mac80211: fix an oops in ieee80211_scan_state_set_channel
[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 #include <net/iw_handler.h>
22
23 #include "ieee80211_i.h"
24 #include "driver-ops.h"
25 #include "mesh.h"
26
27 #define IEEE80211_PROBE_DELAY (HZ / 33)
28 #define IEEE80211_CHANNEL_TIME (HZ / 33)
29 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
30
31 struct ieee80211_bss *
32 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
33                      u8 *ssid, u8 ssid_len)
34 {
35         return (void *)cfg80211_get_bss(local->hw.wiphy,
36                                         ieee80211_get_channel(local->hw.wiphy,
37                                                               freq),
38                                         bssid, ssid, ssid_len,
39                                         0, 0);
40 }
41
42 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
43 {
44         struct ieee80211_bss *bss = (void *)cbss;
45
46         kfree(bss_mesh_id(bss));
47         kfree(bss_mesh_cfg(bss));
48 }
49
50 void ieee80211_rx_bss_put(struct ieee80211_local *local,
51                           struct ieee80211_bss *bss)
52 {
53         cfg80211_put_bss((struct cfg80211_bss *)bss);
54 }
55
56 struct ieee80211_bss *
57 ieee80211_bss_info_update(struct ieee80211_local *local,
58                           struct ieee80211_rx_status *rx_status,
59                           struct ieee80211_mgmt *mgmt,
60                           size_t len,
61                           struct ieee802_11_elems *elems,
62                           struct ieee80211_channel *channel,
63                           bool beacon)
64 {
65         struct ieee80211_bss *bss;
66         int clen;
67         s32 signal = 0;
68
69         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
70                 signal = rx_status->signal * 100;
71         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
72                 signal = (rx_status->signal * 100) / local->hw.max_signal;
73
74         bss = (void *)cfg80211_inform_bss_frame(local->hw.wiphy, channel,
75                                                 mgmt, len, signal, GFP_ATOMIC);
76
77         if (!bss)
78                 return NULL;
79
80         bss->cbss.free_priv = ieee80211_rx_bss_free;
81
82         /* save the ERP value so that it is available at association time */
83         if (elems->erp_info && elems->erp_info_len >= 1) {
84                 bss->erp_value = elems->erp_info[0];
85                 bss->has_erp_value = 1;
86         }
87
88         if (elems->tim) {
89                 struct ieee80211_tim_ie *tim_ie =
90                         (struct ieee80211_tim_ie *)elems->tim;
91                 bss->dtim_period = tim_ie->dtim_period;
92         }
93
94         /* set default value for buggy APs */
95         if (!elems->tim || bss->dtim_period == 0)
96                 bss->dtim_period = 1;
97
98         bss->supp_rates_len = 0;
99         if (elems->supp_rates) {
100                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
101                 if (clen > elems->supp_rates_len)
102                         clen = elems->supp_rates_len;
103                 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
104                        clen);
105                 bss->supp_rates_len += clen;
106         }
107         if (elems->ext_supp_rates) {
108                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
109                 if (clen > elems->ext_supp_rates_len)
110                         clen = elems->ext_supp_rates_len;
111                 memcpy(&bss->supp_rates[bss->supp_rates_len],
112                        elems->ext_supp_rates, clen);
113                 bss->supp_rates_len += clen;
114         }
115
116         bss->wmm_used = elems->wmm_param || elems->wmm_info;
117
118         if (!beacon)
119                 bss->last_probe_resp = jiffies;
120
121         return bss;
122 }
123
124 ieee80211_rx_result
125 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
126 {
127         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
128         struct ieee80211_mgmt *mgmt;
129         struct ieee80211_bss *bss;
130         u8 *elements;
131         struct ieee80211_channel *channel;
132         size_t baselen;
133         int freq;
134         __le16 fc;
135         bool presp, beacon = false;
136         struct ieee802_11_elems elems;
137
138         if (skb->len < 2)
139                 return RX_DROP_UNUSABLE;
