xref: /openbmc/linux/net/mac80211/scan.c (revision 161f4089)
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/etherdevice.h>
17 #include <linux/rtnetlink.h>
18 #include <linux/pm_qos.h>
19 #include <net/sch_generic.h>
20 #include <linux/slab.h>
21 #include <linux/export.h>
22 #include <net/mac80211.h>
23 
24 #include "ieee80211_i.h"
25 #include "driver-ops.h"
26 #include "mesh.h"
27 
28 #define IEEE80211_PROBE_DELAY (HZ / 33)
29 #define IEEE80211_CHANNEL_TIME (HZ / 33)
30 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 9)
31 
32 void ieee80211_rx_bss_put(struct ieee80211_local *local,
33 			  struct ieee80211_bss *bss)
34 {
35 	if (!bss)
36 		return;
37 	cfg80211_put_bss(local->hw.wiphy,
38 			 container_of((void *)bss, struct cfg80211_bss, priv));
39 }
40 
41 static bool is_uapsd_supported(struct ieee802_11_elems *elems)
42 {
43 	u8 qos_info;
44 
45 	if (elems->wmm_info && elems->wmm_info_len == 7
46 	    && elems->wmm_info[5] == 1)
47 		qos_info = elems->wmm_info[6];
48 	else if (elems->wmm_param && elems->wmm_param_len == 24
49 		 && elems->wmm_param[5] == 1)
50 		qos_info = elems->wmm_param[6];
51 	else
52 		/* no valid wmm information or parameter element found */
53 		return false;
54 
55 	return qos_info & IEEE80211_WMM_IE_AP_QOSINFO_UAPSD;
56 }
57 
58 struct ieee80211_bss *
59 ieee80211_bss_info_update(struct ieee80211_local *local,
60 			  struct ieee80211_rx_status *rx_status,
61 			  struct ieee80211_mgmt *mgmt, size_t len,
62 			  struct ieee802_11_elems *elems,
63 			  struct ieee80211_channel *channel)
64 {
65 	bool beacon = ieee80211_is_beacon(mgmt->frame_control);
66 	struct cfg80211_bss *cbss;
67 	struct ieee80211_bss *bss;
68 	int clen, srlen;
69 	enum nl80211_bss_scan_width scan_width;
70 	s32 signal = 0;
71 
72 	if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
73 		signal = rx_status->signal * 100;
74 	else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
75 		signal = (rx_status->signal * 100) / local->hw.max_signal;
76 
77 	scan_width = NL80211_BSS_CHAN_WIDTH_20;
78 	if (rx_status->flag & RX_FLAG_5MHZ)
79 		scan_width = NL80211_BSS_CHAN_WIDTH_5;
80 	if (rx_status->flag & RX_FLAG_10MHZ)
81 		scan_width = NL80211_BSS_CHAN_WIDTH_10;
82 
83 	cbss = cfg80211_inform_bss_width_frame(local->hw.wiphy, channel,
84 					       scan_width, mgmt, len, signal,
85 					       GFP_ATOMIC);
86 	if (!cbss)
87 		return NULL;
88 
89 	bss = (void *)cbss->priv;
90 
91 	if (beacon)
92 		bss->device_ts_beacon = rx_status->device_timestamp;
93 	else
94 		bss->device_ts_presp = rx_status->device_timestamp;
95 
96 	if (elems->parse_error) {
97 		if (beacon)
98 			bss->corrupt_data |= IEEE80211_BSS_CORRUPT_BEACON;
99 		else
100 			bss->corrupt_data |= IEEE80211_BSS_CORRUPT_PROBE_RESP;
101 	} else {
102 		if (beacon)
103 			bss->corrupt_data &= ~IEEE80211_BSS_CORRUPT_BEACON;
104 		else
105 			bss->corrupt_data &= ~IEEE80211_BSS_CORRUPT_PROBE_RESP;
106 	}
107 
108 	/* save the ERP value so that it is available at association time */
109 	if (elems->erp_info && (!elems->parse_error ||
110 				!(bss->valid_data & IEEE80211_BSS_VALID_ERP))) {
111 		bss->erp_value = elems->erp_info[0];
112 		bss->has_erp_value = true;
113 		if (!elems->parse_error)
114 			bss->valid_data |= IEEE80211_BSS_VALID_ERP;
115 	}
116 
117 	/* replace old supported rates if we get new values */
118 	if (!elems->parse_error ||
119 	    !(bss->valid_data & IEEE80211_BSS_VALID_RATES)) {
120 		srlen = 0;
121 		if (elems->supp_rates) {
122 			clen = IEEE80211_MAX_SUPP_RATES;
123 			if (clen > elems->supp_rates_len)
124 				clen = elems->supp_rates_len;
125 			memcpy(bss->supp_rates, elems->supp_rates, clen);
126 			srlen += clen;
127 		}
128 		if (elems->ext_supp_rates) {
129 			clen = IEEE80211_MAX_SUPP_RATES - srlen;
130 			if (clen > elems->ext_supp_rates_len)
131 				clen = elems->ext_supp_rates_len;
132 			memcpy(bss->supp_rates + srlen, elems->ext_supp_rates,
133 			       clen);
134 			srlen += clen;
135 		}
136 		if (srlen) {
137 			bss->supp_rates_len = srlen;
138 			if (!elems->parse_error)
139 				bss->valid_data |= IEEE80211_BSS_VALID_RATES;
140 		}
141 	}
142 
143 	if (!elems->parse_error ||
144 	    !(bss->valid_data & IEEE80211_BSS_VALID_WMM)) {
145 		bss->wmm_used = elems->wmm_param || elems->wmm_info;
