Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2069 insertions, 0 deletions

diff --git a/net/mac80211/chan.c b/net/mac80211/chan.c
new file mode 100644
index 0000000000..68952752b5
--- /dev/null
+++ b/net/mac80211/chan.c
@@ -0,0 +1,2069 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * mac80211 - channel management
+ * Copyright 2020 - 2022 Intel Corporation
+ */
+
+#include <linux/nl80211.h>
+#include <linux/export.h>
+#include <linux/rtnetlink.h>
+#include <net/cfg80211.h>
+#include "ieee80211_i.h"
+#include "driver-ops.h"
+#include "rate.h"
+
+static int ieee80211_chanctx_num_assigned(struct ieee80211_local *local,
+					  struct ieee80211_chanctx *ctx)
+{
+	struct ieee80211_link_data *link;
+	int num = 0;
+
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	list_for_each_entry(link, &ctx->assigned_links, assigned_chanctx_list)
+		num++;
+
+	return num;
+}
+
+static int ieee80211_chanctx_num_reserved(struct ieee80211_local *local,
+					  struct ieee80211_chanctx *ctx)
+{
+	struct ieee80211_link_data *link;
+	int num = 0;
+
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	list_for_each_entry(link, &ctx->reserved_links, reserved_chanctx_list)
+		num++;
+
+	return num;
+}
+
+int ieee80211_chanctx_refcount(struct ieee80211_local *local,
+			       struct ieee80211_chanctx *ctx)
+{
+	return ieee80211_chanctx_num_assigned(local, ctx) +
+	       ieee80211_chanctx_num_reserved(local, ctx);
+}
+
+static int ieee80211_num_chanctx(struct ieee80211_local *local)
+{
+	struct ieee80211_chanctx *ctx;
+	int num = 0;
+
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	list_for_each_entry(ctx, &local->chanctx_list, list)
+		num++;
+
+	return num;
+}
+
+static bool ieee80211_can_create_new_chanctx(struct ieee80211_local *local)
+{
+	lockdep_assert_held(&local->chanctx_mtx);
+	return ieee80211_num_chanctx(local) < ieee80211_max_num_channels(local);
+}
+
+static struct ieee80211_chanctx *
+ieee80211_link_get_chanctx(struct ieee80211_link_data *link)
+{
+	struct ieee80211_local *local __maybe_unused = link->sdata->local;
+	struct ieee80211_chanctx_conf *conf;
+
+	conf = rcu_dereference_protected(link->conf->chanctx_conf,
+					 lockdep_is_held(&local->chanctx_mtx));
+	if (!conf)
+		return NULL;
+
+	return container_of(conf, struct ieee80211_chanctx, conf);
+}
+
+static const struct cfg80211_chan_def *
+ieee80211_chanctx_reserved_chandef(struct ieee80211_local *local,
+				   struct ieee80211_chanctx *ctx,
+				   const struct cfg80211_chan_def *compat)
+{
+	struct ieee80211_link_data *link;
+
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	list_for_each_entry(link, &ctx->reserved_links,
+			    reserved_chanctx_list) {
+		if (!compat)
+			compat = &link->reserved_chandef;
+
+		compat = cfg80211_chandef_compatible(&link->reserved_chandef,
+						     compat);
+		if (!compat)
+			break;
+	}
+
+	return compat;
+}
+
+static const struct cfg80211_chan_def *
+ieee80211_chanctx_non_reserved_chandef(struct ieee80211_local *local,
+				       struct ieee80211_chanctx *ctx,
+				       const struct cfg80211_chan_def *compat)
+{
+	struct ieee80211_link_data *link;
+
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	list_for_each_entry(link, &ctx->assigned_links,
+			    assigned_chanctx_list) {
+		struct ieee80211_bss_conf *link_conf = link->conf;
+
+		if (link->reserved_chanctx)
+			continue;
+
+		if (!compat)
+			compat = &link_conf->chandef;
+
+		compat = cfg80211_chandef_compatible(
+				&link_conf->chandef, compat);
+		if (!compat)
+			break;
+	}
+
+	return compat;
+}
+
+static const struct cfg80211_chan_def *
+ieee80211_chanctx_combined_chandef(struct ieee80211_local *local,
+				   struct ieee80211_chanctx *ctx,
+				   const struct cfg80211_chan_def *compat)
+{
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	compat = ieee80211_chanctx_reserved_chandef(local, ctx, compat);
+	if (!compat)
+		return NULL;
+
+	compat = ieee80211_chanctx_non_reserved_chandef(local, ctx, compat);
+	if (!compat)
+		return NULL;
+
+	return compat;
+}
+
+static bool