140
141         mgmt = (struct ieee80211_mgmt *) skb->data;
142         fc = mgmt->frame_control;
143
144         if (ieee80211_is_ctl(fc))
145                 return RX_CONTINUE;
146
147         if (skb->len < 24)
148                 return RX_DROP_MONITOR;
149
150         presp = ieee80211_is_probe_resp(fc);
151         if (presp) {
152                 /* ignore ProbeResp to foreign address */
153                 if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
154                         return RX_DROP_MONITOR;
155
156                 presp = true;
157                 elements = mgmt->u.probe_resp.variable;
158                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
159         } else {
160                 beacon = ieee80211_is_beacon(fc);
161                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
162                 elements = mgmt->u.beacon.variable;
163         }
164
165         if (!presp && !beacon)
166                 return RX_CONTINUE;
167
168         if (baselen > skb->len)
169                 return RX_DROP_MONITOR;
170
171         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
172
173         if (elems.ds_params && elems.ds_params_len == 1)
174                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
175         else
176                 freq = rx_status->freq;
177
178         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
179
180         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
181                 return RX_DROP_MONITOR;
182
183         bss = ieee80211_bss_info_update(sdata->local, rx_status,
184                                         mgmt, skb->len, &elems,
185                                         channel, beacon);
186         if (bss)
187                 ieee80211_rx_bss_put(sdata->local, bss);
188
189         dev_kfree_skb(skb);
190         return RX_QUEUED;
191 }
192
193 /*
194  * inform AP that we will go to sleep so that it will buffer the frames
195  * while we scan
196  */
197 static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
198 {
199         struct ieee80211_local *local = sdata->local;
200         bool ps = false;
201
202         /* FIXME: what to do when local->pspolling is true? */
203
204         del_timer_sync(&local->dynamic_ps_timer);
205         cancel_work_sync(&local->dynamic_ps_enable_work);
206
207         if (local->hw.conf.flags & IEEE80211_CONF_PS) {
208                 ps = true;
209                 local->hw.conf.flags &= ~IEEE80211_CONF_PS;
210                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
211         }
212
213         if (!ps || !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
214                 /*
215                  * If power save was enabled, no need to send a nullfunc
216                  * frame because AP knows that we are sleeping. But if the
217                  * hardware is creating the nullfunc frame for power save
218                  * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
219                  * enabled) and power save was enabled, the firmware just
220                  * sent a null frame with power save disabled. So we need
221                  * to send a new nullfunc frame to inform the AP that we
222                  * are again sleeping.
223                  */
224                 ieee80211_send_nullfunc(local, sdata, 1);
225 }
226
227 /* inform AP that we are awake again, unless power save is enabled */
228 static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
229 {
230         struct ieee80211_local *local = sdata->local;
231
232         if (!local->ps_sdata)
233                 ieee80211_send_nullfunc(local, sdata, 0);
234         else {
235                 /*
236                  * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
237                  * will send a nullfunc frame with the powersave bit set
238                  * even though the AP already knows that we are sleeping.
239                  * This could be avoided by sending a null frame with power
240                  * save bit disabled before enabling the power save, but
241                  * this doesn't gain anything.
242                  *
243                  * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
244                  * to send a nullfunc frame because AP already knows that
245                  * we are sleeping, let's just enable power save mode in
246                  * hardware.