146 		bss->uapsd_supported = is_uapsd_supported(elems);
147 		if (!elems->parse_error)
148 			bss->valid_data |= IEEE80211_BSS_VALID_WMM;
149 	}
150 
151 	if (beacon) {
152 		struct ieee80211_supported_band *sband =
153 			local->hw.wiphy->bands[rx_status->band];
154 		if (!(rx_status->flag & RX_FLAG_HT) &&
155 		    !(rx_status->flag & RX_FLAG_VHT))
156 			bss->beacon_rate =
157 				&sband->bitrates[rx_status->rate_idx];
158 	}
159 
160 	return bss;
161 }
162 
163 void ieee80211_scan_rx(struct ieee80211_local *local, struct sk_buff *skb)
164 {
165 	struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
166 	struct ieee80211_sub_if_data *sdata1, *sdata2;
167 	struct ieee80211_mgmt *mgmt = (void *)skb->data;
168 	struct ieee80211_bss *bss;
169 	u8 *elements;
170 	struct ieee80211_channel *channel;
171 	size_t baselen;
172 	struct ieee802_11_elems elems;
173 
174 	if (skb->len < 24 ||
175 	    (!ieee80211_is_probe_resp(mgmt->frame_control) &&
176 	     !ieee80211_is_beacon(mgmt->frame_control)))
177 		return;
178 
179 	sdata1 = rcu_dereference(local->scan_sdata);
180 	sdata2 = rcu_dereference(local->sched_scan_sdata);
181 
182 	if (likely(!sdata1 && !sdata2))
183 		return;
184 
185 	if (ieee80211_is_probe_resp(mgmt->frame_control)) {
186 		/* ignore ProbeResp to foreign address */
187 		if ((!sdata1 || !ether_addr_equal(mgmt->da, sdata1->vif.addr)) &&
188 		    (!sdata2 || !ether_addr_equal(mgmt->da, sdata2->vif.addr)))
189 			return;
190 
191 		elements = mgmt->u.probe_resp.variable;
192 		baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
193 	} else {
194 		baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
195 		elements = mgmt->u.beacon.variable;
196 	}
197 
198 	if (baselen > skb->len)
199 		return;
200 
201 	ieee802_11_parse_elems(elements, skb->len - baselen, false, &elems);
202 
203 	channel = ieee80211_get_channel(local->hw.wiphy, rx_status->freq);
204 
205 	if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
206 		return;
207 
208 	bss = ieee80211_bss_info_update(local, rx_status,
209 					mgmt, skb->len, &elems,
210 					channel);
211 	if (bss)
212 		ieee80211_rx_bss_put(local, bss);
213 }
214 
215 static void
216 ieee80211_prepare_scan_chandef(struct cfg80211_chan_def *chandef,
217 			       enum nl80211_bss_scan_width scan_width)
218 {
219 	memset(chandef, 0, sizeof(*chandef));
220 	switch (scan_width) {
221 	case NL80211_BSS_CHAN_WIDTH_5:
222 		chandef->width = NL80211_CHAN_WIDTH_5;
223 		break;
224 	case NL80211_BSS_CHAN_WIDTH_10:
225 		chandef->width = NL80211_CHAN_WIDTH_10;
226 		break;
227 	default:
228 		chandef->width = NL80211_CHAN_WIDTH_20_NOHT;
229 		break;
230 	}
231 }
232 
233 /* return false if no more work */
234 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
235 {
236 	struct cfg80211_scan_request *req = local->scan_req;
237 	struct cfg80211_chan_def chandef;
238 	enum ieee80211_band band;
239 	int i, ielen, n_chans;
240 
241 	if (test_bit(SCAN_HW_CANCELLED, &local->scanning))
242 		return false;
243 
244 	do {
245 		if (local->hw_scan_band == IEEE80211_NUM_BANDS)
246 			return false;
247 
248 		band = local->hw_scan_band;
249 		n_chans = 0;
250 		for (i = 0; i < req->n_channels; i++) {
251 			if (req->channels[i]->band == band) {
252 				local->hw_scan_req->channels[n_chans] =
253 							req->channels[i];
254 				n_chans++;
255 			}
256 		}
257 
258 		local->hw_scan_band++;
259 	} while (!n_chans);
260 
261 	local->hw_scan_req->n_channels = n_chans;
262 	ieee80211_prepare_scan_chandef(&chandef, req->scan_width);
263 
264 	ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
265 					 local->hw_scan_ies_bufsize,
266 					 req->ie, req->ie_len, band,
267 					 req->rates[band], &chandef);
268 	local->hw_scan_req->ie_len = ielen;
269 	local->hw_scan_req->no_cck = req->no_cck;
270 
271 	return true;
272 }
273 
274 static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted,
275 				       bool was_hw_scan)
276 {
277 	struct ieee80211_local *local = hw_to_local(hw);
278 
279 	lockdep_assert_held(&local->mtx);
280 
281 	/*
282 	 * It's ok to abort a not-yet-running scan (that
283 	 * we have one at all will be verified by checking
284 	 * local->scan_req next), but not to complete it
285 	 * successfully.
