by sending a null frame with power
 279                  * save bit disabled before enabling the power save, but
 280                  * this doesn't gain anything.
 281                  *
 282                  * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
 283                  * to send a nullfunc frame because AP already knows that
 284                  * we are sleeping, let's just enable power save mode in
 285                  * hardware.
 286                  */
 287                 local->hw.conf.flags |= IEEE80211_CONF_PS;
 288                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
 289         } else if (local->hw.conf.dynamic_ps_timeout > 0) {
 290                 /*
 291                  * If IEEE80211_CONF_PS was not set and the dynamic_ps_timer
 292                  * had been running before leaving the operating channel,
 293                  * restart the timer now and send a nullfunc frame to inform
 294                  * the AP that we are awake.
 295                  */
 296                 ieee80211_send_nullfunc(local, sdata, 0);
 297                 mod_timer(&local->dynamic_ps_timer, jiffies +
 298                           msecs_to_jiffies(local->hw.conf.dynamic_ps_timeout));
 299         }
 300 }
 301
 302 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 303 {
 304         struct ieee80211_local *local = hw_to_local(hw);
 305         struct ieee80211_sub_if_data *sdata;
 306         bool was_hw_scan;
 307
 308         mutex_lock(&local->scan_mtx);
 309
 310         /*
 311          * It's ok to abort a not-yet-running scan (that
 312          * we have one at all will be verified by checking
 313          * local->scan_req next), but not to complete it
 314          * successfully.
 315          */
 316         if (WARN_ON(!local->scanning && !aborted))
 317                 aborted = true;
 318
 319         if (WARN_ON(!local->scan_req)) {
 320                 mutex_unlock(&local->scan_mtx);
 321                 return;
 322         }
 323
 324         was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 325         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 326                 ieee80211_queue_delayed_work(&local->hw,
 327                                              &local->scan_work, 0);
 328                 mutex_unlock(&local->scan_mtx);
 329                 return;
 330         }
 331
 332         kfree(local->hw_scan_req);
 333         local->hw_scan_req = NULL;
 334
 335         if (local->scan_req != local->int_scan_req)
 336                 cfg80211_scan_done(local->scan_req, aborted);
 337         local->scan_req = NULL;
 338         local->scan_sdata = NULL;
 339
 340         local->scanning = 0;
 341         local->scan_channel = NULL;
 342
 343         /* we only have to protect scan_req and hw/sw scan */
 344         mutex_unlock(&local->scan_mtx);
 345
 346         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 347         if (was_hw_scan)
 348                 goto done;
 349
 350         ieee80211_configure_filter(local);
 351
 352         drv_sw_scan_complete(local);
 353
 354         mutex_lock(&local->iflist_mtx);
 355         list_for_each_entry(sdata, &local->interfaces, list) {
 356                 if (!ieee80211_sdata_running(sdata))
 357                         continue;
 358
 359                 /* Tell AP we're back */
 360                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 361                         if (sdata->u.mgd.associated) {
 362                                 ieee80211_scan_ps_disable(sdata);
 363                                 netif_wake_queue(sdata->dev);
 364                         }
 365                 } else
 366                         netif_wake_queue(sdata->dev);
 367
 368                 /* re-enable beaconing */
 369                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
 370                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
 371                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 372                         ieee80211_bss_info_change_notify(
 373                                 sdata, BSS_CHANGED_BEACON_ENABLED);
 374         }
 375         mutex_unlock(&local->iflist_mtx);
 376
 377  done:
 378         ieee80211_recalc_idle(local);
 379         ieee80211_mlme_notify_scan_completed(local);
 380         ieee80211_ibss_notify_scan_completed(local);
 381         ieee80211_mesh_notify_scan_completed(local);
 382 }
 383 EXPORT_SYMBOL(ieee80211_scan_completed);
 384
 385 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 386 {
 387         struct ieee80211_sub_if_data *sdata;
 388
 389         /*
 390          * Hardware/driver doesn't support hw_scan, so use software
 391          * scanning instead. First send a nullfunc frame with power save
 392          * bit on so that AP will buffer the frames for us while we are not
 393          * listening, then send probe requests to each channel and wait for
 394          * the responses. After all channels are scanned, tune back to the
 395          * original channel and send a nullfunc frame with power save bit
 396          * off to trigger the AP to send us all the buffered frames.
 397          *
 398          * Note that while local->sw_scanning is true everything else but
 399          * nullfunc frames and probe requests will be dropped in
 400          * ieee80211_tx_h_check_assoc().
