// SPDX-License-Identifier: GPL-2.0-only

  /*

   * Scanning implementation
   *

   * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
   * Copyright 2004, Instant802 Networks, Inc.
   * Copyright 2005, Devicescape Software, Inc.
   * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
   * Copyright 2007, Michael Wu <flamingice@sourmilk.net>

   * Copyright 2013-2015  Intel Mobile Communications GmbH

   * Copyright 2016-2017  Intel Deutschland GmbH

   * Copyright (C) 2018-2020 Intel Corporation

   */

  #include <linux/if_arp.h>

  #include <linux/etherdevice.h>

  #include <linux/rtnetlink.h>

  #include <net/sch_generic.h>

  #include <linux/slab.h>

  #include <linux/export.h>

  #include <linux/random.h>

  #include <net/mac80211.h>

  
  #include "ieee80211_i.h"

  #include "driver-ops.h"

  #include "mesh.h"

  
  #define IEEE80211_PROBE_DELAY (HZ / 33)
  #define IEEE80211_CHANNEL_TIME (HZ / 33)

  #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 9)

  void ieee80211_rx_bss_put(struct ieee80211_local *local,

  			  struct ieee80211_bss *bss)

  {

  	if (!bss)
  		return;

  	cfg80211_put_bss(local->hw.wiphy,
  			 container_of((void *)bss, struct cfg80211_bss, priv));

  }

  static bool is_uapsd_supported(struct ieee802_11_elems *elems)
  {
  	u8 qos_info;
  
  	if (elems->wmm_info && elems->wmm_info_len == 7
  	    && elems->wmm_info[5] == 1)
  		qos_info = elems->wmm_info[6];
  	else if (elems->wmm_param && elems->wmm_param_len == 24
  		 && elems->wmm_param[5] == 1)
  		qos_info = elems->wmm_param[6];
  	else
  		/* no valid wmm information or parameter element found */
  		return false;
  
  	return qos_info & IEEE80211_WMM_IE_AP_QOSINFO_UAPSD;
  }

  static void
  ieee80211_update_bss_from_elems(struct ieee80211_local *local,
  				struct ieee80211_bss *bss,
  				struct ieee802_11_elems *elems,
  				struct ieee80211_rx_status *rx_status,
  				bool beacon)
  {
  	int clen, srlen;
  
  	if (beacon)
  		bss->device_ts_beacon = rx_status->device_timestamp;
  	else
  		bss->device_ts_presp = rx_status->device_timestamp;
  
  	if (elems->parse_error) {
  		if (beacon)
  			bss->corrupt_data |= IEEE80211_BSS_CORRUPT_BEACON;
  		else
  			bss->corrupt_data |= IEEE80211_BSS_CORRUPT_PROBE_RESP;
  	} else {
  		if (beacon)
  			bss->corrupt_data &= ~IEEE80211_BSS_CORRUPT_BEACON;
  		else
  			bss->corrupt_data &= ~IEEE80211_BSS_CORRUPT_PROBE_RESP;
  	}
  
  	/* save the ERP value so that it is available at association time */
  	if (elems->erp_info && (!elems->parse_error ||
  				!(bss->valid_data & IEEE80211_BSS_VALID_ERP))) {
  		bss->erp_value = elems->erp_info[0];
  		bss->has_erp_value = true;
  		if (!elems->parse_error)
  			bss->valid_data |= IEEE80211_BSS_VALID_ERP;
  	}
  
  	/* replace old supported rates if we get new values */
  	if (!elems->parse_error ||
  	    !(bss->valid_data & IEEE80211_BSS_VALID_RATES)) {
  		srlen = 0;
  		if (elems->supp_rates) {
  			clen = IEEE80211_MAX_SUPP_RATES;
  			if (clen > elems->supp_rates_len)
  				clen = elems->supp_rates_len;
  			memcpy(bss->supp_rates, elems->supp_rates, clen);
  			srlen += clen;
  		}
  		if (elems->ext_supp_rates) {
  			clen = IEEE80211_MAX_SUPP_RATES - srlen;
  			if (clen > elems->ext_supp_rates_len)
  				clen = elems->ext_supp_rates_len;
  			memcpy(bss->supp_rates + srlen, elems->ext_supp_rates,
  			       clen);
  			srlen += clen;
  		}
  		if (srlen) {
  			bss->supp_rates_len = srlen;
  			if (!elems->parse_error)
  				bss->valid_data |= IEEE80211_BSS_VALID_RATES;
  		}
  	}
  
  	if (!elems->parse_error ||
  	    !(bss->valid_data & IEEE80211_BSS_VALID_WMM)) {
  		bss->wmm_used = elems->wmm_param || elems->wmm_info;
  		bss->uapsd_supported = is_uapsd_supported(elems);
  		if (!elems->parse_error)
  			bss->valid_data |= IEEE80211_BSS_VALID_WMM;
  	}
  
  	if (beacon) {
  		struct ieee80211_supported_band *sband =
  			local->hw.wiphy->bands[rx_status->band];
  		if (!(rx_status->encoding == RX_ENC_HT) &&
  		    !(rx_status->encoding == RX_ENC_VHT))
  			bss->beacon_rate =
  				&sband->bitrates[rx_status->rate_idx];
  	}

  
  	if (elems->vht_cap_elem)
  		bss->vht_cap_info =
  			le32_to_cpu(elems->vht_cap_elem->vht_cap_info);
  	else
  		bss->vht_cap_info = 0;

  }

  struct ieee80211_bss *

  ieee80211_bss_info_update(struct ieee80211_local *local,
  			  struct ieee80211_rx_status *rx_status,

  			  struct ieee80211_mgmt *mgmt, size_t len,

  			  struct ieee80211_channel *channel)