247                  */
248                 local->hw.conf.flags |= IEEE80211_CONF_PS;
249                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
250         }
251 }
252
253 static void ieee80211_restore_scan_ies(struct ieee80211_local *local)
254 {
255         kfree(local->scan_req->ie);
256         local->scan_req->ie = local->orig_ies;
257         local->scan_req->ie_len = local->orig_ies_len;
258 }
259
260 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
261 {
262         struct ieee80211_local *local = hw_to_local(hw);
263         struct ieee80211_sub_if_data *sdata;
264         bool was_hw_scan;
265
266         mutex_lock(&local->scan_mtx);
267
268         if (WARN_ON(!local->scanning)) {
269                 mutex_unlock(&local->scan_mtx);
270                 return;
271         }
272
273         if (WARN_ON(!local->scan_req)) {
274                 mutex_unlock(&local->scan_mtx);
275                 return;
276         }
277
278         if (test_bit(SCAN_HW_SCANNING, &local->scanning))
279                 ieee80211_restore_scan_ies(local);
280
281         if (local->scan_req != &local->int_scan_req)
282                 cfg80211_scan_done(local->scan_req, aborted);
283         local->scan_req = NULL;
284
285         was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
286         local->scanning = 0;
287         local->scan_channel = NULL;
288
289         /* we only have to protect scan_req and hw/sw scan */
290         mutex_unlock(&local->scan_mtx);
291
292         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
293         if (was_hw_scan)
294                 goto done;
295
296         spin_lock_bh(&local->filter_lock);
297         local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
298         drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
299                              &local->filter_flags,
300                              local->mc_count,
301                              local->mc_list);
302         spin_unlock_bh(&local->filter_lock);
303
304         drv_sw_scan_complete(local);
305
306         mutex_lock(&local->iflist_mtx);
307         list_for_each_entry(sdata, &local->interfaces, list) {
308                 if (!netif_running(sdata->dev))
309                         continue;
310
311                 /* Tell AP we're back */
312                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
313                         if (sdata->u.mgd.associated) {
314                                 ieee80211_scan_ps_disable(sdata);
315                                 netif_tx_wake_all_queues(sdata->dev);
316                         }
317                 } else
318                         netif_tx_wake_all_queues(sdata->dev);
319
320                 /* re-enable beaconing */
321                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
322                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
323                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
324                         ieee80211_bss_info_change_notify(
325                                 sdata, BSS_CHANGED_BEACON_ENABLED);
326         }
327         mutex_unlock(&local->iflist_mtx);
328
329  done:
330         ieee80211_recalc_idle(local);
331         ieee80211_mlme_notify_scan_completed(local);
332         ieee80211_ibss_notify_scan_completed(local);
333         ieee80211_mesh_notify_scan_completed(local);
334 }
335 EXPORT_SYMBOL(ieee80211_scan_completed);
336
337 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
338 {
339         struct ieee80211_sub_if_data *sdata;
340
341         /*
342          * Hardware/driver doesn't support hw_scan, so use software
343          * scanning instead. First send a nullfunc frame with power save
344          * bit on so that AP will buffer the frames for us while we are not
345          * listening, then send probe requests to each channel and wait for
346          * the responses. After all channels are scanned, tune back to the
347          * original channel and send a nullfunc frame with power save bit
348          * off to trigger the AP to send us all the buffered frames.
349          *
350          * Note that while local->sw_scanning is true everything else but
351          * nullfunc frames and probe requests will be dropped in
352          * ieee80211_tx_h_check_assoc().