 401          */
 402         drv_sw_scan_start(local);
 403
 404         mutex_lock(&local->iflist_mtx);
 405         list_for_each_entry(sdata, &local->interfaces, list) {
 406                 if (!ieee80211_sdata_running(sdata))
 407                         continue;
 408
 409                 /* disable beaconing */
 410                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
 411                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
 412                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 413                         ieee80211_bss_info_change_notify(
 414                                 sdata, BSS_CHANGED_BEACON_ENABLED);
 415
 416                 /*
 417                  * only handle non-STA interfaces here, STA interfaces
 418                  * are handled in the scan state machine
 419                  */
 420                 if (sdata->vif.type != NL80211_IFTYPE_STATION)
 421                         netif_stop_queue(sdata->dev);
 422         }
 423         mutex_unlock(&local->iflist_mtx);
 424
 425         local->next_scan_state = SCAN_DECISION;
 426         local->scan_channel_idx = 0;
 427
 428         drv_flush(local, false);
 429
 430         ieee80211_configure_filter(local);
 431
 432         ieee80211_queue_delayed_work(&local->hw,
 433                                      &local->scan_work,
 434                                      IEEE80211_CHANNEL_TIME);
 435
 436         return 0;
 437 }
 438
 439
 440 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 441                                   struct cfg80211_scan_request *req)
 442 {
 443         struct ieee80211_local *local = sdata->local;
 444         int rc;
 445
 446         if (local->scan_req)
 447                 return -EBUSY;
 448
 449         if (local->ops->hw_scan) {
 450                 u8 *ies;
 451
 452                 local->hw_scan_req = kmalloc(
 453                                 sizeof(*local->hw_scan_req) +
 454                                 req->n_channels * sizeof(req->channels[0]) +
 455                                 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
 456                                 req->ie_len, GFP_KERNEL);
 457                 if (!local->hw_scan_req)
 458                         return -ENOMEM;
 459
 460                 local->hw_scan_req->ssids = req->ssids;
 461                 local->hw_scan_req->n_ssids = req->n_ssids;
 462                 ies = (u8 *)local->hw_scan_req +
 463                         sizeof(*local->hw_scan_req) +
 464                         req->n_channels * sizeof(req->channels[0]);
 465                 local->hw_scan_req->ie = ies;
 466
 467                 local->hw_scan_band = 0;
 468         }
 469
 470         local->scan_req = req;
 471         local->scan_sdata = sdata;
 472
 473         if (!list_empty(&local->work_list)) {
 474                 /* wait for the work to finish/time out */
 475                 return 0;
 476         }
 477
 478         if (local->ops->hw_scan)
 479                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 480         else
 481                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 482         /*
 483          * Kicking off the scan need not be protected,
 484          * only the scan variable stuff, since now
 485          * local->scan_req is assigned and other callers
 486          * will abort their scan attempts.
 487          *
 488          * This avoids getting a scan_mtx -> iflist_mtx
 489          * dependency, so that the scan completed calls
 490          * have more locking freedom.
 491          */
 492
 493         ieee80211_recalc_idle(local);
 494         mutex_unlock(&local->scan_mtx);
 495
 496         if (local->ops->hw_scan) {
 497                 WARN_ON(!ieee80211_prep_hw_scan(local));
 498                 rc = drv_hw_scan(local, local->hw_scan_req);
 499         } else
 500                 rc = ieee80211_start_sw_scan(local);
 501
 502         mutex_lock(&local->scan_mtx);
 503
 504         if (rc) {
 505                 kfree(local->hw_scan_req);
 506                 local->hw_scan_req = NULL;
 507                 local->scanning = 0;
 508
 509                 ieee80211_recalc_idle(local);
 510
 511                 local->scan_req = NULL;
 512                 local->scan_sdata = NULL;
 513         }
 514
 515         return rc;
 516 }
 517
 518 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
 519                                          unsigned long *next_delay)
 520 {
 521         bool associated = false;
 522         struct ieee80211_sub_if_data *sdata;
 523
 524         /* if no more bands/channels left, complete scan and advance to the idle state */
 525         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 526                 ieee80211_scan_completed(&local->hw, false);
 527                 return 1;
 528         }
 529
 530         /* check if at least one STA interface is associated */
 531         mutex_lock(&local->iflist_mtx);
 532         list_for_each_entry(sdata, &local->interfaces, list) {
 533                 if (!ieee80211_sdata_running(sdata))
 534                         continue;
 535
 536                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 537                         if (sdata->u.mgd.associated) {
 538                                 associated = true;
 539                                 break;
 540                         }
 541                 }
 542         }
 543         mutex_unlock(&local->iflist_mtx);
 544
 545         if (local->scan_channel) {
 546                 /*
 547                  * we're currently scanning a different channel, let's
 548                  * switch back to the operating channel now if at least
