xref: /linux/net/mac80211/scan.c (revision 28b3df1fe6ba2cb439ba109f095aa841fef3a54f)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Scanning implementation
4  *
5  * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
6  * Copyright 2004, Instant802 Networks, Inc.
7  * Copyright 2005, Devicescape Software, Inc.
8  * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
9  * Copyright 2007, Michael Wu <flamingice@sourmilk.net>
10  * Copyright 2013-2015  Intel Mobile Communications GmbH
11  * Copyright 2016-2017  Intel Deutschland GmbH
12  * Copyright (C) 2018-2023 Intel Corporation
13  */
14 
15 #include <linux/if_arp.h>
16 #include <linux/etherdevice.h>
17 #include <linux/rtnetlink.h>
18 #include <net/sch_generic.h>
19 #include <linux/slab.h>
20 #include <linux/export.h>
21 #include <linux/random.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 inform_bss_update_data {
59 	struct ieee80211_rx_status *rx_status;
60 	bool beacon;
61 };
62 
63 void ieee80211_inform_bss(struct wiphy *wiphy,
64 			  struct cfg80211_bss *cbss,
65 			  const struct cfg80211_bss_ies *ies,
66 			  void *data)
67 {
68 	struct ieee80211_local *local = wiphy_priv(wiphy);
69 	struct inform_bss_update_data *update_data = data;
70 	struct ieee80211_bss *bss = (void *)cbss->priv;
71 	struct ieee80211_rx_status *rx_status;
72 	struct ieee802_11_elems *elems;
73 	int clen, srlen;
74 
75 	/* This happens while joining an IBSS */
76 	if (!update_data)
77 		return;
78 
79 	elems = ieee802_11_parse_elems(ies->data, ies->len, false, NULL);
80 	if (!elems)
81 		return;
82 
83 	rx_status = update_data->rx_status;
84 
85 	if (update_data->beacon)
86 		bss->device_ts_beacon = rx_status->device_timestamp;
87 	else
88 		bss->device_ts_presp = rx_status->device_timestamp;
89 
90 	if (elems->parse_error) {
91 		if (update_data->beacon)
92 			bss->corrupt_data |= IEEE80211_BSS_CORRUPT_BEACON;
93 		else
94 			bss->corrupt_data |= IEEE80211_BSS_CORRUPT_PROBE_RESP;
95 	} else {
96 		if (update_data->beacon)
97 			bss->corrupt_data &= ~IEEE80211_BSS_CORRUPT_BEACON;
98 		else
99 			bss->corrupt_data &= ~IEEE80211_BSS_CORRUPT_PROBE_RESP;
100 	}
101 
102 	/* save the ERP value so that it is available at association time */
103 	if (elems->erp_info && (!elems->parse_error ||
104 				!(bss->valid_data & IEEE80211_BSS_VALID_ERP))) {
105 		bss->erp_value = elems->erp_info[0];
106 		bss->has_erp_value = true;
107 		if (!elems->parse_error)
108 			bss->valid_data |= IEEE80211_BSS_VALID_ERP;
109 	}
110 
111 	/* replace old supported rates if we get new values */
112 	if (!elems->parse_error ||
113 	    !(bss->valid_data & IEEE80211_BSS_VALID_RATES)) {
114 		srlen = 0;
115 		if (elems->supp_rates) {
116 			clen = IEEE80211_MAX_SUPP_RATES;
117 			if (clen > elems->supp_rates_len)
118 				clen = elems->supp_rates_len;
119 			memcpy(bss->supp_rates, elems->supp_rates, clen);
120 			srlen += clen;
121 		}
122 		if (elems->ext_supp_rates) {
123 			clen = IEEE80211_MAX_SUPP_RATES - srlen;
124 			if (clen > elems->ext_supp_rates_len)
125 				clen = elems->ext_supp_rates_len;
126 			memcpy(bss->supp_rates + srlen, elems->ext_supp_rates,
127 			       clen);
128 			srlen += clen;
129 		}
130 		if (srlen) {
131 			bss->supp_rates_len = srlen;
132 			if (!elems->parse_error)
133 				bss->valid_data |= IEEE80211_BSS_VALID_RATES;
134 		}
135 	}
136 
137 	if (!elems->parse_error ||
138 	    !(bss->valid_data & IEEE80211_BSS_VALID_WMM)) {
139 		bss->wmm_used = elems->wmm_param || elems->wmm_info;
140 		bss->uapsd_supported = is_uapsd_supported(elems);
141 		if (!elems->parse_error)
142 			bss->valid_data |= IEEE80211_BSS_VALID_WMM;
143 	}
144 
145 	if (update_data->beacon) {
146 		struct ieee80211_supported_band *sband =
147 			local->hw.wiphy->bands[rx_status->band];
148 		if (!(rx_status->encoding == RX_ENC_HT) &&
149 		    !(rx_status->encoding == RX_ENC_VHT))
150 			bss->beacon_rate =
151 				&sband->bitrates[rx_status->rate_idx];
152 	}
153 
154 	if (elems->vht_cap_elem)
155 		bss->vht_cap_info =
156 			le32_to_cpu(elems->vht_cap_elem->vht_cap_info);
157 	else
158 		bss->vht_cap_info = 0;
159 
160 	kfree(elems);
161 }
162 
163 struct ieee80211_bss *
164 ieee80211_bss_info_update(struct ieee80211_local *local,
165 			  struct ieee80211_rx_status *rx_status,
166 			  struct ieee80211_mgmt *mgmt, size_t len,
167 			  struct ieee80211_channel *channel)
168 {
169 	bool beacon = ieee80211_is_beacon(mgmt->frame_control) ||
170 		      ieee80211_is_s1g_beacon(mgmt->frame_control);
171 	struct cfg80211_bss *cbss;
172 	struct inform_bss_update_data update_data = {
173 		.rx_status = rx_status,
174 		.beacon = beacon,
175 	};
176 	struct cfg80211_inform_bss bss_meta = {
177 		.boottime_ns = rx_status->boottime_ns,
178 		.drv_data = (void *)&update_data,
179 	};
180 	bool signal_valid;
181 	struct ieee80211_sub_if_data *scan_sdata;
182 
183 	if (rx_status->flag & RX_FLAG_NO_SIGNAL_VAL)
184 		bss_meta.signal = 0; /* invalid signal indication */
185 	else if (ieee80211_hw_check(&local->hw, SIGNAL_DBM))
186 		bss_meta.signal = rx_status->signal * 100;
187 	else if (ieee80211_hw_check(&local->hw, SIGNAL_UNSPEC))
188 		bss_meta.signal = (rx_status->signal * 100) / local->hw.max_signal;
189 
190 	bss_meta.chan = channel;
191 
192 	rcu_read_lock();
193 	scan_sdata = rcu_dereference(local->scan_sdata);
194 	if (scan_sdata && scan_sdata->vif.type == NL80211_IFTYPE_STATION &&
195 	    scan_sdata->vif.cfg.assoc &&
196 	    ieee80211_have_rx_timestamp(rx_status)) {
