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 <linux/slab.h>
  20 #include <net/mac80211.h>
  21
  22 #include "ieee80211_i.h"
  23 #include "driver-ops.h"
  24 #include "mesh.h"
  25
  26 #define IEEE80211_PROBE_DELAY (HZ / 33)
  27 #define IEEE80211_CHANNEL_TIME (HZ / 33)
  28 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
  29
  30 struct ieee80211_bss *
  31 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
  32                      u8 *ssid, u8 ssid_len)
  33 {
  34         struct cfg80211_bss *cbss;
  35
  36         cbss = cfg80211_get_bss(local->hw.wiphy,
  37                                 ieee80211_get_channel(local->hw.wiphy, freq),
  38                                 bssid, ssid, ssid_len, 0, 0);
  39         if (!cbss)
  40                 return NULL;
  41         return (void *)cbss->priv;
  42 }
  43
  44 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
  45 {
  46         struct ieee80211_bss *bss = (void *)cbss->priv;
  47
  48         kfree(bss_mesh_id(bss));
  49         kfree(bss_mesh_cfg(bss));
  50 }
  51
  52 void ieee80211_rx_bss_put(struct ieee80211_local *local,
  53                           struct ieee80211_bss *bss)
  54 {
  55         if (!bss)
  56                 return;
  57         cfg80211_put_bss(container_of((void *)bss, struct cfg80211_bss, priv));
  58 }
  59
  60 static bool is_uapsd_supported(struct ieee802_11_elems *elems)
  61 {
  62         u8 qos_info;
  63
  64         if (elems->wmm_info && elems->wmm_info_len == 7
  65             && elems->wmm_info[5] == 1)
  66                 qos_info = elems->wmm_info[6];
  67         else if (elems->wmm_param && elems->wmm_param_len == 24
  68                  && elems->wmm_param[5] == 1)
  69                 qos_info = elems->wmm_param[6];
  70         else
  71                 /* no valid wmm information or parameter element found */
  72                 return false;
  73
  74         return qos_info & IEEE80211_WMM_IE_AP_QOSINFO_UAPSD;
  75 }
  76
  77 struct ieee80211_bss *
  78 ieee80211_bss_info_update(struct ieee80211_local *local,
  79                           struct ieee80211_rx_status *rx_status,
  80                           struct ieee80211_mgmt *mgmt,
  81                           size_t len,
  82                           struct ieee802_11_elems *elems,
  83                           struct ieee80211_channel *channel,
  84                           bool beacon)
  85 {
  86         struct cfg80211_bss *cbss;
  87         struct ieee80211_bss *bss;
  88         int clen, srlen;
  89         s32 signal = 0;
  90
  91         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
  92                 signal = rx_status->signal * 100;
  93         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
  94                 signal = (rx_status->signal * 100) / local->hw.max_signal;
  95
  96         cbss = cfg80211_inform_bss_frame(local->hw.wiphy, channel,
  97                                          mgmt, len, signal, GFP_ATOMIC);
  98
  99         if (!cbss)
 100                 return NULL;
 101
 102         cbss->free_priv = ieee80211_rx_bss_free;
 103         bss = (void *)cbss->priv;
 104
 105         /* save the ERP value so that it is available at association time */
 106         if (elems->erp_info && elems->erp_info_len >= 1) {
 107                 bss->erp_value = elems->erp_info[0];
 108                 bss->has_erp_value = 1;
 109         }
 110
 111         if (elems->tim) {
 112                 struct ieee80211_tim_ie *tim_ie =
 113                         (struct ieee80211_tim_ie *)elems->tim;
 114                 bss->dtim_period = tim_ie->dtim_period;
 115         }
 116
 117         /* If the beacon had no TIM IE, or it was invalid, use 1 */
 118         if (beacon && !bss->dtim_period)
 119                 bss->dtim_period = 1;
 120
 121         /* replace old supported rates if we get new values */
 122         srlen = 0;
 123         if (elems->supp_rates) {
 124                 clen = IEEE80211_MAX_SUPP_RATES;
 125                 if (clen > elems->supp_rates_len)
 126                         clen = elems->supp_rates_len;
 127                 memcpy(bss->supp_rates, elems->supp_rates, clen);
 128                 srlen += clen;
 129         }
 130         if (elems->ext_supp_rates) {
 131                 clen = IEEE80211_MAX_SUPP_RATES - srlen;
 132                 if (clen > elems->ext_supp_rates_len)
 133                         clen = elems->ext_supp_rates_len;
 134                 memcpy(bss->supp_rates + srlen, elems->ext_supp_rates, clen);
 135                 srlen += clen;
 136         }
 137         if (srlen)
 138                 bss->supp_rates_len = srlen;
 139
 140         bss->wmm_used = elems->wmm_param || elems->wmm_info;
 141         bss->uapsd_supported = is_uapsd_supported(elems);
 142
 143         if (!beacon)
 144                 bss->last_probe_resp = jiffies;