286 	 */
287 	if (WARN_ON(!local->scanning && !aborted))
288 		aborted = true;
289 
290 	if (WARN_ON(!local->scan_req))
291 		return;
292 
293 	if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
294 		int rc;
295 
296 		rc = drv_hw_scan(local,
297 			rcu_dereference_protected(local->scan_sdata,
298 						  lockdep_is_held(&local->mtx)),
299 			local->hw_scan_req);
300 
301 		if (rc == 0)
302 			return;
303 	}
304 
305 	kfree(local->hw_scan_req);
306 	local->hw_scan_req = NULL;
307 
308 	if (local->scan_req != local->int_scan_req)
309 		cfg80211_scan_done(local->scan_req, aborted);
310 	local->scan_req = NULL;
311 	rcu_assign_pointer(local->scan_sdata, NULL);
312 
313 	local->scanning = 0;
314 	local->scan_chandef.chan = NULL;
315 
316 	/* Set power back to normal operating levels. */
317 	ieee80211_hw_config(local, 0);
318 
319 	if (!was_hw_scan) {
320 		ieee80211_configure_filter(local);
321 		drv_sw_scan_complete(local);
322 		ieee80211_offchannel_return(local);
323 	}
324 
325 	ieee80211_recalc_idle(local);
326 
327 	ieee80211_mlme_notify_scan_completed(local);
328 	ieee80211_ibss_notify_scan_completed(local);
329 	ieee80211_mesh_notify_scan_completed(local);
330 	ieee80211_start_next_roc(local);
331 }
332 
333 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
334 {
335 	struct ieee80211_local *local = hw_to_local(hw);
336 
337 	trace_api_scan_completed(local, aborted);
338 
339 	set_bit(SCAN_COMPLETED, &local->scanning);
340 	if (aborted)
341 		set_bit(SCAN_ABORTED, &local->scanning);
342 	ieee80211_queue_delayed_work(&local->hw, &local->scan_work, 0);
343 }
344 EXPORT_SYMBOL(ieee80211_scan_completed);
345 
346 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
347 {
348 	/* Software scan is not supported in multi-channel cases */
349 	if (local->use_chanctx)
350 		return -EOPNOTSUPP;
351 
352 	/*
353 	 * Hardware/driver doesn't support hw_scan, so use software
354 	 * scanning instead. First send a nullfunc frame with power save
355 	 * bit on so that AP will buffer the frames for us while we are not
356 	 * listening, then send probe requests to each channel and wait for
357 	 * the responses. After all channels are scanned, tune back to the
358 	 * original channel and send a nullfunc frame with power save bit
359 	 * off to trigger the AP to send us all the buffered frames.
360 	 *
361 	 * Note that while local->sw_scanning is true everything else but
362 	 * nullfunc frames and probe requests will be dropped in
363 	 * ieee80211_tx_h_check_assoc().