197 		struct ieee80211_bss_conf *link_conf = NULL;
198 
199 		/* for an MLO connection, set the TSF data only in case we have
200 		 * an indication on which of the links the frame was received
201 		 */
202 		if (ieee80211_vif_is_mld(&scan_sdata->vif)) {
203 			if (rx_status->link_valid) {
204 				s8 link_id = rx_status->link_id;
205 
206 				link_conf =
207 					rcu_dereference(scan_sdata->vif.link_conf[link_id]);
208 			}
209 		} else {
210 			link_conf = &scan_sdata->vif.bss_conf;
211 		}
212 
213 		if (link_conf) {
214 			bss_meta.parent_tsf =
215 				ieee80211_calculate_rx_timestamp(local,
216 								 rx_status,
217 								 len + FCS_LEN,
218 								 24);
219 
220 			ether_addr_copy(bss_meta.parent_bssid,
221 					link_conf->bssid);
222 		}
223 	}
224 	rcu_read_unlock();
225 
226 	cbss = cfg80211_inform_bss_frame_data(local->hw.wiphy, &bss_meta,
227 					      mgmt, len, GFP_ATOMIC);
228 	if (!cbss)
229 		return NULL;
230 
231 	/* In case the signal is invalid update the status */
232 	signal_valid = channel == cbss->channel;
233 	if (!signal_valid)
234 		rx_status->flag |= RX_FLAG_NO_SIGNAL_VAL;
235 
236 	return (void *)cbss->priv;
237 }
238 
239 static bool ieee80211_scan_accept_presp(struct ieee80211_sub_if_data *sdata,
240 					u32 scan_flags, const u8 *da)
241 {
242 	if (!sdata)
243 		return false;
244 	/* accept broadcast for OCE */
245 	if (scan_flags & NL80211_SCAN_FLAG_ACCEPT_BCAST_PROBE_RESP &&
246 	    is_broadcast_ether_addr(da))
247 		return true;
248 	if (scan_flags & NL80211_SCAN_FLAG_RANDOM_ADDR)
249 		return true;
250 	return ether_addr_equal(da, sdata->vif.addr);
251 }
252 
253 void ieee80211_scan_rx(struct ieee80211_local *local, struct sk_buff *skb)
254 {
255 	struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
256 	struct ieee80211_sub_if_data *sdata1, *sdata2;
257 	struct ieee80211_mgmt *mgmt = (void *)skb->data;
258 	struct ieee80211_bss *bss;
259 	struct ieee80211_channel *channel;
260 	size_t min_hdr_len = offsetof(struct ieee80211_mgmt,
261 				      u.probe_resp.variable);
262 
263 	if (!ieee80211_is_probe_resp(mgmt->frame_control) &&
264 	    !ieee80211_is_beacon(mgmt->frame_control) &&
265 	    !ieee80211_is_s1g_beacon(mgmt->frame_control))
266 		return;
267 
268 	if (ieee80211_is_s1g_beacon(mgmt->frame_control)) {
269 		if (ieee80211_is_s1g_short_beacon(mgmt->frame_control))
270 			min_hdr_len = offsetof(struct ieee80211_ext,
271 					       u.s1g_short_beacon.variable);
272 		else
273 			min_hdr_len = offsetof(struct ieee80211_ext,
274 					       u.s1g_beacon);
275 	}
276 
277 	if (skb->len < min_hdr_len)
278 		return;
279 
280 	sdata1 = rcu_dereference(local->scan_sdata);
281 	sdata2 = rcu_dereference(local->sched_scan_sdata);
282 
283 	if (likely(!sdata1 && !sdata2))
284 		return;
285 
286 	if (test_and_clear_bit(SCAN_BEACON_WAIT, &local->scanning)) {
287 		/*
288 		 * we were passive scanning because of radar/no-IR, but
289 		 * the beacon/proberesp rx gives us an opportunity to upgrade
290 		 * to active scan
291 		 */
292 		set_bit(SCAN_BEACON_DONE, &local->scanning);
293 		wiphy_delayed_work_queue(local->hw.wiphy, &local->scan_work, 0);
294 	}
295 
296 	if (ieee80211_is_probe_resp(mgmt->frame_control)) {
297 		struct cfg80211_scan_request *scan_req;
298 		struct cfg80211_sched_scan_request *sched_scan_req;
299 		u32 scan_req_flags = 0, sched_scan_req_flags = 0;
300 
301 		scan_req = rcu_dereference(local->scan_req);
302 		sched_scan_req = rcu_dereference(local->sched_scan_req);
303 
304 		if (scan_req)
305 			scan_req_flags = scan_req->flags;
306 
307 		if (sched_scan_req)
308 			sched_scan_req_flags = sched_scan_req->flags;
309 
310 		/* ignore ProbeResp to foreign address or non-bcast (OCE)
311 		 * unless scanning with randomised address
312 		 */
313 		if (!ieee80211_scan_accept_presp(sdata1, scan_req_flags,
314 						 mgmt->da) &&
315 		    !ieee80211_scan_accept_presp(sdata2, sched_scan_req_flags,
316 						 mgmt->da))
317 			return;
318 	}
319 
320 	channel = ieee80211_get_channel_khz(local->hw.wiphy,
321 					ieee80211_rx_status_to_khz(rx_status));
322 
323 	if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
324 		return;
325 
326 	bss = ieee80211_bss_info_update(local, rx_status,
327 					mgmt, skb->len,
328 					channel);
329 	if (bss)
330 		ieee80211_rx_bss_put(local, bss);
331 }
332 
333 static void ieee80211_prepare_scan_chandef(struct cfg80211_chan_def *chandef)
334 {
335 	memset(chandef, 0, sizeof(*chandef));
336 
337 	chandef->width = NL80211_CHAN_WIDTH_20_NOHT;
338 }
339 
340 /* return false if no more work */
341 static bool ieee80211_prep_hw_scan(struct ieee80211_sub_if_data *sdata)
342 {
343 	struct ieee80211_local *local = sdata->local;
344 	struct cfg80211_scan_request *req;
345 	struct cfg80211_chan_def chandef;
346 	u8 bands_used = 0;
347 	int i, ielen, n_chans;
348 	u32 flags = 0;
349 
350 	req = rcu_dereference_protected(local->scan_req,
351 					lockdep_is_held(&local->hw.wiphy->mtx));
352 
353 	if (test_bit(SCAN_HW_CANCELLED, &local->scanning))
354 		return false;
355 
356 	if (ieee80211_hw_check(&local->hw, SINGLE_SCAN_ON_ALL_BANDS)) {
357 		for (i = 0; i < req->n_channels; i++) {
358 			local->hw_scan_req->req.channels[i] = req->channels[i];
359 			bands_used |= BIT(req->channels[i]->band);
360 		}
361 
362 		n_chans = req->n_channels;
363 	} else {
364 		do {
365 			if (local->hw_scan_band == NUM_NL80211_BANDS)
366 				return false;
367 
368 			n_chans = 0;
369 
370 			for (i = 0; i < req->n_channels; i++) {