 145
 146         return bss;
 147 }
 148
 149 ieee80211_rx_result
 150 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
 151 {
 152         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
 153         struct ieee80211_mgmt *mgmt;
 154         struct ieee80211_bss *bss;
 155         u8 *elements;
 156         struct ieee80211_channel *channel;
 157         size_t baselen;
 158         int freq;
 159         __le16 fc;
 160         bool presp, beacon = false;
 161         struct ieee802_11_elems elems;
 162
 163         if (skb->len < 2)
 164                 return RX_DROP_UNUSABLE;
 165
 166         mgmt = (struct ieee80211_mgmt *) skb->data;
 167         fc = mgmt->frame_control;
 168
 169         if (ieee80211_is_ctl(fc))
 170                 return RX_CONTINUE;
 171
 172         if (skb->len < 24)
 173                 return RX_DROP_MONITOR;
 174
 175         presp = ieee80211_is_probe_resp(fc);
 176         if (presp) {
 177                 /* ignore ProbeResp to foreign address */
 178                 if (memcmp(mgmt->da, sdata->vif.addr, ETH_ALEN))
 179                         return RX_DROP_MONITOR;
 180
 181                 presp = true;
 182                 elements = mgmt->u.probe_resp.variable;
 183                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 184         } else {
 185                 beacon = ieee80211_is_beacon(fc);
 186                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 187                 elements = mgmt->u.beacon.variable;
 188         }
 189
 190         if (!presp && !beacon)
 191                 return RX_CONTINUE;
 192
 193         if (baselen > skb->len)
 194                 return RX_DROP_MONITOR;
 195
 196         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
 197
 198         if (elems.ds_params && elems.ds_params_len == 1)
 199                 freq = ieee80211_channel_to_frequency(elems.ds_params[0],
 200                                                       rx_status->band);
 201         else
 202                 freq = rx_status->freq;
 203
 204         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
 205
 206         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
 207                 return RX_DROP_MONITOR;
 208
 209         bss = ieee80211_bss_info_update(sdata->local, rx_status,
 210                                         mgmt, skb->len, &elems,
 211                                         channel, beacon);
 212         if (bss)
 213                 ieee80211_rx_bss_put(sdata->local, bss);
 214
 215         /* If we are on-operating-channel, and this packet is for the
 216          * current channel, pass the pkt on up the stack so that
 217          * the rest of the stack can make use of it.
 218          */
 219         if (ieee80211_cfg_on_oper_channel(sdata->local)
 220             && (channel == sdata->local->oper_channel))
 221                 return RX_CONTINUE;
 222
 223         dev_kfree_skb(skb);
 224         return RX_QUEUED;
 225 }
 226
 227 /* return false if no more work */
 228 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 229 {
 230         struct cfg80211_scan_request *req = local->scan_req;
 231         enum ieee80211_band band;
 232         int i, ielen, n_chans;
 233
 234         do {
 235                 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
 236                         return false;
 237
 238                 band = local->hw_scan_band;
 239                 n_chans = 0;
 240                 for (i = 0; i < req->n_channels; i++) {
 241                         if (req->channels[i]->band == band) {
 242                                 local->hw_scan_req->channels[n_chans] =
 243                                                         req->channels[i];
 244                                 n_chans++;
 245                         }
 246                 }
 247
 248                 local->hw_scan_band++;
 249         } while (!n_chans);
 250
 251         local->hw_scan_req->n_channels = n_chans;
 252
 253         ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
 254                                          req->ie, req->ie_len, band, (u32) -1,
 255                                          0);
 256         local->hw_scan_req->ie_len = ielen;
 257
 258         return true;
 259 }
 260
 261 static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted,
 262                                        bool was_hw_scan)
 263 {
 264         struct ieee80211_local *local = hw_to_local(hw);
 265         bool on_oper_chan;
 266         bool enable_beacons = false;
 267
 268         lockdep_assert_held(&local->mtx);
 269
 270         /*
 271          * It's ok to abort a not-yet-running scan (that
 272          * we have one at all will be verified by checking
 273          * local->scan_req next), but not to complete it
 274          * successfully.
