SAFE public projects git trees. - safe/jmp/linux-2.6/blob - net/mac80211/scan.c

   1 /*
   2  * Scanning implementation
   3  *
   4  * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
   5  * Copyright 2004, Instant802 Networks, Inc.
   6  * Copyright 2005, Devicescape Software, Inc.
   7  * Copyright 2006-2007  Jiri Benc <jbenc@suse.cz>
   8  * Copyright 2007, Michael Wu <flamingice@sourmilk.net>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  */
  14
  15 #include <linux/if_arp.h>
  16 #include <linux/rtnetlink.h>
  17 #include <linux/pm_qos_params.h>
  18 #include <net/sch_generic.h>
  19 #include <net/mac80211.h>
  20
  21 #include "ieee80211_i.h"
  22 #include "driver-ops.h"
  23 #include "mesh.h"
  24
  25 #define IEEE80211_PROBE_DELAY (HZ / 33)
  26 #define IEEE80211_CHANNEL_TIME (HZ / 33)
  27 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
  28
  29 struct ieee80211_bss *
  30 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
  31                      u8 *ssid, u8 ssid_len)
  32 {
  33         struct cfg80211_bss *cbss;
  34
  35         cbss = cfg80211_get_bss(local->hw.wiphy,
  36                                 ieee80211_get_channel(local->hw.wiphy, freq),
  37                                 bssid, ssid, ssid_len, 0, 0);
  38         if (!cbss)
  39                 return NULL;
  40         return (void *)cbss->priv;
  41 }
  42
  43 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
  44 {
  45         struct ieee80211_bss *bss = (void *)cbss->priv;
  46
  47         kfree(bss_mesh_id(bss));
  48         kfree(bss_mesh_cfg(bss));
  49 }
  50
  51 void ieee80211_rx_bss_put(struct ieee80211_local *local,
  52                           struct ieee80211_bss *bss)
  53 {
  54         if (!bss)
  55                 return;
  56         cfg80211_put_bss(container_of((void *)bss, struct cfg80211_bss, priv));
  57 }
  58
  59 static bool is_uapsd_supported(struct ieee802_11_elems *elems)
  60 {
  61         u8 qos_info;
  62
  63         if (elems->wmm_info && elems->wmm_info_len == 7
  64             && elems->wmm_info[5] == 1)
  65                 qos_info = elems->wmm_info[6];
  66         else if (elems->wmm_param && elems->wmm_param_len == 24
  67                  && elems->wmm_param[5] == 1)
  68                 qos_info = elems->wmm_param[6];
  69         else
  70                 /* no valid wmm information or parameter element found */
  71                 return false;
  72
  73         return qos_info & IEEE80211_WMM_IE_AP_QOSINFO_UAPSD;
  74 }
  75
  76 struct ieee80211_bss *
  77 ieee80211_bss_info_update(struct ieee80211_local *local,
  78                           struct ieee80211_rx_status *rx_status,
  79                           struct ieee80211_mgmt *mgmt,
  80                           size_t len,
  81                           struct ieee802_11_elems *elems,
  82                           struct ieee80211_channel *channel,
  83                           bool beacon)
  84 {
  85         struct cfg80211_bss *cbss;
  86         struct ieee80211_bss *bss;
  87         int clen;
  88         s32 signal = 0;
  89
  90         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
  91                 signal = rx_status->signal * 100;
  92         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
  93                 signal = (rx_status->signal * 100) / local->hw.max_signal;
  94
  95         cbss = cfg80211_inform_bss_frame(local->hw.wiphy, channel,
  96                                          mgmt, len, signal, GFP_ATOMIC);
  97
  98         if (!cbss)
  99                 return NULL;
 100
 101         cbss->free_priv = ieee80211_rx_bss_free;
 102         bss = (void *)cbss->priv;
 103
 104         /* save the ERP value so that it is available at association time */
 105         if (elems->erp_info && elems->erp_info_len >= 1) {
 106                 bss->erp_value = elems->erp_info[0];
 107                 bss->has_erp_value = 1;
 108         }
 109
 110         if (elems->tim) {
 111                 struct ieee80211_tim_ie *tim_ie =
 112                         (struct ieee80211_tim_ie *)elems->tim;
 113                 bss->dtim_period = tim_ie->dtim_period;
 114         }
 115
 116         bss->supp_rates_len = 0;
 117         if (elems->supp_rates) {
 118                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 119                 if (clen > elems->supp_rates_len)
 120                         clen = elems->supp_rates_len;
 121                 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
 122                        clen);
 123                 bss->supp_rates_len += clen;
 124         }
 125         if (elems->ext_supp_rates) {
 126                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 127                 if (clen > elems->ext_supp_rates_len)