364 	 */
365 	drv_sw_scan_start(local);
366 
367 	local->leave_oper_channel_time = jiffies;
368 	local->next_scan_state = SCAN_DECISION;
369 	local->scan_channel_idx = 0;
370 
371 	ieee80211_offchannel_stop_vifs(local);
372 
373 	/* ensure nullfunc is transmitted before leaving operating channel */
374 	ieee80211_flush_queues(local, NULL);
375 
376 	ieee80211_configure_filter(local);
377 
378 	/* We need to set power level at maximum rate for scanning. */
379 	ieee80211_hw_config(local, 0);
380 
381 	ieee80211_queue_delayed_work(&local->hw,
382 				     &local->scan_work, 0);
383 
384 	return 0;
385 }
386 
387 static bool ieee80211_can_scan(struct ieee80211_local *local,
388 			       struct ieee80211_sub_if_data *sdata)
389 {
390 	if (local->radar_detect_enabled)
391 		return false;
392 
393 	if (!list_empty(&local->roc_list))
394 		return false;
395 
396 	if (sdata->vif.type == NL80211_IFTYPE_STATION &&
397 	    sdata->u.mgd.flags & (IEEE80211_STA_BEACON_POLL |
398 				  IEEE80211_STA_CONNECTION_POLL))
399 		return false;
400 
401 	return true;
402 }
403 
404 void ieee80211_run_deferred_scan(struct ieee80211_local *local)
405 {
406 	lockdep_assert_held(&local->mtx);
407 
408 	if (!local->scan_req || local->scanning)
409 		return;
410 
411 	if (!ieee80211_can_scan(local,
412 				rcu_dereference_protected(
413 					local->scan_sdata,
414 					lockdep_is_held(&local->mtx))))
415 		return;
416 
417 	ieee80211_queue_delayed_work(&local->hw, &local->scan_work,
418 				     round_jiffies_relative(0));
419 }
420 
421 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
422 					    unsigned long *next_delay)
423 {
424 	int i;
425 	struct ieee80211_sub_if_data *sdata;
426 	enum ieee80211_band band = local->hw.conf.chandef.chan->band;
427 	u32 tx_flags;
428 
429 	tx_flags = IEEE80211_TX_INTFL_OFFCHAN_TX_OK;
430 	if (local->scan_req->no_cck)
431 		tx_flags |= IEEE80211_TX_CTL_NO_CCK_RATE;
432 
433 	sdata = rcu_dereference_protected(local->scan_sdata,
434 					  lockdep_is_held(&local->mtx));
435 
436 	for (i = 0; i < local->scan_req->n_ssids; i++)
437 		ieee80211_send_probe_req(
438 			sdata, NULL,
439 			local->scan_req->ssids[i].ssid,
440 			local->scan_req->ssids[i].ssid_len,
441 			local->scan_req->ie, local->scan_req->ie_len,
442 			local->scan_req->rates[band], false,
443 			tx_flags, local->hw.conf.chandef.chan, true);
444 
445 	/*
446 	 * After sending probe requests, wait for probe responses
447 	 * on the channel.
448 	 */
449 	*next_delay = IEEE80211_CHANNEL_TIME;
450 	local->next_scan_state = SCAN_DECISION;
451 }
452 
453 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
454 				  struct cfg80211_scan_request *req)
455 {
456 	struct ieee80211_local *local = sdata->local;
457 	int rc;
458 
459 	lockdep_assert_held(&local->mtx);
460 
461 	if (local->scan_req)
462 		return -EBUSY;
463 
464 	if (!ieee80211_can_scan(local, sdata)) {
465 		/* wait for the work to finish/time out */
466 		local->scan_req = req;
467 		rcu_assign_pointer(local->scan_sdata, sdata);
468 		return 0;
469 	}
470 
471 	if (local->ops->hw_scan) {
472 		u8 *ies;
473 
474 		local->hw_scan_ies_bufsize = 2 + IEEE80211_MAX_SSID_LEN +
475 					     local->scan_ies_len +
476 					     req->ie_len;
477 		local->hw_scan_req = kmalloc(
478 				sizeof(*local->hw_scan_req) +
479 				req->n_channels * sizeof(req->channels[0]) +
480 				local->hw_scan_ies_bufsize, GFP_KERNEL);
481 		if (!local->hw_scan_req)
482 			return -ENOMEM;
483 
484 		local->hw_scan_req->ssids = req->ssids;
485 		local->hw_scan_req->n_ssids = req->n_ssids;
486 		ies = (u8 *)local->hw_scan_req +
487 			sizeof(*local->hw_scan_req) +
488 			req->n_channels * sizeof(req->channels[0]);
489 		local->hw_scan_req->ie = ies;
490 		local->hw_scan_req->flags = req->flags;
491 
492 		local->hw_scan_band = 0;
493 
494 		/*
495 		 * After allocating local->hw_scan_req, we must
496 		 * go through until ieee80211_prep_hw_scan(), so
497 		 * anything that might be changed here and leave
498 		 * this function early must not go after this
499 		 * allocation.