  {

  	bool beacon = ieee80211_is_beacon(mgmt->frame_control) ||
  		      ieee80211_is_s1g_beacon(mgmt->frame_control);

  	struct cfg80211_bss *cbss, *non_tx_cbss;
  	struct ieee80211_bss *bss, *non_tx_bss;

  	struct cfg80211_inform_bss bss_meta = {
  		.boottime_ns = rx_status->boottime_ns,
  	};

  	bool signal_valid;

  	struct ieee80211_sub_if_data *scan_sdata;

  	struct ieee802_11_elems elems;
  	size_t baselen;
  	u8 *elements;

  	if (rx_status->flag & RX_FLAG_NO_SIGNAL_VAL)
  		bss_meta.signal = 0; /* invalid signal indication */
  	else if (ieee80211_hw_check(&local->hw, SIGNAL_DBM))

  		bss_meta.signal = rx_status->signal * 100;

  	else if (ieee80211_hw_check(&local->hw, SIGNAL_UNSPEC))

  		bss_meta.signal = (rx_status->signal * 100) / local->hw.max_signal;

  	bss_meta.scan_width = NL80211_BSS_CHAN_WIDTH_20;

  	if (rx_status->bw == RATE_INFO_BW_5)

  		bss_meta.scan_width = NL80211_BSS_CHAN_WIDTH_5;

  	else if (rx_status->bw == RATE_INFO_BW_10)

  		bss_meta.scan_width = NL80211_BSS_CHAN_WIDTH_10;

  	bss_meta.chan = channel;

  
  	rcu_read_lock();
  	scan_sdata = rcu_dereference(local->scan_sdata);
  	if (scan_sdata && scan_sdata->vif.type == NL80211_IFTYPE_STATION &&
  	    scan_sdata->vif.bss_conf.assoc &&
  	    ieee80211_have_rx_timestamp(rx_status)) {
  		bss_meta.parent_tsf =
  			ieee80211_calculate_rx_timestamp(local, rx_status,
  							 len + FCS_LEN, 24);
  		ether_addr_copy(bss_meta.parent_bssid,
  				scan_sdata->vif.bss_conf.bssid);
  	}
  	rcu_read_unlock();

  	cbss = cfg80211_inform_bss_frame_data(local->hw.wiphy, &bss_meta,
  					      mgmt, len, GFP_ATOMIC);

  	if (!cbss)

  		return NULL;

  
  	if (ieee80211_is_probe_resp(mgmt->frame_control)) {
  		elements = mgmt->u.probe_resp.variable;
  		baselen = offsetof(struct ieee80211_mgmt,
  				   u.probe_resp.variable);

  	} else if (ieee80211_is_s1g_beacon(mgmt->frame_control)) {
  		struct ieee80211_ext *ext = (void *) mgmt;
  
  		baselen = offsetof(struct ieee80211_ext, u.s1g_beacon.variable);
  		elements = ext->u.s1g_beacon.variable;

  	} else {
  		baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
  		elements = mgmt->u.beacon.variable;
  	}
  
  	if (baselen > len)
  		return NULL;
  
  	ieee802_11_parse_elems(elements, len - baselen, false, &elems,
  			       mgmt->bssid, cbss->bssid);

  	/* In case the signal is invalid update the status */

  	signal_valid = channel == cbss->channel;

  	if (!signal_valid)
  		rx_status->flag |= RX_FLAG_NO_SIGNAL_VAL;

  	bss = (void *)cbss->priv;

  	ieee80211_update_bss_from_elems(local, bss, &elems, rx_status, beacon);

  	list_for_each_entry(non_tx_cbss, &cbss->nontrans_list, nontrans_list) {
  		non_tx_bss = (void *)non_tx_cbss->priv;
  
  		ieee80211_update_bss_from_elems(local, non_tx_bss, &elems,
  						rx_status, beacon);
  	}

  	return bss;
  }

  static bool ieee80211_scan_accept_presp(struct ieee80211_sub_if_data *sdata,
  					u32 scan_flags, const u8 *da)
  {
  	if (!sdata)
  		return false;
  	/* accept broadcast for OCE */
  	if (scan_flags & NL80211_SCAN_FLAG_ACCEPT_BCAST_PROBE_RESP &&
  	    is_broadcast_ether_addr(da))
  		return true;
  	if (scan_flags & NL80211_SCAN_FLAG_RANDOM_ADDR)
  		return true;
  	return ether_addr_equal(da, sdata->vif.addr);
  }

  void ieee80211_scan_rx(struct ieee80211_local *local, struct sk_buff *skb)

  {

  	struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);

  	struct ieee80211_sub_if_data *sdata1, *sdata2;
  	struct ieee80211_mgmt *mgmt = (void *)skb->data;

  	struct ieee80211_bss *bss;

  	struct ieee80211_channel *channel;

  	if (ieee80211_is_s1g_beacon(mgmt->frame_control)) {
  		if (skb->len < 15)
  			return;
  	} else if (skb->len < 24 ||
  		 (!ieee80211_is_probe_resp(mgmt->frame_control) &&
  		  !ieee80211_is_beacon(mgmt->frame_control)))

  		return;

  	sdata1 = rcu_dereference(local->scan_sdata);
  	sdata2 = rcu_dereference(local->sched_scan_sdata);

  	if (likely(!sdata1 && !sdata2))
  		return;

  	if (ieee80211_is_probe_resp(mgmt->frame_control)) {

  		struct cfg80211_scan_request *scan_req;
  		struct cfg80211_sched_scan_request *sched_scan_req;

  		u32 scan_req_flags = 0, sched_scan_req_flags = 0;

  
  		scan_req = rcu_dereference(local->scan_req);
  		sched_scan_req = rcu_dereference(local->sched_scan_req);

  		if (scan_req)
  			scan_req_flags = scan_req->flags;
  
  		if (sched_scan_req)
  			sched_scan_req_flags = sched_scan_req->flags;
  
  		/* ignore ProbeResp to foreign address or non-bcast (OCE)
  		 * unless scanning with randomised address

  		 */

  		if (!ieee80211_scan_accept_presp(sdata1, scan_req_flags,
  						 mgmt->da) &&
  		    !ieee80211_scan_accept_presp(sdata2, sched_scan_req_flags,
  						 mgmt->da))

  			return;

  	}

  	channel = ieee80211_get_channel_khz(local->hw.wiphy,
  					ieee80211_rx_status_to_khz(rx_status));

  
  	if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)

  		return;

  	bss = ieee80211_bss_info_update(local, rx_status,

  					mgmt, skb->len,

  					channel);

  	if (bss)

  		ieee80211_rx_bss_put(local, bss);

  }

  static void
  ieee80211_prepare_scan_chandef(struct cfg80211_chan_def *chandef,
  			       enum nl80211_bss_scan_width scan_width)
  {
  	memset(chandef, 0, sizeof(*chandef));
  	switch (scan_width) {
  	case NL80211_BSS_CHAN_WIDTH_5:
  		chandef->width = NL80211_CHAN_WIDTH_5;
  		break;
  	case NL80211_BSS_CHAN_WIDTH_10:
  		chandef->width = NL80211_CHAN_WIDTH_10;
  		break;
  	default:
  		chandef->width = NL80211_CHAN_WIDTH_20_NOHT;
  		break;
  	}
  }