 275          */
 276         if (WARN_ON(!local->scanning && !aborted))
 277                 aborted = true;
 278
 279         if (WARN_ON(!local->scan_req))
 280                 return;
 281
 282         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 283                 int rc = drv_hw_scan(local, local->scan_sdata, local->hw_scan_req);
 284                 if (rc == 0)
 285                         return;
 286         }
 287
 288         kfree(local->hw_scan_req);
 289         local->hw_scan_req = NULL;
 290
 291         if (local->scan_req != local->int_scan_req)
 292                 cfg80211_scan_done(local->scan_req, aborted);
 293         local->scan_req = NULL;
 294         local->scan_sdata = NULL;
 295
 296         local->scanning = 0;
 297         local->scan_channel = NULL;
 298
 299         on_oper_chan = ieee80211_cfg_on_oper_channel(local);
 300
 301         if (was_hw_scan || !on_oper_chan)
 302                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 303         else
 304                 /* Set power back to normal operating levels. */
 305                 ieee80211_hw_config(local, 0);
 306
 307         if (!was_hw_scan) {
 308                 bool on_oper_chan2;
 309                 ieee80211_configure_filter(local);
 310                 drv_sw_scan_complete(local);
 311                 on_oper_chan2 = ieee80211_cfg_on_oper_channel(local);
 312                 /* We should always be on-channel at this point. */
 313                 WARN_ON(!on_oper_chan2);
 314                 if (on_oper_chan2 && (on_oper_chan != on_oper_chan2))
 315                         enable_beacons = true;
 316
 317                 ieee80211_offchannel_return(local, enable_beacons, true);
 318         }
 319
 320         ieee80211_recalc_idle(local);
 321
 322         ieee80211_mlme_notify_scan_completed(local);
 323         ieee80211_ibss_notify_scan_completed(local);
 324         ieee80211_mesh_notify_scan_completed(local);
 325         ieee80211_queue_work(&local->hw, &local->work_work);
 326 }
 327
 328 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 329 {
 330         struct ieee80211_local *local = hw_to_local(hw);
 331
 332         trace_api_scan_completed(local, aborted);
 333
 334         set_bit(SCAN_COMPLETED, &local->scanning);
 335         if (aborted)
 336                 set_bit(SCAN_ABORTED, &local->scanning);
 337         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, 0);
 338 }
 339 EXPORT_SYMBOL(ieee80211_scan_completed);
 340
 341 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 342 {
 343         /*
 344          * Hardware/driver doesn't support hw_scan, so use software
 345          * scanning instead. First send a nullfunc frame with power save
 346          * bit on so that AP will buffer the frames for us while we are not
 347          * listening, then send probe requests to each channel and wait for
 348          * the responses. After all channels are scanned, tune back to the
 349          * original channel and send a nullfunc frame with power save bit
 350          * off to trigger the AP to send us all the buffered frames.
 351          *
 352          * Note that while local->sw_scanning is true everything else but
 353          * nullfunc frames and probe requests will be dropped in
 354          * ieee80211_tx_h_check_assoc().
 355          */
 356         drv_sw_scan_start(local);
 357
 358         local->leave_oper_channel_time = 0;
 359         local->next_scan_state = SCAN_DECISION;
 360         local->scan_channel_idx = 0;
 361
 362         /* We always want to use off-channel PS, even if we
 363          * are not really leaving oper-channel.  Don't
 364          * tell the AP though, as long as we are on-channel.