 128                         clen = elems->ext_supp_rates_len;
 129                 memcpy(&bss->supp_rates[bss->supp_rates_len],
 130                        elems->ext_supp_rates, clen);
 131                 bss->supp_rates_len += clen;
 132         }
 133
 134         bss->wmm_used = elems->wmm_param || elems->wmm_info;
 135         bss->uapsd_supported = is_uapsd_supported(elems);
 136
 137         if (!beacon)
 138                 bss->last_probe_resp = jiffies;
 139
 140         return bss;
 141 }
 142
 143 ieee80211_rx_result
 144 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
 145 {
 146         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
 147         struct ieee80211_mgmt *mgmt;
 148         struct ieee80211_bss *bss;
 149         u8 *elements;
 150         struct ieee80211_channel *channel;
 151         size_t baselen;
 152         int freq;
 153         __le16 fc;
 154         bool presp, beacon = false;
 155         struct ieee802_11_elems elems;
 156
 157         if (skb->len < 2)
 158                 return RX_DROP_UNUSABLE;
 159
 160         mgmt = (struct ieee80211_mgmt *) skb->data;
 161         fc = mgmt->frame_control;
 162
 163         if (ieee80211_is_ctl(fc))
 164                 return RX_CONTINUE;
 165
 166         if (skb->len < 24)
 167                 return RX_DROP_MONITOR;
 168
 169         presp = ieee80211_is_probe_resp(fc);
 170         if (presp) {
 171                 /* ignore ProbeResp to foreign address */
 172                 if (memcmp(mgmt->da, sdata->vif.addr, ETH_ALEN))
 173                         return RX_DROP_MONITOR;
 174
 175                 presp = true;
 176                 elements = mgmt->u.probe_resp.variable;
 177                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 178         } else {
 179                 beacon = ieee80211_is_beacon(fc);
 180                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 181                 elements = mgmt->u.beacon.variable;
 182         }
 183
 184         if (!presp && !beacon)
 185                 return RX_CONTINUE;
 186
 187         if (baselen > skb->len)
 188                 return RX_DROP_MONITOR;
 189
 190         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
 191
 192         if (elems.ds_params && elems.ds_params_len == 1)
 193                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
 194         else
 195                 freq = rx_status->freq;
 196
 197         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
 198
 199         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 200                 return RX_DROP_MONITOR;
 201
 202         bss = ieee80211_bss_info_update(sdata->local, rx_status,
 203                                         mgmt, skb->len, &elems,
 204                                         channel, beacon);
 205         if (bss)
 206                 ieee80211_rx_bss_put(sdata->local, bss);
 207
 208         dev_kfree_skb(skb);
 209         return RX_QUEUED;
 210 }
 211
 212 /* return false if no more work */
 213 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 214 {
 215         struct cfg80211_scan_request *req = local->scan_req;
 216         enum ieee80211_band band;
 217         int i, ielen, n_chans;
 218
 219         do {
 220                 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
 221                         return false;
 222
 223                 band = local->hw_scan_band;
 224                 n_chans = 0;
 225                 for (i = 0; i < req->n_channels; i++) {
 226                         if (req->channels[i]->band == band) {
 227                                 local->hw_scan_req->channels[n_chans] =
 228                                                         req->channels[i];
 229                                 n_chans++;
 230                         }
 231                 }
 232
 233                 local->hw_scan_band++;
 234         } while (!n_chans);
 235
 236         local->hw_scan_req->n_channels = n_chans;
 237
 238         ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
 239                                          req->ie, req->ie_len, band);
 240         local->hw_scan_req->ie_len = ielen;
 241
 242         return true;
 243 }
 244
 245 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 246 {
 247         struct ieee80211_local *local = hw_to_local(hw);
 248         bool was_hw_scan;
 249
 250         mutex_lock(&local->scan_mtx);
 251
 252         /*
 253          * It's ok to abort a not-yet-running scan (that
 254          * we have one at all will be verified by checking
 255          * local->scan_req next), but not to complete it
 256          * successfully.
