net/mac80211/chan.c - kernel/msm-4.9 - Gitiles

 /*
  * mac80211 - channel management
  */

 #include <linux/nl80211.h>
 #include <linux/export.h>
 #include <linux/rtnetlink.h>
 #include <net/cfg80211.h>
 #include "ieee80211_i.h"
 #include "driver-ops.h"

 static enum nl80211_chan_width ieee80211_get_sta_bw(struct ieee80211_sta *sta)
 {
 	switch (sta->bandwidth) {
 	case IEEE80211_STA_RX_BW_20:
 		if (sta->ht_cap.ht_supported)
 			return NL80211_CHAN_WIDTH_20;
 		else
 			return NL80211_CHAN_WIDTH_20_NOHT;
 	case IEEE80211_STA_RX_BW_40:
 		return NL80211_CHAN_WIDTH_40;
 	case IEEE80211_STA_RX_BW_80:
 		return NL80211_CHAN_WIDTH_80;
 	case IEEE80211_STA_RX_BW_160:
 		/*
 		 * This applied for both 160 and 80+80. since we use
 		 * the returned value to consider degradation of
 		 * ctx->conf.min_def, we have to make sure to take
 		 * the bigger one (NL80211_CHAN_WIDTH_160).
 		 * Otherwise we might try degrading even when not
 		 * needed, as the max required sta_bw returned (80+80)
 		 * might be smaller than the configured bw (160).
 		 */
 		return NL80211_CHAN_WIDTH_160;
 	default:
 		WARN_ON(1);
 		return NL80211_CHAN_WIDTH_20;
 	}
 }

 static enum nl80211_chan_width
 ieee80211_get_max_required_bw(struct ieee80211_sub_if_data *sdata)
 {
 	enum nl80211_chan_width max_bw = NL80211_CHAN_WIDTH_20_NOHT;
 	struct sta_info *sta;

 	rcu_read_lock();
 	list_for_each_entry_rcu(sta, &sdata->local->sta_list, list) {
 		if (sdata != sta->sdata &&
 		    !(sta->sdata->bss && sta->sdata->bss == sdata->bss))
 			continue;

 		if (!sta->uploaded)
 			continue;

 		max_bw = max(max_bw, ieee80211_get_sta_bw(&sta->sta));
 	}
 	rcu_read_unlock();

 	return max_bw;
 }

 static enum nl80211_chan_width
 ieee80211_get_chanctx_max_required_bw(struct ieee80211_local *local,
 				      struct ieee80211_chanctx_conf *conf)
 {
 	struct ieee80211_sub_if_data *sdata;
 	enum nl80211_chan_width max_bw = NL80211_CHAN_WIDTH_20_NOHT;

 	rcu_read_lock();
 	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
 		struct ieee80211_vif *vif = &sdata->vif;
 		enum nl80211_chan_width width = NL80211_CHAN_WIDTH_20_NOHT;

 		if (!ieee80211_sdata_running(sdata))
 			continue;

 		if (rcu_access_pointer(sdata->vif.chanctx_conf) != conf)
 			continue;

 		switch (vif->type) {
 		case NL80211_IFTYPE_AP:
 		case NL80211_IFTYPE_AP_VLAN:
 			width = ieee80211_get_max_required_bw(sdata);
 			break;
 		case NL80211_IFTYPE_P2P_DEVICE:
 			continue;
 		case NL80211_IFTYPE_STATION:
 		case NL80211_IFTYPE_ADHOC:
 		case NL80211_IFTYPE_WDS:
 		case NL80211_IFTYPE_MESH_POINT:
 			width = vif->bss_conf.chandef.width;
 			break;
 		case NL80211_IFTYPE_UNSPECIFIED:
 		case NUM_NL80211_IFTYPES:
 		case NL80211_IFTYPE_MONITOR:
 		case NL80211_IFTYPE_P2P_CLIENT:
 		case NL80211_IFTYPE_P2P_GO:
 			WARN_ON_ONCE(1);
 		}
 		max_bw = max(max_bw, width);
 	}
 	rcu_read_unlock();

 	return max_bw;
 }

 /*
  * recalc the min required chan width of the channel context, which is
  * the max of min required widths of all the interfaces bound to this
  * channel context.
  */
 void ieee80211_recalc_chanctx_min_def(struct ieee80211_local *local,
 				      struct ieee80211_chanctx *ctx)
 {
 	enum nl80211_chan_width max_bw;
 	struct cfg80211_chan_def min_def;

 	lockdep_assert_held(&local->chanctx_mtx);

 	/* don't optimize 5MHz, 10MHz, and radar_enabled confs */
 	if (ctx->conf.def.width == NL80211_CHAN_WIDTH_5 ||
 	    ctx->conf.def.width == NL80211_CHAN_WIDTH_10 ||
 	    ctx->conf.radar_enabled) {
 		ctx->conf.min_def = ctx->conf.def;
 		return;
 	}

 	max_bw = ieee80211_get_chanctx_max_required_bw(local, &ctx->conf);

 	/* downgrade chandef up to max_bw */
 	min_def = ctx->conf.def;
 	while (min_def.width > max_bw)
 		ieee80211_chandef_downgrade(&min_def);

 	if (cfg80211_chandef_identical(&ctx->conf.min_def, &min_def))
 		return;

 	ctx->conf.min_def = min_def;
 	if (!ctx->driver_present)
 		return;

 	drv_change_chanctx(local, ctx, IEEE80211_CHANCTX_CHANGE_MIN_WIDTH);
 }

 static void ieee80211_change_chanctx(struct ieee80211_local *local,
 				     struct ieee80211_chanctx *ctx,
 				     const struct cfg80211_chan_def *chandef)
 {
 	if (cfg80211_chandef_identical(&ctx->conf.def, chandef))
 		return;