353          */
354         drv_sw_scan_start(local);
355
356         mutex_lock(&local->iflist_mtx);
357         list_for_each_entry(sdata, &local->interfaces, list) {
358                 if (!netif_running(sdata->dev))
359                         continue;
360
361                 /* disable beaconing */
362                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
363                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
364                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
365                         ieee80211_bss_info_change_notify(
366                                 sdata, BSS_CHANGED_BEACON_ENABLED);
367
368                 /*
369                  * only handle non-STA interfaces here, STA interfaces
370                  * are handled in the scan state machine
371                  */
372                 if (sdata->vif.type != NL80211_IFTYPE_STATION)
373                         netif_tx_stop_all_queues(sdata->dev);
374         }
375         mutex_unlock(&local->iflist_mtx);
376
377         local->next_scan_state = SCAN_DECISION;
378         local->scan_channel_idx = 0;
379
380         spin_lock_bh(&local->filter_lock);
381         local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
382         drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
383                              &local->filter_flags,
384                              local->mc_count,
385                              local->mc_list);
386         spin_unlock_bh(&local->filter_lock);
387
388         /* TODO: start scan as soon as all nullfunc frames are ACKed */
389         queue_delayed_work(local->hw.workqueue, &local->scan_work,
390                            IEEE80211_CHANNEL_TIME);
391
392         return 0;
393 }
394
395
396 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
397                                   struct cfg80211_scan_request *req)
398 {
399         struct ieee80211_local *local = sdata->local;
400         struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
401         int rc;
402
403         if (local->scan_req)
404                 return -EBUSY;
405
406         if (local->ops->hw_scan) {
407                 u8 *ies;
408                 int ielen;
409
410                 ies = kmalloc(2 + IEEE80211_MAX_SSID_LEN +
411                               local->scan_ies_len + req->ie_len, GFP_KERNEL);
412                 if (!ies)
413                         return -ENOMEM;
414
415                 ielen = ieee80211_build_preq_ies(local, ies,
416                                                  req->ie, req->ie_len);
417                 local->orig_ies = req->ie;
418                 local->orig_ies_len = req->ie_len;
419                 req->ie = ies;
420                 req->ie_len = ielen;
421         }
422
423         local->scan_req = req;
424         local->scan_sdata = sdata;
425
426         if (req != &local->int_scan_req &&
427             sdata->vif.type == NL80211_IFTYPE_STATION &&
428             !list_empty(&ifmgd->work_list)) {
429                 /* actually wait for the work it's doing to finish/time out */
430                 set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
431                 return 0;
432         }
433
434         if (local->ops->hw_scan)
435                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
436         else
437                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
438         /*
439          * Kicking off the scan need not be protected,
440          * only the scan variable stuff, since now
441          * local->scan_req is assigned and other callers
442          * will abort their scan attempts.
443          *
444          * This avoids getting a scan_mtx -> iflist_mtx
445          * dependency, so that the scan completed calls
446          * have more locking freedom.
447          */
448
449         ieee80211_recalc_idle(local);
450         mutex_unlock(&local->scan_mtx);
451
452         if (local->ops->hw_scan)
453                 rc = drv_hw_scan(local, local->scan_req);
454         else
455                 rc = ieee80211_start_sw_scan(local);
456
457         mutex_lock(&local->scan_mtx);
458
459         if (rc) {
460                 if (local->ops->hw_scan)
461                         ieee80211_restore_scan_ies(local);
462                 local->scanning = 0;
463
464                 ieee80211_recalc_idle(local);
465
466                 local->scan_req = NULL;
467                 local->scan_sdata = NULL;
468         }
469
470         return rc;
471 }
472
473 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
474                                          unsigned long *next_delay)
475 {
476         bool associated = false;
477         struct ieee80211_sub_if_data *sdata;
478
479         /* if no more bands/channels left, complete scan and advance to the idle state */
480         if (local->scan_channel_idx >= local->scan_req->n_channels) {
481                 ieee80211_scan_completed(&local->hw, false);
482                 return 1;
483         }
484
485         /* check if at least one STA interface is associated */
486         mutex_lock(&local->iflist_mtx);
487         list_for_each_entry(sdata, &local->interfaces, list) {
488                 if (!netif_running(sdata->dev))
489                         continue;
490
491                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
492                         if (sdata->u.mgd.associated) {
493                                 associated = true;
494                                 break;
495                         }
496                 }
497         }
498         mutex_unlock(&local->iflist_mtx);
499
500         if (local->scan_channel) {
501                 /*
502                  * we're currently scanning a different channel, let's
503                  * switch back to the operating channel now if at least
