cfg80211: self-contained wext handling where possible
[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 /* TODO: figure out how to avoid that the "current BSS" expires */
16
17 #include <linux/wireless.h>
18 #include <linux/if_arp.h>
19 #include <linux/rtnetlink.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         return (void *)cfg80211_get_bss(local->hw.wiphy,
35                                         ieee80211_get_channel(local->hw.wiphy,
36                                                               freq),
37                                         bssid, ssid, ssid_len,
38                                         0, 0);
39 }
40
41 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
42 {
43         struct ieee80211_bss *bss = (void *)cbss;
44
45         kfree(bss_mesh_id(bss));
46         kfree(bss_mesh_cfg(bss));
47 }
48
49 void ieee80211_rx_bss_put(struct ieee80211_local *local,
50                           struct ieee80211_bss *bss)
51 {
52         cfg80211_put_bss((struct cfg80211_bss *)bss);
53 }
54
55 struct ieee80211_bss *
56 ieee80211_bss_info_update(struct ieee80211_local *local,
57                           struct ieee80211_rx_status *rx_status,
58                           struct ieee80211_mgmt *mgmt,
59                           size_t len,
60                           struct ieee802_11_elems *elems,
61                           struct ieee80211_channel *channel,
62                           bool beacon)
63 {
64         struct ieee80211_bss *bss;
65         int clen;
66         s32 signal = 0;
67
68         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
69                 signal = rx_status->signal * 100;
70         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
71                 signal = (rx_status->signal * 100) / local->hw.max_signal;
72
73         bss = (void *)cfg80211_inform_bss_frame(local->hw.wiphy, channel,
74                                                 mgmt, len, signal, GFP_ATOMIC);
75
76         if (!bss)
77                 return NULL;
78
79         bss->cbss.free_priv = ieee80211_rx_bss_free;
80
81         /* save the ERP value so that it is available at association time */
82         if (elems->erp_info && elems->erp_info_len >= 1) {
83                 bss->erp_value = elems->erp_info[0];
84                 bss->has_erp_value = 1;
85         }
86
87         if (elems->tim) {
88                 struct ieee80211_tim_ie *tim_ie =
89                         (struct ieee80211_tim_ie *)elems->tim;
90                 bss->dtim_period = tim_ie->dtim_period;
91         }
92
93         /* set default value for buggy APs */
94         if (!elems->tim || bss->dtim_period == 0)
95                 bss->dtim_period = 1;
96
97         bss->supp_rates_len = 0;
98         if (elems->supp_rates) {
99                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
100                 if (clen > elems->supp_rates_len)
101                         clen = elems->supp_rates_len;
102                 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
103                        clen);
104                 bss->supp_rates_len += clen;
105         }
106         if (elems->ext_supp_rates) {
107                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
108                 if (clen > elems->ext_supp_rates_len)
109                         clen = elems->ext_supp_rates_len;
110                 memcpy(&bss->supp_rates[bss->supp_rates_len],
111                        elems->ext_supp_rates, clen);
112                 bss->supp_rates_len += clen;
113         }
114
115         bss->wmm_used = elems->wmm_param || elems->wmm_info;
116
117         if (!beacon)
118                 bss->last_probe_resp = jiffies;
119
120         return bss;
121 }
122
123 ieee80211_rx_result
124 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
125 {
126         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
127         struct ieee80211_mgmt *mgmt;
128         struct ieee80211_bss *bss;
129         u8 *elements;
130         struct ieee80211_channel *channel;
131         size_t baselen;
132         int freq;
133         __le16 fc;
134         bool presp, beacon = false;
135         struct ieee802_11_elems elems;
136
137         if (skb->len < 2)
138                 return RX_DROP_UNUSABLE;
139
140         mgmt = (struct ieee80211_mgmt *) skb->data;
141         fc = mgmt->frame_control;
142
143         if (ieee80211_is_ctl(fc))
144                 return RX_CONTINUE;
145
146         if (skb->len < 24)
147                 return RX_DROP_MONITOR;
148
149         presp = ieee80211_is_probe_resp(fc);
150         if (presp) {
151                 /* ignore ProbeResp to foreign address */
152                 if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
153                         return RX_DROP_MONITOR;
154
155                 presp = true;
156                 elements = mgmt->u.probe_resp.variable;
157                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
158         } else {
159                 beacon = ieee80211_is_beacon(fc);
160                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
161                 elements = mgmt->u.beacon.variable;
162         }
163
164         if (!presp && !beacon)
165                 return RX_CONTINUE;
166
167         if (baselen > skb->len)
168                 return RX_DROP_MONITOR;
169
170         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
171
172         if (elems.ds_params && elems.ds_params_len == 1)
173                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
174         else
175                 freq = rx_status->freq;
176
177         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
178
179         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
180                 return RX_DROP_MONITOR;
181
182         bss = ieee80211_bss_info_update(sdata->local, rx_status,
183                                         mgmt, skb->len, &elems,
184                                         channel, beacon);
185         if (bss)
186                 ieee80211_rx_bss_put(sdata->local, bss);
187
188         dev_kfree_skb(skb);
189         return RX_QUEUED;
190 }
191
192 /*
193  * inform AP that we will go to sleep so that it will buffer the frames
194  * while we scan
195  */
196 static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
197 {
198         struct ieee80211_local *local = sdata->local;
199         bool ps = false;