 	WARN_ON(!cfg80211_chandef_compatible(&ctx->conf.def, chandef));

 	ctx->conf.def = *chandef;
 	drv_change_chanctx(local, ctx, IEEE80211_CHANCTX_CHANGE_WIDTH);
 	ieee80211_recalc_chanctx_min_def(local, ctx);

 	if (!local->use_chanctx) {
 		local->_oper_chandef = *chandef;
 		ieee80211_hw_config(local, 0);
 	}
 }

 static struct ieee80211_chanctx *
 ieee80211_find_chanctx(struct ieee80211_local *local,
 		       const struct cfg80211_chan_def *chandef,
 		       enum ieee80211_chanctx_mode mode)
 {
 	struct ieee80211_chanctx *ctx;

 	lockdep_assert_held(&local->chanctx_mtx);

 	if (mode == IEEE80211_CHANCTX_EXCLUSIVE)
 		return NULL;

 	list_for_each_entry(ctx, &local->chanctx_list, list) {
 		const struct cfg80211_chan_def *compat;

 		if (ctx->mode == IEEE80211_CHANCTX_EXCLUSIVE)
 			continue;

 		compat = cfg80211_chandef_compatible(&ctx->conf.def, chandef);
 		if (!compat)
 			continue;

 		ieee80211_change_chanctx(local, ctx, compat);

 		return ctx;
 	}

 	return NULL;
 }

 static bool ieee80211_is_radar_required(struct ieee80211_local *local)
 {
 	struct ieee80211_sub_if_data *sdata;

 	lockdep_assert_held(&local->mtx);

 	rcu_read_lock();
 	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
 		if (sdata->radar_required) {
 			rcu_read_unlock();
 			return true;
 		}
 	}
 	rcu_read_unlock();

 	return false;
 }

 static struct ieee80211_chanctx *
 ieee80211_new_chanctx(struct ieee80211_local *local,
 		      const struct cfg80211_chan_def *chandef,
 		      enum ieee80211_chanctx_mode mode)
 {
 	struct ieee80211_chanctx *ctx;
 	u32 changed;
 	int err;

 	lockdep_assert_held(&local->chanctx_mtx);

 	ctx = kzalloc(sizeof(*ctx) + local->hw.chanctx_data_size, GFP_KERNEL);
 	if (!ctx)
 		return ERR_PTR(-ENOMEM);

 	ctx->conf.def = *chandef;
 	ctx->conf.rx_chains_static = 1;
 	ctx->conf.rx_chains_dynamic = 1;
 	ctx->mode = mode;
 	ctx->conf.radar_enabled = ieee80211_is_radar_required(local);
 	ieee80211_recalc_chanctx_min_def(local, ctx);
 	if (!local->use_chanctx)
 		local->hw.conf.radar_enabled = ctx->conf.radar_enabled;

 	/* we hold the mutex to prevent idle from changing */
 	lockdep_assert_held(&local->mtx);
 	/* turn idle off *before* setting channel -- some drivers need that */
 	changed = ieee80211_idle_off(local);
 	if (changed)
 		ieee80211_hw_config(local, changed);

 	if (!local->use_chanctx) {
 		local->_oper_chandef = *chandef;
 		ieee80211_hw_config(local, 0);
 	} else {
 		err = drv_add_chanctx(local, ctx);
 		if (err) {
 			kfree(ctx);
 			ieee80211_recalc_idle(local);
 			return ERR_PTR(err);
 		}
 	}

 	/* and keep the mutex held until the new chanctx is on the list */
 	list_add_rcu(&ctx->list, &local->chanctx_list);

 	return ctx;
 }

 static void ieee80211_free_chanctx(struct ieee80211_local *local,
 				   struct ieee80211_chanctx *ctx)
 {
 	bool check_single_channel = false;
 	lockdep_assert_held(&local->chanctx_mtx);

 	WARN_ON_ONCE(ctx->refcount != 0);

 	if (!local->use_chanctx) {
 		struct cfg80211_chan_def *chandef = &local->_oper_chandef;
 		chandef->width = NL80211_CHAN_WIDTH_20_NOHT;
 		chandef->center_freq1 = chandef->chan->center_freq;
 		chandef->center_freq2 = 0;

 		/* NOTE: Disabling radar is only valid here for
 		 * single channel context. To be sure, check it ...
 		 */
 		if (local->hw.conf.radar_enabled)
 			check_single_channel = true;
 		local->hw.conf.radar_enabled = false;

 		ieee80211_hw_config(local, 0);
 	} else {
 		drv_remove_chanctx(local, ctx);
 	}

 	list_del_rcu(&ctx->list);
 	kfree_rcu(ctx, rcu_head);

 	/* throw a warning if this wasn't the only channel context. */
 	WARN_ON(check_single_channel && !list_empty(&local->chanctx_list));

 	ieee80211_recalc_idle(local);
 }

 static int ieee80211_assign_vif_chanctx(struct ieee80211_sub_if_data *sdata,
 					struct ieee80211_chanctx *ctx)
 {
 	struct ieee80211_local *local = sdata->local;
 	int ret;

 	lockdep_assert_held(&local->chanctx_mtx);

 	ret = drv_assign_vif_chanctx(local, sdata, ctx);
 	if (ret)
 		return ret;

 	rcu_assign_pointer(sdata->vif.chanctx_conf, &ctx->conf);
 	ctx->refcount++;

 	ieee80211_recalc_txpower(sdata);
 	ieee80211_recalc_chanctx_min_def(local, ctx);
 	sdata->vif.bss_conf.idle = false;

 	if (sdata->vif.type != NL80211_IFTYPE_P2P_DEVICE &&
 	    sdata->vif.type != NL80211_IFTYPE_MONITOR)
 		ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_IDLE);

 	return 0;
 }

 static void ieee80211_recalc_chanctx_chantype(struct ieee80211_local *local,
 					      struct ieee80211_chanctx *ctx)
 {
 	struct ieee80211_chanctx_conf *conf = &ctx->conf;
 	struct ieee80211_sub_if_data *sdata;
 	const struct cfg80211_chan_def *compat = NULL;

 	lockdep_assert_held(&local->chanctx_mtx);

 	rcu_read_lock();
 	list_for_each_entry_rcu(sdata, &local->interfaces, list) {

 		if (!ieee80211_sdata_running(sdata))
 			continue;
 		if (rcu_access_pointer(sdata->vif.chanctx_conf) != conf)
 			continue;

 		if (!compat)
 			compat = &sdata->vif.bss_conf.chandef;

 		compat = cfg80211_chandef_compatible(
 				&sdata->vif.bss_conf.chandef, compat);
 		if (!compat)
 			break;
 	}
 	rcu_read_unlock();

 	if (WARN_ON_ONCE(!compat))
 		return;

 	ieee80211_change_chanctx(local, ctx, compat);
 }

 static void ieee80211_recalc_radar_chanctx(struct ieee80211_local *local,
 					   struct ieee80211_chanctx *chanctx)
 {
 	bool radar_enabled;

 	lockdep_assert_held(&local->chanctx_mtx);
 	/* for setting local->radar_detect_enabled */
 	lockdep_assert_held(&local->mtx);