  /* return false if no more work */

  static bool ieee80211_prep_hw_scan(struct ieee80211_sub_if_data *sdata)

  {

  	struct ieee80211_local *local = sdata->local;

  	struct cfg80211_scan_request *req;

  	struct cfg80211_chan_def chandef;

  	u8 bands_used = 0;

  	int i, ielen, n_chans;

  	u32 flags = 0;

  	req = rcu_dereference_protected(local->scan_req,
  					lockdep_is_held(&local->mtx));

  	if (test_bit(SCAN_HW_CANCELLED, &local->scanning))
  		return false;

  	if (ieee80211_hw_check(&local->hw, SINGLE_SCAN_ON_ALL_BANDS)) {

  		for (i = 0; i < req->n_channels; i++) {

  			local->hw_scan_req->req.channels[i] = req->channels[i];
  			bands_used |= BIT(req->channels[i]->band);
  		}
  
  		n_chans = req->n_channels;
  	} else {
  		do {

  			if (local->hw_scan_band == NUM_NL80211_BANDS)

  				return false;
  
  			n_chans = 0;
  
  			for (i = 0; i < req->n_channels; i++) {
  				if (req->channels[i]->band !=
  				    local->hw_scan_band)
  					continue;
  				local->hw_scan_req->req.channels[n_chans] =

  							req->channels[i];
  				n_chans++;

  				bands_used |= BIT(req->channels[i]->band);

  			}

  			local->hw_scan_band++;
  		} while (!n_chans);
  	}

  	local->hw_scan_req->req.n_channels = n_chans;

  	ieee80211_prepare_scan_chandef(&chandef, req->scan_width);

  	if (req->flags & NL80211_SCAN_FLAG_MIN_PREQ_CONTENT)
  		flags |= IEEE80211_PROBE_FLAG_MIN_CONTENT;

  	ielen = ieee80211_build_preq_ies(sdata,

  					 (u8 *)local->hw_scan_req->req.ie,

  					 local->hw_scan_ies_bufsize,

  					 &local->hw_scan_req->ies,
  					 req->ie, req->ie_len,

  					 bands_used, req->rates, &chandef,
  					 flags);

  	local->hw_scan_req->req.ie_len = ielen;
  	local->hw_scan_req->req.no_cck = req->no_cck;

  	ether_addr_copy(local->hw_scan_req->req.mac_addr, req->mac_addr);
  	ether_addr_copy(local->hw_scan_req->req.mac_addr_mask,
  			req->mac_addr_mask);

  	ether_addr_copy(local->hw_scan_req->req.bssid, req->bssid);

  
  	return true;
  }

  static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)

  {
  	struct ieee80211_local *local = hw_to_local(hw);

  	bool hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);

  	bool was_scanning = local->scanning;

  	struct cfg80211_scan_request *scan_req;

  	struct ieee80211_sub_if_data *scan_sdata;

  	struct ieee80211_sub_if_data *sdata;

  	lockdep_assert_held(&local->mtx);

  	/*
  	 * It's ok to abort a not-yet-running scan (that
  	 * we have one at all will be verified by checking
  	 * local->scan_req next), but not to complete it
  	 * successfully.
  	 */
  	if (WARN_ON(!local->scanning && !aborted))
  		aborted = true;

  	if (WARN_ON(!local->scan_req))

  		return;

  	scan_sdata = rcu_dereference_protected(local->scan_sdata,
  					       lockdep_is_held(&local->mtx));

  	if (hw_scan && !aborted &&

  	    !ieee80211_hw_check(&local->hw, SINGLE_SCAN_ON_ALL_BANDS) &&

  	    ieee80211_prep_hw_scan(scan_sdata)) {

  		int rc;
  
  		rc = drv_hw_scan(local,
  			rcu_dereference_protected(local->scan_sdata,
  						  lockdep_is_held(&local->mtx)),
  			local->hw_scan_req);

  		if (rc == 0)

  			return;

  		/* HW scan failed and is going to be reported as aborted,
  		 * so clear old scan info.

  		 */
  		memset(&local->scan_info, 0, sizeof(local->scan_info));

  		aborted = true;

  	}
  
  	kfree(local->hw_scan_req);
  	local->hw_scan_req = NULL;

  	scan_req = rcu_dereference_protected(local->scan_req,
  					     lockdep_is_held(&local->mtx));

  	if (scan_req != local->int_scan_req) {

  		local->scan_info.aborted = aborted;
  		cfg80211_scan_done(scan_req, &local->scan_info);

  	}

  	RCU_INIT_POINTER(local->scan_req, NULL);

  	RCU_INIT_POINTER(local->scan_sdata, NULL);

  	local->scanning = 0;

  	local->scan_chandef.chan = NULL;

  	/* Set power back to normal operating levels. */
  	ieee80211_hw_config(local, 0);

  	if (!hw_scan) {

  		ieee80211_configure_filter(local);

  		drv_sw_scan_complete(local, scan_sdata);

  		ieee80211_offchannel_return(local);

  	}

  	ieee80211_recalc_idle(local);

  	ieee80211_mlme_notify_scan_completed(local);

  	ieee80211_ibss_notify_scan_completed(local);

  
  	/* Requeue all the work that might have been ignored while
  	 * the scan was in progress; if there was none this will
  	 * just be a no-op for the particular interface.
  	 */
  	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
  		if (ieee80211_sdata_running(sdata))
  			ieee80211_queue_work(&sdata->local->hw, &sdata->work);
  	}

  	if (was_scanning)
  		ieee80211_start_next_roc(local);

  }

  void ieee80211_scan_completed(struct ieee80211_hw *hw,
  			      struct cfg80211_scan_info *info)

  {
  	struct ieee80211_local *local = hw_to_local(hw);

  	trace_api_scan_completed(local, info->aborted);

  
  	set_bit(SCAN_COMPLETED, &local->scanning);

  	if (info->aborted)

  		set_bit(SCAN_ABORTED, &local->scanning);

  
  	memcpy(&local->scan_info, info, sizeof(*info));

  	ieee80211_queue_delayed_work(&local->hw, &local->scan_work, 0);
  }

  EXPORT_SYMBOL(ieee80211_scan_completed);

  static int ieee80211_start_sw_scan(struct ieee80211_local *local,
  				   struct ieee80211_sub_if_data *sdata)

