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 bool __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
 266         lockdep_assert_held(&local->mtx);
 267
 268         /*
 269          * It's ok to abort a not-yet-running scan (that
 270          * we have one at all will be verified by checking
 271          * local->scan_req next), but not to complete it
 272          * successfully.
 273          */
 274         if (WARN_ON(!local->scanning && !aborted))
 275                 aborted = true;
 276
 277         if (WARN_ON(!local->scan_req))
 278                 return false;
 279
 280         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
 281                 int rc = drv_hw_scan(local, local->scan_sdata, local->hw_scan_req);
 282                 if (rc == 0)
 283                         return false;
 284         }
 285
 286         kfree(local->hw_scan_req);
 287         local->hw_scan_req = NULL;
 288
 289         if (local->scan_req != local->int_scan_req)
 290                 cfg80211_scan_done(local->scan_req, aborted);
 291         local->scan_req = NULL;
 292         local->scan_sdata = NULL;
 293
 294         local->scanning = 0;
 295         local->scan_channel = NULL;
 296
 297         return true;
 298 }
 299
 300 static void __ieee80211_scan_completed_finish(struct ieee80211_hw *hw,
 301                                               bool was_hw_scan)
 302 {
 303         struct ieee80211_local *local = hw_to_local(hw);
 304         bool on_oper_chan;
 305         bool enable_beacons = false;
 306
 307         mutex_lock(&local->mtx);
 308         on_oper_chan = ieee80211_cfg_on_oper_channel(local);
 309
 310         if (was_hw_scan || !on_oper_chan) {
 311                 if (WARN_ON(local->scan_channel))
 312                         local->scan_channel = NULL;
 313                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 314         }
 315
 316         if (!was_hw_scan) {
 317                 bool on_oper_chan2;
 318                 ieee80211_configure_filter(local);
 319                 drv_sw_scan_complete(local);
 320                 on_oper_chan2 = ieee80211_cfg_on_oper_channel(local);
 321                 /* We should always be on-channel at this point. */
 322                 WARN_ON(!on_oper_chan2);
 323                 if (on_oper_chan2 && (on_oper_chan != on_oper_chan2))
 324                         enable_beacons = true;
 325
 326                 ieee80211_offchannel_return(local, enable_beacons, true);
 327         }
 328
 329         ieee80211_recalc_idle(local);
 330         mutex_unlock(&local->mtx);
 331
 332         ieee80211_mlme_notify_scan_completed(local);
 333         ieee80211_ibss_notify_scan_completed(local);
 334         ieee80211_mesh_notify_scan_completed(local);
 335         ieee80211_queue_work(&local->hw, &local->work_work);
 336 }
 337
 338 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 339 {
 340         struct ieee80211_local *local = hw_to_local(hw);
 341
 342         trace_api_scan_completed(local, aborted);
 343
 344         set_bit(SCAN_COMPLETED, &local->scanning);
 345         if (aborted)
 346                 set_bit(SCAN_ABORTED, &local->scanning);
 347         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, 0);
 348 }
 349 EXPORT_SYMBOL(ieee80211_scan_completed);
 350
 351 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
 352 {
 353         /*
 354          * Hardware/driver doesn't support hw_scan, so use software
 355          * scanning instead. First send a nullfunc frame with power save
 356          * bit on so that AP will buffer the frames for us while we are not
 357          * listening, then send probe requests to each channel and wait for
 358          * the responses. After all channels are scanned, tune back to the
 359          * original channel and send a nullfunc frame with power save bit
 360          * off to trigger the AP to send us all the buffered frames.
 361          *
 362          * Note that while local->sw_scanning is true everything else but
 363          * nullfunc frames and probe requests will be dropped in
 364          * ieee80211_tx_h_check_assoc().
 365          */
 366         drv_sw_scan_start(local);
 367
 368         local->leave_oper_channel_time = 0;
 369         local->next_scan_state = SCAN_DECISION;
 370         local->scan_channel_idx = 0;
 371
 372         /* We always want to use off-channel PS, even if we
 373          * are not really leaving oper-channel.  Don't
 374          * tell the AP though, as long as we are on-channel.