 	radar_enabled = ieee80211_is_radar_required(local);

 	if (radar_enabled == chanctx->conf.radar_enabled)
 		return;

 	chanctx->conf.radar_enabled = radar_enabled;
 	local->radar_detect_enabled = chanctx->conf.radar_enabled;

 	if (!local->use_chanctx) {
 		local->hw.conf.radar_enabled = chanctx->conf.radar_enabled;
 		ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 	}

 	drv_change_chanctx(local, chanctx, IEEE80211_CHANCTX_CHANGE_RADAR);
 }

 static void ieee80211_unassign_vif_chanctx(struct ieee80211_sub_if_data *sdata,
 					   struct ieee80211_chanctx *ctx)
 {
 	struct ieee80211_local *local = sdata->local;

 	lockdep_assert_held(&local->chanctx_mtx);

 	ctx->refcount--;
 	rcu_assign_pointer(sdata->vif.chanctx_conf, NULL);

 	sdata->vif.bss_conf.idle = true;

 	if (sdata->vif.type != NL80211_IFTYPE_P2P_DEVICE &&
 	    sdata->vif.type != NL80211_IFTYPE_MONITOR)
 		ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_IDLE);

 	drv_unassign_vif_chanctx(local, sdata, ctx);

 	if (ctx->refcount > 0) {
 		ieee80211_recalc_chanctx_chantype(sdata->local, ctx);
 		ieee80211_recalc_smps_chanctx(local, ctx);
 		ieee80211_recalc_radar_chanctx(local, ctx);
 		ieee80211_recalc_chanctx_min_def(local, ctx);
 	}
 }

 static void __ieee80211_vif_release_channel(struct ieee80211_sub_if_data *sdata)
 {
 	struct ieee80211_local *local = sdata->local;
 	struct ieee80211_chanctx_conf *conf;
 	struct ieee80211_chanctx *ctx;

 	lockdep_assert_held(&local->chanctx_mtx);

 	conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
 					 lockdep_is_held(&local->chanctx_mtx));
 	if (!conf)
 		return;

 	ctx = container_of(conf, struct ieee80211_chanctx, conf);

 	ieee80211_unassign_vif_chanctx(sdata, ctx);
 	if (ctx->refcount == 0)
 		ieee80211_free_chanctx(local, ctx);
 }

 void ieee80211_recalc_smps_chanctx(struct ieee80211_local *local,
 				   struct ieee80211_chanctx *chanctx)
 {
 	struct ieee80211_sub_if_data *sdata;
 	u8 rx_chains_static, rx_chains_dynamic;

 	lockdep_assert_held(&local->chanctx_mtx);

 	rx_chains_static = 1;
 	rx_chains_dynamic = 1;

 	rcu_read_lock();
 	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
 		u8 needed_static, needed_dynamic;

 		if (!ieee80211_sdata_running(sdata))
 			continue;

 		if (rcu_access_pointer(sdata->vif.chanctx_conf) !=
 						&chanctx->conf)
 			continue;

 		switch (sdata->vif.type) {
 		case NL80211_IFTYPE_P2P_DEVICE:
 			continue;
 		case NL80211_IFTYPE_STATION:
 			if (!sdata->u.mgd.associated)
 				continue;
 			break;
 		case NL80211_IFTYPE_AP_VLAN:
 			continue;
 		case NL80211_IFTYPE_AP:
 		case NL80211_IFTYPE_ADHOC:
 		case NL80211_IFTYPE_WDS:
 		case NL80211_IFTYPE_MESH_POINT:
 			break;
 		default:
 			WARN_ON_ONCE(1);
 		}

 		switch (sdata->smps_mode) {
 		default:
 			WARN_ONCE(1, "Invalid SMPS mode %d\n",
 				  sdata->smps_mode);
 			/* fall through */
 		case IEEE80211_SMPS_OFF:
 			needed_static = sdata->needed_rx_chains;
 			needed_dynamic = sdata->needed_rx_chains;
 			break;
 		case IEEE80211_SMPS_DYNAMIC:
 			needed_static = 1;
 			needed_dynamic = sdata->needed_rx_chains;
 			break;
 		case IEEE80211_SMPS_STATIC:
 			needed_static = 1;
 			needed_dynamic = 1;
 			break;
 		}

 		rx_chains_static = max(rx_chains_static, needed_static);
 		rx_chains_dynamic = max(rx_chains_dynamic, needed_dynamic);
 	}
 	rcu_read_unlock();

 	if (!local->use_chanctx) {
 		if (rx_chains_static > 1)
 			local->smps_mode = IEEE80211_SMPS_OFF;
 		else if (rx_chains_dynamic > 1)
 			local->smps_mode = IEEE80211_SMPS_DYNAMIC;
 		else
 			local->smps_mode = IEEE80211_SMPS_STATIC;
 		ieee80211_hw_config(local, 0);
 	}

 	if (rx_chains_static == chanctx->conf.rx_chains_static &&
 	    rx_chains_dynamic == chanctx->conf.rx_chains_dynamic)
 		return;

 	chanctx->conf.rx_chains_static = rx_chains_static;
 	chanctx->conf.rx_chains_dynamic = rx_chains_dynamic;
 	drv_change_chanctx(local, chanctx, IEEE80211_CHANCTX_CHANGE_RX_CHAINS);
 }

 int ieee80211_vif_use_channel(struct ieee80211_sub_if_data *sdata,
 			      const struct cfg80211_chan_def *chandef,
 			      enum ieee80211_chanctx_mode mode)
 {
 	struct ieee80211_local *local = sdata->local;
 	struct ieee80211_chanctx *ctx;
 	int ret;

 	lockdep_assert_held(&local->mtx);