 549                  * one interface is associated. Otherwise just scan the
 550                  * next channel
 551                  */
 552                 if (associated)
 553                         local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
 554                 else
 555                         local->next_scan_state = SCAN_SET_CHANNEL;
 556         } else {
 557                 /*
 558                  * we're on the operating channel currently, let's
 559                  * leave that channel now to scan another one
 560                  */
 561                 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
 562         }
 563
 564         *next_delay = 0;
 565         return 0;
 566 }
 567
 568 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
 569                                                     unsigned long *next_delay)
 570 {
 571         struct ieee80211_sub_if_data *sdata;
 572
 573         /*
 574          * notify the AP about us leaving the channel and stop all STA interfaces
 575          */
 576         mutex_lock(&local->iflist_mtx);
 577         list_for_each_entry(sdata, &local->interfaces, list) {
 578                 if (!ieee80211_sdata_running(sdata))
 579                         continue;
 580
 581                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 582                         netif_stop_queue(sdata->dev);
 583                         if (sdata->u.mgd.associated)
 584                                 ieee80211_scan_ps_enable(sdata);
 585                 }
 586         }
 587         mutex_unlock(&local->iflist_mtx);
 588
 589         __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
 590
 591         /*
 592          * What if the nullfunc frames didn't arrive?
 593          */
 594         drv_flush(local, false);
 595         if (local->ops->flush)
 596                 *next_delay = 0;
 597         else
 598                 *next_delay = HZ / 10;
 599
 600         /* advance to the next channel to be scanned */
 601         local->next_scan_state = SCAN_SET_CHANNEL;
 602 }
 603
 604 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
 605                                                     unsigned long *next_delay)
 606 {
 607         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 608
 609         /* switch back to the operating channel */
 610         local->scan_channel = NULL;
 611         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 612
 613         /*
 614          * notify the AP about us being back and restart all STA interfaces
 615          */
 616         mutex_lock(&local->iflist_mtx);
 617         list_for_each_entry(sdata, &local->interfaces, list) {
 618                 if (!ieee80211_sdata_running(sdata))
 619                         continue;
 620
 621                 /* Tell AP we're back */
 622                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 623                         if (sdata->u.mgd.associated)
 624                                 ieee80211_scan_ps_disable(sdata);
 625                         netif_wake_queue(sdata->dev);
 626                 }
 627         }
 628         mutex_unlock(&local->iflist_mtx);
 629
 630         __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
 631
 632         *next_delay = HZ / 5;
 633         local->next_scan_state = SCAN_DECISION;
 634 }
 635
 636 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 637                                              unsigned long *next_delay)
 638 {
 639         int skip;
 640         struct ieee80211_channel *chan;
 641
 642         skip = 0;
 643         chan = local->scan_req->channels[local->scan_channel_idx];
 644
 645         local->scan_channel = chan;
 646         if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 647                 skip = 1;
 648
 649         /* advance state machine to next channel/band */
 650         local->scan_channel_idx++;
 651
 652         if (skip) {
 653                 /* if we skip this channel return to the decision state */
 654                 local->next_scan_state = SCAN_DECISION;
 655                 return;
 656         }
 657
 658         /*
 659          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 660          * (which unfortunately doesn't say _why_ step a) is done,
 661          * but it waits for the probe delay or until a frame is
 662          * received - and the received frame would update the NAV).
 663          * For now, we do not support waiting until a frame is
 664          * received.
 665          *
 666          * In any case, it is not necessary for a passive scan.
 667          */
 668         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 669             !local->scan_req->n_ssids) {
 670                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 671                 local->next_scan_state = SCAN_DECISION;
 672                 return;
 673         }
 674
 675         /* active scan, send probes */
 676         *next_delay = IEEE80211_PROBE_DELAY;
 677         local->next_scan_state = SCAN_SEND_PROBE;
 678 }
 679
 680 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 681                                             unsigned long *next_delay)
 682 {
 683         int i;
 684         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 685
 686         for (i = 0; i < local->scan_req->n_ssids; i++)
 687                 ieee80211_send_probe_req(
 688                         sdata, NULL,
 689                         local->scan_req->ssids[i].ssid,
 690                         local->scan_req->ssids[i].ssid_len,
 691                         local->scan_req->ie, local->scan_req->ie_len);
 692
 693         /*
 694          * After sending probe requests, wait for probe responses
 695          * on the channel.