 375          */
 376         ieee80211_offchannel_enable_all_ps(local, false);
 377
 378         ieee80211_configure_filter(local);
 379
 380         ieee80211_queue_delayed_work(&local->hw,
 381                                      &local->scan_work,
 382                                      IEEE80211_CHANNEL_TIME);
 383
 384         return 0;
 385 }
 386
 387
 388 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 389                                   struct cfg80211_scan_request *req)
 390 {
 391         struct ieee80211_local *local = sdata->local;
 392         int rc;
 393
 394         lockdep_assert_held(&local->mtx);
 395
 396         if (local->scan_req)
 397                 return -EBUSY;
 398
 399         if (!list_empty(&local->work_list)) {
 400                 /* wait for the work to finish/time out */
 401                 local->scan_req = req;
 402                 local->scan_sdata = sdata;
 403                 return 0;
 404         }
 405
 406         if (local->ops->hw_scan) {
 407                 u8 *ies;
 408
 409                 local->hw_scan_req = kmalloc(
 410                                 sizeof(*local->hw_scan_req) +
 411                                 req->n_channels * sizeof(req->channels[0]) +
 412                                 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
 413                                 req->ie_len, GFP_KERNEL);
 414                 if (!local->hw_scan_req)
 415                         return -ENOMEM;
 416
 417                 local->hw_scan_req->ssids = req->ssids;
 418                 local->hw_scan_req->n_ssids = req->n_ssids;
 419                 ies = (u8 *)local->hw_scan_req +
 420                         sizeof(*local->hw_scan_req) +
 421                         req->n_channels * sizeof(req->channels[0]);
 422                 local->hw_scan_req->ie = ies;
 423
 424                 local->hw_scan_band = 0;
 425
 426                 /*
 427                  * After allocating local->hw_scan_req, we must
 428                  * go through until ieee80211_prep_hw_scan(), so
 429                  * anything that might be changed here and leave
 430                  * this function early must not go after this
 431                  * allocation.
 432                  */
 433         }
 434
 435         local->scan_req = req;
 436         local->scan_sdata = sdata;
 437
 438         if (local->ops->hw_scan)
 439                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
 440         else
 441                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
 442
 443         ieee80211_recalc_idle(local);
 444
 445         if (local->ops->hw_scan) {
 446                 WARN_ON(!ieee80211_prep_hw_scan(local));
 447                 rc = drv_hw_scan(local, sdata, local->hw_scan_req);
 448         } else
 449                 rc = ieee80211_start_sw_scan(local);
 450
 451         if (rc) {
 452                 kfree(local->hw_scan_req);
 453                 local->hw_scan_req = NULL;
 454                 local->scanning = 0;
 455
 456                 ieee80211_recalc_idle(local);
 457
 458                 local->scan_req = NULL;
 459                 local->scan_sdata = NULL;
 460         }
 461
 462         return rc;
 463 }
 464
 465 static unsigned long
 466 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
 467 {
 468         /*
 469          * TODO: channel switching also consumes quite some time,
 470          * add that delay as well to get a better estimation
 471          */
 472         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN)
 473                 return IEEE80211_PASSIVE_CHANNEL_TIME;
 474         return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
 475 }
 476
 477 static void ieee80211_scan_state_decision(struct ieee80211_local *local,
 478                                           unsigned long *next_delay)
 479 {
 480         bool associated = false;
 481         bool tx_empty = true;
 482         bool bad_latency;
 483         bool listen_int_exceeded;
 484         unsigned long min_beacon_int = 0;
 485         struct ieee80211_sub_if_data *sdata;
 486         struct ieee80211_channel *next_chan;
 487
 488         /*
 489          * check if at least one STA interface is associated,
 490          * check if at least one STA interface has pending tx frames
 491          * and grab the lowest used beacon interval
 492          */
 493         mutex_lock(&local->iflist_mtx);
 494         list_for_each_entry(sdata, &local->interfaces, list) {
 495                 if (!ieee80211_sdata_running(sdata))
 496                         continue;
 497
 498                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 499                         if (sdata->u.mgd.associated) {
 500                                 associated = true;
 501
 502                                 if (sdata->vif.bss_conf.beacon_int <
 503                                     min_beacon_int || min_beacon_int == 0)
 504                                         min_beacon_int =
 505                                                 sdata->vif.bss_conf.beacon_int;
 506
 507                                 if (!qdisc_all_tx_empty(sdata->dev)) {
 508                                         tx_empty = false;
 509                                         break;
 510                                 }
 511                         }
 512                 }
 513         }
 514         mutex_unlock(&local->iflist_mtx);
 515
 516         next_chan = local->scan_req->channels[local->scan_channel_idx];
 517
 518         if (ieee80211_cfg_on_oper_channel(local)) {
 519                 /* We're currently on operating channel. */
 520                 if ((next_chan == local->oper_channel) &&
 521                     (local->_oper_channel_type == NL80211_CHAN_NO_HT))
 522                         /* We don't need to move off of operating channel. */
 523                         local->next_scan_state = SCAN_SET_CHANNEL;
 524                 else
 525                         /*
 526                          * We do need to leave operating channel, as next
 527                          * scan is somewhere else.