500 		 */
501 	}
502 
503 	local->scan_req = req;
504 	rcu_assign_pointer(local->scan_sdata, sdata);
505 
506 	if (local->ops->hw_scan) {
507 		__set_bit(SCAN_HW_SCANNING, &local->scanning);
508 	} else if ((req->n_channels == 1) &&
509 		   (req->channels[0] == local->_oper_chandef.chan)) {
510 		/*
511 		 * If we are scanning only on the operating channel
512 		 * then we do not need to stop normal activities
513 		 */
514 		unsigned long next_delay;
515 
516 		__set_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning);
517 
518 		ieee80211_recalc_idle(local);
519 
520 		/* Notify driver scan is starting, keep order of operations
521 		 * same as normal software scan, in case that matters. */
522 		drv_sw_scan_start(local);
523 
524 		ieee80211_configure_filter(local); /* accept probe-responses */
525 
526 		/* We need to ensure power level is at max for scanning. */
527 		ieee80211_hw_config(local, 0);
528 
529 		if ((req->channels[0]->flags &
530 		     IEEE80211_CHAN_PASSIVE_SCAN) ||
531 		    !local->scan_req->n_ssids) {
532 			next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
533 		} else {
534 			ieee80211_scan_state_send_probe(local, &next_delay);
535 			next_delay = IEEE80211_CHANNEL_TIME;
536 		}
537 
538 		/* Now, just wait a bit and we are all done! */
539 		ieee80211_queue_delayed_work(&local->hw, &local->scan_work,
540 					     next_delay);
541 		return 0;
542 	} else {
543 		/* Do normal software scan */
544 		__set_bit(SCAN_SW_SCANNING, &local->scanning);
545 	}
546 
547 	ieee80211_recalc_idle(local);
548 
549 	if (local->ops->hw_scan) {
550 		WARN_ON(!ieee80211_prep_hw_scan(local));
551 		rc = drv_hw_scan(local, sdata, local->hw_scan_req);
552 	} else
553 		rc = ieee80211_start_sw_scan(local);
554 
555 	if (rc) {
556 		kfree(local->hw_scan_req);
557 		local->hw_scan_req = NULL;
558 		local->scanning = 0;
559 
560 		ieee80211_recalc_idle(local);
561 
562 		local->scan_req = NULL;
563 		rcu_assign_pointer(local->scan_sdata, NULL);
564 	}
565 
566 	return rc;
567 }
568 
569 static unsigned long
570 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
571 {
572 	/*
573 	 * TODO: channel switching also consumes quite some time,
574 	 * add that delay as well to get a better estimation
575 	 */
576 	if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN)
577 		return IEEE80211_PASSIVE_CHANNEL_TIME;
578 	return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
579 }
580 
581 static void ieee80211_scan_state_decision(struct ieee80211_local *local,
582 					  unsigned long *next_delay)
583 {
584 	bool associated = false;
585 	bool tx_empty = true;
586 	bool bad_latency;
587 	struct ieee80211_sub_if_data *sdata;
588 	struct ieee80211_channel *next_chan;
589 	enum mac80211_scan_state next_scan_state;
590 
591 	/*
592 	 * check if at least one STA interface is associated,
593 	 * check if at least one STA interface has pending tx frames
594 	 * and grab the lowest used beacon interval
595 	 */
596 	mutex_lock(&local->iflist_mtx);
597 	list_for_each_entry(sdata, &local->interfaces, list) {
598 		if (!ieee80211_sdata_running(sdata))
599 			continue;
600 
601 		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
602 			if (sdata->u.mgd.associated) {
603 				associated = true;
604 
605 				if (!qdisc_all_tx_empty(sdata->dev)) {
606 					tx_empty = false;
607 					break;
608 				}
609 			}
610 		}
611 	}
612 	mutex_unlock(&local->iflist_mtx);
613 
614 	next_chan = local->scan_req->channels[local->scan_channel_idx];
615 
616 	/*
617 	 * we're currently scanning a different channel, let's
618 	 * see if we can scan another channel without interfering
619 	 * with the current traffic situation.
620 	 *
621 	 * Keep good latency, do not stay off-channel more than 125 ms.
622 	 */
623 
624 	bad_latency = time_after(jiffies +
625 				 ieee80211_scan_get_channel_time(next_chan),
626 				 local->leave_oper_channel_time + HZ / 8);
627 
628 	if (associated && !tx_empty) {
629 		if (local->scan_req->flags & NL80211_SCAN_FLAG_LOW_PRIORITY)
630 			next_scan_state = SCAN_ABORT;
631 		else
632 			next_scan_state = SCAN_SUSPEND;
633 	} else if (associated && bad_latency) {
634 		next_scan_state = SCAN_SUSPEND;
635 	} else {
636 		next_scan_state = SCAN_SET_CHANNEL;
637 	}
638 
639 	local->next_scan_state = next_scan_state;
640 
641 	*next_delay = 0;
642 }
643 
644 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
645 					     unsigned long *next_delay)
646 {
647 	int skip;
648 	struct ieee80211_channel *chan;
649 	enum nl80211_bss_scan_width oper_scan_width;
650 
651 	skip = 0;
652 	chan = local->scan_req->channels[local->scan_channel_idx];
653 
654 	local->scan_chandef.chan = chan;
655 	local->scan_chandef.center_freq1 = chan->center_freq;
656 	local->scan_chandef.center_freq2 = 0;
657 	switch (local->scan_req->scan_width) {
658 	case NL80211_BSS_CHAN_WIDTH_5:
659 		local->scan_chandef.width = NL80211_CHAN_WIDTH_5;
660 		break;
661 	case NL80211_BSS_CHAN_WIDTH_10:
662 		local->scan_chandef.width = NL80211_CHAN_WIDTH_10;
663 		break;
664 	case NL80211_BSS_CHAN_WIDTH_20:
665 		/* If scanning on oper channel, use whatever channel-type
666 		 * is currently in use.