371 				if (req->channels[i]->band !=
372 				    local->hw_scan_band)
373 					continue;
374 				local->hw_scan_req->req.channels[n_chans] =
375 							req->channels[i];
376 				n_chans++;
377 				bands_used |= BIT(req->channels[i]->band);
378 			}
379 
380 			local->hw_scan_band++;
381 		} while (!n_chans);
382 	}
383 
384 	local->hw_scan_req->req.n_channels = n_chans;
385 	ieee80211_prepare_scan_chandef(&chandef);
386 
387 	if (req->flags & NL80211_SCAN_FLAG_MIN_PREQ_CONTENT)
388 		flags |= IEEE80211_PROBE_FLAG_MIN_CONTENT;
389 
390 	ielen = ieee80211_build_preq_ies(sdata,
391 					 (u8 *)local->hw_scan_req->req.ie,
392 					 local->hw_scan_ies_bufsize,
393 					 &local->hw_scan_req->ies,
394 					 req->ie, req->ie_len,
395 					 bands_used, req->rates, &chandef,
396 					 flags);
397 	local->hw_scan_req->req.ie_len = ielen;
398 	local->hw_scan_req->req.no_cck = req->no_cck;
399 	ether_addr_copy(local->hw_scan_req->req.mac_addr, req->mac_addr);
400 	ether_addr_copy(local->hw_scan_req->req.mac_addr_mask,
401 			req->mac_addr_mask);
402 	ether_addr_copy(local->hw_scan_req->req.bssid, req->bssid);
403 
404 	return true;
405 }
406 
407 static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
408 {
409 	struct ieee80211_local *local = hw_to_local(hw);
410 	bool hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
411 	bool was_scanning = local->scanning;
412 	struct cfg80211_scan_request *scan_req;
413 	struct ieee80211_sub_if_data *scan_sdata;
414 	struct ieee80211_sub_if_data *sdata;
415 
416 	lockdep_assert_wiphy(local->hw.wiphy);
417 
418 	/*
419 	 * It's ok to abort a not-yet-running scan (that
420 	 * we have one at all will be verified by checking
421 	 * local->scan_req next), but not to complete it
422 	 * successfully.
423 	 */
424 	if (WARN_ON(!local->scanning && !aborted))
425 		aborted = true;
426 
427 	if (WARN_ON(!local->scan_req))
428 		return;
429 
430 	scan_sdata = rcu_dereference_protected(local->scan_sdata,
431 					       lockdep_is_held(&local->hw.wiphy->mtx));
432 
433 	if (hw_scan && !aborted &&
434 	    !ieee80211_hw_check(&local->hw, SINGLE_SCAN_ON_ALL_BANDS) &&
435 	    ieee80211_prep_hw_scan(scan_sdata)) {
436 		int rc;
437 
438 		rc = drv_hw_scan(local,
439 			rcu_dereference_protected(local->scan_sdata,
440 						  lockdep_is_held(&local->hw.wiphy->mtx)),
441 			local->hw_scan_req);
442 
443 		if (rc == 0)
444 			return;
445 
446 		/* HW scan failed and is going to be reported as aborted,
447 		 * so clear old scan info.
448 		 */
449 		memset(&local->scan_info, 0, sizeof(local->scan_info));
450 		aborted = true;
451 	}
452 
453 	kfree(local->hw_scan_req);
454 	local->hw_scan_req = NULL;
455 
456 	scan_req = rcu_dereference_protected(local->scan_req,
457 					     lockdep_is_held(&local->hw.wiphy->mtx));
458 
459 	RCU_INIT_POINTER(local->scan_req, NULL);
460 	RCU_INIT_POINTER(local->scan_sdata, NULL);
461 
462 	local->scanning = 0;
463 	local->scan_chandef.chan = NULL;
464 
465 	synchronize_rcu();
466 
467 	if (scan_req != local->int_scan_req) {
468 		local->scan_info.aborted = aborted;
469 		cfg80211_scan_done(scan_req, &local->scan_info);
470 	}
471 
472 	/* Set power back to normal operating levels. */
473 	ieee80211_hw_config(local, 0);
474 
475 	if (!hw_scan && was_scanning) {
476 		ieee80211_configure_filter(local);
477 		drv_sw_scan_complete(local, scan_sdata);
478 		ieee80211_offchannel_return(local);
479 	}
480 
481 	ieee80211_recalc_idle(local);
482 
483 	ieee80211_mlme_notify_scan_completed(local);
484 	ieee80211_ibss_notify_scan_completed(local);
485 
486 	/* Requeue all the work that might have been ignored while
487 	 * the scan was in progress; if there was none this will
488 	 * just be a no-op for the particular interface.
489 	 */
490 	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
491 		if (ieee80211_sdata_running(sdata))
492 			wiphy_work_queue(sdata->local->hw.wiphy, &sdata->work);
493 	}
494 
495 	if (was_scanning)
496 		ieee80211_start_next_roc(local);
497 }
498 
499 void ieee80211_scan_completed(struct ieee80211_hw *hw,
500 			      struct cfg80211_scan_info *info)
501 {
502 	struct ieee80211_local *local = hw_to_local(hw);
503 
504 	trace_api_scan_completed(local, info->aborted);
505 
506 	set_bit(SCAN_COMPLETED, &local->scanning);
507 	if (info->aborted)
508 		set_bit(SCAN_ABORTED, &local->scanning);
509 
510 	memcpy(&local->scan_info, info, sizeof(*info));
511 
512 	wiphy_delayed_work_queue(local->hw.wiphy, &local->scan_work, 0);
513 }
514 EXPORT_SYMBOL(ieee80211_scan_completed);
515 
516 static int ieee80211_start_sw_scan(struct ieee80211_local *local,
517 				   struct ieee80211_sub_if_data *sdata)
518 {
519 	/* Software scan is not supported in multi-channel cases */
520 	if (local->use_chanctx)
521 		return -EOPNOTSUPP;
522 
523 	/*
524 	 * Hardware/driver doesn't support hw_scan, so use software
525 	 * scanning instead. First send a nullfunc frame with power save
526 	 * bit on so that AP will buffer the frames for us while we are not
527 	 * listening, then send probe requests to each channel and wait for
528 	 * the responses. After all channels are scanned, tune back to the
529 	 * original channel and send a nullfunc frame with power save bit
530 	 * off to trigger the AP to send us all the buffered frames.
531 	 *
532 	 * Note that while local->sw_scanning is true everything else but
533 	 * nullfunc frames and probe requests will be dropped in
534 	 * ieee80211_tx_h_check_assoc().