 696          */
 697         *next_delay = IEEE80211_CHANNEL_TIME;
 698         local->next_scan_state = SCAN_DECISION;
 699 }
 700
 701 void ieee80211_scan_work(struct work_struct *work)
 702 {
 703         struct ieee80211_local *local =
 704                 container_of(work, struct ieee80211_local, scan_work.work);
 705         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 706         unsigned long next_delay = 0;
 707
 708         mutex_lock(&local->scan_mtx);
 709         if (!sdata || !local->scan_req) {
 710                 mutex_unlock(&local->scan_mtx);
 711                 return;
 712         }
 713
 714         if (local->hw_scan_req) {
 715                 int rc = drv_hw_scan(local, local->hw_scan_req);
 716                 mutex_unlock(&local->scan_mtx);
 717                 if (rc)
 718                         ieee80211_scan_completed(&local->hw, true);
 719                 return;
 720         }
 721
 722         if (local->scan_req && !local->scanning) {
 723                 struct cfg80211_scan_request *req = local->scan_req;
 724                 int rc;
 725
 726                 local->scan_req = NULL;
 727                 local->scan_sdata = NULL;
 728
 729                 rc = __ieee80211_start_scan(sdata, req);
 730                 mutex_unlock(&local->scan_mtx);
 731
 732                 if (rc)
 733                         ieee80211_scan_completed(&local->hw, true);
 734                 return;
 735         }
 736
 737         mutex_unlock(&local->scan_mtx);
 738
 739         /*
 740          * Avoid re-scheduling when the sdata is going away.
 741          */
 742         if (!ieee80211_sdata_running(sdata)) {
 743                 ieee80211_scan_completed(&local->hw, true);
 744                 return;
 745         }
 746
 747         /*
 748          * as long as no delay is required advance immediately
 749          * without scheduling a new work
 750          */
 751         do {
 752                 switch (local->next_scan_state) {
 753                 case SCAN_DECISION:
 754                         if (ieee80211_scan_state_decision(local, &next_delay))
 755                                 return;
 756                         break;
 757                 case SCAN_SET_CHANNEL:
 758                         ieee80211_scan_state_set_channel(local, &next_delay);
 759                         break;
 760                 case SCAN_SEND_PROBE:
 761                         ieee80211_scan_state_send_probe(local, &next_delay);
 762                         break;
 763                 case SCAN_LEAVE_OPER_CHANNEL:
 764                         ieee80211_scan_state_leave_oper_channel(local, &next_delay);
 765                         break;
 766                 case SCAN_ENTER_OPER_CHANNEL:
 767                         ieee80211_scan_state_enter_oper_channel(local, &next_delay);
 768                         break;
 769                 }
 770         } while (next_delay == 0);
 771
 772         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
 773 }
 774
 775 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 776                            struct cfg80211_scan_request *req)
 777 {
 778         int res;
 779
 780         mutex_lock(&sdata->local->scan_mtx);
 781         res = __ieee80211_start_scan(sdata, req);
 782         mutex_unlock(&sdata->local->scan_mtx);
 783
 784         return res;
 785 }
 786
 787 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 788                                     const u8 *ssid, u8 ssid_len)
 789 {
 790         struct ieee80211_local *local = sdata->local;
 791         int ret = -EBUSY;
 792
 793         mutex_lock(&local->scan_mtx);
 794
 795         /* busy scanning */
 796         if (local->scan_req)
 797                 goto unlock;
 798
 799         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 800         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 801
 802         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 803  unlock:
 804         mutex_unlock(&local->scan_mtx);
 805         return ret;
 806 }
 807
 808 void ieee80211_scan_cancel(struct ieee80211_local *local)
 809 {
 810         bool abortscan;
 811
 812         cancel_delayed_work_sync(&local->scan_work);
 813
 814         /*
 815          * Only call this function when a scan can't be
 816          * queued -- mostly at suspend under RTNL.
 817          */
 818         mutex_lock(&local->scan_mtx);
 819         abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
 820                     (!local->scanning && local->scan_req);
 821         mutex_unlock(&local->scan_mtx);
 822
 823         if (abortscan)
 824                 ieee80211_scan_completed(&local->hw, true);
 825 }