mac80211: split hardware scan by band
[linux-2.6.git] / net / mac80211 / scan.c
1 /*
2  * Scanning implementation
3  *
4  * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
5  * Copyright 2004, Instant802 Networks, Inc.
6  * Copyright 2005, Devicescape Software, Inc.
7  * Copyright 2006-2007  Jiri Benc <jbenc@suse.cz>
8  * Copyright 2007, Michael Wu <flamingice@sourmilk.net>
9  *
10  * This program is free software; you can redistribute it and/or modify
11  * it under the terms of the GNU General Public License version 2 as
12  * published by the Free Software Foundation.
13  */
14
15 #include <linux/wireless.h>
16 #include <linux/if_arp.h>
17 #include <linux/rtnetlink.h>
18 #include <net/mac80211.h>
19
20 #include "ieee80211_i.h"
21 #include "driver-ops.h"
22 #include "mesh.h"
23
24 #define IEEE80211_PROBE_DELAY (HZ / 33)
25 #define IEEE80211_CHANNEL_TIME (HZ / 33)
26 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
27
28 struct ieee80211_bss *
29 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
30                      u8 *ssid, u8 ssid_len)
31 {
32         return (void *)cfg80211_get_bss(local->hw.wiphy,
33                                         ieee80211_get_channel(local->hw.wiphy,
34                                                               freq),
35                                         bssid, ssid, ssid_len,
36                                         0, 0);
37 }
38
39 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
40 {
41         struct ieee80211_bss *bss = (void *)cbss;
42
43         kfree(bss_mesh_id(bss));
44         kfree(bss_mesh_cfg(bss));
45 }
46
47 void ieee80211_rx_bss_put(struct ieee80211_local *local,
48                           struct ieee80211_bss *bss)
49 {
50         cfg80211_put_bss((struct cfg80211_bss *)bss);
51 }
52
53 struct ieee80211_bss *
54 ieee80211_bss_info_update(struct ieee80211_local *local,
55                           struct ieee80211_rx_status *rx_status,
56                           struct ieee80211_mgmt *mgmt,
57                           size_t len,
58                           struct ieee802_11_elems *elems,
59                           struct ieee80211_channel *channel,
60                           bool beacon)
61 {
62         struct ieee80211_bss *bss;
63         int clen;
64         s32 signal = 0;
65
66         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
67                 signal = rx_status->signal * 100;
68         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
69                 signal = (rx_status->signal * 100) / local->hw.max_signal;
70
71         bss = (void *)cfg80211_inform_bss_frame(local->hw.wiphy, channel,
72                                                 mgmt, len, signal, GFP_ATOMIC);
73
74         if (!bss)
75                 return NULL;
76
77         bss->cbss.free_priv = ieee80211_rx_bss_free;
78
79         /* save the ERP value so that it is available at association time */
80         if (elems->erp_info && elems->erp_info_len >= 1) {
81                 bss->erp_value = elems->erp_info[0];
82                 bss->has_erp_value = 1;
83         }
84
85         if (elems->tim) {
86                 struct ieee80211_tim_ie *tim_ie =
87                         (struct ieee80211_tim_ie *)elems->tim;
88                 bss->dtim_period = tim_ie->dtim_period;
89         }
90
91         /* set default value for buggy AP/no TIM element */
92         if (bss->dtim_period == 0)
93                 bss->dtim_period = 1;
94
95         bss->supp_rates_len = 0;
96         if (elems->supp_rates) {
97                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
98                 if (clen > elems->supp_rates_len)
99                         clen = elems->supp_rates_len;
100                 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
101                        clen);
102                 bss->supp_rates_len += clen;
103         }
104         if (elems->ext_supp_rates) {
105                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
106                 if (clen > elems->ext_supp_rates_len)
107                         clen = elems->ext_supp_rates_len;
108                 memcpy(&bss->supp_rates[bss->supp_rates_len],
109                        elems->ext_supp_rates, clen);
110                 bss->supp_rates_len += clen;
111         }
112
113         bss->wmm_used = elems->wmm_param || elems->wmm_info;
114
115         if (!beacon)
116                 bss->last_probe_resp = jiffies;
117
118         return bss;
119 }
120
121 ieee80211_rx_result
122 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
123 {
124         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
125         struct ieee80211_mgmt *mgmt;
126         struct ieee80211_bss *bss;
127         u8 *elements;
128         struct ieee80211_channel *channel;
129         size_t baselen;
130         int freq;
131         __le16 fc;
132         bool presp, beacon = false;
133         struct ieee802_11_elems elems;
134
135         if (skb->len < 2)
136                 return RX_DROP_UNUSABLE;
137
138         mgmt = (struct ieee80211_mgmt *) skb->data;