535 	 */
536 	drv_sw_scan_start(local, sdata, local->scan_addr);
537 
538 	local->leave_oper_channel_time = jiffies;
539 	local->next_scan_state = SCAN_DECISION;
540 	local->scan_channel_idx = 0;
541 
542 	ieee80211_offchannel_stop_vifs(local);
543 
544 	/* ensure nullfunc is transmitted before leaving operating channel */
545 	ieee80211_flush_queues(local, NULL, false);
546 
547 	ieee80211_configure_filter(local);
548 
549 	/* We need to set power level at maximum rate for scanning. */
550 	ieee80211_hw_config(local, 0);
551 
552 	wiphy_delayed_work_queue(local->hw.wiphy, &local->scan_work, 0);
553 
554 	return 0;
555 }
556 
557 static bool __ieee80211_can_leave_ch(struct ieee80211_sub_if_data *sdata)
558 {
559 	struct ieee80211_local *local = sdata->local;
560 	struct ieee80211_sub_if_data *sdata_iter;
561 
562 	lockdep_assert_wiphy(local->hw.wiphy);
563 
564 	if (!ieee80211_is_radar_required(local))
565 		return true;
566 
567 	if (!regulatory_pre_cac_allowed(local->hw.wiphy))
568 		return false;
569 
570 	list_for_each_entry(sdata_iter, &local->interfaces, list) {
571 		if (sdata_iter->wdev.cac_started)
572 			return false;
573 	}
574 
575 	return true;
576 }
577 
578 static bool ieee80211_can_scan(struct ieee80211_local *local,
579 			       struct ieee80211_sub_if_data *sdata)
580 {
581 	if (!__ieee80211_can_leave_ch(sdata))
582 		return false;
583 
584 	if (!list_empty(&local->roc_list))
585 		return false;
586 
587 	if (sdata->vif.type == NL80211_IFTYPE_STATION &&
588 	    sdata->u.mgd.flags & IEEE80211_STA_CONNECTION_POLL)
589 		return false;
590 
591 	return true;
592 }
593 
594 void ieee80211_run_deferred_scan(struct ieee80211_local *local)
595 {
596 	lockdep_assert_wiphy(local->hw.wiphy);
597 
598 	if (!local->scan_req || local->scanning)
599 		return;
600 
601 	if (!ieee80211_can_scan(local,
602 				rcu_dereference_protected(
603 					local->scan_sdata,
604 					lockdep_is_held(&local->hw.wiphy->mtx))))
605 		return;
606 
607 	wiphy_delayed_work_queue(local->hw.wiphy, &local->scan_work,
608 				 round_jiffies_relative(0));
609 }
610 
611 static void ieee80211_send_scan_probe_req(struct ieee80211_sub_if_data *sdata,
612 					  const u8 *src, const u8 *dst,
613 					  const u8 *ssid, size_t ssid_len,
614 					  const u8 *ie, size_t ie_len,
615 					  u32 ratemask, u32 flags, u32 tx_flags,
616 					  struct ieee80211_channel *channel)
617 {
618 	struct sk_buff *skb;
619 
620 	skb = ieee80211_build_probe_req(sdata, src, dst, ratemask, channel,
621 					ssid, ssid_len,
622 					ie, ie_len, flags);
623 
624 	if (skb) {
625 		if (flags & IEEE80211_PROBE_FLAG_RANDOM_SN) {
626 			struct ieee80211_hdr *hdr = (void *)skb->data;
627 			struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
628 			u16 sn = get_random_u16();
629 
630 			info->control.flags |= IEEE80211_TX_CTRL_NO_SEQNO;
631 			hdr->seq_ctrl =
632 				cpu_to_le16(IEEE80211_SN_TO_SEQ(sn));
633 		}
634 		IEEE80211_SKB_CB(skb)->flags |= tx_flags;
635 		ieee80211_tx_skb_tid_band(sdata, skb, 7, channel->band);
636 	}
637 }
638 
639 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
640 					    unsigned long *next_delay)
641 {
642 	int i;
643 	struct ieee80211_sub_if_data *sdata;
644 	struct cfg80211_scan_request *scan_req;
645 	enum nl80211_band band = local->hw.conf.chandef.chan->band;
646 	u32 flags = 0, tx_flags;
647 
648 	scan_req = rcu_dereference_protected(local->scan_req,
649 					     lockdep_is_held(&local->hw.wiphy->mtx));
650 
651 	tx_flags = IEEE80211_TX_INTFL_OFFCHAN_TX_OK;
652 	if (scan_req->no_cck)
653 		tx_flags |= IEEE80211_TX_CTL_NO_CCK_RATE;
654 	if (scan_req->flags & NL80211_SCAN_FLAG_MIN_PREQ_CONTENT)
655 		flags |= IEEE80211_PROBE_FLAG_MIN_CONTENT;
656 	if (scan_req->flags & NL80211_SCAN_FLAG_RANDOM_SN)
657 		flags |= IEEE80211_PROBE_FLAG_RANDOM_SN;
658 
659 	sdata = rcu_dereference_protected(local->scan_sdata,
660 					  lockdep_is_held(&local->hw.wiphy->mtx));
661 
662 	for (i = 0; i < scan_req->n_ssids; i++)
663 		ieee80211_send_scan_probe_req(
664 			sdata, local->scan_addr, scan_req->bssid,
665 			scan_req->ssids[i].ssid, scan_req->ssids[i].ssid_len,
666 			scan_req->ie, scan_req->ie_len,
667 			scan_req->rates[band], flags,
668 			tx_flags, local->hw.conf.chandef.chan);
669 
670 	/*
671 	 * After sending probe requests, wait for probe responses
672 	 * on the channel.
673 	 */
674 	*next_delay = msecs_to_jiffies(scan_req->duration) >
675 		      IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME ?
676 		      msecs_to_jiffies(scan_req->duration) - IEEE80211_PROBE_DELAY :
677 		      IEEE80211_CHANNEL_TIME;
678 	local->next_scan_state = SCAN_DECISION;
679 }
680 
681 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
682 				  struct cfg80211_scan_request *req)
683 {
684 	struct ieee80211_local *local = sdata->local;
685 	bool hw_scan = local->ops->hw_scan;
686 	int rc;
687 
688 	lockdep_assert_wiphy(local->hw.wiphy);
689 
690 	if (local->scan_req)
691 		return -EBUSY;
692 
693 	/* For an MLO connection, if a link ID was specified, validate that it
694 	 * is indeed active. If no link ID was specified, select one of the
695 	 * active links.