  {

  	/* Software scan is not supported in multi-channel cases */
  	if (local->use_chanctx)
  		return -EOPNOTSUPP;

  	/*
  	 * Hardware/driver doesn't support hw_scan, so use software
  	 * scanning instead. First send a nullfunc frame with power save
  	 * bit on so that AP will buffer the frames for us while we are not
  	 * listening, then send probe requests to each channel and wait for
  	 * the responses. After all channels are scanned, tune back to the
  	 * original channel and send a nullfunc frame with power save bit
  	 * off to trigger the AP to send us all the buffered frames.
  	 *
  	 * Note that while local->sw_scanning is true everything else but
  	 * nullfunc frames and probe requests will be dropped in
  	 * ieee80211_tx_h_check_assoc().
  	 */

  	drv_sw_scan_start(local, sdata, local->scan_addr);

  	local->leave_oper_channel_time = jiffies;

  	local->next_scan_state = SCAN_DECISION;

  	local->scan_channel_idx = 0;

  	ieee80211_offchannel_stop_vifs(local);

  	/* ensure nullfunc is transmitted before leaving operating channel */

  	ieee80211_flush_queues(local, NULL, false);

  	ieee80211_configure_filter(local);

  	/* We need to set power level at maximum rate for scanning. */
  	ieee80211_hw_config(local, 0);

  	ieee80211_queue_delayed_work(&local->hw,

  				     &local->scan_work, 0);

  
  	return 0;
  }

  static bool __ieee80211_can_leave_ch(struct ieee80211_sub_if_data *sdata)
  {
  	struct ieee80211_local *local = sdata->local;
  	struct ieee80211_sub_if_data *sdata_iter;
  
  	if (!ieee80211_is_radar_required(local))
  		return true;
  
  	if (!regulatory_pre_cac_allowed(local->hw.wiphy))
  		return false;
  
  	mutex_lock(&local->iflist_mtx);
  	list_for_each_entry(sdata_iter, &local->interfaces, list) {
  		if (sdata_iter->wdev.cac_started) {
  			mutex_unlock(&local->iflist_mtx);
  			return false;
  		}
  	}
  	mutex_unlock(&local->iflist_mtx);
  
  	return true;
  }

  static bool ieee80211_can_scan(struct ieee80211_local *local,
  			       struct ieee80211_sub_if_data *sdata)
  {

  	if (!__ieee80211_can_leave_ch(sdata))

  		return false;

  	if (!list_empty(&local->roc_list))

  		return false;
  
  	if (sdata->vif.type == NL80211_IFTYPE_STATION &&

  	    sdata->u.mgd.flags & IEEE80211_STA_CONNECTION_POLL)

  		return false;
  
  	return true;
  }
  
  void ieee80211_run_deferred_scan(struct ieee80211_local *local)
  {
  	lockdep_assert_held(&local->mtx);
  
  	if (!local->scan_req || local->scanning)
  		return;

  	if (!ieee80211_can_scan(local,
  				rcu_dereference_protected(
  					local->scan_sdata,
  					lockdep_is_held(&local->mtx))))

  		return;
  
  	ieee80211_queue_delayed_work(&local->hw, &local->scan_work,
  				     round_jiffies_relative(0));
  }

  static void ieee80211_send_scan_probe_req(struct ieee80211_sub_if_data *sdata,
  					  const u8 *src, const u8 *dst,
  					  const u8 *ssid, size_t ssid_len,
  					  const u8 *ie, size_t ie_len,
  					  u32 ratemask, u32 flags, u32 tx_flags,
  					  struct ieee80211_channel *channel)
  {
  	struct sk_buff *skb;
  
  	skb = ieee80211_build_probe_req(sdata, src, dst, ratemask, channel,
  					ssid, ssid_len,
  					ie, ie_len, flags);

  	if (skb) {

  		if (flags & IEEE80211_PROBE_FLAG_RANDOM_SN) {
  			struct ieee80211_hdr *hdr = (void *)skb->data;

  			struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);

  			u16 sn = get_random_u32();

  			info->control.flags |= IEEE80211_TX_CTRL_NO_SEQNO;

  			hdr->seq_ctrl =
  				cpu_to_le16(IEEE80211_SN_TO_SEQ(sn));
  		}

  		IEEE80211_SKB_CB(skb)->flags |= tx_flags;

  		ieee80211_tx_skb_tid_band(sdata, skb, 7, channel->band);

  	}
  }

  static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
  					    unsigned long *next_delay)
  {
  	int i;

  	struct ieee80211_sub_if_data *sdata;

  	struct cfg80211_scan_request *scan_req;

  	enum nl80211_band band = local->hw.conf.chandef.chan->band;

  	u32 flags = 0, tx_flags;

  	scan_req = rcu_dereference_protected(local->scan_req,
  					     lockdep_is_held(&local->mtx));

  	tx_flags = IEEE80211_TX_INTFL_OFFCHAN_TX_OK;

  	if (scan_req->no_cck)

  		tx_flags |= IEEE80211_TX_CTL_NO_CCK_RATE;

  	if (scan_req->flags & NL80211_SCAN_FLAG_MIN_PREQ_CONTENT)
  		flags |= IEEE80211_PROBE_FLAG_MIN_CONTENT;
  	if (scan_req->flags & NL80211_SCAN_FLAG_RANDOM_SN)
  		flags |= IEEE80211_PROBE_FLAG_RANDOM_SN;

  	sdata = rcu_dereference_protected(local->scan_sdata,

  					  lockdep_is_held(&local->mtx));

  	for (i = 0; i < scan_req->n_ssids; i++)

  		ieee80211_send_scan_probe_req(

  			sdata, local->scan_addr, scan_req->bssid,

  			scan_req->ssids[i].ssid, scan_req->ssids[i].ssid_len,
  			scan_req->ie, scan_req->ie_len,

  			scan_req->rates[band], flags,

  			tx_flags, local->hw.conf.chandef.chan);