200
201         /* FIXME: what to do when local->pspolling is true? */
202
203         del_timer_sync(&local->dynamic_ps_timer);
204         cancel_work_sync(&local->dynamic_ps_enable_work);
205
206         if (local->hw.conf.flags & IEEE80211_CONF_PS) {
207                 ps = true;
208                 local->hw.conf.flags &= ~IEEE80211_CONF_PS;
209                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
210         }
211
212         if (!ps || !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
213                 /*
214                  * If power save was enabled, no need to send a nullfunc
215                  * frame because AP knows that we are sleeping. But if the
216                  * hardware is creating the nullfunc frame for power save
217                  * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
218                  * enabled) and power save was enabled, the firmware just
219                  * sent a null frame with power save disabled. So we need
220                  * to send a new nullfunc frame to inform the AP that we
221                  * are again sleeping.
222                  */
223                 ieee80211_send_nullfunc(local, sdata, 1);
224 }
225
226 /* inform AP that we are awake again, unless power save is enabled */
227 static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
228 {
229         struct ieee80211_local *local = sdata->local;
230
231         if (!local->ps_sdata)
232                 ieee80211_send_nullfunc(local, sdata, 0);
233         else {
234                 /*
235                  * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
236                  * will send a nullfunc frame with the powersave bit set
237                  * even though the AP already knows that we are sleeping.
238                  * This could be avoided by sending a null frame with power
239                  * save bit disabled before enabling the power save, but
240                  * this doesn't gain anything.
241                  *
242                  * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
243                  * to send a nullfunc frame because AP already knows that
244                  * we are sleeping, let's just enable power save mode in
245                  * hardware.
246                  */
247                 local->hw.conf.flags |= IEEE80211_CONF_PS;
248                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
249         }
250 }
251
252 static void ieee80211_restore_scan_ies(struct ieee80211_local *local)
253 {
254         kfree(local->scan_req->ie);
255         local->scan_req->ie = local->orig_ies;
256         local->scan_req->ie_len = local->orig_ies_len;
257 }
258
259 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
260 {
261         struct ieee80211_local *local = hw_to_local(hw);
262         struct ieee80211_sub_if_data *sdata;
263         bool was_hw_scan;
264
265         mutex_lock(&local->scan_mtx);
266
267         if (WARN_ON(!local->scanning)) {
268                 mutex_unlock(&local->scan_mtx);
269                 return;
270         }
271
272         if (WARN_ON(!local->scan_req)) {
273                 mutex_unlock(&local->scan_mtx);
274                 return;
275         }
276
277         if (test_bit(SCAN_HW_SCANNING, &local->scanning))
278                 ieee80211_restore_scan_ies(local);
279
280         if (local->scan_req != &local->int_scan_req)
281                 cfg80211_scan_done(local->scan_req, aborted);
282         local->scan_req = NULL;
283
284         was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
285         local->scanning = 0;
286         local->scan_channel = NULL;
287
288         /* we only have to protect scan_req and hw/sw scan */
289         mutex_unlock(&local->scan_mtx);
290
291         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
292         if (was_hw_scan)
293                 goto done;
294
295         spin_lock_bh(&local->filter_lock);
296         local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
297         drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
298                              &local->filter_flags,
299                              local->mc_count,
300                              local->mc_list);
301         spin_unlock_bh(&local->filter_lock);
302
303         drv_sw_scan_complete(local);
304
305         mutex_lock(&local->iflist_mtx);
306         list_for_each_entry(sdata, &local->interfaces, list) {
307                 if (!netif_running(sdata->dev))
308                         continue;
309
310                 /* Tell AP we're back */
311                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
312                         if (sdata->u.mgd.associated) {
313                                 ieee80211_scan_ps_disable(sdata);
314                                 netif_tx_wake_all_queues(sdata->dev);
315                         }
316                 } else
317                         netif_tx_wake_all_queues(sdata->dev);
318
319                 /* re-enable beaconing */
320                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
321                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
322                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
323                         ieee80211_bss_info_change_notify(
324                                 sdata, BSS_CHANGED_BEACON_ENABLED);
325         }
326         mutex_unlock(&local->iflist_mtx);
327
328  done:
329         ieee80211_recalc_idle(local);
330         ieee80211_mlme_notify_scan_completed(local);
331         ieee80211_ibss_notify_scan_completed(local);
332         ieee80211_mesh_notify_scan_completed(local);
333 }
334 EXPORT_SYMBOL(ieee80211_scan_completed);
335
336 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
337 {
338         struct ieee80211_sub_if_data *sdata;
339
340         /*
341          * Hardware/driver doesn't support hw_scan, so use software
342          * scanning instead. First send a nullfunc frame with power save
343          * bit on so that AP will buffer the frames for us while we are not
344          * listening, then send probe requests to each channel and wait for
345          * the responses. After all channels are scanned, tune back to the
346          * original channel and send a nullfunc frame with power save bit
347          * off to trigger the AP to send us all the buffered frames.