139         fc = mgmt->frame_control;
140
141         if (ieee80211_is_ctl(fc))
142                 return RX_CONTINUE;
143
144         if (skb->len < 24)
145                 return RX_DROP_MONITOR;
146
147         presp = ieee80211_is_probe_resp(fc);
148         if (presp) {
149                 /* ignore ProbeResp to foreign address */
150                 if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
151                         return RX_DROP_MONITOR;
152
153                 presp = true;
154                 elements = mgmt->u.probe_resp.variable;
155                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
156         } else {
157                 beacon = ieee80211_is_beacon(fc);
158                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
159                 elements = mgmt->u.beacon.variable;
160         }
161
162         if (!presp && !beacon)
163                 return RX_CONTINUE;
164
165         if (baselen > skb->len)
166                 return RX_DROP_MONITOR;
167
168         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
169
170         if (elems.ds_params && elems.ds_params_len == 1)
171                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
172         else
173                 freq = rx_status->freq;
174
175         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
176
177         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
178                 return RX_DROP_MONITOR;
179
180         bss = ieee80211_bss_info_update(sdata->local, rx_status,
181                                         mgmt, skb->len, &elems,
182                                         channel, beacon);
183         if (bss)
184                 ieee80211_rx_bss_put(sdata->local, bss);
185
186         dev_kfree_skb(skb);
187         return RX_QUEUED;
188 }
189
190 /* return false if no more work */
191 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
192 {
193         struct cfg80211_scan_request *req = local->scan_req;
194         enum ieee80211_band band;
195         int i, ielen, n_chans;
196
197         do {
198                 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
199                         return false;
200
201                 band = local->hw_scan_band;
202                 n_chans = 0;
203                 for (i = 0; i < req->n_channels; i++) {
204                         if (req->channels[i]->band == band) {
205                                 local->hw_scan_req->channels[n_chans] =
206                                                         req->channels[i];
207                                 n_chans++;
208                         }
209                 }
210
211                 local->hw_scan_band++;
212         } while (!n_chans);
213
214         local->hw_scan_req->n_channels = n_chans;
215
216         ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
217                                          req->ie, req->ie_len, band);
218         local->hw_scan_req->ie_len = ielen;
219
220         return true;
221 }
222
223 /*
224  * inform AP that we will go to sleep so that it will buffer the frames
225  * while we scan
226  */
227 static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
228 {
229         struct ieee80211_local *local = sdata->local;
230         bool ps = false;
231
232         /* FIXME: what to do when local->pspolling is true? */
233
234         del_timer_sync(&local->dynamic_ps_timer);
235         cancel_work_sync(&local->dynamic_ps_enable_work);
236
237         if (local->hw.conf.flags & IEEE80211_CONF_PS) {
238                 ps = true;
239                 local->hw.conf.flags &= ~IEEE80211_CONF_PS;
240                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
241         }
242
243         if (!ps || !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
244                 /*
245                  * If power save was enabled, no need to send a nullfunc
246                  * frame because AP knows that we are sleeping. But if the
247                  * hardware is creating the nullfunc frame for power save
248                  * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
249                  * enabled) and power save was enabled, the firmware just
250                  * sent a null frame with power save disabled. So we need
251                  * to send a new nullfunc frame to inform the AP that we
252                  * are again sleeping.
253                  */
254                 ieee80211_send_nullfunc(local, sdata, 1);
255 }
256
257 /* inform AP that we are awake again, unless power save is enabled */
258 static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
259 {
260         struct ieee80211_local *local = sdata->local;
261
262         if (!local->ps_sdata)
263                 ieee80211_send_nullfunc(local, sdata, 0);
264         else {
265                 /*
266                  * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
267                  * will send a nullfunc frame with the powersave bit set
268                  * even though the AP already knows that we are sleeping.