  
  	/*
  	 * After sending probe requests, wait for probe responses
  	 * on the channel.
  	 */
  	*next_delay = IEEE80211_CHANNEL_TIME;
  	local->next_scan_state = SCAN_DECISION;
  }

  static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
  				  struct cfg80211_scan_request *req)
  {
  	struct ieee80211_local *local = sdata->local;

  	bool hw_scan = local->ops->hw_scan;

  	int rc;

  	lockdep_assert_held(&local->mtx);

  	if (local->scan_req)
  		return -EBUSY;
  
  	if (!__ieee80211_can_leave_ch(sdata))

  		return -EBUSY;

  	if (!ieee80211_can_scan(local, sdata)) {

  		/* wait for the work to finish/time out */

  		rcu_assign_pointer(local->scan_req, req);

  		rcu_assign_pointer(local->scan_sdata, sdata);

  		return 0;
  	}

   again:
  	if (hw_scan) {

  		u8 *ies;

  		local->hw_scan_ies_bufsize = local->scan_ies_len + req->ie_len;

  		if (ieee80211_hw_check(&local->hw, SINGLE_SCAN_ON_ALL_BANDS)) {

  			int i, n_bands = 0;
  			u8 bands_counted = 0;
  
  			for (i = 0; i < req->n_channels; i++) {
  				if (bands_counted & BIT(req->channels[i]->band))
  					continue;
  				bands_counted |= BIT(req->channels[i]->band);
  				n_bands++;
  			}
  
  			local->hw_scan_ies_bufsize *= n_bands;
  		}

  		local->hw_scan_req = kmalloc(
  				sizeof(*local->hw_scan_req) +
  				req->n_channels * sizeof(req->channels[0]) +

  				local->hw_scan_ies_bufsize, GFP_KERNEL);

  		if (!local->hw_scan_req)

  			return -ENOMEM;

  		local->hw_scan_req->req.ssids = req->ssids;
  		local->hw_scan_req->req.n_ssids = req->n_ssids;

  		ies = (u8 *)local->hw_scan_req +
  			sizeof(*local->hw_scan_req) +
  			req->n_channels * sizeof(req->channels[0]);

  		local->hw_scan_req->req.ie = ies;
  		local->hw_scan_req->req.flags = req->flags;

  		eth_broadcast_addr(local->hw_scan_req->req.bssid);

  		local->hw_scan_req->req.duration = req->duration;
  		local->hw_scan_req->req.duration_mandatory =
  			req->duration_mandatory;

  
  		local->hw_scan_band = 0;

  		local->hw_scan_req->req.n_6ghz_params = req->n_6ghz_params;
  		local->hw_scan_req->req.scan_6ghz_params =
  			req->scan_6ghz_params;
  		local->hw_scan_req->req.scan_6ghz = req->scan_6ghz;

  
  		/*
  		 * After allocating local->hw_scan_req, we must
  		 * go through until ieee80211_prep_hw_scan(), so
  		 * anything that might be changed here and leave
  		 * this function early must not go after this
  		 * allocation.
  		 */

  	}

  	rcu_assign_pointer(local->scan_req, req);

  	rcu_assign_pointer(local->scan_sdata, sdata);

  	if (req->flags & NL80211_SCAN_FLAG_RANDOM_ADDR)
  		get_random_mask_addr(local->scan_addr,
  				     req->mac_addr,
  				     req->mac_addr_mask);
  	else
  		memcpy(local->scan_addr, sdata->vif.addr, ETH_ALEN);

  	if (hw_scan) {

  		__set_bit(SCAN_HW_SCANNING, &local->scanning);

  	} else if ((req->n_channels == 1) &&

  		   (req->channels[0] == local->_oper_chandef.chan)) {

  		/*
  		 * If we are scanning only on the operating channel
  		 * then we do not need to stop normal activities

  		 */
  		unsigned long next_delay;
  
  		__set_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning);
  
  		ieee80211_recalc_idle(local);
  
  		/* Notify driver scan is starting, keep order of operations
  		 * same as normal software scan, in case that matters. */

  		drv_sw_scan_start(local, sdata, local->scan_addr);

  
  		ieee80211_configure_filter(local); /* accept probe-responses */
  
  		/* We need to ensure power level is at max for scanning. */
  		ieee80211_hw_config(local, 0);

  		if ((req->channels[0]->flags & (IEEE80211_CHAN_NO_IR |
  						IEEE80211_CHAN_RADAR)) ||

  		    !req->n_ssids) {

  			next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
  		} else {
  			ieee80211_scan_state_send_probe(local, &next_delay);
  			next_delay = IEEE80211_CHANNEL_TIME;
  		}
  
  		/* Now, just wait a bit and we are all done! */
  		ieee80211_queue_delayed_work(&local->hw, &local->scan_work,
  					     next_delay);
  		return 0;
  	} else {
  		/* Do normal software scan */

  		__set_bit(SCAN_SW_SCANNING, &local->scanning);

  	}

  	ieee80211_recalc_idle(local);

  	if (hw_scan) {

  		WARN_ON(!ieee80211_prep_hw_scan(sdata));

  		rc = drv_hw_scan(local, sdata, local->hw_scan_req);

  	} else {
  		rc = ieee80211_start_sw_scan(local, sdata);
  	}

  	if (rc) {

  		kfree(local->hw_scan_req);
  		local->hw_scan_req = NULL;

  		local->scanning = 0;

  		ieee80211_recalc_idle(local);

  		local->scan_req = NULL;

  		RCU_INIT_POINTER(local->scan_sdata, NULL);

  	}

  	if (hw_scan && rc == 1) {
  		/*
  		 * we can't fall back to software for P2P-GO
  		 * as it must update NoA etc.
  		 */
  		if (ieee80211_vif_type_p2p(&sdata->vif) ==
  				NL80211_IFTYPE_P2P_GO)
  			return -EOPNOTSUPP;
  		hw_scan = false;
  		goto again;
  	}

  	return rc;
  }

  static unsigned long
  ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
  {
  	/*
  	 * TODO: channel switching also consumes quite some time,
  	 * add that delay as well to get a better estimation
  	 */

  	if (chan->flags & (IEEE80211_CHAN_NO_IR | IEEE80211_CHAN_RADAR))

  		return IEEE80211_PASSIVE_CHANNEL_TIME;
  	return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
  }

  static void ieee80211_scan_state_decision(struct ieee80211_local *local,
  					  unsigned long *next_delay)

  {

  	bool associated = false;

  	bool tx_empty = true;
  	bool bad_latency;

  	struct ieee80211_sub_if_data *sdata;

  	struct ieee80211_channel *next_chan;

  	enum mac80211_scan_state next_scan_state;

  	struct cfg80211_scan_request *scan_req;

  	/*
  	 * check if at least one STA interface is associated,
  	 * check if at least one STA interface has pending tx frames
  	 * and grab the lowest used beacon interval
  	 */

  	mutex_lock(&local->iflist_mtx);
  	list_for_each_entry(sdata, &local->interfaces, list) {

  		if (!ieee80211_sdata_running(sdata))

  			continue;
  
  		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
  			if (sdata->u.mgd.associated) {
  				associated = true;

  				if (!qdisc_all_tx_empty(sdata->dev)) {
  					tx_empty = false;
  					break;
  				}

  			}
  		}
  	}
  	mutex_unlock(&local->iflist_mtx);

  	scan_req = rcu_dereference_protected(local->scan_req,
  					     lockdep_is_held(&local->mtx));
  
  	next_chan = scan_req->channels[local->scan_channel_idx];

  	/*

  	 * we're currently scanning a different channel, let's
  	 * see if we can scan another channel without interfering
  	 * with the current traffic situation.
  	 *

  	 * Keep good latency, do not stay off-channel more than 125 ms.