 257          */
 258         if (WARN_ON(!local->scanning && !aborted))
 259                 aborted = true;
 260
 261         if (WARN_ON(!local->scan_req)) {
 262                 mutex_unlock(&local->scan_mtx);
 263                 return;
 264         }
 265
 266         was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 267         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 268                 ieee80211_queue_delayed_work(&local->hw,
 269                                              &local->scan_work, 0);
 270                 mutex_unlock(&local->scan_mtx);
 271                 return;
 272         }
 273
 274         kfree(local->hw_scan_req);
 275         local->hw_scan_req = NULL;
 276
 277         if (local->scan_req != local->int_scan_req)
 278                 cfg80211_scan_done(local->scan_req, aborted);
 279         local->scan_req = NULL;
 280         local->scan_sdata = NULL;
 281
 282         local->scanning = 0;
 283         local->scan_channel = NULL;
 284
 285         /* we only have to protect scan_req and hw/sw scan */
 286         mutex_unlock(&local->scan_mtx);
 287
 288         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 289         if (was_hw_scan)
 290                 goto done;
 291
 292         ieee80211_configure_filter(local);
 293
 294         drv_sw_scan_complete(local);
 295
 296         ieee80211_offchannel_return(local, true);
 297
 298  done:
 299         ieee80211_recalc_idle(local);
 300         ieee80211_mlme_notify_scan_completed(local);
 301         ieee80211_ibss_notify_scan_completed(local);
 302         ieee80211_mesh_notify_scan_completed(local);
 303         ieee80211_queue_work(&local->hw, &local->work_work);
 304 }
 305 EXPORT_SYMBOL(ieee80211_scan_completed);
 306
 307 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 308 {
 309         /*
 310          * Hardware/driver doesn't support hw_scan, so use software
 311          * scanning instead. First send a nullfunc frame with power save
 312          * bit on so that AP will buffer the frames for us while we are not
 313          * listening, then send probe requests to each channel and wait for
 314          * the responses. After all channels are scanned, tune back to the
 315          * original channel and send a nullfunc frame with power save bit
 316          * off to trigger the AP to send us all the buffered frames.
 317          *
 318          * Note that while local->sw_scanning is true everything else but
 319          * nullfunc frames and probe requests will be dropped in
 320          * ieee80211_tx_h_check_assoc().
 321          */
 322         drv_sw_scan_start(local);
 323
 324         ieee80211_offchannel_stop_beaconing(local);
 325
 326         local->leave_oper_channel_time = 0;
 327         local->next_scan_state = SCAN_DECISION;
 328         local->scan_channel_idx = 0;
 329
 330         drv_flush(local, false);
 331
 332         ieee80211_configure_filter(local);
 333
 334         ieee80211_queue_delayed_work(&local->hw,
 335                                      &local->scan_work,
 336                                      IEEE80211_CHANNEL_TIME);
 337
 338         return 0;
 339 }
 340
 341
 342 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 343                                   struct cfg80211_scan_request *req)
 344 {
 345         struct ieee80211_local *local = sdata->local;
 346         int rc;
 347
 348         if (local->scan_req)
 349                 return -EBUSY;
 350
 351         if (!list_empty(&local->work_list)) {
 352                 /* wait for the work to finish/time out */
 353                 local->scan_req = req;
 354                 local->scan_sdata = sdata;
 355                 return 0;
 356         }
 357
 358         if (local->ops->hw_scan) {
 359                 u8 *ies;
 360
 361                 local->hw_scan_req = kmalloc(
 362                                 sizeof(*local->hw_scan_req) +
 363                                 req->n_channels * sizeof(req->channels[0]) +
 364                                 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
 365                                 req->ie_len, GFP_KERNEL);
 366                 if (!local->hw_scan_req)
 367                         return -ENOMEM;
 368
 369                 local->hw_scan_req->ssids = req->ssids;
 370                 local->hw_scan_req->n_ssids = req->n_ssids;
 371                 ies = (u8 *)local->hw_scan_req +
 372                         sizeof(*local->hw_scan_req) +
 373                         req->n_channels * sizeof(req->channels[0]);
 374                 local->hw_scan_req->ie = ies;
 375
 376                 local->hw_scan_band = 0;
 377
 378                 /*
 379                  * After allocating local->hw_scan_req, we must
 380                  * go through until ieee80211_prep_hw_scan(), so
 381                  * anything that might be changed here and leave
 382                  * this function early must not go after this
 383                  * allocation.