504                  * one interface is associated. Otherwise just scan the
505                  * next channel
506                  */
507                 if (associated)
508                         local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
509                 else
510                         local->next_scan_state = SCAN_SET_CHANNEL;
511         } else {
512                 /*
513                  * we're on the operating channel currently, let's
514                  * leave that channel now to scan another one
515                  */
516                 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
517         }
518
519         *next_delay = 0;
520         return 0;
521 }
522
523 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
524                                                     unsigned long *next_delay)
525 {
526         struct ieee80211_sub_if_data *sdata;
527
528         /*
529          * notify the AP about us leaving the channel and stop all STA interfaces
530          */
531         mutex_lock(&local->iflist_mtx);
532         list_for_each_entry(sdata, &local->interfaces, list) {
533                 if (!netif_running(sdata->dev))
534                         continue;
535
536                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
537                         netif_tx_stop_all_queues(sdata->dev);
538                         if (sdata->u.mgd.associated)
539                                 ieee80211_scan_ps_enable(sdata);
540                 }
541         }
542         mutex_unlock(&local->iflist_mtx);
543
544         __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
545
546         /* advance to the next channel to be scanned */
547         *next_delay = HZ / 10;
548         local->next_scan_state = SCAN_SET_CHANNEL;
549 }
550
551 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
552                                                     unsigned long *next_delay)
553 {
554         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
555
556         /* switch back to the operating channel */
557         local->scan_channel = NULL;
558         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
559
560         /*
561          * notify the AP about us being back and restart all STA interfaces
562          */
563         mutex_lock(&local->iflist_mtx);
564         list_for_each_entry(sdata, &local->interfaces, list) {
565                 if (!netif_running(sdata->dev))
566                         continue;
567
568                 /* Tell AP we're back */
569                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
570                         if (sdata->u.mgd.associated)
571                                 ieee80211_scan_ps_disable(sdata);
572                         netif_tx_wake_all_queues(sdata->dev);
573                 }
574         }
575         mutex_unlock(&local->iflist_mtx);
576
577         __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
578
579         *next_delay = HZ / 5;
580         local->next_scan_state = SCAN_DECISION;
581 }
582
583 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
584                                              unsigned long *next_delay)
585 {
586         int skip;
587         struct ieee80211_channel *chan;
588         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
589
590         skip = 0;
591         chan = local->scan_req->channels[local->scan_channel_idx];
592
593         if (chan->flags & IEEE80211_CHAN_DISABLED ||
594             (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
595              chan->flags & IEEE80211_CHAN_NO_IBSS))
596                 skip = 1;
597
598         if (!skip) {
599                 local->scan_channel = chan;
600                 if (ieee80211_hw_config(local,
601                                         IEEE80211_CONF_CHANGE_CHANNEL))
602                         skip = 1;
603         }
604
605         /* advance state machine to next channel/band */
606         local->scan_channel_idx++;
607
608         if (skip) {
609                 /* if we skip this channel return to the decision state */
610                 local->next_scan_state = SCAN_DECISION;
611                 return;
612         }
613
614         /*
615          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
616          * (which unfortunately doesn't say _why_ step a) is done,
617          * but it waits for the probe delay or until a frame is
618          * received - and the received frame would update the NAV).
619          * For now, we do not support waiting until a frame is
620          * received.
621          *
622          * In any case, it is not necessary for a passive scan.
623          */
624         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
625             !local->scan_req->n_ssids) {
626                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
627                 local->next_scan_state = SCAN_DECISION;
628                 return;
629         }
630
631         /* active scan, send probes */
632         *next_delay = IEEE80211_PROBE_DELAY;
633         local->next_scan_state = SCAN_SEND_PROBE;
634 }
635
636 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
637                                             unsigned long *next_delay)
638 {
639         int i;
640         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
641
642         for (i = 0; i < local->scan_req->n_ssids; i++)
643                 ieee80211_send_probe_req(
644                         sdata, NULL,
645                         local->scan_req->ssids[i].ssid,
646                         local->scan_req->ssids[i].ssid_len,
647                         local->scan_req->ie, local->scan_req->ie_len);
648
649         /*
650          * After sending probe requests, wait for probe responses
651          * on the channel.