 	WARN_ON(sdata->dev && netif_carrier_ok(sdata->dev));

 	mutex_lock(&local->chanctx_mtx);
 	__ieee80211_vif_release_channel(sdata);

 	ctx = ieee80211_find_chanctx(local, chandef, mode);
 	if (!ctx)
 		ctx = ieee80211_new_chanctx(local, chandef, mode);
 	if (IS_ERR(ctx)) {
 		ret = PTR_ERR(ctx);
 		goto out;
 	}

 	sdata->vif.bss_conf.chandef = *chandef;

 	ret = ieee80211_assign_vif_chanctx(sdata, ctx);
 	if (ret) {
 		/* if assign fails refcount stays the same */
 		if (ctx->refcount == 0)
 			ieee80211_free_chanctx(local, ctx);
 		goto out;
 	}

 	ieee80211_recalc_smps_chanctx(local, ctx);
 	ieee80211_recalc_radar_chanctx(local, ctx);
  out:
 	mutex_unlock(&local->chanctx_mtx);
 	return ret;
 }

 int ieee80211_vif_change_channel(struct ieee80211_sub_if_data *sdata,
 				 u32 *changed)
 {
 	struct ieee80211_local *local = sdata->local;
 	struct ieee80211_chanctx_conf *conf;
 	struct ieee80211_chanctx *ctx;
 	const struct cfg80211_chan_def *chandef = &sdata->csa_chandef;
 	int ret;
 	u32 chanctx_changed = 0;

 	lockdep_assert_held(&local->mtx);

 	/* should never be called if not performing a channel switch. */
 	if (WARN_ON(!sdata->vif.csa_active))
 		return -EINVAL;

 	if (!cfg80211_chandef_usable(sdata->local->hw.wiphy, chandef,
 				     IEEE80211_CHAN_DISABLED))
 		return -EINVAL;

 	mutex_lock(&local->chanctx_mtx);
 	conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
 					 lockdep_is_held(&local->chanctx_mtx));
 	if (!conf) {
 		ret = -EINVAL;
 		goto out;
 	}

 	ctx = container_of(conf, struct ieee80211_chanctx, conf);
 	if (ctx->refcount != 1) {
 		ret = -EINVAL;
 		goto out;
 	}

 	if (sdata->vif.bss_conf.chandef.width != chandef->width) {
 		chanctx_changed = IEEE80211_CHANCTX_CHANGE_WIDTH;
 		*changed |= BSS_CHANGED_BANDWIDTH;
 	}

 	sdata->vif.bss_conf.chandef = *chandef;
 	ctx->conf.def = *chandef;

 	chanctx_changed |= IEEE80211_CHANCTX_CHANGE_CHANNEL;
 	drv_change_chanctx(local, ctx, chanctx_changed);

 	ieee80211_recalc_chanctx_chantype(local, ctx);
 	ieee80211_recalc_smps_chanctx(local, ctx);
 	ieee80211_recalc_radar_chanctx(local, ctx);
 	ieee80211_recalc_chanctx_min_def(local, ctx);

 	ret = 0;
  out:
 	mutex_unlock(&local->chanctx_mtx);
 	return ret;
 }

 int ieee80211_vif_change_bandwidth(struct ieee80211_sub_if_data *sdata,
 				   const struct cfg80211_chan_def *chandef,
 				   u32 *changed)
 {
 	struct ieee80211_local *local = sdata->local;
 	struct ieee80211_chanctx_conf *conf;
 	struct ieee80211_chanctx *ctx;
 	int ret;

 	if (!cfg80211_chandef_usable(sdata->local->hw.wiphy, chandef,
 				     IEEE80211_CHAN_DISABLED))
 		return -EINVAL;

 	mutex_lock(&local->chanctx_mtx);
 	if (cfg80211_chandef_identical(chandef, &sdata->vif.bss_conf.chandef)) {
 		ret = 0;
 		goto out;
 	}

 	if (chandef->width == NL80211_CHAN_WIDTH_20_NOHT ||
 	    sdata->vif.bss_conf.chandef.width == NL80211_CHAN_WIDTH_20_NOHT) {
 		ret = -EINVAL;
 		goto out;
 	}

 	conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
 					 lockdep_is_held(&local->chanctx_mtx));
 	if (!conf) {
 		ret = -EINVAL;
 		goto out;
 	}

 	ctx = container_of(conf, struct ieee80211_chanctx, conf);
 	if (!cfg80211_chandef_compatible(&conf->def, chandef)) {
 		ret = -EINVAL;
 		goto out;
 	}

 	sdata->vif.bss_conf.chandef = *chandef;

 	ieee80211_recalc_chanctx_chantype(local, ctx);

 	*changed |= BSS_CHANGED_BANDWIDTH;
 	ret = 0;
  out:
 	mutex_unlock(&local->chanctx_mtx);
 	return ret;
 }

 void ieee80211_vif_release_channel(struct ieee80211_sub_if_data *sdata)
 {
 	WARN_ON(sdata->dev && netif_carrier_ok(sdata->dev));

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

 	mutex_lock(&sdata->local->chanctx_mtx);
 	__ieee80211_vif_release_channel(sdata);
 	mutex_unlock(&sdata->local->chanctx_mtx);
 }

 void ieee80211_vif_vlan_copy_chanctx(struct ieee80211_sub_if_data *sdata)
 {
 	struct ieee80211_local *local = sdata->local;
 	struct ieee80211_sub_if_data *ap;
 	struct ieee80211_chanctx_conf *conf;

 	if (WARN_ON(sdata->vif.type != NL80211_IFTYPE_AP_VLAN || !sdata->bss))
 		return;

 	ap = container_of(sdata->bss, struct ieee80211_sub_if_data, u.ap);

 	mutex_lock(&local->chanctx_mtx);

 	conf = rcu_dereference_protected(ap->vif.chanctx_conf,
 					 lockdep_is_held(&local->chanctx_mtx));
 	rcu_assign_pointer(sdata->vif.chanctx_conf, conf);
 	mutex_unlock(&local->chanctx_mtx);
 }

 void ieee80211_vif_copy_chanctx_to_vlans(struct ieee80211_sub_if_data *sdata,
 					 bool clear)
 {
 	struct ieee80211_local *local = sdata->local;
 	struct ieee80211_sub_if_data *vlan;
 	struct ieee80211_chanctx_conf *conf;

 	ASSERT_RTNL();

 	if (WARN_ON(sdata->vif.type != NL80211_IFTYPE_AP))
 		return;

 	mutex_lock(&local->chanctx_mtx);