348          *
349          * Note that while local->sw_scanning is true everything else but
350          * nullfunc frames and probe requests will be dropped in
351          * ieee80211_tx_h_check_assoc().
352          */
353         drv_sw_scan_start(local);
354
355         mutex_lock(&local->iflist_mtx);
356         list_for_each_entry(sdata, &local->interfaces, list) {
357                 if (!netif_running(sdata->dev))
358                         continue;
359
360                 /* disable beaconing */
361                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
362                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
363                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
364                         ieee80211_bss_info_change_notify(
365                                 sdata, BSS_CHANGED_BEACON_ENABLED);
366
367                 /*
368                  * only handle non-STA interfaces here, STA interfaces
369                  * are handled in the scan state machine
370                  */
371                 if (sdata->vif.type != NL80211_IFTYPE_STATION)
372                         netif_tx_stop_all_queues(sdata->dev);
373         }
374         mutex_unlock(&local->iflist_mtx);
375
376         local->next_scan_state = SCAN_DECISION;
377         local->scan_channel_idx = 0;
378
379         spin_lock_bh(&local->filter_lock);
380         local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
381         drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
382                              &local->filter_flags,
383                              local->mc_count,
384                              local->mc_list);
385         spin_unlock_bh(&local->filter_lock);
386
387         /* TODO: start scan as soon as all nullfunc frames are ACKed */
388         queue_delayed_work(local->hw.workqueue, &local->scan_work,
389                            IEEE80211_CHANNEL_TIME);
390
391         return 0;
392 }
393
394
395 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
396                                   struct cfg80211_scan_request *req)
397 {
398         struct ieee80211_local *local = sdata->local;
399         struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
400         int rc;
401
402         if (local->scan_req)
403                 return -EBUSY;
404
405         if (local->ops->hw_scan) {
406                 u8 *ies;
407                 int ielen;
408
409                 ies = kmalloc(2 + IEEE80211_MAX_SSID_LEN +
410                               local->scan_ies_len + req->ie_len, GFP_KERNEL);
411                 if (!ies)
412                         return -ENOMEM;
413
414                 ielen = ieee80211_build_preq_ies(local, ies,
415                                                  req->ie, req->ie_len);
416                 local->orig_ies = req->ie;
417                 local->orig_ies_len = req->ie_len;
418                 req->ie = ies;
419                 req->ie_len = ielen;
420         }
421
422         local->scan_req = req;
423         local->scan_sdata = sdata;
424
425         if (req != &local->int_scan_req &&
426             sdata->vif.type == NL80211_IFTYPE_STATION &&
427             !list_empty(&ifmgd->work_list)) {
428                 /* actually wait for the work it's doing to finish/time out */
429                 set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
430                 return 0;
431         }
432
433         if (local->ops->hw_scan)
434                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
435         else
436                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
437         /*
438          * Kicking off the scan need not be protected,
439          * only the scan variable stuff, since now
440          * local->scan_req is assigned and other callers
441          * will abort their scan attempts.
442          *
443          * This avoids getting a scan_mtx -> iflist_mtx
444          * dependency, so that the scan completed calls
445          * have more locking freedom.