 528                          */
 529                         local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
 530         } else {
 531                 /*
 532                  * we're currently scanning a different channel, let's
 533                  * see if we can scan another channel without interfering
 534                  * with the current traffic situation.
 535                  *
 536                  * Since we don't know if the AP has pending frames for us
 537                  * we can only check for our tx queues and use the current
 538                  * pm_qos requirements for rx. Hence, if no tx traffic occurs
 539                  * at all we will scan as many channels in a row as the pm_qos
 540                  * latency allows us to. Additionally we also check for the
 541                  * currently negotiated listen interval to prevent losing
 542                  * frames unnecessarily.
 543                  *
 544                  * Otherwise switch back to the operating channel.
 545                  */
 546
 547                 bad_latency = time_after(jiffies +
 548                                 ieee80211_scan_get_channel_time(next_chan),
 549                                 local->leave_oper_channel_time +
 550                                 usecs_to_jiffies(pm_qos_request(PM_QOS_NETWORK_LATENCY)));
 551
 552                 listen_int_exceeded = time_after(jiffies +
 553                                 ieee80211_scan_get_channel_time(next_chan),
 554                                 local->leave_oper_channel_time +
 555                                 usecs_to_jiffies(min_beacon_int * 1024) *
 556                                 local->hw.conf.listen_interval);
 557
 558                 if (associated && ( !tx_empty || bad_latency ||
 559                     listen_int_exceeded))
 560                         local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
 561                 else
 562                         local->next_scan_state = SCAN_SET_CHANNEL;
 563         }
 564
 565         *next_delay = 0;
 566 }
 567
 568 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
 569                                                     unsigned long *next_delay)
 570 {
 571         /* PS will already be in off-channel mode,
 572          * we do that once at the beginning of scanning.
 573          */
 574         ieee80211_offchannel_stop_vifs(local, false);
 575
 576         /*
 577          * What if the nullfunc frames didn't arrive?
 578          */
 579         drv_flush(local, false);
 580         if (local->ops->flush)
 581                 *next_delay = 0;
 582         else
 583                 *next_delay = HZ / 10;
 584
 585         /* remember when we left the operating channel */
 586         local->leave_oper_channel_time = jiffies;
 587
 588         /* advance to the next channel to be scanned */
 589         local->next_scan_state = SCAN_SET_CHANNEL;
 590 }
 591
 592 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
 593                                                     unsigned long *next_delay)
 594 {
 595         /* switch back to the operating channel */
 596         local->scan_channel = NULL;
 597         if (!ieee80211_cfg_on_oper_channel(local))
 598                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 599
 600         /*
 601          * Re-enable vifs and beaconing.  Leave PS
 602          * in off-channel state..will put that back
 603          * on-channel at the end of scanning.