652          */
653         *next_delay = IEEE80211_CHANNEL_TIME;
654         local->next_scan_state = SCAN_DECISION;
655 }
656
657 void ieee80211_scan_work(struct work_struct *work)
658 {
659         struct ieee80211_local *local =
660                 container_of(work, struct ieee80211_local, scan_work.work);
661         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
662         unsigned long next_delay = 0;
663
664         mutex_lock(&local->scan_mtx);
665         if (!sdata || !local->scan_req) {
666                 mutex_unlock(&local->scan_mtx);
667                 return;
668         }
669
670         if (local->scan_req && !local->scanning) {
671                 struct cfg80211_scan_request *req = local->scan_req;
672                 int rc;
673
674                 local->scan_req = NULL;
675
676                 rc = __ieee80211_start_scan(sdata, req);
677                 mutex_unlock(&local->scan_mtx);
678
679                 if (rc)
680                         ieee80211_scan_completed(&local->hw, true);
681                 return;
682         }
683
684         mutex_unlock(&local->scan_mtx);
685
686         /*
687          * Avoid re-scheduling when the sdata is going away.
688          */
689         if (!netif_running(sdata->dev)) {
690                 ieee80211_scan_completed(&local->hw, true);
691                 return;
692         }
693
694         /*
695          * as long as no delay is required advance immediately
696          * without scheduling a new work
697          */
698         do {
699                 switch (local->next_scan_state) {
700                 case SCAN_DECISION:
701                         if (ieee80211_scan_state_decision(local, &next_delay))
702                                 return;
703                         break;
704                 case SCAN_SET_CHANNEL:
705                         ieee80211_scan_state_set_channel(local, &next_delay);
706                         break;
707                 case SCAN_SEND_PROBE:
708                         ieee80211_scan_state_send_probe(local, &next_delay);
709                         break;
710                 case SCAN_LEAVE_OPER_CHANNEL:
711                         ieee80211_scan_state_leave_oper_channel(local, &next_delay);
712                         break;
713                 case SCAN_ENTER_OPER_CHANNEL:
714                         ieee80211_scan_state_enter_oper_channel(local, &next_delay);
715                         break;
716                 }
717         } while (next_delay == 0);
718
719         queue_delayed_work(local->hw.workqueue, &local->scan_work,
720                            next_delay);
721 }
722
723 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
724                            struct cfg80211_scan_request *req)
725 {
726         int res;
727
728         mutex_lock(&sdata->local->scan_mtx);
729         res = __ieee80211_start_scan(sdata, req);
730         mutex_unlock(&sdata->local->scan_mtx);
731
732         return res;
733 }
734
735 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
736                                     const u8 *ssid, u8 ssid_len)
737 {
738         struct ieee80211_local *local = sdata->local;
739         int ret = -EBUSY;
740
741         mutex_lock(&local->scan_mtx);
742
743         /* busy scanning */
744         if (local->scan_req)
745                 goto unlock;
746
747         memcpy(local->int_scan_req.ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
748         local->int_scan_req.ssids[0].ssid_len = ssid_len;
749
750         ret = __ieee80211_start_scan(sdata, &sdata->local->int_scan_req);
751  unlock:
752         mutex_unlock(&local->scan_mtx);
753         return ret;
754 }
755
756 void ieee80211_scan_cancel(struct ieee80211_local *local)
757 {
758         bool swscan;
759
760         cancel_delayed_work_sync(&local->scan_work);
761
762         /*
763          * Only call this function when a scan can't be
764          * queued -- mostly at suspend under RTNL.
765          */
766         mutex_lock(&local->scan_mtx);
767         swscan = test_bit(SCAN_SW_SCANNING, &local->scanning);
768         mutex_unlock(&local->scan_mtx);
769
770         if (swscan)
771                 ieee80211_scan_completed(&local->hw, true);
772 }