667 		 */
668 		oper_scan_width = cfg80211_chandef_to_scan_width(
669 					&local->_oper_chandef);
670 		if (chan == local->_oper_chandef.chan &&
671 		    oper_scan_width == local->scan_req->scan_width)
672 			local->scan_chandef = local->_oper_chandef;
673 		else
674 			local->scan_chandef.width = NL80211_CHAN_WIDTH_20_NOHT;
675 		break;
676 	}
677 
678 	if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
679 		skip = 1;
680 
681 	/* advance state machine to next channel/band */
682 	local->scan_channel_idx++;
683 
684 	if (skip) {
685 		/* if we skip this channel return to the decision state */
686 		local->next_scan_state = SCAN_DECISION;
687 		return;
688 	}
689 
690 	/*
691 	 * Probe delay is used to update the NAV, cf. 11.1.3.2.2
692 	 * (which unfortunately doesn't say _why_ step a) is done,
693 	 * but it waits for the probe delay or until a frame is
694 	 * received - and the received frame would update the NAV).
695 	 * For now, we do not support waiting until a frame is
696 	 * received.
697 	 *
698 	 * In any case, it is not necessary for a passive scan.
699 	 */
700 	if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
701 	    !local->scan_req->n_ssids) {
702 		*next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
703 		local->next_scan_state = SCAN_DECISION;
704 		return;
705 	}
706 
707 	/* active scan, send probes */
708 	*next_delay = IEEE80211_PROBE_DELAY;
709 	local->next_scan_state = SCAN_SEND_PROBE;
710 }
711 
712 static void ieee80211_scan_state_suspend(struct ieee80211_local *local,
713 					 unsigned long *next_delay)
714 {
715 	/* switch back to the operating channel */
716 	local->scan_chandef.chan = NULL;
717 	ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
718 
719 	/* disable PS */
720 	ieee80211_offchannel_return(local);
721 
722 	*next_delay = HZ / 5;
723 	/* afterwards, resume scan & go to next channel */
724 	local->next_scan_state = SCAN_RESUME;
725 }
726 
727 static void ieee80211_scan_state_resume(struct ieee80211_local *local,
728 					unsigned long *next_delay)
729 {
730 	ieee80211_offchannel_stop_vifs(local);
731 
732 	if (local->ops->flush) {
733 		ieee80211_flush_queues(local, NULL);
734 		*next_delay = 0;
735 	} else
736 		*next_delay = HZ / 10;
737 
738 	/* remember when we left the operating channel */
739 	local->leave_oper_channel_time = jiffies;
740 
741 	/* advance to the next channel to be scanned */
742 	local->next_scan_state = SCAN_SET_CHANNEL;
743 }
744 
745 void ieee80211_scan_work(struct work_struct *work)
746 {
747 	struct ieee80211_local *local =
748 		container_of(work, struct ieee80211_local, scan_work.work);
749 	struct ieee80211_sub_if_data *sdata;
750 	unsigned long next_delay = 0;
751 	bool aborted, hw_scan;
752 
753 	mutex_lock(&local->mtx);
754 
755 	sdata = rcu_dereference_protected(local->scan_sdata,
756 					  lockdep_is_held(&local->mtx));
757 
758 	/* When scanning on-channel, the first-callback means completed. */
759 	if (test_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning)) {
760 		aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
761 		goto out_complete;
762 	}
763 
764 	if (test_and_clear_bit(SCAN_COMPLETED, &local->scanning)) {
765 		aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
766 		goto out_complete;
767 	}
768 
769 	if (!sdata || !local->scan_req)
770 		goto out;
771 
772 	if (local->scan_req && !local->scanning) {
773 		struct cfg80211_scan_request *req = local->scan_req;
774 		int rc;
775 
776 		local->scan_req = NULL;
777 		rcu_assign_pointer(local->scan_sdata, NULL);
778 
779 		rc = __ieee80211_start_scan(sdata, req);
780 		if (rc) {
781 			/* need to complete scan in cfg80211 */
782 			local->scan_req = req;
783 			aborted = true;
784 			goto out_complete;
785 		} else
786 			goto out;
787 	}
788 
789 	/*
790 	 * Avoid re-scheduling when the sdata is going away.