269                  * This could be avoided by sending a null frame with power
270                  * save bit disabled before enabling the power save, but
271                  * this doesn't gain anything.
272                  *
273                  * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
274                  * to send a nullfunc frame because AP already knows that
275                  * we are sleeping, let's just enable power save mode in
276                  * hardware.
277                  */
278                 local->hw.conf.flags |= IEEE80211_CONF_PS;
279                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
280         }
281 }
282
283 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
284 {
285         struct ieee80211_local *local = hw_to_local(hw);
286         struct ieee80211_sub_if_data *sdata;
287         bool was_hw_scan;
288
289         mutex_lock(&local->scan_mtx);
290
291         if (WARN_ON(!local->scanning)) {
292                 mutex_unlock(&local->scan_mtx);
293                 return;
294         }
295
296         if (WARN_ON(!local->scan_req)) {
297                 mutex_unlock(&local->scan_mtx);
298                 return;
299         }
300
301         was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
302         if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
303                 ieee80211_queue_delayed_work(&local->hw,
304                                              &local->scan_work, 0);
305                 mutex_unlock(&local->scan_mtx);
306                 return;
307         }
308
309         kfree(local->hw_scan_req);
310         local->hw_scan_req = NULL;
311
312         if (local->scan_req != local->int_scan_req)
313                 cfg80211_scan_done(local->scan_req, aborted);
314         local->scan_req = NULL;
315         local->scan_sdata = NULL;
316
317         local->scanning = 0;
318         local->scan_channel = NULL;
319
320         /* we only have to protect scan_req and hw/sw scan */
321         mutex_unlock(&local->scan_mtx);
322
323         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
324         if (was_hw_scan)
325                 goto done;
326
327         ieee80211_configure_filter(local);
328
329         drv_sw_scan_complete(local);
330
331         mutex_lock(&local->iflist_mtx);
332         list_for_each_entry(sdata, &local->interfaces, list) {
333                 if (!netif_running(sdata->dev))
334                         continue;
335
336                 /* Tell AP we're back */
337                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
338                         if (sdata->u.mgd.associated) {
339                                 ieee80211_scan_ps_disable(sdata);
340                                 netif_wake_queue(sdata->dev);
341                         }
342                 } else
343                         netif_wake_queue(sdata->dev);
344
345                 /* re-enable beaconing */
346                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
347                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
348                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
349                         ieee80211_bss_info_change_notify(
350                                 sdata, BSS_CHANGED_BEACON_ENABLED);
351         }
352         mutex_unlock(&local->iflist_mtx);
353
354  done:
355         ieee80211_recalc_idle(local);
356         ieee80211_mlme_notify_scan_completed(local);
357         ieee80211_ibss_notify_scan_completed(local);
358         ieee80211_mesh_notify_scan_completed(local);
359 }
360 EXPORT_SYMBOL(ieee80211_scan_completed);
361
362 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
363 {
364         struct ieee80211_sub_if_data *sdata;
365
366         /*
367          * Hardware/driver doesn't support hw_scan, so use software
368          * scanning instead. First send a nullfunc frame with power save
369          * bit on so that AP will buffer the frames for us while we are not
370          * listening, then send probe requests to each channel and wait for
371          * the responses. After all channels are scanned, tune back to the
372          * original channel and send a nullfunc frame with power save bit
373          * off to trigger the AP to send us all the buffered frames.
374          *
375          * Note that while local->sw_scanning is true everything else but
376          * nullfunc frames and probe requests will be dropped in
377          * ieee80211_tx_h_check_assoc().