  	 */

  	bad_latency = time_after(jiffies +

  				 ieee80211_scan_get_channel_time(next_chan),
  				 local->leave_oper_channel_time + HZ / 8);

  	if (associated && !tx_empty) {

  		if (scan_req->flags & NL80211_SCAN_FLAG_LOW_PRIORITY)

  			next_scan_state = SCAN_ABORT;
  		else
  			next_scan_state = SCAN_SUSPEND;

  	} else if (associated && bad_latency) {

  		next_scan_state = SCAN_SUSPEND;
  	} else {
  		next_scan_state = SCAN_SET_CHANNEL;
  	}
  
  	local->next_scan_state = next_scan_state;

  	*next_delay = 0;

  }

  static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
  					     unsigned long *next_delay)
  {
  	int skip;
  	struct ieee80211_channel *chan;

  	enum nl80211_bss_scan_width oper_scan_width;

  	struct cfg80211_scan_request *scan_req;
  
  	scan_req = rcu_dereference_protected(local->scan_req,
  					     lockdep_is_held(&local->mtx));

  	skip = 0;

  	chan = scan_req->channels[local->scan_channel_idx];

  	local->scan_chandef.chan = chan;
  	local->scan_chandef.center_freq1 = chan->center_freq;

  	local->scan_chandef.freq1_offset = chan->freq_offset;

  	local->scan_chandef.center_freq2 = 0;

  
  	/* For scanning on the S1G band, ignore scan_width (which is constant
  	 * across all channels) for now since channel width is specific to each
  	 * channel. Detect the required channel width here and likely revisit
  	 * later. Maybe scan_width could be used to build the channel scan list?
  	 */
  	if (chan->band == NL80211_BAND_S1GHZ) {
  		local->scan_chandef.width = ieee80211_s1g_channel_width(chan);
  		goto set_channel;
  	}

  	switch (scan_req->scan_width) {

  	case NL80211_BSS_CHAN_WIDTH_5:
  		local->scan_chandef.width = NL80211_CHAN_WIDTH_5;
  		break;
  	case NL80211_BSS_CHAN_WIDTH_10:
  		local->scan_chandef.width = NL80211_CHAN_WIDTH_10;
  		break;

  	default:

  	case NL80211_BSS_CHAN_WIDTH_20:
  		/* If scanning on oper channel, use whatever channel-type
  		 * is currently in use.
  		 */
  		oper_scan_width = cfg80211_chandef_to_scan_width(
  					&local->_oper_chandef);
  		if (chan == local->_oper_chandef.chan &&

  		    oper_scan_width == scan_req->scan_width)

  			local->scan_chandef = local->_oper_chandef;
  		else
  			local->scan_chandef.width = NL80211_CHAN_WIDTH_20_NOHT;
  		break;

  	case NL80211_BSS_CHAN_WIDTH_1:
  	case NL80211_BSS_CHAN_WIDTH_2:
  		/* shouldn't get here, S1G handled above */
  		WARN_ON(1);
  		break;

  	}

  set_channel:

  	if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
  		skip = 1;

  	/* advance state machine to next channel/band */
  	local->scan_channel_idx++;

  	if (skip) {
  		/* if we skip this channel return to the decision state */
  		local->next_scan_state = SCAN_DECISION;

  		return;

  	}

  
  	/*
  	 * Probe delay is used to update the NAV, cf. 11.1.3.2.2
  	 * (which unfortunately doesn't say _why_ step a) is done,
  	 * but it waits for the probe delay or until a frame is
  	 * received - and the received frame would update the NAV).
  	 * For now, we do not support waiting until a frame is
  	 * received.
  	 *
  	 * In any case, it is not necessary for a passive scan.
  	 */

  	if ((chan->flags & (IEEE80211_CHAN_NO_IR | IEEE80211_CHAN_RADAR)) ||
  	    !scan_req->n_ssids) {

  		*next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;

  		local->next_scan_state = SCAN_DECISION;

  		return;

  	}

  	/* active scan, send probes */

  	*next_delay = IEEE80211_PROBE_DELAY;

  	local->next_scan_state = SCAN_SEND_PROBE;

  }

  static void ieee80211_scan_state_suspend(struct ieee80211_local *local,
  					 unsigned long *next_delay)
  {
  	/* switch back to the operating channel */

  	local->scan_chandef.chan = NULL;

  	ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);

  	/* disable PS */
  	ieee80211_offchannel_return(local);

  
  	*next_delay = HZ / 5;
  	/* afterwards, resume scan & go to next channel */
  	local->next_scan_state = SCAN_RESUME;
  }
  
  static void ieee80211_scan_state_resume(struct ieee80211_local *local,
  					unsigned long *next_delay)
  {

  	ieee80211_offchannel_stop_vifs(local);

  
  	if (local->ops->flush) {

  		ieee80211_flush_queues(local, NULL, false);

  		*next_delay = 0;
  	} else
  		*next_delay = HZ / 10;
  
  	/* remember when we left the operating channel */
  	local->leave_oper_channel_time = jiffies;
  
  	/* advance to the next channel to be scanned */

  	local->next_scan_state = SCAN_SET_CHANNEL;

  }

  void ieee80211_scan_work(struct work_struct *work)

  {
  	struct ieee80211_local *local =
  		container_of(work, struct ieee80211_local, scan_work.work);

  	struct ieee80211_sub_if_data *sdata;

  	struct cfg80211_scan_request *scan_req;

  	unsigned long next_delay = 0;

  	bool aborted;

  	mutex_lock(&local->mtx);

  	if (!ieee80211_can_run_worker(local)) {
  		aborted = true;
  		goto out_complete;
  	}

  	sdata = rcu_dereference_protected(local->scan_sdata,
  					  lockdep_is_held(&local->mtx));

  	scan_req = rcu_dereference_protected(local->scan_req,
  					     lockdep_is_held(&local->mtx));