696 	 */
697 	if (ieee80211_vif_is_mld(&sdata->vif)) {
698 		if (req->tsf_report_link_id >= 0) {
699 			if (!(sdata->vif.active_links &
700 			      BIT(req->tsf_report_link_id)))
701 				return -EINVAL;
702 		} else {
703 			req->tsf_report_link_id =
704 				__ffs(sdata->vif.active_links);
705 		}
706 	}
707 
708 	if (!__ieee80211_can_leave_ch(sdata))
709 		return -EBUSY;
710 
711 	if (!ieee80211_can_scan(local, sdata)) {
712 		/* wait for the work to finish/time out */
713 		rcu_assign_pointer(local->scan_req, req);
714 		rcu_assign_pointer(local->scan_sdata, sdata);
715 		return 0;
716 	}
717 
718  again:
719 	if (hw_scan) {
720 		u8 *ies;
721 
722 		local->hw_scan_ies_bufsize = local->scan_ies_len + req->ie_len;
723 
724 		if (ieee80211_hw_check(&local->hw, SINGLE_SCAN_ON_ALL_BANDS)) {
725 			int i, n_bands = 0;
726 			u8 bands_counted = 0;
727 
728 			for (i = 0; i < req->n_channels; i++) {
729 				if (bands_counted & BIT(req->channels[i]->band))
730 					continue;
731 				bands_counted |= BIT(req->channels[i]->band);
732 				n_bands++;
733 			}
734 
735 			local->hw_scan_ies_bufsize *= n_bands;
736 		}
737 
738 		local->hw_scan_req = kmalloc(
739 				sizeof(*local->hw_scan_req) +
740 				req->n_channels * sizeof(req->channels[0]) +
741 				local->hw_scan_ies_bufsize, GFP_KERNEL);
742 		if (!local->hw_scan_req)
743 			return -ENOMEM;
744 
745 		local->hw_scan_req->req.ssids = req->ssids;
746 		local->hw_scan_req->req.n_ssids = req->n_ssids;
747 		ies = (u8 *)local->hw_scan_req +
748 			sizeof(*local->hw_scan_req) +
749 			req->n_channels * sizeof(req->channels[0]);
750 		local->hw_scan_req->req.ie = ies;
751 		local->hw_scan_req->req.flags = req->flags;
752 		eth_broadcast_addr(local->hw_scan_req->req.bssid);
753 		local->hw_scan_req->req.duration = req->duration;
754 		local->hw_scan_req->req.duration_mandatory =
755 			req->duration_mandatory;
756 		local->hw_scan_req->req.tsf_report_link_id =
757 			req->tsf_report_link_id;
758 
759 		local->hw_scan_band = 0;
760 		local->hw_scan_req->req.n_6ghz_params = req->n_6ghz_params;
761 		local->hw_scan_req->req.scan_6ghz_params =
762 			req->scan_6ghz_params;
763 		local->hw_scan_req->req.scan_6ghz = req->scan_6ghz;
764 
765 		/*
766 		 * After allocating local->hw_scan_req, we must
767 		 * go through until ieee80211_prep_hw_scan(), so
768 		 * anything that might be changed here and leave
769 		 * this function early must not go after this
770 		 * allocation.
771 		 */
772 	}
773 
774 	rcu_assign_pointer(local->scan_req, req);
775 	rcu_assign_pointer(local->scan_sdata, sdata);
776 
777 	if (req->flags & NL80211_SCAN_FLAG_RANDOM_ADDR)
778 		get_random_mask_addr(local->scan_addr,
779 				     req->mac_addr,
780 				     req->mac_addr_mask);
781 	else
782 		memcpy(local->scan_addr, sdata->vif.addr, ETH_ALEN);
783 
784 	if (hw_scan) {
785 		__set_bit(SCAN_HW_SCANNING, &local->scanning);
786 	} else if ((req->n_channels == 1) &&
787 		   (req->channels[0] == local->_oper_chandef.chan)) {
788 		/*
789 		 * If we are scanning only on the operating channel
790 		 * then we do not need to stop normal activities
791 		 */
792 		unsigned long next_delay;
793 
794 		__set_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning);
795 
796 		ieee80211_recalc_idle(local);
797 
798 		/* Notify driver scan is starting, keep order of operations
799 		 * same as normal software scan, in case that matters. */
800 		drv_sw_scan_start(local, sdata, local->scan_addr);
801 
802 		ieee80211_configure_filter(local); /* accept probe-responses */
803 
804 		/* We need to ensure power level is at max for scanning. */
805 		ieee80211_hw_config(local, 0);
806 
807 		if ((req->channels[0]->flags & (IEEE80211_CHAN_NO_IR |
808 						IEEE80211_CHAN_RADAR)) ||
809 		    !req->n_ssids) {
810 			next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
811 			if (req->n_ssids)
812 				set_bit(SCAN_BEACON_WAIT, &local->scanning);
813 		} else {
814 			ieee80211_scan_state_send_probe(local, &next_delay);
815 			next_delay = IEEE80211_CHANNEL_TIME;
816 		}
817 
818 		/* Now, just wait a bit and we are all done! */
819 		wiphy_delayed_work_queue(local->hw.wiphy, &local->scan_work,
820 					 next_delay);
821 		return 0;
822 	} else {
823 		/* Do normal software scan */
824 		__set_bit(SCAN_SW_SCANNING, &local->scanning);
825 	}
826 
827 	ieee80211_recalc_idle(local);
828 
829 	if (hw_scan) {
830 		WARN_ON(!ieee80211_prep_hw_scan(sdata));
831 		rc = drv_hw_scan(local, sdata, local->hw_scan_req);
832 	} else {
833 		rc = ieee80211_start_sw_scan(local, sdata);
834 	}
835 
836 	if (rc) {
837 		kfree(local->hw_scan_req);
838 		local->hw_scan_req = NULL;
839 		local->scanning = 0;
840 
841 		ieee80211_recalc_idle(local);
842 
843 		local->scan_req = NULL;
844 		RCU_INIT_POINTER(local->scan_sdata, NULL);
845 	}
846 
847 	if (hw_scan && rc == 1) {
848 		/*
849 		 * we can't fall back to software for P2P-GO
850 		 * as it must update NoA etc.
851 		 */
852 		if (ieee80211_vif_type_p2p(&sdata->vif) ==
853 				NL80211_IFTYPE_P2P_GO)
854 			return -EOPNOTSUPP;
855 		hw_scan = false;
856 		goto again;
857 	}
858 
859 	return rc;
860 }
861 
862 static unsigned long
863 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
864 {
865 	/*
866 	 * TODO: channel switching also consumes quite some time,
867 	 * add that delay as well to get a better estimation
868 	 */
869 	if (chan->flags & (IEEE80211_CHAN_NO_IR | IEEE80211_CHAN_RADAR))
870 		return IEEE80211_PASSIVE_CHANNEL_TIME;
871 	return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
872 }
873 
874 static void ieee80211_scan_state_decision(struct ieee80211_local *local,
875 					  unsigned long *next_delay)
876 {
877 	bool associated = false;
878 	bool tx_empty = true;
879 	bool bad_latency;
880 	struct ieee80211_sub_if_data *sdata;
881 	struct ieee80211_channel *next_chan;
882 	enum mac80211_scan_state next_scan_state;
883 	struct cfg80211_scan_request *scan_req;
884 
885 	lockdep_assert_wiphy(local->hw.wiphy);
886 
887 	/*
888 	 * check if at least one STA interface is associated,
889 	 * check if at least one STA interface has pending tx frames
890 	 * and grab the lowest used beacon interval
891 	 */
892 	list_for_each_entry(sdata, &local->interfaces, list) {
893 		if (!ieee80211_sdata_running(sdata))
894 			continue;
895 
896 		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
897 			if (sdata->u.mgd.associated) {
898 				associated = true;
899 
900 				if (!qdisc_all_tx_empty(sdata->dev)) {
901 					tx_empty = false;
902 					break;
903 				}
904 			}
905 		}
906 	}
907 
908 	scan_req = rcu_dereference_protected(local->scan_req,
909 					     lockdep_is_held(&local->hw.wiphy->mtx));
910 
911 	next_chan = scan_req->channels[local->scan_channel_idx];
912 
913 	/*
914 	 * we're currently scanning a different channel, let's
915 	 * see if we can scan another channel without interfering
916 	 * with the current traffic situation.