446          */
447
448         ieee80211_recalc_idle(local);
449         mutex_unlock(&local->scan_mtx);
450
451         if (local->ops->hw_scan)
452                 rc = drv_hw_scan(local, local->scan_req);
453         else
454                 rc = ieee80211_start_sw_scan(local);
455
456         mutex_lock(&local->scan_mtx);
457
458         if (rc) {
459                 if (local->ops->hw_scan)
460                         ieee80211_restore_scan_ies(local);
461                 local->scanning = 0;
462
463                 ieee80211_recalc_idle(local);
464
465                 local->scan_req = NULL;
466                 local->scan_sdata = NULL;
467         }
468
469         return rc;
470 }
471
472 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
473                                          unsigned long *next_delay)
474 {
475         bool associated = false;
476         struct ieee80211_sub_if_data *sdata;
477
478         /* if no more bands/channels left, complete scan and advance to the idle state */
479         if (local->scan_channel_idx >= local->scan_req->n_channels) {
480                 ieee80211_scan_completed(&local->hw, false);
481                 return 1;
482         }
483
484         /* check if at least one STA interface is associated */
485         mutex_lock(&local->iflist_mtx);
486         list_for_each_entry(sdata, &local->interfaces, list) {
487                 if (!netif_running(sdata->dev))
488                         continue;
489
490                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
491                         if (sdata->u.mgd.associated) {
492                                 associated = true;
493                                 break;
494                         }
495                 }
496         }
497         mutex_unlock(&local->iflist_mtx);
498
499         if (local->scan_channel) {
500                 /*
501                  * we're currently scanning a different channel, let's
502                  * switch back to the operating channel now if at least
503                  * one interface is associated. Otherwise just scan the
504                  * next channel
505                  */
506                 if (associated)
507                         local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
508                 else
509                         local->next_scan_state = SCAN_SET_CHANNEL;
510         } else {
511                 /*
512                  * we're on the operating channel currently, let's
513                  * leave that channel now to scan another one
514                  */
515                 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
516         }
517
518         *next_delay = 0;
519         return 0;
520 }
521
522 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
523                                                     unsigned long *next_delay)
524 {
525         struct ieee80211_sub_if_data *sdata;
526
527         /*
528          * notify the AP about us leaving the channel and stop all STA interfaces
529          */
530         mutex_lock(&local->iflist_mtx);
531         list_for_each_entry(sdata, &local->interfaces, list) {
532                 if (!netif_running(sdata->dev))
533                         continue;
534
535                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
536                         netif_tx_stop_all_queues(sdata->dev);
537                         if (sdata->u.mgd.associated)
538                                 ieee80211_scan_ps_enable(sdata);
539                 }
540         }
541         mutex_unlock(&local->iflist_mtx);
542
543         __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
544
545         /* advance to the next channel to be scanned */
546         *next_delay = HZ / 10;
547         local->next_scan_state = SCAN_SET_CHANNEL;
548 }
549
550 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
551                                                     unsigned long *next_delay)
552 {
553         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
554
555         /* switch back to the operating channel */
556         local->scan_channel = NULL;
557         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
558
559         /*
560          * notify the AP about us being back and restart all STA interfaces
561          */
562         mutex_lock(&local->iflist_mtx);
563         list_for_each_entry(sdata, &local->interfaces, list) {
564                 if (!netif_running(sdata->dev))
565                         continue;
566
567                 /* Tell AP we're back */
568                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
569                         if (sdata->u.mgd.associated)
570                                 ieee80211_scan_ps_disable(sdata);
571                         netif_tx_wake_all_queues(sdata->dev);
572                 }
573         }
574         mutex_unlock(&local->iflist_mtx);
575
576         __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
577
578         *next_delay = HZ / 5;
579         local->next_scan_state = SCAN_DECISION;
580 }
581
582 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
583                                              unsigned long *next_delay)
584 {
585         int skip;
586         struct ieee80211_channel *chan;
587         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
588
589         skip = 0;
590         chan = local->scan_req->channels[local->scan_channel_idx];
591
592         if (chan->flags & IEEE80211_CHAN_DISABLED ||
593             (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
594              chan->flags & IEEE80211_CHAN_NO_IBSS))
595                 skip = 1;
596
597         if (!skip) {
598                 local->scan_channel = chan;
599                 if (ieee80211_hw_config(local,
600                                         IEEE80211_CONF_CHANGE_CHANNEL))
601                         skip = 1;
602         }
603
604         /* advance state machine to next channel/band */
605         local->scan_channel_idx++;
606
607         if (skip) {
608                 /* if we skip this channel return to the decision state */
609                 local->next_scan_state = SCAN_DECISION;
610                 return;
611         }
612
613         /*
614          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
615          * (which unfortunately doesn't say _why_ step a) is done,
616          * but it waits for the probe delay or until a frame is
617          * received - and the received frame would update the NAV).
618          * For now, we do not support waiting until a frame is
619          * received.
620          *
621          * In any case, it is not necessary for a passive scan.