378          */
379         drv_sw_scan_start(local);
380
381         mutex_lock(&local->iflist_mtx);
382         list_for_each_entry(sdata, &local->interfaces, list) {
383                 if (!netif_running(sdata->dev))
384                         continue;
385
386                 /* disable beaconing */
387                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
388                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
389                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
390                         ieee80211_bss_info_change_notify(
391                                 sdata, BSS_CHANGED_BEACON_ENABLED);
392
393                 /*
394                  * only handle non-STA interfaces here, STA interfaces
395                  * are handled in the scan state machine
396                  */
397                 if (sdata->vif.type != NL80211_IFTYPE_STATION)
398                         netif_stop_queue(sdata->dev);
399         }
400         mutex_unlock(&local->iflist_mtx);
401
402         local->next_scan_state = SCAN_DECISION;
403         local->scan_channel_idx = 0;
404
405         ieee80211_configure_filter(local);
406
407         /* TODO: start scan as soon as all nullfunc frames are ACKed */
408         ieee80211_queue_delayed_work(&local->hw,
409                                      &local->scan_work,
410                                      IEEE80211_CHANNEL_TIME);
411
412         return 0;
413 }
414
415
416 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
417                                   struct cfg80211_scan_request *req)
418 {
419         struct ieee80211_local *local = sdata->local;
420         struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
421         int rc;
422
423         if (local->scan_req)
424                 return -EBUSY;
425
426         if (local->ops->hw_scan) {
427                 u8 *ies;
428
429                 local->hw_scan_req = kmalloc(
430                                 sizeof(*local->hw_scan_req) +
431                                 req->n_channels * sizeof(req->channels[0]) +
432                                 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
433                                 req->ie_len, GFP_KERNEL);
434                 if (!local->hw_scan_req)
435                         return -ENOMEM;
436
437                 local->hw_scan_req->ssids = req->ssids;
438                 local->hw_scan_req->n_ssids = req->n_ssids;
439                 ies = (u8 *)local->hw_scan_req +
440                         sizeof(*local->hw_scan_req) +
441                         req->n_channels * sizeof(req->channels[0]);
442                 local->hw_scan_req->ie = ies;
443
444                 local->hw_scan_band = 0;
445         }
446
447         local->scan_req = req;
448         local->scan_sdata = sdata;
449
450         if (req != local->int_scan_req &&
451             sdata->vif.type == NL80211_IFTYPE_STATION &&
452             !list_empty(&ifmgd->work_list)) {
453                 /* actually wait for the work it's doing to finish/time out */
454                 set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
455                 return 0;
456         }
457
458         if (local->ops->hw_scan)
459                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
460         else
461                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
462         /*
463          * Kicking off the scan need not be protected,
464          * only the scan variable stuff, since now
465          * local->scan_req is assigned and other callers
466          * will abort their scan attempts.
467          *
468          * This avoids getting a scan_mtx -> iflist_mtx
469          * dependency, so that the scan completed calls
470          * have more locking freedom.
471          */
472
473         ieee80211_recalc_idle(local);
474         mutex_unlock(&local->scan_mtx);
475
476         if (local->ops->hw_scan) {
477                 WARN_ON(!ieee80211_prep_hw_scan(local));
478                 rc = drv_hw_scan(local, local->hw_scan_req);
479         } else
480                 rc = ieee80211_start_sw_scan(local);
481
482         mutex_lock(&local->scan_mtx);
483
484         if (rc) {
485                 kfree(local->hw_scan_req);
486                 local->hw_scan_req = NULL;
487                 local->scanning = 0;
488
489                 ieee80211_recalc_idle(local);
490
491                 local->scan_req = NULL;
492                 local->scan_sdata = NULL;
493         }
494
495         return rc;
496 }
497
498 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
499                                          unsigned long *next_delay)
500 {
501         bool associated = false;
502         struct ieee80211_sub_if_data *sdata;
503
504         /* if no more bands/channels left, complete scan and advance to the idle state */
505         if (local->scan_channel_idx >= local->scan_req->n_channels) {
506                 ieee80211_scan_completed(&local->hw, false);
507                 return 1;
508         }
509
510         /* check if at least one STA interface is associated */
511         mutex_lock(&local->iflist_mtx);
512         list_for_each_entry(sdata, &local->interfaces, list) {
513                 if (!netif_running(sdata->dev))
514                         continue;
515
516                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
517                         if (sdata->u.mgd.associated) {
518                                 associated = true;
519                                 break;
520                         }
521                 }
522         }
523         mutex_unlock(&local->iflist_mtx);
524
525         if (local->scan_channel) {
526                 /*
527                  * we're currently scanning a different channel, let's