 365          */
 366         ieee80211_offchannel_enable_all_ps(local, false);
 367
 368         ieee80211_configure_filter(local);
 369
 370         /* We need to set power level at maximum rate for scanning. */
 371         ieee80211_hw_config(local, 0);
 372
 373         ieee80211_queue_delayed_work(&local->hw,
 374                                      &local->scan_work,
 375                                      IEEE80211_CHANNEL_TIME);
 376
 377         return 0;
 378 }
 379
 380
 381 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 382                                   struct cfg80211_scan_request *req)
 383 {
 384         struct ieee80211_local *local = sdata->local;
 385         int rc;
 386
 387         lockdep_assert_held(&local->mtx);
 388
 389         if (local->scan_req)
 390                 return -EBUSY;
 391
 392         if (!list_empty(&local->work_list)) {
 393                 /* wait for the work to finish/time out */
 394                 local->scan_req = req;
 395                 local->scan_sdata = sdata;
 396                 return 0;
 397         }
 398
 399         if (local->ops->hw_scan) {
 400                 u8 *ies;
 401
 402                 local->hw_scan_req = kmalloc(
 403                                 sizeof(*local->hw_scan_req) +
 404                                 req->n_channels * sizeof(req->channels[0]) +
 405                                 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
 406                                 req->ie_len, GFP_KERNEL);
 407                 if (!local->hw_scan_req)
 408                         return -ENOMEM;
 409
 410                 local->hw_scan_req->ssids = req->ssids;
 411                 local->hw_scan_req->n_ssids = req->n_ssids;
 412                 ies = (u8 *)local->hw_scan_req +
 413                         sizeof(*local->hw_scan_req) +
 414                         req->n_channels * sizeof(req->channels[0]);
 415                 local->hw_scan_req->ie = ies;
 416
 417                 local->hw_scan_band = 0;
 418
 419                 /*
 420                  * After allocating local->hw_scan_req, we must
 421                  * go through until ieee80211_prep_hw_scan(), so
 422                  * anything that might be changed here and leave
 423                  * this function early must not go after this
 424                  * allocation.
 425                  */
 426         }
 427
 428         local->scan_req = req;
 429         local->scan_sdata = sdata;
 430
 431         if (local->ops->hw_scan)
 432                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 433         else
 434                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 435
 436         ieee80211_recalc_idle(local);
 437
 438         if (local->ops->hw_scan) {
 439                 WARN_ON(!ieee80211_prep_hw_scan(local));
 440                 rc = drv_hw_scan(local, sdata, local->hw_scan_req);
 441         } else
 442                 rc = ieee80211_start_sw_scan(local);
 443
 444         if (rc) {
 445                 kfree(local->hw_scan_req);
 446                 local->hw_scan_req = NULL;
 447                 local->scanning = 0;
 448
 449                 ieee80211_recalc_idle(local);
 450
 451                 local->scan_req = NULL;
 452                 local->scan_sdata = NULL;
 453         }
 454
 455         return rc;
 456 }
 457
 458 static unsigned long
 459 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
 460 {
 461         /*
 462          * TODO: channel switching also consumes quite some time,
 463          * add that delay as well to get a better estimation
 464          */
 465         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN)
 466                 return IEEE80211_PASSIVE_CHANNEL_TIME;
 467         return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
 468 }
 469
 470 static void ieee80211_scan_state_decision(struct ieee80211_local *local,
 471                                           unsigned long *next_delay)
 472 {
 473         bool associated = false;
 474         bool tx_empty = true;
 475         bool bad_latency;
 476         bool listen_int_exceeded;
 477         unsigned long min_beacon_int = 0;
 478         struct ieee80211_sub_if_data *sdata;
 479         struct ieee80211_channel *next_chan;
 480
 481         /*
 482          * check if at least one STA interface is associated,
 483          * check if at least one STA interface has pending tx frames
 484          * and grab the lowest used beacon interval
 485          */
 486         mutex_lock(&local->iflist_mtx);
 487         list_for_each_entry(sdata, &local->interfaces, list) {
 488                 if (!ieee80211_sdata_running(sdata))
 489                         continue;
 490
 491                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 492                         if (sdata->u.mgd.associated) {
 493                                 associated = true;
 494
 495                                 if (sdata->vif.bss_conf.beacon_int <
 496                                     min_beacon_int || min_beacon_int == 0)
 497                                         min_beacon_int =
 498                                                 sdata->vif.bss_conf.beacon_int;
 499
 500                                 if (!qdisc_all_tx_empty(sdata->dev)) {
 501                                         tx_empty = false;
 502                                         break;
 503                                 }
 504                         }
 505                 }
 506         }
 507         mutex_unlock(&local->iflist_mtx);
 508
 509         next_chan = local->scan_req->channels[local->scan_channel_idx];
 510
 511         if (ieee80211_cfg_on_oper_channel(local)) {
 512                 /* We're currently on operating channel. */
 513                 if (next_chan == local->oper_channel)
 514                         /* We don't need to move off of operating channel. */
 515                         local->next_scan_state = SCAN_SET_CHANNEL;
 516                 else
 517                         /*
 518                          * We do need to leave operating channel, as next
 519                          * scan is somewhere else.