622          */
623         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
624             !local->scan_req->n_ssids) {
625                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
626                 local->next_scan_state = SCAN_DECISION;
627                 return;
628         }
629
630         /* active scan, send probes */
631         *next_delay = IEEE80211_PROBE_DELAY;
632         local->next_scan_state = SCAN_SEND_PROBE;
633 }
634
635 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
636                                             unsigned long *next_delay)
637 {
638         int i;
639         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
640
641         for (i = 0; i < local->scan_req->n_ssids; i++)
642                 ieee80211_send_probe_req(
643                         sdata, NULL,
644                         local->scan_req->ssids[i].ssid,
645                         local->scan_req->ssids[i].ssid_len,
646                         local->scan_req->ie, local->scan_req->ie_len);
647
648         /*
649          * After sending probe requests, wait for probe responses
650          * on the channel.
651          */
652         *next_delay = IEEE80211_CHANNEL_TIME;
653         local->next_scan_state = SCAN_DECISION;
654 }
655
656 void ieee80211_scan_work(struct work_struct *work)
657 {
658         struct ieee80211_local *local =
659                 container_of(work, struct ieee80211_local, scan_work.work);
660         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
661         unsigned long next_delay = 0;
662
663         mutex_lock(&local->scan_mtx);
664         if (!sdata || !local->scan_req) {
665                 mutex_unlock(&local->scan_mtx);
666                 return;
667         }
668
669         if (local->scan_req && !local->scanning) {
670                 struct cfg80211_scan_request *req = local->scan_req;
671                 int rc;
672
673                 local->scan_req = NULL;
674
675                 rc = __ieee80211_start_scan(sdata, req);
676                 mutex_unlock(&local->scan_mtx);
677
678                 if (rc)
679                         ieee80211_scan_completed(&local->hw, true);
680                 return;
681         }
682
683         mutex_unlock(&local->scan_mtx);
684
685         /*
686          * Avoid re-scheduling when the sdata is going away.
687          */
688         if (!netif_running(sdata->dev)) {
689                 ieee80211_scan_completed(&local->hw, true);
690                 return;
691         }
692
693         /*
694          * as long as no delay is required advance immediately
695          * without scheduling a new work
696          */
697         do {
698                 switch (local->next_scan_state) {
699                 case SCAN_DECISION:
700                         if (ieee80211_scan_state_decision(local, &next_delay))
701                                 return;
702                         break;
703                 case SCAN_SET_CHANNEL:
704                         ieee80211_scan_state_set_channel(local, &next_delay);
705                         break;
706                 case SCAN_SEND_PROBE:
707                         ieee80211_scan_state_send_probe(local, &next_delay);
708                         break;
709                 case SCAN_LEAVE_OPER_CHANNEL:
710                         ieee80211_scan_state_leave_oper_channel(local, &next_delay);
711                         break;
712                 case SCAN_ENTER_OPER_CHANNEL:
713                         ieee80211_scan_state_enter_oper_channel(local, &next_delay);
714                         break;
715                 }
716         } while (next_delay == 0);
717
718         queue_delayed_work(local->hw.workqueue, &local->scan_work,
719                            next_delay);
720 }
721
722 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
723                            struct cfg80211_scan_request *req)
724 {
725         int res;
726
727         mutex_lock(&sdata->local->scan_mtx);
728         res = __ieee80211_start_scan(sdata, req);
729         mutex_unlock(&sdata->local->scan_mtx);
730
731         return res;
732 }
733
734 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
735                                     const u8 *ssid, u8 ssid_len)
736 {
737         struct ieee80211_local *local = sdata->local;
738         int ret = -EBUSY;
739
740         mutex_lock(&local->scan_mtx);
741
742         /* busy scanning */
743         if (local->scan_req)
744                 goto unlock;
745
746         memcpy(local->int_scan_req.ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
747         local->int_scan_req.ssids[0].ssid_len = ssid_len;
748
749         ret = __ieee80211_start_scan(sdata, &sdata->local->int_scan_req);
750  unlock:
751         mutex_unlock(&local->scan_mtx);
752         return ret;
753 }
754
755 void ieee80211_scan_cancel(struct ieee80211_local *local)
756 {
757         bool swscan;
758
759         cancel_delayed_work_sync(&local->scan_work);
760
761         /*
762          * Only call this function when a scan can't be
763          * queued -- mostly at suspend under RTNL.
764          */
765         mutex_lock(&local->scan_mtx);
766         swscan = test_bit(SCAN_SW_SCANNING, &local->scanning);
767         mutex_unlock(&local->scan_mtx);
768
769         if (swscan)
770                 ieee80211_scan_completed(&local->hw, true);
771 }