791 	 */
792 	if (!ieee80211_sdata_running(sdata)) {
793 		aborted = true;
794 		goto out_complete;
795 	}
796 
797 	/*
798 	 * as long as no delay is required advance immediately
799 	 * without scheduling a new work
800 	 */
801 	do {
802 		if (!ieee80211_sdata_running(sdata)) {
803 			aborted = true;
804 			goto out_complete;
805 		}
806 
807 		switch (local->next_scan_state) {
808 		case SCAN_DECISION:
809 			/* if no more bands/channels left, complete scan */
810 			if (local->scan_channel_idx >= local->scan_req->n_channels) {
811 				aborted = false;
812 				goto out_complete;
813 			}
814 			ieee80211_scan_state_decision(local, &next_delay);
815 			break;
816 		case SCAN_SET_CHANNEL:
817 			ieee80211_scan_state_set_channel(local, &next_delay);
818 			break;
819 		case SCAN_SEND_PROBE:
820 			ieee80211_scan_state_send_probe(local, &next_delay);
821 			break;
822 		case SCAN_SUSPEND:
823 			ieee80211_scan_state_suspend(local, &next_delay);
824 			break;
825 		case SCAN_RESUME:
826 			ieee80211_scan_state_resume(local, &next_delay);
827 			break;
828 		case SCAN_ABORT:
829 			aborted = true;
830 			goto out_complete;
831 		}
832 	} while (next_delay == 0);
833 
834 	ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
835 	goto out;
836 
837 out_complete:
838 	hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
839 	__ieee80211_scan_completed(&local->hw, aborted, hw_scan);
840 out:
841 	mutex_unlock(&local->mtx);
842 }
843 
844 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
845 			   struct cfg80211_scan_request *req)
846 {
847 	int res;
848 
849 	mutex_lock(&sdata->local->mtx);
850 	res = __ieee80211_start_scan(sdata, req);
851 	mutex_unlock(&sdata->local->mtx);
852 
853 	return res;
854 }
855 
856 int ieee80211_request_ibss_scan(struct ieee80211_sub_if_data *sdata,
857 				const u8 *ssid, u8 ssid_len,
858 				struct ieee80211_channel *chan,
859 				enum nl80211_bss_scan_width scan_width)
860 {
861 	struct ieee80211_local *local = sdata->local;
862 	int ret = -EBUSY;
863 	enum ieee80211_band band;
864 
865 	mutex_lock(&local->mtx);
866 
867 	/* busy scanning */
868 	if (local->scan_req)
869 		goto unlock;
870 
871 	/* fill internal scan request */
872 	if (!chan) {
873 		int i, max_n;
874 		int n_ch = 0;
875 
876 		for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
877 			if (!local->hw.wiphy->bands[band])
878 				continue;
879 
880 			max_n = local->hw.wiphy->bands[band]->n_channels;
881 			for (i = 0; i < max_n; i++) {
882 				struct ieee80211_channel *tmp_ch =
883 				    &local->hw.wiphy->bands[band]->channels[i];
884 
885 				if (tmp_ch->flags & (IEEE80211_CHAN_NO_IBSS |
886 						     IEEE80211_CHAN_DISABLED))
887 					continue;
888 
889 				local->int_scan_req->channels[n_ch] = tmp_ch;
890 				n_ch++;
891 			}
892 		}
893 
894 		if (WARN_ON_ONCE(n_ch == 0))
895 			goto unlock;
896 
897 		local->int_scan_req->n_channels = n_ch;
898 	} else {
899 		if (WARN_ON_ONCE(chan->flags & (IEEE80211_CHAN_NO_IBSS |
900 						IEEE80211_CHAN_DISABLED)))
901 			goto unlock;
902 
903 		local->int_scan_req->channels[0] = chan;
904 		local->int_scan_req->n_channels = 1;
905 	}
906 
907 	local->int_scan_req->ssids = &local->scan_ssid;
908 	local->int_scan_req->n_ssids = 1;
909 	local->int_scan_req->scan_width = scan_width;
910 	memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
911 	local->int_scan_req->ssids[0].ssid_len = ssid_len;
912 
913 	ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
914  unlock:
915 	mutex_unlock(&local->mtx);
916 	return ret;
917 }
918 
919 /*
920  * Only call this function when a scan can't be queued -- under RTNL.
921  */
922 void ieee80211_scan_cancel(struct ieee80211_local *local)
923 {
924 	/*
925 	 * We are canceling software scan, or deferred scan that was not
926 	 * yet really started (see __ieee80211_start_scan ).
927 	 *
928 	 * Regarding hardware scan:
929 	 * - we can not call  __ieee80211_scan_completed() as when
930 	 *   SCAN_HW_SCANNING bit is set this function change
931 	 *   local->hw_scan_req to operate on 5G band, what race with
932 	 *   driver which can use local->hw_scan_req
933 	 *
934 	 * - we can not cancel scan_work since driver can schedule it
935 	 *   by ieee80211_scan_completed(..., true) to finish scan
936 	 *
937 	 * Hence we only call the cancel_hw_scan() callback, but the low-level
938 	 * driver is still responsible for calling ieee80211_scan_completed()
939 	 * after the scan was completed/aborted.
940 	 */
941 
942 	mutex_lock(&local->mtx);
943 	if (!local->scan_req)
944 		goto out;
945 
946 	/*
947 	 * We have a scan running and the driver already reported completion,
948 	 * but the worker hasn't run yet or is stuck on the mutex - mark it as
949 	 * cancelled.
950 	 */
951 	if (test_bit(SCAN_HW_SCANNING, &local->scanning) &&
952 	    test_bit(SCAN_COMPLETED, &local->scanning)) {
953 		set_bit(SCAN_HW_CANCELLED, &local->scanning);
954 		goto out;
955 	}
956 
957 	if (test_bit(SCAN_HW_SCANNING, &local->scanning)) {
958 		/*
959 		 * Make sure that __ieee80211_scan_completed doesn't trigger a
960 		 * scan on another band.