 604          */
 605         ieee80211_offchannel_return(local, true, false);
 606
 607         *next_delay = HZ / 5;
 608         local->next_scan_state = SCAN_DECISION;
 609 }
 610
 611 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 612                                              unsigned long *next_delay)
 613 {
 614         int skip;
 615         struct ieee80211_channel *chan;
 616
 617         skip = 0;
 618         chan = local->scan_req->channels[local->scan_channel_idx];
 619
 620         local->scan_channel = chan;
 621
 622         /* Only call hw-config if we really need to change channels. */
 623         if ((chan != local->hw.conf.channel) ||
 624             (local->hw.conf.channel_type != NL80211_CHAN_NO_HT))
 625                 if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
 626                         skip = 1;
 627
 628         /* advance state machine to next channel/band */
 629         local->scan_channel_idx++;
 630
 631         if (skip) {
 632                 /* if we skip this channel return to the decision state */
 633                 local->next_scan_state = SCAN_DECISION;
 634                 return;
 635         }
 636
 637         /*
 638          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
 639          * (which unfortunately doesn't say _why_ step a) is done,
 640          * but it waits for the probe delay or until a frame is
 641          * received - and the received frame would update the NAV).
 642          * For now, we do not support waiting until a frame is
 643          * received.
 644          *
 645          * In any case, it is not necessary for a passive scan.
 646          */
 647         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 648             !local->scan_req->n_ssids) {
 649                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 650                 local->next_scan_state = SCAN_DECISION;
 651                 return;
 652         }
 653
 654         /* active scan, send probes */
 655         *next_delay = IEEE80211_PROBE_DELAY;
 656         local->next_scan_state = SCAN_SEND_PROBE;
 657 }
 658
 659 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
 660                                             unsigned long *next_delay)
 661 {
 662         int i;
 663         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 664
 665         for (i = 0; i < local->scan_req->n_ssids; i++)
 666                 ieee80211_send_probe_req(
 667                         sdata, NULL,
 668                         local->scan_req->ssids[i].ssid,
 669                         local->scan_req->ssids[i].ssid_len,
 670                         local->scan_req->ie, local->scan_req->ie_len);
 671
 672         /*
 673          * After sending probe requests, wait for probe responses
 674          * on the channel.
 675          */
 676         *next_delay = IEEE80211_CHANNEL_TIME;
 677         local->next_scan_state = SCAN_DECISION;
 678 }
 679
 680 void ieee80211_scan_work(struct work_struct *work)
 681 {
 682         struct ieee80211_local *local =
 683                 container_of(work, struct ieee80211_local, scan_work.work);
 684         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 685         unsigned long next_delay = 0;
 686         bool aborted, hw_scan, finish;
 687
 688         mutex_lock(&local->mtx);
 689
 690         if (test_and_clear_bit(SCAN_COMPLETED, &local->scanning)) {
 691                 aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
 692                 goto out_complete;
 693         }
 694
 695         if (!sdata || !local->scan_req)
 696                 goto out;
 697
 698         if (local->scan_req && !local->scanning) {
 699                 struct cfg80211_scan_request *req = local->scan_req;
 700                 int rc;
 701
 702                 local->scan_req = NULL;
 703                 local->scan_sdata = NULL;
 704
 705                 rc = __ieee80211_start_scan(sdata, req);
 706                 if (rc) {
 707                         /* need to complete scan in cfg80211 */
 708                         local->scan_req = req;
 709                         aborted = true;
 710                         goto out_complete;
 711                 } else
 712                         goto out;
 713         }
 714
 715         /*
 716          * Avoid re-scheduling when the sdata is going away.