  	/* When scanning on-channel, the first-callback means completed. */
  	if (test_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning)) {
  		aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
  		goto out_complete;
  	}

  	if (test_and_clear_bit(SCAN_COMPLETED, &local->scanning)) {

  		aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);

  		goto out_complete;

  	}

  	if (!sdata || !scan_req)

  		goto out;

  	if (!local->scanning) {

  		int rc;

  		RCU_INIT_POINTER(local->scan_req, NULL);

  		RCU_INIT_POINTER(local->scan_sdata, NULL);

  		rc = __ieee80211_start_scan(sdata, scan_req);

  		if (rc) {

  			/* need to complete scan in cfg80211 */

  			rcu_assign_pointer(local->scan_req, scan_req);

  			aborted = true;
  			goto out_complete;
  		} else
  			goto out;

  	}

  	/*

  	 * as long as no delay is required advance immediately
  	 * without scheduling a new work
  	 */
  	do {

  		if (!ieee80211_sdata_running(sdata)) {
  			aborted = true;
  			goto out_complete;
  		}

  		switch (local->next_scan_state) {

  		case SCAN_DECISION:

  			/* if no more bands/channels left, complete scan */

  			if (local->scan_channel_idx >= scan_req->n_channels) {

  				aborted = false;
  				goto out_complete;
  			}
  			ieee80211_scan_state_decision(local, &next_delay);

  			break;

  		case SCAN_SET_CHANNEL:
  			ieee80211_scan_state_set_channel(local, &next_delay);
  			break;

  		case SCAN_SEND_PROBE:
  			ieee80211_scan_state_send_probe(local, &next_delay);
  			break;

  		case SCAN_SUSPEND:
  			ieee80211_scan_state_suspend(local, &next_delay);

  			break;

  		case SCAN_RESUME:
  			ieee80211_scan_state_resume(local, &next_delay);

  			break;

  		case SCAN_ABORT:
  			aborted = true;
  			goto out_complete;

  		}
  	} while (next_delay == 0);

  	ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);

  	goto out;

  
  out_complete:

  	__ieee80211_scan_completed(&local->hw, aborted);

  out:
  	mutex_unlock(&local->mtx);

  }

  int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
  			   struct cfg80211_scan_request *req)

  {

  	int res;

  	mutex_lock(&sdata->local->mtx);

  	res = __ieee80211_start_scan(sdata, req);

  	mutex_unlock(&sdata->local->mtx);

  	return res;

  }

  int ieee80211_request_ibss_scan(struct ieee80211_sub_if_data *sdata,
  				const u8 *ssid, u8 ssid_len,

  				struct ieee80211_channel **channels,
  				unsigned int n_channels,

  				enum nl80211_bss_scan_width scan_width)

  {

  	struct ieee80211_local *local = sdata->local;

  	int ret = -EBUSY, i, n_ch = 0;

  	enum nl80211_band band;

  	mutex_lock(&local->mtx);

  	/* busy scanning */
  	if (local->scan_req)
  		goto unlock;

  	/* fill internal scan request */

  	if (!channels) {
  		int max_n;

  		for (band = 0; band < NUM_NL80211_BANDS; band++) {

  			if (!local->hw.wiphy->bands[band] ||
  			    band == NL80211_BAND_6GHZ)

  				continue;

  
  			max_n = local->hw.wiphy->bands[band]->n_channels;
  			for (i = 0; i < max_n; i++) {
  				struct ieee80211_channel *tmp_ch =

  				    &local->hw.wiphy->bands[band]->channels[i];

  				if (tmp_ch->flags & (IEEE80211_CHAN_NO_IR |

  						     IEEE80211_CHAN_DISABLED))
  					continue;
  
  				local->int_scan_req->channels[n_ch] = tmp_ch;
  				n_ch++;

  			}
  		}

  		if (WARN_ON_ONCE(n_ch == 0))
  			goto unlock;
  
  		local->int_scan_req->n_channels = n_ch;

  	} else {

  		for (i = 0; i < n_channels; i++) {
  			if (channels[i]->flags & (IEEE80211_CHAN_NO_IR |
  						  IEEE80211_CHAN_DISABLED))
  				continue;
  
  			local->int_scan_req->channels[n_ch] = channels[i];
  			n_ch++;
  		}
  
  		if (WARN_ON_ONCE(n_ch == 0))

  			goto unlock;

  		local->int_scan_req->n_channels = n_ch;

  	}
  
  	local->int_scan_req->ssids = &local->scan_ssid;
  	local->int_scan_req->n_ssids = 1;

  	local->int_scan_req->scan_width = scan_width;

  	memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
  	local->int_scan_req->ssids[0].ssid_len = ssid_len;

  	ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);

   unlock:

  	mutex_unlock(&local->mtx);

  	return ret;

  }

  /*
   * Only call this function when a scan can't be queued -- under RTNL.
   */

  void ieee80211_scan_cancel(struct ieee80211_local *local)
  {

  	/*

  	 * We are canceling software scan, or deferred scan that was not

  	 * yet really started (see __ieee80211_start_scan ).
  	 *
  	 * Regarding hardware scan:
  	 * - we can not call  __ieee80211_scan_completed() as when
  	 *   SCAN_HW_SCANNING bit is set this function change
  	 *   local->hw_scan_req to operate on 5G band, what race with
  	 *   driver which can use local->hw_scan_req
  	 *
  	 * - we can not cancel scan_work since driver can schedule it
  	 *   by ieee80211_scan_completed(..., true) to finish scan
  	 *

  	 * Hence we only call the cancel_hw_scan() callback, but the low-level
  	 * driver is still responsible for calling ieee80211_scan_completed()
  	 * after the scan was completed/aborted.