961 		 */
962 		set_bit(SCAN_HW_CANCELLED, &local->scanning);
963 		if (local->ops->cancel_hw_scan)
964 			drv_cancel_hw_scan(local,
965 				rcu_dereference_protected(local->scan_sdata,
966 						lockdep_is_held(&local->mtx)));
967 		goto out;
968 	}
969 
970 	/*
971 	 * If the work is currently running, it must be blocked on
972 	 * the mutex, but we'll set scan_sdata = NULL and it'll
973 	 * simply exit once it acquires the mutex.
974 	 */
975 	cancel_delayed_work(&local->scan_work);
976 	/* and clean up */
977 	__ieee80211_scan_completed(&local->hw, true, false);
978 out:
979 	mutex_unlock(&local->mtx);
980 }
981 
982 int ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
983 				       struct cfg80211_sched_scan_request *req)
984 {
985 	struct ieee80211_local *local = sdata->local;
986 	struct ieee80211_sched_scan_ies sched_scan_ies = {};
987 	struct cfg80211_chan_def chandef;
988 	int ret, i, iebufsz;
989 
990 	iebufsz = 2 + IEEE80211_MAX_SSID_LEN +
991 		  local->scan_ies_len + req->ie_len;
992 
993 	mutex_lock(&local->mtx);
994 
995 	if (rcu_access_pointer(local->sched_scan_sdata)) {
996 		ret = -EBUSY;
997 		goto out;
998 	}
999 
1000 	if (!local->ops->sched_scan_start) {
1001 		ret = -ENOTSUPP;
1002 		goto out;
1003 	}
1004 
1005 	for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
1006 		if (!local->hw.wiphy->bands[i])
1007 			continue;
1008 
1009 		sched_scan_ies.ie[i] = kzalloc(iebufsz, GFP_KERNEL);
1010 		if (!sched_scan_ies.ie[i]) {
1011 			ret = -ENOMEM;
1012 			goto out_free;
1013 		}
1014 
1015 		ieee80211_prepare_scan_chandef(&chandef, req->scan_width);
1016 
1017 		sched_scan_ies.len[i] =
1018 			ieee80211_build_preq_ies(local, sched_scan_ies.ie[i],
1019 						 iebufsz, req->ie, req->ie_len,
1020 						 i, (u32) -1, &chandef);
1021 	}
1022 
1023 	ret = drv_sched_scan_start(local, sdata, req, &sched_scan_ies);
1024 	if (ret == 0)
1025 		rcu_assign_pointer(local->sched_scan_sdata, sdata);
1026 
1027 out_free:
1028 	while (i > 0)
1029 		kfree(sched_scan_ies.ie[--i]);
1030 out:
1031 	mutex_unlock(&local->mtx);
1032 	return ret;
1033 }
1034 
1035 int ieee80211_request_sched_scan_stop(struct ieee80211_sub_if_data *sdata)
1036 {
1037 	struct ieee80211_local *local = sdata->local;
1038 	int ret = 0;
1039 
1040 	mutex_lock(&local->mtx);
1041 
1042 	if (!local->ops->sched_scan_stop) {
1043 		ret = -ENOTSUPP;
1044 		goto out;
1045 	}
1046 
1047 	if (rcu_access_pointer(local->sched_scan_sdata))
1048 		drv_sched_scan_stop(local, sdata);
1049 
1050 out:
1051 	mutex_unlock(&local->mtx);
1052 
1053 	return ret;
1054 }
1055 
1056 void ieee80211_sched_scan_results(struct ieee80211_hw *hw)
1057 {
1058 	struct ieee80211_local *local = hw_to_local(hw);
1059 
1060 	trace_api_sched_scan_results(local);
1061 
1062 	cfg80211_sched_scan_results(hw->wiphy);
1063 }
1064 EXPORT_SYMBOL(ieee80211_sched_scan_results);
1065 
1066 void ieee80211_sched_scan_stopped_work(struct work_struct *work)
1067 {
1068 	struct ieee80211_local *local =
1069 		container_of(work, struct ieee80211_local,
1070 			     sched_scan_stopped_work);
1071 
1072 	mutex_lock(&local->mtx);
1073 
1074 	if (!rcu_access_pointer(local->sched_scan_sdata)) {
1075 		mutex_unlock(&local->mtx);
1076 		return;
1077 	}
1078 
1079 	rcu_assign_pointer(local->sched_scan_sdata, NULL);
1080 
1081 	mutex_unlock(&local->mtx);
1082 
1083 	cfg80211_sched_scan_stopped(local->hw.wiphy);
1084 }
1085 
1086 void ieee80211_sched_scan_stopped(struct ieee80211_hw *hw)
1087 {
1088 	struct ieee80211_local *local = hw_to_local(hw);
1089 
1090 	trace_api_sched_scan_stopped(local);
1091 
1092 	ieee80211_queue_work(&local->hw, &local->sched_scan_stopped_work);
1093 }
1094 EXPORT_SYMBOL(ieee80211_sched_scan_stopped);
1095