 520                          */
 521                         local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
 522         } else {
 523                 /*
 524                  * we're currently scanning a different channel, let's
 525                  * see if we can scan another channel without interfering
 526                  * with the current traffic situation.
 527                  *
 528                  * Since we don't know if the AP has pending frames for us
 529                  * we can only check for our tx queues and use the current
 530                  * pm_qos requirements for rx. Hence, if no tx traffic occurs
 531                  * at all we will scan as many channels in a row as the pm_qos
 532                  * latency allows us to. Additionally we also check for the
 533                  * currently negotiated listen interval to prevent losing
 534                  * frames unnecessarily.
 535                  *
 536                  * Otherwise switch back to the operating channel.
 537                  */
 538
 539                 bad_latency = time_after(jiffies +
 540                                 ieee80211_scan_get_channel_time(next_chan),
 541                                 local->leave_oper_channel_time +
 542                                 usecs_to_jiffies(pm_qos_request(PM_QOS_NETWORK_LATENCY)));
 543
 544                 listen_int_exceeded = time_after(jiffies +
 545                                 ieee80211_scan_get_channel_time(next_chan),
 546                                 local->leave_oper_channel_time +
 547                                 usecs_to_jiffies(min_beacon_int * 1024) *
 548                                 local->hw.conf.listen_interval);
 549
 550                 if (associated && ( !tx_empty || bad_latency ||
 551                     listen_int_exceeded))
 552                         local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
 553                 else
 554                         local->next_scan_state = SCAN_SET_CHANNEL;
 555         }
 556
 557         *next_delay = 0;
 558 }
 559
 560 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
 561                                                     unsigned long *next_delay)
 562 {
 563         /* PS will already be in off-channel mode,
 564          * we do that once at the beginning of scanning.
 565          */
 566         ieee80211_offchannel_stop_vifs(local, false);
 567
 568         /*
 569          * What if the nullfunc frames didn't arrive?
 570          */
 571         drv_flush(local, false);
 572         if (local->ops->flush)
 573                 *next_delay = 0;
 574         else
 575                 *next_delay = HZ / 10;
 576
 577         /* remember when we left the operating channel */
 578         local->leave_oper_channel_time = jiffies;
 579
 580         /* advance to the next channel to be scanned */
 581         local->next_scan_state = SCAN_SET_CHANNEL;
 582 }
 583
 584 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
 585                                                     unsigned long *next_delay)
 586 {
 587         /* switch back to the operating channel */
 588         local->scan_channel = NULL;
 589         if (!ieee80211_cfg_on_oper_channel(local))
 590                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 591
 592         /*
 593          * Re-enable vifs and beaconing.  Leave PS
 594          * in off-channel state..will put that back
 595          * on-channel at the end of scanning.