 	/*
 	 * Check that conf exists, even when clearing this function
 	 * must be called with the AP's channel context still there
 	 * as it would otherwise cause VLANs to have an invalid
 	 * channel context pointer for a while, possibly pointing
 	 * to a channel context that has already been freed.
 	 */
 	conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
 				lockdep_is_held(&local->chanctx_mtx));
 	WARN_ON(!conf);

 	if (clear)
 		conf = NULL;

 	list_for_each_entry(vlan, &sdata->u.ap.vlans, u.vlan.list)
 		rcu_assign_pointer(vlan->vif.chanctx_conf, conf);

 	mutex_unlock(&local->chanctx_mtx);
 }

 void ieee80211_iter_chan_contexts_atomic(
 	struct ieee80211_hw *hw,
 	void (*iter)(struct ieee80211_hw *hw,
 		     struct ieee80211_chanctx_conf *chanctx_conf,
 		     void *data),
 	void *iter_data)
 {
 	struct ieee80211_local *local = hw_to_local(hw);
 	struct ieee80211_chanctx *ctx;

 	rcu_read_lock();
 	list_for_each_entry_rcu(ctx, &local->chanctx_list, list)
 		if (ctx->driver_present)
 			iter(hw, &ctx->conf, iter_data);
 	rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(ieee80211_iter_chan_contexts_atomic);
	/*
	* mac80211 - channel management
	*/

	#include <linux/nl80211.h>
	#include <linux/export.h>
	#include <linux/rtnetlink.h>
	#include <net/cfg80211.h>
	#include "ieee80211_i.h"
	#include "driver-ops.h"

	static enum nl80211_chan_width ieee80211_get_sta_bw(struct ieee80211_sta *sta)
	{
	switch (sta->bandwidth) {
	case IEEE80211_STA_RX_BW_20:
	if (sta->ht_cap.ht_supported)
	return NL80211_CHAN_WIDTH_20;
	else
	return NL80211_CHAN_WIDTH_20_NOHT;
	case IEEE80211_STA_RX_BW_40:
	return NL80211_CHAN_WIDTH_40;
	case IEEE80211_STA_RX_BW_80:
	return NL80211_CHAN_WIDTH_80;
	case IEEE80211_STA_RX_BW_160:
	/*
	* This applied for both 160 and 80+80. since we use
	* the returned value to consider degradation of
	* ctx->conf.min_def, we have to make sure to take
	* the bigger one (NL80211_CHAN_WIDTH_160).
	* Otherwise we might try degrading even when not
	* needed, as the max required sta_bw returned (80+80)
	* might be smaller than the configured bw (160).
	*/
	return NL80211_CHAN_WIDTH_160;
	default:
	WARN_ON(1);
	return NL80211_CHAN_WIDTH_20;
	}
	}

	static enum nl80211_chan_width
	ieee80211_get_max_required_bw(struct ieee80211_sub_if_data *sdata)
	{
	enum nl80211_chan_width max_bw = NL80211_CHAN_WIDTH_20_NOHT;
	struct sta_info *sta;

	rcu_read_lock();
	list_for_each_entry_rcu(sta, &sdata->local->sta_list, list) {
	if (sdata != sta->sdata &&
	!(sta->sdata->bss && sta->sdata->bss == sdata->bss))
	continue;

	if (!sta->uploaded)
	continue;

	max_bw = max(max_bw, ieee80211_get_sta_bw(&sta->sta));
	}
	rcu_read_unlock();

	return max_bw;
	}

	static enum nl80211_chan_width
	ieee80211_get_chanctx_max_required_bw(struct ieee80211_local *local,
	struct ieee80211_chanctx_conf *conf)
	{
	struct ieee80211_sub_if_data *sdata;
	enum nl80211_chan_width max_bw = NL80211_CHAN_WIDTH_20_NOHT;

	rcu_read_lock();
	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
	struct ieee80211_vif *vif = &sdata->vif;
	enum nl80211_chan_width width = NL80211_CHAN_WIDTH_20_NOHT;

	if (!ieee80211_sdata_running(sdata))
	continue;

	if (rcu_access_pointer(sdata->vif.chanctx_conf) != conf)
	continue;

	switch (vif->type) {
	case NL80211_IFTYPE_AP:
	case NL80211_IFTYPE_AP_VLAN:
	width = ieee80211_get_max_required_bw(sdata);
	break;
	case NL80211_IFTYPE_P2P_DEVICE:
	continue;
	case NL80211_IFTYPE_STATION:
	case NL80211_IFTYPE_ADHOC:
	case NL80211_IFTYPE_WDS:
	case NL80211_IFTYPE_MESH_POINT:
	width = vif->bss_conf.chandef.width;
	break;
	case NL80211_IFTYPE_UNSPECIFIED:
	case NUM_NL80211_IFTYPES:
	case NL80211_IFTYPE_MONITOR:
	case NL80211_IFTYPE_P2P_CLIENT:
	case NL80211_IFTYPE_P2P_GO:
	WARN_ON_ONCE(1);
	}
	max_bw = max(max_bw, width);
	}
	rcu_read_unlock();

	return max_bw;
	}

	/*
	* recalc the min required chan width of the channel context, which is
	* the max of min required widths of all the interfaces bound to this
	* channel context.
	*/
	void ieee80211_recalc_chanctx_min_def(struct ieee80211_local *local,
	struct ieee80211_chanctx *ctx)
	{
	enum nl80211_chan_width max_bw;
	struct cfg80211_chan_def min_def;

	lockdep_assert_held(&local->chanctx_mtx);

	/* don't optimize 5MHz, 10MHz, and radar_enabled confs */
	if (ctx->conf.def.width == NL80211_CHAN_WIDTH_5 \|\|
	ctx->conf.def.width == NL80211_CHAN_WIDTH_10 \|\|
	ctx->conf.radar_enabled) {
	ctx->conf.min_def = ctx->conf.def;
	return;
	}

	max_bw = ieee80211_get_chanctx_max_required_bw(local, &ctx->conf);

	/* downgrade chandef up to max_bw */
	min_def = ctx->conf.def;
	while (min_def.width > max_bw)
	ieee80211_chandef_downgrade(&min_def);

	if (cfg80211_chandef_identical(&ctx->conf.min_def, &min_def))
	return;

	ctx->conf.min_def = min_def;
	if (!ctx->driver_present)
	return;

	drv_change_chanctx(local, ctx, IEEE80211_CHANCTX_CHANGE_MIN_WIDTH);
	}

	static void ieee80211_change_chanctx(struct ieee80211_local *local,
	struct ieee80211_chanctx *ctx,
	const struct cfg80211_chan_def *chandef)
	{
	if (cfg80211_chandef_identical(&ctx->conf.def, chandef))
	return;