+ieee80211_chanctx_can_reserve_chandef(struct ieee80211_local *local,
+				      struct ieee80211_chanctx *ctx,
+				      const struct cfg80211_chan_def *def)
+{
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	if (ieee80211_chanctx_combined_chandef(local, ctx, def))
+		return true;
+
+	if (!list_empty(&ctx->reserved_links) &&
+	    ieee80211_chanctx_reserved_chandef(local, ctx, def))
+		return true;
+
+	return false;
+}
+
+static struct ieee80211_chanctx *
+ieee80211_find_reservation_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) {
+		if (ctx->replace_state == IEEE80211_CHANCTX_WILL_BE_REPLACED)
+			continue;
+
+		if (ctx->mode == IEEE80211_CHANCTX_EXCLUSIVE)
+			continue;
+
+		if (!ieee80211_chanctx_can_reserve_chandef(local, ctx,
+							   chandef))
+			continue;
+
+		return ctx;
+	}
+
+	return NULL;
+}
+
+static enum nl80211_chan_width ieee80211_get_sta_bw(struct sta_info *sta,
+						    unsigned int link_id)
+{
+	enum ieee80211_sta_rx_bandwidth width;
+	struct link_sta_info *link_sta;
+
+	link_sta = rcu_dereference(sta->link[link_id]);
+
+	/* no effect if this STA has no presence on this link */
+	if (!link_sta)
+		return NL80211_CHAN_WIDTH_20_NOHT;
+
+	width = ieee80211_sta_cap_rx_bw(link_sta);
+
+	switch (width) {
+	case IEEE80211_STA_RX_BW_20:
+		if (link_sta->pub->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;
+	case IEEE80211_STA_RX_BW_320:
+		return NL80211_CHAN_WIDTH_320;
+	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,
+			      unsigned int link_id)
+{
+	enum nl80211_chan_width max_bw = NL80211_CHAN_WIDTH_20_NOHT;
+	struct sta_info *sta;
+
+	list_for_each_entry_rcu(sta, &sdata->local->sta_list, list) {
+		if (sdata != sta->sdata &&
+		    !(sta->sdata->bss && sta->sdata->bss == sdata->bss))
+			continue;
+
+		max_bw = max(max_bw, ieee80211_get_sta_bw(sta, link_id));
+	}
+
+	return max_bw;
+}
+
+static enum nl80211_chan_width
+ieee80211_get_chanctx_vif_max_required_bw(struct ieee80211_sub_if_data *sdata,
+					  struct ieee80211_chanctx *ctx,
+					  struct ieee80211_link_data *rsvd_for)
+{
+	enum nl80211_chan_width max_bw = NL80211_CHAN_WIDTH_20_NOHT;
+	struct ieee80211_vif *vif = &sdata->vif;
+	int link_id;
+
+	rcu_read_lock();
+	for (link_id = 0; link_id < ARRAY_SIZE(sdata->link); link_id++) {
+		enum nl80211_chan_width width = NL80211_CHAN_WIDTH_20_NOHT;
+		struct ieee80211_link_data *link =
+			rcu_dereference(sdata->link[link_id]);
+
+		if (!link)
+			continue;
+
+		if (link != rsvd_for &&
+		    rcu_access_pointer(link->conf->chanctx_conf) != &ctx->conf)
+			continue;
+
+		switch (vif->type) {
+		case NL80211_IFTYPE_AP:
+		case NL80211_IFTYPE_AP_VLAN:
+			width = ieee80211_get_max_required_bw(sdata, link_id);
+			break;
+		case NL80211_IFTYPE_STATION:
+			/*
+			 * The ap's sta->bandwidth is not set yet at this
+			 * point, so take the width from the chandef, but
+			 * account also for TDLS peers
+			 */
+			width = max(link->conf->chandef.width,
+				    ieee80211_get_max_required_bw(sdata, link_id));
+			break;
+		case NL80211_IFTYPE_P2P_DEVICE:
+		case NL80211_IFTYPE_NAN:
+			continue;
+		case NL80211_IFTYPE_ADHOC:
+		case NL80211_IFTYPE_MESH_POINT:
+		case NL80211_IFTYPE_OCB:
+			width = link->conf->chandef.width;
+			break;
+		case NL80211_IFTYPE_WDS:
+		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;
+}
+
+static enum nl80211_chan_width
+ieee80211_get_chanctx_max_required_bw(struct ieee80211_local *local,
+				      struct ieee80211_chanctx *ctx,
+				      struct ieee80211_link_data *rsvd_for)
+{
+	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) {
+		enum nl80211_chan_width width;
+
+		if (!ieee80211_sdata_running(sdata))
+			continue;
+
+		width = ieee80211_get_chanctx_vif_max_required_bw(sdata, ctx,
+								  rsvd_for);
+
+		max_bw = max(max_bw, width);
+	}
+
+	/* use the configured bandwidth in case of monitor interface */
+	sdata = rcu_dereference(local->monitor_sdata);
+	if (sdata &&
+	    rcu_access_pointer(sdata->vif.bss_conf.chanctx_conf) == &ctx->conf)
+		max_bw = max(max_bw, ctx->conf.def.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.