 717          */
 718         if (!ieee80211_sdata_running(sdata)) {
 719                 aborted = true;
 720                 goto out_complete;
 721         }
 722
 723         /*
 724          * as long as no delay is required advance immediately
 725          * without scheduling a new work
 726          */
 727         do {
 728                 switch (local->next_scan_state) {
 729                 case SCAN_DECISION:
 730                         /* if no more bands/channels left, complete scan */
 731                         if (local->scan_channel_idx >= local->scan_req->n_channels) {
 732                                 aborted = false;
 733                                 goto out_complete;
 734                         }
 735                         ieee80211_scan_state_decision(local, &next_delay);
 736                         break;
 737                 case SCAN_SET_CHANNEL:
 738                         ieee80211_scan_state_set_channel(local, &next_delay);
 739                         break;
 740                 case SCAN_SEND_PROBE:
 741                         ieee80211_scan_state_send_probe(local, &next_delay);
 742                         break;
 743                 case SCAN_LEAVE_OPER_CHANNEL:
 744                         ieee80211_scan_state_leave_oper_channel(local, &next_delay);
 745                         break;
 746                 case SCAN_ENTER_OPER_CHANNEL:
 747                         ieee80211_scan_state_enter_oper_channel(local, &next_delay);
 748                         break;
 749                 }
 750         } while (next_delay == 0);
 751
 752         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
 753         mutex_unlock(&local->mtx);
 754         return;
 755
 756 out_complete:
 757         hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
 758         finish = __ieee80211_scan_completed(&local->hw, aborted, hw_scan);
 759         mutex_unlock(&local->mtx);
 760         if (finish)
 761                 __ieee80211_scan_completed_finish(&local->hw, hw_scan);
 762         return;
 763
 764 out:
 765         mutex_unlock(&local->mtx);
 766 }
 767
 768 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 769                            struct cfg80211_scan_request *req)
 770 {
 771         int res;
 772
 773         mutex_lock(&sdata->local->mtx);
 774         res = __ieee80211_start_scan(sdata, req);
 775         mutex_unlock(&sdata->local->mtx);
 776
 777         return res;
 778 }
 779
 780 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
 781                                     const u8 *ssid, u8 ssid_len,
 782                                     struct ieee80211_channel *chan)
 783 {
 784         struct ieee80211_local *local = sdata->local;
 785         int ret = -EBUSY;
 786         enum ieee80211_band band;
 787
 788         mutex_lock(&local->mtx);
 789
 790         /* busy scanning */
 791         if (local->scan_req)
 792                 goto unlock;
 793
 794         /* fill internal scan request */
 795         if (!chan) {
 796                 int i, nchan = 0;
 797
 798                 for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
 799                         if (!local->hw.wiphy->bands[band])
 800                                 continue;
 801                         for (i = 0;
 802                              i < local->hw.wiphy->bands[band]->n_channels;
 803                              i++) {
 804                                 local->int_scan_req->channels[nchan] =
 805                                     &local->hw.wiphy->bands[band]->channels[i];
 806                                 nchan++;
 807                         }
 808                 }
 809
 810                 local->int_scan_req->n_channels = nchan;
 811         } else {
 812                 local->int_scan_req->channels[0] = chan;
 813                 local->int_scan_req->n_channels = 1;
 814         }
 815
 816         local->int_scan_req->ssids = &local->scan_ssid;
 817         local->int_scan_req->n_ssids = 1;
 818         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
 819         local->int_scan_req->ssids[0].ssid_len = ssid_len;
 820
 821         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
 822  unlock:
 823         mutex_unlock(&local->mtx);
 824         return ret;
 825 }
 826
 827 /*
 828  * Only call this function when a scan can't be queued -- under RTNL.
 829  */
 830 void ieee80211_scan_cancel(struct ieee80211_local *local)
 831 {
 832         bool abortscan;
 833         bool finish = false;
 834
 835         /*
 836          * We are only canceling software scan, or deferred scan that was not
 837          * yet really started (see __ieee80211_start_scan ).
 838          *
 839          * Regarding hardware scan:
 840          * - we can not call  __ieee80211_scan_completed() as when
 841          *   SCAN_HW_SCANNING bit is set this function change
 842          *   local->hw_scan_req to operate on 5G band, what race with
 843          *   driver which can use local->hw_scan_req
 844          *
 845          * - we can not cancel scan_work since driver can schedule it
 846          *   by ieee80211_scan_completed(..., true) to finish scan
 847          *
 848          * Hence low lever driver is responsible for canceling HW scan.
 849          */
 850
 851         mutex_lock(&local->mtx);
 852         abortscan = local->scan_req && !test_bit(SCAN_HW_SCANNING, &local->scanning);
 853         if (abortscan)
 854                 finish = __ieee80211_scan_completed(&local->hw, true, false);
 855         mutex_unlock(&local->mtx);
 856
 857         if (abortscan) {
 858                 /* The scan is canceled, but stop work from being pending */
 859                 cancel_delayed_work_sync(&local->scan_work);
 860         }
 861         if (finish)
 862                 __ieee80211_scan_completed_finish(&local->hw, false);
 863 }