917 	 *
918 	 * Keep good latency, do not stay off-channel more than 125 ms.
919 	 */
920 
921 	bad_latency = time_after(jiffies +
922 				 ieee80211_scan_get_channel_time(next_chan),
923 				 local->leave_oper_channel_time + HZ / 8);
924 
925 	if (associated && !tx_empty) {
926 		if (scan_req->flags & NL80211_SCAN_FLAG_LOW_PRIORITY)
927 			next_scan_state = SCAN_ABORT;
928 		else
929 			next_scan_state = SCAN_SUSPEND;
930 	} else if (associated && bad_latency) {
931 		next_scan_state = SCAN_SUSPEND;
932 	} else {
933 		next_scan_state = SCAN_SET_CHANNEL;
934 	}
935 
936 	local->next_scan_state = next_scan_state;
937 
938 	*next_delay = 0;
939 }
940 
941 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
942 					     unsigned long *next_delay)
943 {
944 	int skip;
945 	struct ieee80211_channel *chan;
946 	struct cfg80211_scan_request *scan_req;
947 
948 	scan_req = rcu_dereference_protected(local->scan_req,
949 					     lockdep_is_held(&local->hw.wiphy->mtx));
950 
951 	skip = 0;
952 	chan = scan_req->channels[local->scan_channel_idx];
953 
954 	local->scan_chandef.chan = chan;
955 	local->scan_chandef.center_freq1 = chan->center_freq;
956 	local->scan_chandef.freq1_offset = chan->freq_offset;
957 	local->scan_chandef.center_freq2 = 0;
958 
959 	/* For scanning on the S1G band, detect the channel width according to
960 	 * the channel being scanned.
961 	 */
962 	if (chan->band == NL80211_BAND_S1GHZ) {
963 		local->scan_chandef.width = ieee80211_s1g_channel_width(chan);
964 		goto set_channel;
965 	}
966 
967 	/* If scanning on oper channel, use whatever channel-type
968 	 * is currently in use.
969 	 */
970 	if (chan == local->_oper_chandef.chan)
971 		local->scan_chandef = local->_oper_chandef;
972 	else
973 		local->scan_chandef.width = NL80211_CHAN_WIDTH_20_NOHT;
974 
975 set_channel:
976 	if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
977 		skip = 1;
978 
979 	/* advance state machine to next channel/band */
980 	local->scan_channel_idx++;
981 
982 	if (skip) {
983 		/* if we skip this channel return to the decision state */
984 		local->next_scan_state = SCAN_DECISION;
985 		return;
986 	}
987 
988 	/*
989 	 * Probe delay is used to update the NAV, cf. 11.1.3.2.2
990 	 * (which unfortunately doesn't say _why_ step a) is done,
991 	 * but it waits for the probe delay or until a frame is
992 	 * received - and the received frame would update the NAV).
993 	 * For now, we do not support waiting until a frame is
994 	 * received.
995 	 *
996 	 * In any case, it is not necessary for a passive scan.
997 	 */
998 	if ((chan->flags & (IEEE80211_CHAN_NO_IR | IEEE80211_CHAN_RADAR)) ||
999 	    !scan_req->n_ssids) {
1000 		*next_delay = msecs_to_jiffies(scan_req->duration) >
1001 			      IEEE80211_PASSIVE_CHANNEL_TIME ?
1002 			      msecs_to_jiffies(scan_req->duration) :
1003 			      IEEE80211_PASSIVE_CHANNEL_TIME;
1004 		local->next_scan_state = SCAN_DECISION;
1005 		if (scan_req->n_ssids)
1006 			set_bit(SCAN_BEACON_WAIT, &local->scanning);
1007 		return;
1008 	}
1009 
1010 	/* active scan, send probes */
1011 	*next_delay = IEEE80211_PROBE_DELAY;
1012 	local->next_scan_state = SCAN_SEND_PROBE;
1013 }
1014 
1015 static void ieee80211_scan_state_suspend(struct ieee80211_local *local,
1016 					 unsigned long *next_delay)
1017 {
1018 	/* switch back to the operating channel */
1019 	local->scan_chandef.chan = NULL;
1020 	ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
1021 
1022 	/* disable PS */
1023 	ieee80211_offchannel_return(local);
1024 
1025 	*next_delay = HZ / 5;
1026 	/* afterwards, resume scan & go to next channel */
1027 	local->next_scan_state = SCAN_RESUME;
1028 }
1029 
1030 static void ieee80211_scan_state_resume(struct ieee80211_local *local,
1031 					unsigned long *next_delay)
1032 {
1033 	ieee80211_offchannel_stop_vifs(local);
1034 
1035 	if (local->ops->flush) {
1036 		ieee80211_flush_queues(local, NULL, false);
1037 		*next_delay = 0;
1038 	} else
1039 		*next_delay = HZ / 10;
1040 
1041 	/* remember when we left the operating channel */
1042 	local->leave_oper_channel_time = jiffies;
1043 
1044 	/* advance to the next channel to be scanned */
1045 	local->next_scan_state = SCAN_SET_CHANNEL;
1046 }
1047 
1048 void ieee80211_scan_work(struct wiphy *wiphy, struct wiphy_work *work)
1049 {
1050 	struct ieee80211_local *local =
1051 		container_of(work, struct ieee80211_local, scan_work.work);
1052 	struct ieee80211_sub_if_data *sdata;
1053 	struct cfg80211_scan_request *scan_req;
1054 	unsigned long next_delay = 0;
1055 	bool aborted;
1056 
1057 	lockdep_assert_wiphy(local->hw.wiphy);
1058 
1059 	if (!ieee80211_can_run_worker(local)) {
1060 		aborted = true;
1061 		goto out_complete;
1062 	}
1063 
1064 	sdata = rcu_dereference_protected(local->scan_sdata,
1065 					  lockdep_is_held(&local->hw.wiphy->mtx));
1066 	scan_req = rcu_dereference_protected(local->scan_req,
1067 					     lockdep_is_held(&local->hw.wiphy->mtx));
1068 
1069 	/* When scanning on-channel, the first-callback means completed. */
1070 	if (test_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning)) {
1071 		aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
1072 		goto out_complete;
1073 	}
1074 
1075 	if (test_and_clear_bit(SCAN_COMPLETED, &local->scanning)) {
1076 		aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
1077 		goto out_complete;
1078 	}
1079 
1080 	if (!sdata || !scan_req)
1081 		return;
1082 
1083 	if (!local->scanning) {
1084 		int rc;
1085 
1086 		RCU_INIT_POINTER(local->scan_req, NULL);
1087 		RCU_INIT_POINTER(local->scan_sdata, NULL);