	WARN_ON(!cfg80211_chandef_compatible(&ctx->conf.def, chandef));

	ctx->conf.def = *chandef;
	drv_change_chanctx(local, ctx, IEEE80211_CHANCTX_CHANGE_WIDTH);
	ieee80211_recalc_chanctx_min_def(local, ctx);

	if (!local->use_chanctx) {
	local->_oper_chandef = *chandef;
	ieee80211_hw_config(local, 0);
	}
	}

	static struct ieee80211_chanctx *
	ieee80211_find_chanctx(struct ieee80211_local *local,
	const struct cfg80211_chan_def *chandef,
	enum ieee80211_chanctx_mode mode)
	{
	struct ieee80211_chanctx *ctx;

	lockdep_assert_held(&local->chanctx_mtx);

	if (mode == IEEE80211_CHANCTX_EXCLUSIVE)
	return NULL;

	list_for_each_entry(ctx, &local->chanctx_list, list) {
	const struct cfg80211_chan_def *compat;

	if (ctx->mode == IEEE80211_CHANCTX_EXCLUSIVE)
	continue;

	compat = cfg80211_chandef_compatible(&ctx->conf.def, chandef);
	if (!compat)
	continue;

	ieee80211_change_chanctx(local, ctx, compat);

	return ctx;
	}

	return NULL;
	}

	static bool ieee80211_is_radar_required(struct ieee80211_local *local)
	{
	struct ieee80211_sub_if_data *sdata;

	lockdep_assert_held(&local->mtx);

	rcu_read_lock();
	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
	if (sdata->radar_required) {
	rcu_read_unlock();
	return true;
	}
	}
	rcu_read_unlock();

	return false;
	}

	static struct ieee80211_chanctx *
	ieee80211_new_chanctx(struct ieee80211_local *local,
	const struct cfg80211_chan_def *chandef,
	enum ieee80211_chanctx_mode mode)
	{
	struct ieee80211_chanctx *ctx;
	u32 changed;
	int err;

	lockdep_assert_held(&local->chanctx_mtx);

	ctx = kzalloc(sizeof(*ctx) + local->hw.chanctx_data_size, GFP_KERNEL);
	if (!ctx)
	return ERR_PTR(-ENOMEM);

	ctx->conf.def = *chandef;
	ctx->conf.rx_chains_static = 1;
	ctx->conf.rx_chains_dynamic = 1;
	ctx->mode = mode;
	ctx->conf.radar_enabled = ieee80211_is_radar_required(local);
	ieee80211_recalc_chanctx_min_def(local, ctx);
	if (!local->use_chanctx)
	local->hw.conf.radar_enabled = ctx->conf.radar_enabled;

	/* we hold the mutex to prevent idle from changing */
	lockdep_assert_held(&local->mtx);
	/* turn idle off before setting channel -- some drivers need that */
	changed = ieee80211_idle_off(local);
	if (changed)
	ieee80211_hw_config(local, changed);

	if (!local->use_chanctx) {
	local->_oper_chandef = *chandef;
	ieee80211_hw_config(local, 0);
	} else {
	err = drv_add_chanctx(local, ctx);
	if (err) {
	kfree(ctx);
	ieee80211_recalc_idle(local);
	return ERR_PTR(err);
	}
	}

	/* and keep the mutex held until the new chanctx is on the list */
	list_add_rcu(&ctx->list, &local->chanctx_list);

	return ctx;
	}

	static void ieee80211_free_chanctx(struct ieee80211_local *local,
	struct ieee80211_chanctx *ctx)
	{
	bool check_single_channel = false;
	lockdep_assert_held(&local->chanctx_mtx);

	WARN_ON_ONCE(ctx->refcount != 0);

	if (!local->use_chanctx) {
	struct cfg80211_chan_def *chandef = &local->_oper_chandef;
	chandef->width = NL80211_CHAN_WIDTH_20_NOHT;
	chandef->center_freq1 = chandef->chan->center_freq;
	chandef->center_freq2 = 0;

	/* NOTE: Disabling radar is only valid here for
	* single channel context. To be sure, check it ...
	*/
	if (local->hw.conf.radar_enabled)
	check_single_channel = true;
	local->hw.conf.radar_enabled = false;

	ieee80211_hw_config(local, 0);
	} else {
	drv_remove_chanctx(local, ctx);
	}

	list_del_rcu(&ctx->list);
	kfree_rcu(ctx, rcu_head);

	/* throw a warning if this wasn't the only channel context. */
	WARN_ON(check_single_channel && !list_empty(&local->chanctx_list));

	ieee80211_recalc_idle(local);
	}

	static int ieee80211_assign_vif_chanctx(struct ieee80211_sub_if_data *sdata,
	struct ieee80211_chanctx *ctx)
	{
	struct ieee80211_local *local = sdata->local;
	int ret;

	lockdep_assert_held(&local->chanctx_mtx);

	ret = drv_assign_vif_chanctx(local, sdata, ctx);
	if (ret)
	return ret;

	rcu_assign_pointer(sdata->vif.chanctx_conf, &ctx->conf);
	ctx->refcount++;

	ieee80211_recalc_txpower(sdata);
	ieee80211_recalc_chanctx_min_def(local, ctx);
	sdata->vif.bss_conf.idle = false;

	if (sdata->vif.type != NL80211_IFTYPE_P2P_DEVICE &&
	sdata->vif.type != NL80211_IFTYPE_MONITOR)
	ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_IDLE);

	return 0;
	}

	static void ieee80211_recalc_chanctx_chantype(struct ieee80211_local *local,
	struct ieee80211_chanctx *ctx)
	{
	struct ieee80211_chanctx_conf *conf = &ctx->conf;
	struct ieee80211_sub_if_data *sdata;
	const struct cfg80211_chan_def *compat = NULL;

	lockdep_assert_held(&local->chanctx_mtx);

	rcu_read_lock();
	list_for_each_entry_rcu(sdata, &local->interfaces, list) {

	if (!ieee80211_sdata_running(sdata))
	continue;
	if (rcu_access_pointer(sdata->vif.chanctx_conf) != conf)
	continue;

	if (!compat)
	compat = &sdata->vif.bss_conf.chandef;

	compat = cfg80211_chandef_compatible(
	&sdata->vif.bss_conf.chandef, compat);
	if (!compat)
	break;
	}
	rcu_read_unlock();

	if (WARN_ON_ONCE(!compat))
	return;

	ieee80211_change_chanctx(local, ctx, compat);
	}

	static void ieee80211_recalc_radar_chanctx(struct ieee80211_local *local,
	struct ieee80211_chanctx *chanctx)
	{
	bool radar_enabled;

	lockdep_assert_held(&local->chanctx_mtx);
	/* for setting local->radar_detect_enabled */
	lockdep_assert_held(&local->mtx);