 384                  */
 385         }
 386
 387         local->scan_req = req;
 388         local->scan_sdata = sdata;
 389
 390         if (local->ops->hw_scan)
 391                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 392         else
 393                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 394
 395         /*
 396          * Kicking off the scan need not be protected,
 397          * only the scan variable stuff, since now
 398          * local->scan_req is assigned and other callers
 399          * will abort their scan attempts.
 400          *
 401          * This avoids too many locking dependencies
 402          * so that the scan completed calls have more
 403          * locking freedom.
 404          */
 405
 406         ieee80211_recalc_idle(local);
 407         mutex_unlock(&local->scan_mtx);
 408
 409         if (local->ops->hw_scan) {
 410                 WARN_ON(!ieee80211_prep_hw_scan(local));
 411                 rc = drv_hw_scan(local, local->hw_scan_req);
 412         } else
 413                 rc = ieee80211_start_sw_scan(local);
 414
 415         mutex_lock(&local->scan_mtx);
 416
 417         if (rc) {
 418                 kfree(local->hw_scan_req);
 419                 local->hw_scan_req = NULL;
 420                 local->scanning = 0;
 421
 422                 ieee80211_recalc_idle(local);
 423
 424                 local->scan_req = NULL;
 425                 local->scan_sdata = NULL;
 426         }
 427
 428         return rc;
 429 }
 430
 431 static unsigned long
 432 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
 433 {
 434         /*
 435          * TODO: channel switching also consumes quite some time,
 436          * add that delay as well to get a better estimation
 437          */
 438         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN)
 439                 return IEEE80211_PASSIVE_CHANNEL_TIME;
 440         return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
 441 }
 442
 443 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
 444                                          unsigned long *next_delay)
 445 {
 446         bool associated = false;
 447         bool tx_empty = true;
 448         bool bad_latency;
 449         bool listen_int_exceeded;
 450         unsigned long min_beacon_int = 0;
 451         struct ieee80211_sub_if_data *sdata;
 452         struct ieee80211_channel *next_chan;
 453
 454         /* if no more bands/channels left, complete scan and advance to the idle state */
 455         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 456                 ieee80211_scan_completed(&local->hw, false);
 457                 return 1;
 458         }
 459
 460         /*
 461          * check if at least one STA interface is associated,
 462          * check if at least one STA interface has pending tx frames
 463          * and grab the lowest used beacon interval
 464          */
 465         mutex_lock(&local->iflist_mtx);
 466         list_for_each_entry(sdata, &local->interfaces, list) {
 467                 if (!ieee80211_sdata_running(sdata))
 468                         continue;
 469
 470                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 471                         if (sdata->u.mgd.associated) {
 472                                 associated = true;
 473
 474                                 if (sdata->vif.bss_conf.beacon_int <
 475                                     min_beacon_int || min_beacon_int == 0)
 476                                         min_beacon_int =
 477                                                 sdata->vif.bss_conf.beacon_int;
 478
 479                                 if (!qdisc_all_tx_empty(sdata->dev)) {
 480                                         tx_empty = false;
 481                                         break;
 482                                 }
 483                         }
 484                 }
 485         }
 486         mutex_unlock(&local->iflist_mtx);
 487
 488         if (local->scan_channel) {
 489                 /*
 490                  * we're currently scanning a different channel, let's
 491                  * see if we can scan another channel without interfering
 492                  * with the current traffic situation.
 493                  *
 494                  * Since we don't know if the AP has pending frames for us
 495                  * we can only check for our tx queues and use the current
 496                  * pm_qos requirements for rx. Hence, if no tx traffic occurs
 497                  * at all we will scan as many channels in a row as the pm_qos
 498                  * latency allows us to. Additionally we also check for the
 499                  * currently negotiated listen interval to prevent losing
 500                  * frames unnecessarily.