1088 
1089 		rc = __ieee80211_start_scan(sdata, scan_req);
1090 		if (!rc)
1091 			return;
1092 		/* need to complete scan in cfg80211 */
1093 		rcu_assign_pointer(local->scan_req, scan_req);
1094 		aborted = true;
1095 		goto out_complete;
1096 	}
1097 
1098 	clear_bit(SCAN_BEACON_WAIT, &local->scanning);
1099 
1100 	/*
1101 	 * as long as no delay is required advance immediately
1102 	 * without scheduling a new work
1103 	 */
1104 	do {
1105 		if (!ieee80211_sdata_running(sdata)) {
1106 			aborted = true;
1107 			goto out_complete;
1108 		}
1109 
1110 		if (test_and_clear_bit(SCAN_BEACON_DONE, &local->scanning) &&
1111 		    local->next_scan_state == SCAN_DECISION)
1112 			local->next_scan_state = SCAN_SEND_PROBE;
1113 
1114 		switch (local->next_scan_state) {
1115 		case SCAN_DECISION:
1116 			/* if no more bands/channels left, complete scan */
1117 			if (local->scan_channel_idx >= scan_req->n_channels) {
1118 				aborted = false;
1119 				goto out_complete;
1120 			}
1121 			ieee80211_scan_state_decision(local, &next_delay);
1122 			break;
1123 		case SCAN_SET_CHANNEL:
1124 			ieee80211_scan_state_set_channel(local, &next_delay);
1125 			break;
1126 		case SCAN_SEND_PROBE:
1127 			ieee80211_scan_state_send_probe(local, &next_delay);
1128 			break;
1129 		case SCAN_SUSPEND:
1130 			ieee80211_scan_state_suspend(local, &next_delay);
1131 			break;
1132 		case SCAN_RESUME:
1133 			ieee80211_scan_state_resume(local, &next_delay);
1134 			break;
1135 		case SCAN_ABORT:
1136 			aborted = true;
1137 			goto out_complete;
1138 		}
1139 	} while (next_delay == 0);
1140 
1141 	wiphy_delayed_work_queue(local->hw.wiphy, &local->scan_work,
1142 				 next_delay);
1143 	return;
1144 
1145 out_complete:
1146 	__ieee80211_scan_completed(&local->hw, aborted);
1147 }
1148 
1149 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
1150 			   struct cfg80211_scan_request *req)
1151 {
1152 	lockdep_assert_wiphy(sdata->local->hw.wiphy);
1153 
1154 	return __ieee80211_start_scan(sdata, req);
1155 }
1156 
1157 int ieee80211_request_ibss_scan(struct ieee80211_sub_if_data *sdata,
1158 				const u8 *ssid, u8 ssid_len,
1159 				struct ieee80211_channel **channels,
1160 				unsigned int n_channels)
1161 {
1162 	struct ieee80211_local *local = sdata->local;
1163 	int ret = -EBUSY, i, n_ch = 0;
1164 	enum nl80211_band band;
1165 
1166 	lockdep_assert_wiphy(local->hw.wiphy);
1167 
1168 	/* busy scanning */
1169 	if (local->scan_req)
1170 		goto unlock;
1171 
1172 	/* fill internal scan request */
1173 	if (!channels) {
1174 		int max_n;
1175 
1176 		for (band = 0; band < NUM_NL80211_BANDS; band++) {
1177 			if (!local->hw.wiphy->bands[band] ||
1178 			    band == NL80211_BAND_6GHZ)
1179 				continue;
1180 
1181 			max_n = local->hw.wiphy->bands[band]->n_channels;
1182 			for (i = 0; i < max_n; i++) {
1183 				struct ieee80211_channel *tmp_ch =
1184 				    &local->hw.wiphy->bands[band]->channels[i];
1185 
1186 				if (tmp_ch->flags & (IEEE80211_CHAN_NO_IR |
1187 						     IEEE80211_CHAN_DISABLED))
1188 					continue;
1189 
1190 				local->int_scan_req->channels[n_ch] = tmp_ch;
1191 				n_ch++;
1192 			}
1193 		}
1194 
1195 		if (WARN_ON_ONCE(n_ch == 0))
1196 			goto unlock;
1197 
1198 		local->int_scan_req->n_channels = n_ch;
1199 	} else {
1200 		for (i = 0; i < n_channels; i++) {
1201 			if (channels[i]->flags & (IEEE80211_CHAN_NO_IR |
1202 						  IEEE80211_CHAN_DISABLED))
1203 				continue;
1204 
1205 			local->int_scan_req->channels[n_ch] = channels[i];
1206 			n_ch++;
1207 		}
1208 
1209 		if (WARN_ON_ONCE(n_ch == 0))
1210 			goto unlock;
1211 
1212 		local->int_scan_req->n_channels = n_ch;
1213 	}
1214 
1215 	local->int_scan_req->ssids = &local->scan_ssid;
1216 	local->int_scan_req->n_ssids = 1;
1217 	memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
1218 	local->int_scan_req->ssids[0].ssid_len = ssid_len;
1219 
1220 	ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
1221  unlock:
1222 	return ret;
1223 }
1224 
1225 void ieee80211_scan_cancel(struct ieee80211_local *local)
1226 {
1227 	/* ensure a new scan cannot be queued */
1228 	lockdep_assert_wiphy(local->hw.wiphy);
1229 
1230 	/*
1231 	 * We are canceling software scan, or deferred scan that was not
1232 	 * yet really started (see __ieee80211_start_scan ).
1233 	 *
1234 	 * Regarding hardware scan:
1235 	 * - we can not call  __ieee80211_scan_completed() as when
1236 	 *   SCAN_HW_SCANNING bit is set this function change
1237 	 *   local->hw_scan_req to operate on 5G band, what race with
1238 	 *   driver which can use local->hw_scan_req
1239 	 *
1240 	 * - we can not cancel scan_work since driver can schedule it
1241 	 *   by ieee80211_scan_completed(..., true) to finish scan
1242 	 *
1243 	 * Hence we only call the cancel_hw_scan() callback, but the low-level
1244 	 * driver is still responsible for calling ieee80211_scan_completed()
1245 	 * after the scan was completed/aborted.
1246 	 */
1247 
1248 	if (!local->scan_req)
1249 		return;
1250 
1251 	/*
1252 	 * We have a scan running and the driver already reported completion,
1253 	 * but the worker hasn't run yet or is stuck on the mutex - mark it as
1254 	 * cancelled.
1255 	 */
1256 	if (test_bit(SCAN_HW_SCANNING, &local->scanning) &&
1257 	    test_bit(SCAN_COMPLETED, &local->scanning)) {
1258 		set_bit(SCAN_HW_CANCELLED, &local->scanning);
1259 		return;
1260 	}
1261 
1262 	if (test_bit(SCAN_HW_SCANNING, &local->scanning)) {
1263 		/*
1264 		 * Make sure that __ieee80211_scan_completed doesn't trigger a
1265 		 * scan on another band.