	radar_enabled = ieee80211_is_radar_required(local);

	if (radar_enabled == chanctx->conf.radar_enabled)
	return;

	chanctx->conf.radar_enabled = radar_enabled;
	local->radar_detect_enabled = chanctx->conf.radar_enabled;

	if (!local->use_chanctx) {
	local->hw.conf.radar_enabled = chanctx->conf.radar_enabled;
	ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
	}

	drv_change_chanctx(local, chanctx, IEEE80211_CHANCTX_CHANGE_RADAR);
	}

	static void ieee80211_unassign_vif_chanctx(struct ieee80211_sub_if_data *sdata,
	struct ieee80211_chanctx *ctx)
	{
	struct ieee80211_local *local = sdata->local;

	lockdep_assert_held(&local->chanctx_mtx);

	ctx->refcount--;
	rcu_assign_pointer(sdata->vif.chanctx_conf, NULL);

	sdata->vif.bss_conf.idle = true;

	if (sdata->vif.type != NL80211_IFTYPE_P2P_DEVICE &&
	sdata->vif.type != NL80211_IFTYPE_MONITOR)
	ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_IDLE);

	drv_unassign_vif_chanctx(local, sdata, ctx);

	if (ctx->refcount > 0) {
	ieee80211_recalc_chanctx_chantype(sdata->local, ctx);
	ieee80211_recalc_smps_chanctx(local, ctx);
	ieee80211_recalc_radar_chanctx(local, ctx);
	ieee80211_recalc_chanctx_min_def(local, ctx);
	}
	}

	static void __ieee80211_vif_release_channel(struct ieee80211_sub_if_data *sdata)
	{
	struct ieee80211_local *local = sdata->local;
	struct ieee80211_chanctx_conf *conf;
	struct ieee80211_chanctx *ctx;

	lockdep_assert_held(&local->chanctx_mtx);

	conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
	lockdep_is_held(&local->chanctx_mtx));
	if (!conf)
	return;

	ctx = container_of(conf, struct ieee80211_chanctx, conf);

	ieee80211_unassign_vif_chanctx(sdata, ctx);
	if (ctx->refcount == 0)
	ieee80211_free_chanctx(local, ctx);
	}

	void ieee80211_recalc_smps_chanctx(struct ieee80211_local *local,
	struct ieee80211_chanctx *chanctx)
	{
	struct ieee80211_sub_if_data *sdata;
	u8 rx_chains_static, rx_chains_dynamic;

	lockdep_assert_held(&local->chanctx_mtx);

	rx_chains_static = 1;
	rx_chains_dynamic = 1;

	rcu_read_lock();
	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
	u8 needed_static, needed_dynamic;

	if (!ieee80211_sdata_running(sdata))
	continue;

	if (rcu_access_pointer(sdata->vif.chanctx_conf) !=
	&chanctx->conf)
	continue;

	switch (sdata->vif.type) {
	case NL80211_IFTYPE_P2P_DEVICE:
	continue;
	case NL80211_IFTYPE_STATION:
	if (!sdata->u.mgd.associated)
	continue;
	break;
	case NL80211_IFTYPE_AP_VLAN:
	continue;
	case NL80211_IFTYPE_AP:
	case NL80211_IFTYPE_ADHOC:
	case NL80211_IFTYPE_WDS:
	case NL80211_IFTYPE_MESH_POINT:
	break;
	default:
	WARN_ON_ONCE(1);
	}

	switch (sdata->smps_mode) {
	default:
	WARN_ONCE(1, "Invalid SMPS mode %d\n",
	sdata->smps_mode);
	/* fall through */
	case IEEE80211_SMPS_OFF:
	needed_static = sdata->needed_rx_chains;
	needed_dynamic = sdata->needed_rx_chains;
	break;
	case IEEE80211_SMPS_DYNAMIC:
	needed_static = 1;
	needed_dynamic = sdata->needed_rx_chains;
	break;
	case IEEE80211_SMPS_STATIC:
	needed_static = 1;
	needed_dynamic = 1;
	break;
	}

	rx_chains_static = max(rx_chains_static, needed_static);
	rx_chains_dynamic = max(rx_chains_dynamic, needed_dynamic);
	}
	rcu_read_unlock();

	if (!local->use_chanctx) {
	if (rx_chains_static > 1)
	local->smps_mode = IEEE80211_SMPS_OFF;
	else if (rx_chains_dynamic > 1)
	local->smps_mode = IEEE80211_SMPS_DYNAMIC;
	else
	local->smps_mode = IEEE80211_SMPS_STATIC;
	ieee80211_hw_config(local, 0);
	}

	if (rx_chains_static == chanctx->conf.rx_chains_static &&
	rx_chains_dynamic == chanctx->conf.rx_chains_dynamic)
	return;

	chanctx->conf.rx_chains_static = rx_chains_static;
	chanctx->conf.rx_chains_dynamic = rx_chains_dynamic;
	drv_change_chanctx(local, chanctx, IEEE80211_CHANCTX_CHANGE_RX_CHAINS);
	}

	int ieee80211_vif_use_channel(struct ieee80211_sub_if_data *sdata,
	const struct cfg80211_chan_def *chandef,
	enum ieee80211_chanctx_mode mode)
	{
	struct ieee80211_local *local = sdata->local;
	struct ieee80211_chanctx *ctx;
	int ret;

	lockdep_assert_held(&local->mtx);

	WARN_ON(sdata->dev && netif_carrier_ok(sdata->dev));

	mutex_lock(&local->chanctx_mtx);
	__ieee80211_vif_release_channel(sdata);

	ctx = ieee80211_find_chanctx(local, chandef, mode);
	if (!ctx)
	ctx = ieee80211_new_chanctx(local, chandef, mode);
	if (IS_ERR(ctx)) {
	ret = PTR_ERR(ctx);
	goto out;
	}

	sdata->vif.bss_conf.chandef = *chandef;

	ret = ieee80211_assign_vif_chanctx(sdata, ctx);
	if (ret) {
	/* if assign fails refcount stays the same */
	if (ctx->refcount == 0)
	ieee80211_free_chanctx(local, ctx);
	goto out;
	}

	ieee80211_recalc_smps_chanctx(local, ctx);
	ieee80211_recalc_radar_chanctx(local, ctx);
	out:
	mutex_unlock(&local->chanctx_mtx);
	return ret;
	}

	int ieee80211_vif_change_channel(struct ieee80211_sub_if_data *sdata,
	u32 *changed)
	{
	struct ieee80211_local *local = sdata->local;
	struct ieee80211_chanctx_conf *conf;
	struct ieee80211_chanctx *ctx;
	const struct cfg80211_chan_def *chandef = &sdata->csa_chandef;
	int ret;
	u32 chanctx_changed = 0;

	lockdep_assert_held(&local->mtx);