 596          */
 597         ieee80211_offchannel_return(local, true, false);
 598
 599         *next_delay = HZ / 5;
 600         local->next_scan_state = SCAN_DECISION;
 601 }
 602
 603 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 604                                              unsigned long *next_delay)
 605 {
 606         int skip;
 607         struct ieee80211_channel *chan;
 608
 609         skip = 0;
 610         chan = local->scan_req->channels[local->scan_channel_idx];
 611
 612         local->scan_channel = chan;
 613
 614         /* Only call hw-config if we really need to change channels. */
 615         if (chan != local->hw.conf.channel)
 616                 if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 617                         skip = 1;
 618
 619         /* advance state machine to next channel/band */
 620         local->scan_channel_idx++;
 621
 622         if (skip) {
 623                 /* if we skip this channel return to the decision state */
 624                 local->next_scan_state = SCAN_DECISION;
 625                 return;
 626         }
 627
 628         /*
 629          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 630          * (which unfortunately doesn't say _why_ step a) is done,
 631          * but it waits for the probe delay or until a frame is
 632          * received - and the received frame would update the NAV).
 633          * For now, we do not support waiting until a frame is
 634          * received.
 635          *
 636          * In any case, it is not necessary for a passive scan.
 637          */
 638         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 639             !local->scan_req->n_ssids) {
 640                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 641                 local->next_scan_state = SCAN_DECISION;
 642                 return;
 643         }
 644
 645         /* active scan, send probes */
 646         *next_delay = IEEE80211_PROBE_DELAY;
 647         local->next_scan_state = SCAN_SEND_PROBE;
 648 }
 649
 650 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 651                                             unsigned long *next_delay)
 652 {
 653         int i;
 654         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 655
 656         for (i = 0; i < local->scan_req->n_ssids; i++)
 657                 ieee80211_send_probe_req(
 658                         sdata, NULL,
 659                         local->scan_req->ssids[i].ssid,
 660                         local->scan_req->ssids[i].ssid_len,
 661                         local->scan_req->ie, local->scan_req->ie_len);
 662
 663         /*
 664          * After sending probe requests, wait for probe responses
 665          * on the channel.
 666          */
 667         *next_delay = IEEE80211_CHANNEL_TIME;
 668         local->next_scan_state = SCAN_DECISION;
 669 }
 670
 671 void ieee80211_scan_work(struct work_struct *work)
 672 {
 673         struct ieee80211_local *local =
 674                 container_of(work, struct ieee80211_local, scan_work.work);
 675         struct ieee80211_sub_if_data *sdata;
 676         unsigned long next_delay = 0;
 677         bool aborted, hw_scan;
 678
 679         mutex_lock(&local->mtx);
 680
 681         sdata = local->scan_sdata;
 682
 683         if (test_and_clear_bit(SCAN_COMPLETED, &local->scanning)) {
 684                 aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
 685                 goto out_complete;
 686         }
 687
 688         if (!sdata || !local->scan_req)
 689                 goto out;
 690
 691         if (local->scan_req && !local->scanning) {
 692                 struct cfg80211_scan_request *req = local->scan_req;
 693                 int rc;
 694
 695                 local->scan_req = NULL;
 696                 local->scan_sdata = NULL;
 697
 698                 rc = __ieee80211_start_scan(sdata, req);
 699                 if (rc) {
 700                         /* need to complete scan in cfg80211 */
 701                         local->scan_req = req;
 702                         aborted = true;
 703                         goto out_complete;
 704                 } else
 705                         goto out;
 706         }
 707
 708         /*
 709          * Avoid re-scheduling when the sdata is going away.