 501                  *
 502                  * Otherwise switch back to the operating channel.
 503                  */
 504                 next_chan = local->scan_req->channels[local->scan_channel_idx];
 505
 506                 bad_latency = time_after(jiffies +
 507                                 ieee80211_scan_get_channel_time(next_chan),
 508                                 local->leave_oper_channel_time +
 509                                 usecs_to_jiffies(pm_qos_requirement(PM_QOS_NETWORK_LATENCY)));
 510
 511                 listen_int_exceeded = time_after(jiffies +
 512                                 ieee80211_scan_get_channel_time(next_chan),
 513                                 local->leave_oper_channel_time +
 514                                 usecs_to_jiffies(min_beacon_int * 1024) *
 515                                 local->hw.conf.listen_interval);
 516
 517                 if (associated && ( !tx_empty || bad_latency ||
 518                     listen_int_exceeded))
 519                         local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
 520                 else
 521                         local->next_scan_state = SCAN_SET_CHANNEL;
 522         } else {
 523                 /*
 524                  * we're on the operating channel currently, let's
 525                  * leave that channel now to scan another one
 526                  */
 527                 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
 528         }
 529
 530         *next_delay = 0;
 531         return 0;
 532 }
 533
 534 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
 535                                                     unsigned long *next_delay)
 536 {
 537         ieee80211_offchannel_stop_station(local);
 538
 539         __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
 540
 541         /*
 542          * What if the nullfunc frames didn't arrive?
 543          */
 544         drv_flush(local, false);
 545         if (local->ops->flush)
 546                 *next_delay = 0;
 547         else
 548                 *next_delay = HZ / 10;
 549
 550         /* remember when we left the operating channel */
 551         local->leave_oper_channel_time = jiffies;
 552
 553         /* advance to the next channel to be scanned */
 554         local->next_scan_state = SCAN_SET_CHANNEL;
 555 }
 556
 557 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
 558                                                     unsigned long *next_delay)
 559 {
 560         /* switch back to the operating channel */
 561         local->scan_channel = NULL;
 562         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 563
 564         /*
 565          * Only re-enable station mode interface now; beaconing will be
 566          * re-enabled once the full scan has been completed.
 567          */
 568         ieee80211_offchannel_return(local, false);
 569
 570         __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
 571
 572         *next_delay = HZ / 5;
 573         local->next_scan_state = SCAN_DECISION;
 574 }
 575
 576 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 577                                              unsigned long *next_delay)
 578 {
 579         int skip;
 580         struct ieee80211_channel *chan;
 581
 582         skip = 0;
 583         chan = local->scan_req->channels[local->scan_channel_idx];
 584
 585         local->scan_channel = chan;
 586         if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 587                 skip = 1;
 588
 589         /* advance state machine to next channel/band */
 590         local->scan_channel_idx++;
 591
 592         if (skip) {
 593                 /* if we skip this channel return to the decision state */
 594                 local->next_scan_state = SCAN_DECISION;
 595                 return;
 596         }
 597
 598         /*
 599          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 600          * (which unfortunately doesn't say _why_ step a) is done,
 601          * but it waits for the probe delay or until a frame is
 602          * received - and the received frame would update the NAV).
 603          * For now, we do not support waiting until a frame is
 604          * received.
 605          *
 606          * In any case, it is not necessary for a passive scan.
 607          */
 608         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 609             !local->scan_req->n_ssids) {
 610                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 611                 local->next_scan_state = SCAN_DECISION;
 612                 return;
 613         }
 614
 615         /* active scan, send probes */
 616         *next_delay = IEEE80211_PROBE_DELAY;
 617         local->next_scan_state = SCAN_SEND_PROBE;
 618 }
 619
 620 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 621                                             unsigned long *next_delay)
 622 {
 623         int i;
 624         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 625
 626         for (i = 0; i < local->scan_req->n_ssids; i++)
 627                 ieee80211_send_probe_req(
 628                         sdata, NULL,
 629                         local->scan_req->ssids[i].ssid,
 630                         local->scan_req->ssids[i].ssid_len,
 631                         local->scan_req->ie, local->scan_req->ie_len);
 632
 633         /*
 634          * After sending probe requests, wait for probe responses
 635          * on the channel.