	/* should never be called if not performing a channel switch. */
	if (WARN_ON(!sdata->vif.csa_active))
	return -EINVAL;

	if (!cfg80211_chandef_usable(sdata->local->hw.wiphy, chandef,
	IEEE80211_CHAN_DISABLED))
	return -EINVAL;

	mutex_lock(&local->chanctx_mtx);
	conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
	lockdep_is_held(&local->chanctx_mtx));
	if (!conf) {
	ret = -EINVAL;
	goto out;
	}

	ctx = container_of(conf, struct ieee80211_chanctx, conf);
	if (ctx->refcount != 1) {
	ret = -EINVAL;
	goto out;
	}

	if (sdata->vif.bss_conf.chandef.width != chandef->width) {
	chanctx_changed = IEEE80211_CHANCTX_CHANGE_WIDTH;
	*changed \|= BSS_CHANGED_BANDWIDTH;
	}

	sdata->vif.bss_conf.chandef = *chandef;
	ctx->conf.def = *chandef;

	chanctx_changed \|= IEEE80211_CHANCTX_CHANGE_CHANNEL;
	drv_change_chanctx(local, ctx, chanctx_changed);

	ieee80211_recalc_chanctx_chantype(local, ctx);
	ieee80211_recalc_smps_chanctx(local, ctx);
	ieee80211_recalc_radar_chanctx(local, ctx);
	ieee80211_recalc_chanctx_min_def(local, ctx);

	ret = 0;
	out:
	mutex_unlock(&local->chanctx_mtx);
	return ret;
	}

	int ieee80211_vif_change_bandwidth(struct ieee80211_sub_if_data *sdata,
	const struct cfg80211_chan_def *chandef,
	u32 *changed)
	{
	struct ieee80211_local *local = sdata->local;
	struct ieee80211_chanctx_conf *conf;
	struct ieee80211_chanctx *ctx;
	int ret;

	if (!cfg80211_chandef_usable(sdata->local->hw.wiphy, chandef,
	IEEE80211_CHAN_DISABLED))
	return -EINVAL;

	mutex_lock(&local->chanctx_mtx);
	if (cfg80211_chandef_identical(chandef, &sdata->vif.bss_conf.chandef)) {
	ret = 0;
	goto out;
	}

	if (chandef->width == NL80211_CHAN_WIDTH_20_NOHT \|\|
	sdata->vif.bss_conf.chandef.width == NL80211_CHAN_WIDTH_20_NOHT) {
	ret = -EINVAL;
	goto out;
	}

	conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
	lockdep_is_held(&local->chanctx_mtx));
	if (!conf) {
	ret = -EINVAL;
	goto out;
	}

	ctx = container_of(conf, struct ieee80211_chanctx, conf);
	if (!cfg80211_chandef_compatible(&conf->def, chandef)) {
	ret = -EINVAL;
	goto out;
	}

	sdata->vif.bss_conf.chandef = *chandef;

	ieee80211_recalc_chanctx_chantype(local, ctx);

	*changed \|= BSS_CHANGED_BANDWIDTH;
	ret = 0;
	out:
	mutex_unlock(&local->chanctx_mtx);
	return ret;
	}

	void ieee80211_vif_release_channel(struct ieee80211_sub_if_data *sdata)
	{
	WARN_ON(sdata->dev && netif_carrier_ok(sdata->dev));

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

	mutex_lock(&sdata->local->chanctx_mtx);
	__ieee80211_vif_release_channel(sdata);
	mutex_unlock(&sdata->local->chanctx_mtx);
	}

	void ieee80211_vif_vlan_copy_chanctx(struct ieee80211_sub_if_data *sdata)
	{
	struct ieee80211_local *local = sdata->local;
	struct ieee80211_sub_if_data *ap;
	struct ieee80211_chanctx_conf *conf;

	if (WARN_ON(sdata->vif.type != NL80211_IFTYPE_AP_VLAN \|\| !sdata->bss))
	return;

	ap = container_of(sdata->bss, struct ieee80211_sub_if_data, u.ap);

	mutex_lock(&local->chanctx_mtx);

	conf = rcu_dereference_protected(ap->vif.chanctx_conf,
	lockdep_is_held(&local->chanctx_mtx));
	rcu_assign_pointer(sdata->vif.chanctx_conf, conf);
	mutex_unlock(&local->chanctx_mtx);
	}

	void ieee80211_vif_copy_chanctx_to_vlans(struct ieee80211_sub_if_data *sdata,
	bool clear)
	{
	struct ieee80211_local *local = sdata->local;
	struct ieee80211_sub_if_data *vlan;
	struct ieee80211_chanctx_conf *conf;

	ASSERT_RTNL();

	if (WARN_ON(sdata->vif.type != NL80211_IFTYPE_AP))
	return;

	mutex_lock(&local->chanctx_mtx);

	/*
	* Check that conf exists, even when clearing this function
	* must be called with the AP's channel context still there
	* as it would otherwise cause VLANs to have an invalid
	* channel context pointer for a while, possibly pointing
	* to a channel context that has already been freed.
	*/
	conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
	lockdep_is_held(&local->chanctx_mtx));
	WARN_ON(!conf);

	if (clear)
	conf = NULL;

	list_for_each_entry(vlan, &sdata->u.ap.vlans, u.vlan.list)
	rcu_assign_pointer(vlan->vif.chanctx_conf, conf);

	mutex_unlock(&local->chanctx_mtx);
	}

	void ieee80211_iter_chan_contexts_atomic(
	struct ieee80211_hw *hw,
	void (iter)(struct ieee80211_hw hw,
	struct ieee80211_chanctx_conf *chanctx_conf,
	void *data),
	void *iter_data)
	{
	struct ieee80211_local *local = hw_to_local(hw);
	struct ieee80211_chanctx *ctx;

	rcu_read_lock();
	list_for_each_entry_rcu(ctx, &local->chanctx_list, list)
	if (ctx->driver_present)
	iter(hw, &ctx->conf, iter_data);
	rcu_read_unlock();
	}
	EXPORT_SYMBOL_GPL(ieee80211_iter_chan_contexts_atomic);