528                  * switch back to the operating channel now if at least
529                  * one interface is associated. Otherwise just scan the
530                  * next channel
531                  */
532                 if (associated)
533                         local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
534                 else
535                         local->next_scan_state = SCAN_SET_CHANNEL;
536         } else {
537                 /*
538                  * we're on the operating channel currently, let's
539                  * leave that channel now to scan another one
540                  */
541                 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
542         }
543
544         *next_delay = 0;
545         return 0;
546 }
547
548 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
549                                                     unsigned long *next_delay)
550 {
551         struct ieee80211_sub_if_data *sdata;
552
553         /*
554          * notify the AP about us leaving the channel and stop all STA interfaces
555          */
556         mutex_lock(&local->iflist_mtx);
557         list_for_each_entry(sdata, &local->interfaces, list) {
558                 if (!netif_running(sdata->dev))
559                         continue;
560
561                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
562                         netif_stop_queue(sdata->dev);
563                         if (sdata->u.mgd.associated)
564                                 ieee80211_scan_ps_enable(sdata);
565                 }
566         }
567         mutex_unlock(&local->iflist_mtx);
568
569         __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
570
571         /* advance to the next channel to be scanned */
572         *next_delay = HZ / 10;
573         local->next_scan_state = SCAN_SET_CHANNEL;
574 }
575
576 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
577                                                     unsigned long *next_delay)
578 {
579         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
580
581         /* switch back to the operating channel */
582         local->scan_channel = NULL;
583         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
584
585         /*
586          * notify the AP about us being back and restart all STA interfaces
587          */
588         mutex_lock(&local->iflist_mtx);
589         list_for_each_entry(sdata, &local->interfaces, list) {
590                 if (!netif_running(sdata->dev))
591                         continue;
592
593                 /* Tell AP we're back */
594                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
595                         if (sdata->u.mgd.associated)
596                                 ieee80211_scan_ps_disable(sdata);
597                         netif_wake_queue(sdata->dev);
598                 }
599         }
600         mutex_unlock(&local->iflist_mtx);
601
602         __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
603
604         *next_delay = HZ / 5;
605         local->next_scan_state = SCAN_DECISION;
606 }
607
608 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
609                                              unsigned long *next_delay)
610 {
611         int skip;
612         struct ieee80211_channel *chan;
613         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
614
615         skip = 0;
616         chan = local->scan_req->channels[local->scan_channel_idx];
617
618         if (chan->flags & IEEE80211_CHAN_DISABLED ||
619             (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
620              chan->flags & IEEE80211_CHAN_NO_IBSS))
621                 skip = 1;
622
623         if (!skip) {
624                 local->scan_channel = chan;
625                 if (ieee80211_hw_config(local,
626                                         IEEE80211_CONF_CHANGE_CHANNEL))
627                         skip = 1;
628         }
629
630         /* advance state machine to next channel/band */
631         local->scan_channel_idx++;
632
633         if (skip) {
634                 /* if we skip this channel return to the decision state */
635                 local->next_scan_state = SCAN_DECISION;
636                 return;
637         }
638
639         /*
640          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
641          * (which unfortunately doesn't say _why_ step a) is done,
642          * but it waits for the probe delay or until a frame is
643          * received - and the received frame would update the NAV).
644          * For now, we do not support waiting until a frame is
645          * received.
646          *
647          * In any case, it is not necessary for a passive scan.
648          */
649         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
650             !local->scan_req->n_ssids) {
651                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
652                 local->next_scan_state = SCAN_DECISION;
653                 return;
654         }
655
656         /* active scan, send probes */
657         *next_delay = IEEE80211_PROBE_DELAY;
658         local->next_scan_state = SCAN_SEND_PROBE;
659 }
660
661 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
662                                             unsigned long *next_delay)
663 {
664         int i;
665         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
666
667         for (i = 0; i < local->scan_req->n_ssids; i++)
668                 ieee80211_send_probe_req(
669                         sdata, NULL,
670                         local->scan_req->ssids[i].ssid,
671                         local->scan_req->ssids[i].ssid_len,
672                         local->scan_req->ie, local->scan_req->ie_len);
673
674         /*
675          * After sending probe requests, wait for probe responses
676          * on the channel.