 636          */
 637         *next_delay = IEEE80211_CHANNEL_TIME;
 638         local->next_scan_state = SCAN_DECISION;
 639 }
 640
 641 void ieee80211_scan_work(struct work_struct *work)
 642 {
 643         struct ieee80211_local *local =
 644                 container_of(work, struct ieee80211_local, scan_work.work);
 645         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 646         unsigned long next_delay = 0;
 647
 648         mutex_lock(&local->scan_mtx);
 649         if (!sdata || !local->scan_req) {
 650                 mutex_unlock(&local->scan_mtx);
 651                 return;
 652         }
 653
 654         if (local->hw_scan_req) {
 655                 int rc = drv_hw_scan(local, local->hw_scan_req);
 656                 mutex_unlock(&local->scan_mtx);
 657                 if (rc)
 658                         ieee80211_scan_completed(&local->hw, true);
 659                 return;
 660         }
 661
 662         if (local->scan_req && !local->scanning) {
 663                 struct cfg80211_scan_request *req = local->scan_req;
 664                 int rc;
 665
 666                 local->scan_req = NULL;
 667                 local->scan_sdata = NULL;
 668
 669                 rc = __ieee80211_start_scan(sdata, req);
 670                 mutex_unlock(&local->scan_mtx);
 671
 672                 if (rc)
 673                         ieee80211_scan_completed(&local->hw, true);
 674                 return;
 675         }
 676
 677         mutex_unlock(&local->scan_mtx);
 678
 679         /*
 680          * Avoid re-scheduling when the sdata is going away.
 681          */
 682         if (!ieee80211_sdata_running(sdata)) {
 683                 ieee80211_scan_completed(&local->hw, true);
 684                 return;
 685         }
 686
 687         /*
 688          * as long as no delay is required advance immediately
 689          * without scheduling a new work
 690          */
 691         do {
 692                 switch (local->next_scan_state) {
 693                 case SCAN_DECISION:
 694                         if (ieee80211_scan_state_decision(local, &next_delay))
 695                                 return;
 696                         break;
 697                 case SCAN_SET_CHANNEL:
 698                         ieee80211_scan_state_set_channel(local, &next_delay);
 699                         break;
 700                 case SCAN_SEND_PROBE:
 701                         ieee80211_scan_state_send_probe(local, &next_delay);
 702                         break;
 703                 case SCAN_LEAVE_OPER_CHANNEL:
 704                         ieee80211_scan_state_leave_oper_channel(local, &next_delay);
 705                         break;
 706                 case SCAN_ENTER_OPER_CHANNEL:
 707                         ieee80211_scan_state_enter_oper_channel(local, &next_delay);
 708                         break;
 709                 }
 710         } while (next_delay == 0);
 711
 712         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
 713 }
 714
 715 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 716                            struct cfg80211_scan_request *req)
 717 {
 718         int res;
 719
 720         mutex_lock(&sdata->local->scan_mtx);
 721         res = __ieee80211_start_scan(sdata, req);
 722         mutex_unlock(&sdata->local->scan_mtx);
 723
 724         return res;
 725 }
 726
 727 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 728                                     const u8 *ssid, u8 ssid_len)
 729 {
 730         struct ieee80211_local *local = sdata->local;
 731         int ret = -EBUSY;
 732
 733         mutex_lock(&local->scan_mtx);
 734
 735         /* busy scanning */
 736         if (local->scan_req)
 737                 goto unlock;
 738
 739         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 740         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 741
 742         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 743  unlock:
 744         mutex_unlock(&local->scan_mtx);
 745         return ret;
 746 }
 747
 748 void ieee80211_scan_cancel(struct ieee80211_local *local)
 749 {
 750         bool abortscan;
 751
 752         cancel_delayed_work_sync(&local->scan_work);
 753
 754         /*
 755          * Only call this function when a scan can't be
 756          * queued -- mostly at suspend under RTNL.
 757          */
 758         mutex_lock(&local->scan_mtx);
 759         abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
 760                     (!local->scanning && local->scan_req);
 761         mutex_unlock(&local->scan_mtx);
 762
 763         if (abortscan)
 764                 ieee80211_scan_completed(&local->hw, true);
 765 }