mac80211: Allow scanning on existing channel-type.
[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/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                         /* We don't need to move off of operating channel. */
522                         local->next_scan_state = SCAN_SET_CHANNEL;
523                 else
524                         /*
525                          * We do need to leave operating channel, as next
526                          * scan is somewhere else.
527                          */
528                         local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
529         } else {
530                 /*
531                  * we're currently scanning a different channel, let's
532                  * see if we can scan another channel without interfering
533                  * with the current traffic situation.
534                  *
535                  * Since we don't know if the AP has pending frames for us
536                  * we can only check for our tx queues and use the current
537                  * pm_qos requirements for rx. Hence, if no tx traffic occurs
538                  * at all we will scan as many channels in a row as the pm_qos
539                  * latency allows us to. Additionally we also check for the
540                  * currently negotiated listen interval to prevent losing
541                  * frames unnecessarily.
542                  *
543                  * Otherwise switch back to the operating channel.
544                  */
545
546                 bad_latency = time_after(jiffies +
547                                 ieee80211_scan_get_channel_time(next_chan),
548                                 local->leave_oper_channel_time +
549                                 usecs_to_jiffies(pm_qos_request(PM_QOS_NETWORK_LATENCY)));
550
551                 listen_int_exceeded = time_after(jiffies +
552                                 ieee80211_scan_get_channel_time(next_chan),
553                                 local->leave_oper_channel_time +
554                                 usecs_to_jiffies(min_beacon_int * 1024) *
555                                 local->hw.conf.listen_interval);
556
557                 if (associated && ( !tx_empty || bad_latency ||
558                     listen_int_exceeded))
559                         local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
560                 else
561                         local->next_scan_state = SCAN_SET_CHANNEL;
562         }
563
564         *next_delay = 0;
565 }
566
567 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
568                                                     unsigned long *next_delay)
569 {
570         /* PS will already be in off-channel mode,
571          * we do that once at the beginning of scanning.
572          */
573         ieee80211_offchannel_stop_vifs(local, false);
574
575         /*
576          * What if the nullfunc frames didn't arrive?
577          */
578         drv_flush(local, false);
579         if (local->ops->flush)
580                 *next_delay = 0;
581         else
582                 *next_delay = HZ / 10;
583
584         /* remember when we left the operating channel */
585         local->leave_oper_channel_time = jiffies;
586
587         /* advance to the next channel to be scanned */
588         local->next_scan_state = SCAN_SET_CHANNEL;
589 }
590
591 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
592                                                     unsigned long *next_delay)
593 {
594         /* switch back to the operating channel */
595         local->scan_channel = NULL;
596         if (!ieee80211_cfg_on_oper_channel(local))
597                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
598
599         /*
600          * Re-enable vifs and beaconing.  Leave PS
601          * in off-channel state..will put that back
602          * on-channel at the end of scanning.
603          */
604         ieee80211_offchannel_return(local, true, false);
605
606         *next_delay = HZ / 5;
607         local->next_scan_state = SCAN_DECISION;
608 }
609
610 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
611                                              unsigned long *next_delay)
612 {
613         int skip;
614         struct ieee80211_channel *chan;
615
616         skip = 0;
617         chan = local->scan_req->channels[local->scan_channel_idx];
618
619         local->scan_channel = chan;
620
621         /* Only call hw-config if we really need to change channels. */
622         if (chan != local->hw.conf.channel)
623                 if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
624                         skip = 1;
625
626         /* advance state machine to next channel/band */
627         local->scan_channel_idx++;
628
629         if (skip) {
630                 /* if we skip this channel return to the decision state */
631                 local->next_scan_state = SCAN_DECISION;
632                 return;
633         }
634
635         /*
636          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
637          * (which unfortunately doesn't say _why_ step a) is done,
638          * but it waits for the probe delay or until a frame is
639          * received - and the received frame would update the NAV).
640          * For now, we do not support waiting until a frame is
641          * received.
642          *
643          * In any case, it is not necessary for a passive scan.
644          */
645         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
646             !local->scan_req->n_ssids) {
647                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
648                 local->next_scan_state = SCAN_DECISION;
649                 return;
650         }
651
652         /* active scan, send probes */
653         *next_delay = IEEE80211_PROBE_DELAY;
654         local->next_scan_state = SCAN_SEND_PROBE;
655 }
656
657 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
658                                             unsigned long *next_delay)
659 {
660         int i;
661         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
662
663         for (i = 0; i < local->scan_req->n_ssids; i++)
664                 ieee80211_send_probe_req(
665                         sdata, NULL,
666                         local->scan_req->ssids[i].ssid,
667                         local->scan_req->ssids[i].ssid_len,
668                         local->scan_req->ie, local->scan_req->ie_len);
669
670         /*
671          * After sending probe requests, wait for probe responses
672          * on the channel.