677          */
678         *next_delay = IEEE80211_CHANNEL_TIME;
679         local->next_scan_state = SCAN_DECISION;
680 }
681
682 void ieee80211_scan_work(struct work_struct *work)
683 {
684         struct ieee80211_local *local =
685                 container_of(work, struct ieee80211_local, scan_work.work);
686         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
687         unsigned long next_delay = 0;
688
689         mutex_lock(&local->scan_mtx);
690         if (!sdata || !local->scan_req) {
691                 mutex_unlock(&local->scan_mtx);
692                 return;
693         }
694
695         if (local->hw_scan_req) {
696                 int rc = drv_hw_scan(local, local->hw_scan_req);
697                 mutex_unlock(&local->scan_mtx);
698                 if (rc)
699                         ieee80211_scan_completed(&local->hw, true);
700                 return;
701         }
702
703         if (local->scan_req && !local->scanning) {
704                 struct cfg80211_scan_request *req = local->scan_req;
705                 int rc;
706
707                 local->scan_req = NULL;
708                 local->scan_sdata = NULL;
709
710                 rc = __ieee80211_start_scan(sdata, req);
711                 mutex_unlock(&local->scan_mtx);
712
713                 if (rc)
714                         ieee80211_scan_completed(&local->hw, true);
715                 return;
716         }
717
718         mutex_unlock(&local->scan_mtx);
719
720         /*
721          * Avoid re-scheduling when the sdata is going away.
722          */
723         if (!netif_running(sdata->dev)) {
724                 ieee80211_scan_completed(&local->hw, true);
725                 return;
726         }
727
728         /*
729          * as long as no delay is required advance immediately
730          * without scheduling a new work
731          */
732         do {
733                 switch (local->next_scan_state) {
734                 case SCAN_DECISION:
735                         if (ieee80211_scan_state_decision(local, &next_delay))
736                                 return;
737                         break;
738                 case SCAN_SET_CHANNEL:
739                         ieee80211_scan_state_set_channel(local, &next_delay);
740                         break;
741                 case SCAN_SEND_PROBE:
742                         ieee80211_scan_state_send_probe(local, &next_delay);
743                         break;
744                 case SCAN_LEAVE_OPER_CHANNEL:
745                         ieee80211_scan_state_leave_oper_channel(local, &next_delay);
746                         break;
747                 case SCAN_ENTER_OPER_CHANNEL:
748                         ieee80211_scan_state_enter_oper_channel(local, &next_delay);
749                         break;
750                 }
751         } while (next_delay == 0);
752
753         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
754 }
755
756 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
757                            struct cfg80211_scan_request *req)
758 {
759         int res;
760
761         mutex_lock(&sdata->local->scan_mtx);
762         res = __ieee80211_start_scan(sdata, req);
763         mutex_unlock(&sdata->local->scan_mtx);
764
765         return res;
766 }
767
768 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
769                                     const u8 *ssid, u8 ssid_len)
770 {
771         struct ieee80211_local *local = sdata->local;
772         int ret = -EBUSY;
773
774         mutex_lock(&local->scan_mtx);
775
776         /* busy scanning */
777         if (local->scan_req)
778                 goto unlock;
779
780         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
781         local->int_scan_req->ssids[0].ssid_len = ssid_len;
782
783         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
784  unlock:
785         mutex_unlock(&local->scan_mtx);
786         return ret;
787 }
788
789 void ieee80211_scan_cancel(struct ieee80211_local *local)
790 {
791         bool abortscan;
792
793         cancel_delayed_work_sync(&local->scan_work);
794
795         /*
796          * Only call this function when a scan can't be
797          * queued -- mostly at suspend under RTNL.
798          */
799         mutex_lock(&local->scan_mtx);
800         abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
801                     (!local->scanning && local->scan_req);
802         mutex_unlock(&local->scan_mtx);
803
804         if (abortscan)
805                 ieee80211_scan_completed(&local->hw, true);
806 }