1266 		 */
1267 		set_bit(SCAN_HW_CANCELLED, &local->scanning);
1268 		if (local->ops->cancel_hw_scan)
1269 			drv_cancel_hw_scan(local,
1270 				rcu_dereference_protected(local->scan_sdata,
1271 						lockdep_is_held(&local->hw.wiphy->mtx)));
1272 		return;
1273 	}
1274 
1275 	wiphy_delayed_work_cancel(local->hw.wiphy, &local->scan_work);
1276 	/* and clean up */
1277 	memset(&local->scan_info, 0, sizeof(local->scan_info));
1278 	__ieee80211_scan_completed(&local->hw, true);
1279 }
1280 
1281 int __ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
1282 					struct cfg80211_sched_scan_request *req)
1283 {
1284 	struct ieee80211_local *local = sdata->local;
1285 	struct ieee80211_scan_ies sched_scan_ies = {};
1286 	struct cfg80211_chan_def chandef;
1287 	int ret, i, iebufsz, num_bands = 0;
1288 	u32 rate_masks[NUM_NL80211_BANDS] = {};
1289 	u8 bands_used = 0;
1290 	u8 *ie;
1291 	u32 flags = 0;
1292 
1293 	lockdep_assert_wiphy(local->hw.wiphy);
1294 
1295 	iebufsz = local->scan_ies_len + req->ie_len;
1296 
1297 	if (!local->ops->sched_scan_start)
1298 		return -EOPNOTSUPP;
1299 
1300 	for (i = 0; i < NUM_NL80211_BANDS; i++) {
1301 		if (local->hw.wiphy->bands[i]) {
1302 			bands_used |= BIT(i);
1303 			rate_masks[i] = (u32) -1;
1304 			num_bands++;
1305 		}
1306 	}
1307 
1308 	if (req->flags & NL80211_SCAN_FLAG_MIN_PREQ_CONTENT)
1309 		flags |= IEEE80211_PROBE_FLAG_MIN_CONTENT;
1310 
1311 	ie = kcalloc(iebufsz, num_bands, GFP_KERNEL);
1312 	if (!ie) {
1313 		ret = -ENOMEM;
1314 		goto out;
1315 	}
1316 
1317 	ieee80211_prepare_scan_chandef(&chandef);
1318 
1319 	ieee80211_build_preq_ies(sdata, ie, num_bands * iebufsz,
1320 				 &sched_scan_ies, req->ie,
1321 				 req->ie_len, bands_used, rate_masks, &chandef,
1322 				 flags);
1323 
1324 	ret = drv_sched_scan_start(local, sdata, req, &sched_scan_ies);
1325 	if (ret == 0) {
1326 		rcu_assign_pointer(local->sched_scan_sdata, sdata);
1327 		rcu_assign_pointer(local->sched_scan_req, req);
1328 	}
1329 
1330 	kfree(ie);
1331 
1332 out:
1333 	if (ret) {
1334 		/* Clean in case of failure after HW restart or upon resume. */
1335 		RCU_INIT_POINTER(local->sched_scan_sdata, NULL);
1336 		RCU_INIT_POINTER(local->sched_scan_req, NULL);
1337 	}
1338 
1339 	return ret;
1340 }
1341 
1342 int ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
1343 				       struct cfg80211_sched_scan_request *req)
1344 {
1345 	struct ieee80211_local *local = sdata->local;
1346 
1347 	lockdep_assert_wiphy(local->hw.wiphy);
1348 
1349 	if (rcu_access_pointer(local->sched_scan_sdata))
1350 		return -EBUSY;
1351 
1352 	return __ieee80211_request_sched_scan_start(sdata, req);
1353 }
1354 
1355 int ieee80211_request_sched_scan_stop(struct ieee80211_local *local)
1356 {
1357 	struct ieee80211_sub_if_data *sched_scan_sdata;
1358 	int ret = -ENOENT;
1359 
1360 	lockdep_assert_wiphy(local->hw.wiphy);
1361 
1362 	if (!local->ops->sched_scan_stop)
1363 		return -EOPNOTSUPP;
1364 
1365 	/* We don't want to restart sched scan anymore. */
1366 	RCU_INIT_POINTER(local->sched_scan_req, NULL);
1367 
1368 	sched_scan_sdata = rcu_dereference_protected(local->sched_scan_sdata,
1369 						lockdep_is_held(&local->hw.wiphy->mtx));
1370 	if (sched_scan_sdata) {
1371 		ret = drv_sched_scan_stop(local, sched_scan_sdata);
1372 		if (!ret)
1373 			RCU_INIT_POINTER(local->sched_scan_sdata, NULL);
1374 	}
1375 
1376 	return ret;
1377 }
1378 
1379 void ieee80211_sched_scan_results(struct ieee80211_hw *hw)
1380 {
1381 	struct ieee80211_local *local = hw_to_local(hw);
1382 
1383 	trace_api_sched_scan_results(local);
1384 
1385 	cfg80211_sched_scan_results(hw->wiphy, 0);
1386 }
1387 EXPORT_SYMBOL(ieee80211_sched_scan_results);
1388 
1389 void ieee80211_sched_scan_end(struct ieee80211_local *local)
1390 {
1391 	lockdep_assert_wiphy(local->hw.wiphy);
1392 
1393 	if (!rcu_access_pointer(local->sched_scan_sdata))
1394 		return;
1395 
1396 	RCU_INIT_POINTER(local->sched_scan_sdata, NULL);
1397 
1398 	/* If sched scan was aborted by the driver. */
1399 	RCU_INIT_POINTER(local->sched_scan_req, NULL);
1400 
1401 	cfg80211_sched_scan_stopped_locked(local->hw.wiphy, 0);
1402 }
1403 
1404 void ieee80211_sched_scan_stopped_work(struct wiphy *wiphy,
1405 				       struct wiphy_work *work)
1406 {
1407 	struct ieee80211_local *local =
1408 		container_of(work, struct ieee80211_local,
1409 			     sched_scan_stopped_work);
1410 
1411 	ieee80211_sched_scan_end(local);
1412 }
1413 
1414 void ieee80211_sched_scan_stopped(struct ieee80211_hw *hw)
1415 {
1416 	struct ieee80211_local *local = hw_to_local(hw);
1417 
1418 	trace_api_sched_scan_stopped(local);
1419 
1420 	/*
1421 	 * this shouldn't really happen, so for simplicity
1422 	 * simply ignore it, and let mac80211 reconfigure
1423 	 * the sched scan later on.
1424 	 */
1425 	if (local->in_reconfig)
1426 		return;
1427 
1428 	wiphy_work_queue(hw->wiphy, &local->sched_scan_stopped_work);
1429 }
1430 EXPORT_SYMBOL(ieee80211_sched_scan_stopped);
1431