  	 */

  	mutex_lock(&local->mtx);

  	if (!local->scan_req)
  		goto out;

  	/*
  	 * We have a scan running and the driver already reported completion,
  	 * but the worker hasn't run yet or is stuck on the mutex - mark it as
  	 * cancelled.
  	 */
  	if (test_bit(SCAN_HW_SCANNING, &local->scanning) &&
  	    test_bit(SCAN_COMPLETED, &local->scanning)) {
  		set_bit(SCAN_HW_CANCELLED, &local->scanning);
  		goto out;
  	}

  	if (test_bit(SCAN_HW_SCANNING, &local->scanning)) {

  		/*
  		 * Make sure that __ieee80211_scan_completed doesn't trigger a
  		 * scan on another band.
  		 */
  		set_bit(SCAN_HW_CANCELLED, &local->scanning);

  		if (local->ops->cancel_hw_scan)

  			drv_cancel_hw_scan(local,
  				rcu_dereference_protected(local->scan_sdata,
  						lockdep_is_held(&local->mtx)));

  		goto out;

  	}

  
  	/*
  	 * If the work is currently running, it must be blocked on
  	 * the mutex, but we'll set scan_sdata = NULL and it'll
  	 * simply exit once it acquires the mutex.
  	 */
  	cancel_delayed_work(&local->scan_work);
  	/* and clean up */

  	memset(&local->scan_info, 0, sizeof(local->scan_info));

  	__ieee80211_scan_completed(&local->hw, true);

  out:

  	mutex_unlock(&local->mtx);

  }

  int __ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
  					struct cfg80211_sched_scan_request *req)

  {
  	struct ieee80211_local *local = sdata->local;

  	struct ieee80211_scan_ies sched_scan_ies = {};

  	struct cfg80211_chan_def chandef;

  	int ret, i, iebufsz, num_bands = 0;

  	u32 rate_masks[NUM_NL80211_BANDS] = {};

  	u8 bands_used = 0;
  	u8 *ie;

  	u32 flags = 0;

  	iebufsz = local->scan_ies_len + req->ie_len;

  	lockdep_assert_held(&local->mtx);

  	if (!local->ops->sched_scan_start)
  		return -ENOTSUPP;

  	for (i = 0; i < NUM_NL80211_BANDS; i++) {

  		if (local->hw.wiphy->bands[i]) {
  			bands_used |= BIT(i);
  			rate_masks[i] = (u32) -1;
  			num_bands++;

  		}

  	}

  	if (req->flags & NL80211_SCAN_FLAG_MIN_PREQ_CONTENT)
  		flags |= IEEE80211_PROBE_FLAG_MIN_CONTENT;

  	ie = kcalloc(iebufsz, num_bands, GFP_KERNEL);

  	if (!ie) {
  		ret = -ENOMEM;
  		goto out;

  	}

  	ieee80211_prepare_scan_chandef(&chandef, req->scan_width);

  	ieee80211_build_preq_ies(sdata, ie, num_bands * iebufsz,

  				 &sched_scan_ies, req->ie,

  				 req->ie_len, bands_used, rate_masks, &chandef,

  				 flags);

  	ret = drv_sched_scan_start(local, sdata, req, &sched_scan_ies);

  	if (ret == 0) {

  		rcu_assign_pointer(local->sched_scan_sdata, sdata);

  		rcu_assign_pointer(local->sched_scan_req, req);

  	}

  	kfree(ie);

  out:

  	if (ret) {
  		/* Clean in case of failure after HW restart or upon resume. */

  		RCU_INIT_POINTER(local->sched_scan_sdata, NULL);

  		RCU_INIT_POINTER(local->sched_scan_req, NULL);

  	}
  
  	return ret;
  }
  
  int ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
  				       struct cfg80211_sched_scan_request *req)
  {
  	struct ieee80211_local *local = sdata->local;
  	int ret;
  
  	mutex_lock(&local->mtx);
  
  	if (rcu_access_pointer(local->sched_scan_sdata)) {
  		mutex_unlock(&local->mtx);
  		return -EBUSY;
  	}
  
  	ret = __ieee80211_request_sched_scan_start(sdata, req);

  	mutex_unlock(&local->mtx);

  	return ret;
  }

  int ieee80211_request_sched_scan_stop(struct ieee80211_local *local)

  {

  	struct ieee80211_sub_if_data *sched_scan_sdata;
  	int ret = -ENOENT;

  	mutex_lock(&local->mtx);

  
  	if (!local->ops->sched_scan_stop) {
  		ret = -ENOTSUPP;
  		goto out;
  	}

  	/* We don't want to restart sched scan anymore. */

  	RCU_INIT_POINTER(local->sched_scan_req, NULL);

  	sched_scan_sdata = rcu_dereference_protected(local->sched_scan_sdata,
  						lockdep_is_held(&local->mtx));
  	if (sched_scan_sdata) {
  		ret = drv_sched_scan_stop(local, sched_scan_sdata);

  		if (!ret)

  			RCU_INIT_POINTER(local->sched_scan_sdata, NULL);

  	}

  out:

  	mutex_unlock(&local->mtx);

  
  	return ret;
  }
  
  void ieee80211_sched_scan_results(struct ieee80211_hw *hw)
  {
  	struct ieee80211_local *local = hw_to_local(hw);
  
  	trace_api_sched_scan_results(local);

  	cfg80211_sched_scan_results(hw->wiphy, 0);

  }
  EXPORT_SYMBOL(ieee80211_sched_scan_results);

  void ieee80211_sched_scan_end(struct ieee80211_local *local)

  {

  	mutex_lock(&local->mtx);

  	if (!rcu_access_pointer(local->sched_scan_sdata)) {

  		mutex_unlock(&local->mtx);
  		return;
  	}

  	RCU_INIT_POINTER(local->sched_scan_sdata, NULL);

  	/* If sched scan was aborted by the driver. */

  	RCU_INIT_POINTER(local->sched_scan_req, NULL);

  	mutex_unlock(&local->mtx);

  	cfg80211_sched_scan_stopped(local->hw.wiphy, 0);

  }

  void ieee80211_sched_scan_stopped_work(struct work_struct *work)
  {
  	struct ieee80211_local *local =
  		container_of(work, struct ieee80211_local,
  			     sched_scan_stopped_work);
  
  	ieee80211_sched_scan_end(local);
  }

  void ieee80211_sched_scan_stopped(struct ieee80211_hw *hw)
  {
  	struct ieee80211_local *local = hw_to_local(hw);
  
  	trace_api_sched_scan_stopped(local);

  	/*
  	 * this shouldn't really happen, so for simplicity
  	 * simply ignore it, and let mac80211 reconfigure
  	 * the sched scan later on.
  	 */
  	if (local->in_reconfig)
  		return;

  	schedule_work(&local->sched_scan_stopped_work);

  }
  EXPORT_SYMBOL(ieee80211_sched_scan_stopped);