 710          */
 711         if (!ieee80211_sdata_running(sdata)) {
 712                 aborted = true;
 713                 goto out_complete;
 714         }
 715
 716         /*
 717          * as long as no delay is required advance immediately
 718          * without scheduling a new work
 719          */
 720         do {
 721                 switch (local->next_scan_state) {
 722                 case SCAN_DECISION:
 723                         /* if no more bands/channels left, complete scan */
 724                         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 725                                 aborted = false;
 726                                 goto out_complete;
 727                         }
 728                         ieee80211_scan_state_decision(local, &next_delay);
 729                         break;
 730                 case SCAN_SET_CHANNEL:
 731                         ieee80211_scan_state_set_channel(local, &next_delay);
 732                         break;
 733                 case SCAN_SEND_PROBE:
 734                         ieee80211_scan_state_send_probe(local, &next_delay);
 735                         break;
 736                 case SCAN_LEAVE_OPER_CHANNEL:
 737                         ieee80211_scan_state_leave_oper_channel(local, &next_delay);
 738                         break;
 739                 case SCAN_ENTER_OPER_CHANNEL:
 740                         ieee80211_scan_state_enter_oper_channel(local, &next_delay);
 741                         break;
 742                 }
 743         } while (next_delay == 0);
 744
 745         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
 746         goto out;
 747
 748 out_complete:
 749         hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 750         __ieee80211_scan_completed(&local->hw, aborted, hw_scan);
 751 out:
 752         mutex_unlock(&local->mtx);
 753 }
 754
 755 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 756                            struct cfg80211_scan_request *req)
 757 {
 758         int res;
 759
 760         mutex_lock(&sdata->local->mtx);
 761         res = __ieee80211_start_scan(sdata, req);
 762         mutex_unlock(&sdata->local->mtx);
 763
 764         return res;
 765 }
 766
 767 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 768                                     const u8 *ssid, u8 ssid_len,
 769                                     struct ieee80211_channel *chan)
 770 {
 771         struct ieee80211_local *local = sdata->local;
 772         int ret = -EBUSY;
 773         enum ieee80211_band band;
 774
 775         mutex_lock(&local->mtx);
 776
 777         /* busy scanning */
 778         if (local->scan_req)
 779                 goto unlock;
 780
 781         /* fill internal scan request */
 782         if (!chan) {
 783                 int i, nchan = 0;
 784
 785                 for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
 786                         if (!local->hw.wiphy->bands[band])
 787                                 continue;
 788                         for (i = 0;
 789                              i < local->hw.wiphy->bands[band]->n_channels;
 790                              i++) {
 791                                 local->int_scan_req->channels[nchan] =
 792                                     &local->hw.wiphy->bands[band]->channels[i];
 793                                 nchan++;
 794                         }
 795                 }
 796
 797                 local->int_scan_req->n_channels = nchan;
 798         } else {
 799                 local->int_scan_req->channels[0] = chan;
 800                 local->int_scan_req->n_channels = 1;
 801         }
 802
 803         local->int_scan_req->ssids = &local->scan_ssid;
 804         local->int_scan_req->n_ssids = 1;
 805         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 806         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 807
 808         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 809  unlock:
 810         mutex_unlock(&local->mtx);
 811         return ret;
 812 }
 813
 814 /*
 815  * Only call this function when a scan can't be queued -- under RTNL.
 816  */
 817 void ieee80211_scan_cancel(struct ieee80211_local *local)
 818 {
 819         bool abortscan;
 820
 821         /*
 822          * We are only canceling software scan, or deferred scan that was not
 823          * yet really started (see __ieee80211_start_scan ).
 824          *
 825          * Regarding hardware scan:
 826          * - we can not call  __ieee80211_scan_completed() as when
 827          *   SCAN_HW_SCANNING bit is set this function change
 828          *   local->hw_scan_req to operate on 5G band, what race with
 829          *   driver which can use local->hw_scan_req
 830          *
 831          * - we can not cancel scan_work since driver can schedule it
 832          *   by ieee80211_scan_completed(..., true) to finish scan
 833          *
 834          * Hence low lever driver is responsible for canceling HW scan.
 835          */
 836
 837         mutex_lock(&local->mtx);
 838         abortscan = local->scan_req && !test_bit(SCAN_HW_SCANNING, &local->scanning);
 839         if (abortscan) {
 840                 /*
 841                  * The scan is canceled, but stop work from being pending.
 842                  *
 843                  * If the work is currently running, it must be blocked on
 844                  * the mutex, but we'll set scan_sdata = NULL and it'll
 845                  * simply exit once it acquires the mutex.
 846                  */
 847                 cancel_delayed_work(&local->scan_work);
 848                 /* and clean up */
 849                 __ieee80211_scan_completed(&local->hw, true, false);
 850         }
 851         mutex_unlock(&local->mtx);
 852 }