673          */
674         *next_delay = IEEE80211_CHANNEL_TIME;
675         local->next_scan_state = SCAN_DECISION;
676 }
677
678 void ieee80211_scan_work(struct work_struct *work)
679 {
680         struct ieee80211_local *local =
681                 container_of(work, struct ieee80211_local, scan_work.work);
682         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
683         unsigned long next_delay = 0;
684         bool aborted, hw_scan, finish;
685
686         mutex_lock(&local->mtx);
687
688         if (test_and_clear_bit(SCAN_COMPLETED, &local->scanning)) {
689                 aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
690                 goto out_complete;
691         }
692
693         if (!sdata || !local->scan_req)
694                 goto out;
695
696         if (local->scan_req && !local->scanning) {
697                 struct cfg80211_scan_request *req = local->scan_req;
698                 int rc;
699
700                 local->scan_req = NULL;
701                 local->scan_sdata = NULL;
702
703                 rc = __ieee80211_start_scan(sdata, req);
704                 if (rc) {
705                         /* need to complete scan in cfg80211 */
706                         local->scan_req = req;
707                         aborted = true;
708                         goto out_complete;
709                 } else
710                         goto out;
711         }
712
713         /*
714          * Avoid re-scheduling when the sdata is going away.
715          */
716         if (!ieee80211_sdata_running(sdata)) {
717                 aborted = true;
718                 goto out_complete;
719         }
720
721         /*
722          * as long as no delay is required advance immediately
723          * without scheduling a new work
724          */
725         do {
726                 switch (local->next_scan_state) {
727                 case SCAN_DECISION:
728                         /* if no more bands/channels left, complete scan */
729                         if (local->scan_channel_idx >= local->scan_req->n_channels) {
730                                 aborted = false;
731                                 goto out_complete;
732                         }
733                         ieee80211_scan_state_decision(local, &next_delay);
734                         break;
735                 case SCAN_SET_CHANNEL:
736                         ieee80211_scan_state_set_channel(local, &next_delay);
737                         break;
738                 case SCAN_SEND_PROBE:
739                         ieee80211_scan_state_send_probe(local, &next_delay);
740                         break;
741                 case SCAN_LEAVE_OPER_CHANNEL:
742                         ieee80211_scan_state_leave_oper_channel(local, &next_delay);
743                         break;
744                 case SCAN_ENTER_OPER_CHANNEL:
745                         ieee80211_scan_state_enter_oper_channel(local, &next_delay);
746                         break;
747                 }
748         } while (next_delay == 0);
749
750         ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
751         mutex_unlock(&local->mtx);
752         return;
753
754 out_complete:
755         hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
756         finish = __ieee80211_scan_completed(&local->hw, aborted, hw_scan);
757         mutex_unlock(&local->mtx);
758         if (finish)
759                 __ieee80211_scan_completed_finish(&local->hw, hw_scan);
760         return;
761
762 out:
763         mutex_unlock(&local->mtx);
764 }
765
766 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
767                            struct cfg80211_scan_request *req)
768 {
769         int res;
770
771         mutex_lock(&sdata->local->mtx);
772         res = __ieee80211_start_scan(sdata, req);
773         mutex_unlock(&sdata->local->mtx);
774
775         return res;
776 }
777
778 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
779                                     const u8 *ssid, u8 ssid_len,
780                                     struct ieee80211_channel *chan)
781 {
782         struct ieee80211_local *local = sdata->local;
783         int ret = -EBUSY;
784         enum ieee80211_band band;
785
786         mutex_lock(&local->mtx);
787
788         /* busy scanning */
789         if (local->scan_req)
790                 goto unlock;
791
792         /* fill internal scan request */
793         if (!chan) {
794                 int i, nchan = 0;
795
796                 for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
797                         if (!local->hw.wiphy->bands[band])
798                                 continue;
799                         for (i = 0;
800                              i < local->hw.wiphy->bands[band]->n_channels;
801                              i++) {
802                                 local->int_scan_req->channels[nchan] =
803                                     &local->hw.wiphy->bands[band]->channels[i];
804                                 nchan++;
805                         }
806                 }
807
808                 local->int_scan_req->n_channels = nchan;
809         } else {
810                 local->int_scan_req->channels[0] = chan;
811                 local->int_scan_req->n_channels = 1;
812         }
813
814         local->int_scan_req->ssids = &local->scan_ssid;
815         local->int_scan_req->n_ssids = 1;
816         memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
817         local->int_scan_req->ssids[0].ssid_len = ssid_len;
818
819         ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
820  unlock:
821         mutex_unlock(&local->mtx);
822         return ret;
823 }
824
825 /*
826  * Only call this function when a scan can't be queued -- under RTNL.
827  */
828 void ieee80211_scan_cancel(struct ieee80211_local *local)
829 {
830         bool abortscan;
831         bool finish = false;
832
833         /*
834          * We are only canceling software scan, or deferred scan that was not
835          * yet really started (see __ieee80211_start_scan ).
836          *
837          * Regarding hardware scan:
838          * - we can not call  __ieee80211_scan_completed() as when
839          *   SCAN_HW_SCANNING bit is set this function change
840          *   local->hw_scan_req to operate on 5G band, what race with
841          *   driver which can use local->hw_scan_req
842          *
843          * - we can not cancel scan_work since driver can schedule it
844          *   by ieee80211_scan_completed(..., true) to finish scan
845          *
846          * Hence low lever driver is responsible for canceling HW scan.
847          */
848
849         mutex_lock(&local->mtx);
850         abortscan = local->scan_req && !test_bit(SCAN_HW_SCANNING, &local->scanning);
851         if (abortscan)
852                 finish = __ieee80211_scan_completed(&local->hw, true, false);
853         mutex_unlock(&local->mtx);
854
855         if (abortscan) {
856                 /* The scan is canceled, but stop work from being pending */
857                 cancel_delayed_work_sync(&local->scan_work);
858         }
859         if (finish)
860                 __ieee80211_scan_completed_finish(&local->hw, false);
861 }