+ */
+static u32
+_ieee80211_recalc_chanctx_min_def(struct ieee80211_local *local,
+				  struct ieee80211_chanctx *ctx,
+				  struct ieee80211_link_data *rsvd_for)
+{
+	enum nl80211_chan_width max_bw;
+	struct cfg80211_chan_def min_def;
+
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	/* don't optimize non-20MHz based and radar_enabled confs */
+	if (ctx->conf.def.width == NL80211_CHAN_WIDTH_5 ||
+	    ctx->conf.def.width == NL80211_CHAN_WIDTH_10 ||
+	    ctx->conf.def.width == NL80211_CHAN_WIDTH_1 ||
+	    ctx->conf.def.width == NL80211_CHAN_WIDTH_2 ||
+	    ctx->conf.def.width == NL80211_CHAN_WIDTH_4 ||
+	    ctx->conf.def.width == NL80211_CHAN_WIDTH_8 ||
+	    ctx->conf.def.width == NL80211_CHAN_WIDTH_16 ||
+	    ctx->conf.radar_enabled) {
+		ctx->conf.min_def = ctx->conf.def;
+		return 0;
+	}
+
+	max_bw = ieee80211_get_chanctx_max_required_bw(local, ctx, rsvd_for);
+
+	/* 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 0;
+
+	ctx->conf.min_def = min_def;
+	if (!ctx->driver_present)
+		return 0;
+
+	return IEEE80211_CHANCTX_CHANGE_MIN_WIDTH;
+}
+
+/* calling this function is assuming that station vif is updated to
+ * lates changes by calling ieee80211_link_update_chandef
+ */
+static void ieee80211_chan_bw_change(struct ieee80211_local *local,
+				     struct ieee80211_chanctx *ctx,
+				     bool narrowed)
+{
+	struct sta_info *sta;
+	struct ieee80211_supported_band *sband =
+		local->hw.wiphy->bands[ctx->conf.def.chan->band];
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(sta, &local->sta_list,
+				list) {
+		struct ieee80211_sub_if_data *sdata = sta->sdata;
+		enum ieee80211_sta_rx_bandwidth new_sta_bw;
+		unsigned int link_id;
+
+		if (!ieee80211_sdata_running(sta->sdata))
+			continue;
+
+		for (link_id = 0; link_id < ARRAY_SIZE(sta->sdata->link); link_id++) {
+			struct ieee80211_bss_conf *link_conf =
+				rcu_dereference(sdata->vif.link_conf[link_id]);
+			struct link_sta_info *link_sta;
+
+			if (!link_conf)
+				continue;
+
+			if (rcu_access_pointer(link_conf->chanctx_conf) != &ctx->conf)
+				continue;
+
+			link_sta = rcu_dereference(sta->link[link_id]);
+			if (!link_sta)
+				continue;
+
+			new_sta_bw = ieee80211_sta_cur_vht_bw(link_sta);
+
+			/* nothing change */
+			if (new_sta_bw == link_sta->pub->bandwidth)
+				continue;
+
+			/* vif changed to narrow BW and narrow BW for station wasn't
+			 * requested or vise versa */
+			if ((new_sta_bw < link_sta->pub->bandwidth) == !narrowed)
+				continue;
+
+			link_sta->pub->bandwidth = new_sta_bw;
+			rate_control_rate_update(local, sband, sta, link_id,
+						 IEEE80211_RC_BW_CHANGED);
+		}
+	}
+	rcu_read_unlock();
+}
+
+/*
+ * 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,
+				      struct ieee80211_link_data *rsvd_for)
+{
+	u32 changed = _ieee80211_recalc_chanctx_min_def(local, ctx, rsvd_for);
+
+	if (!changed)
+		return;
+
+	/* check is BW narrowed */
+	ieee80211_chan_bw_change(local, ctx, true);
+
+	drv_change_chanctx(local, ctx, changed);
+
+	/* check is BW wider */
+	ieee80211_chan_bw_change(local, ctx, false);
+}
+
+static void _ieee80211_change_chanctx(struct ieee80211_local *local,
+				      struct ieee80211_chanctx *ctx,
+				      struct ieee80211_chanctx *old_ctx,
+				      const struct cfg80211_chan_def *chandef,
+				      struct ieee80211_link_data *rsvd_for)
+{
+	u32 changed;
+
+	/* expected to handle only 20/40/80/160/320 channel widths */
+	switch (chandef->width) {
+	case NL80211_CHAN_WIDTH_20_NOHT:
+	case NL80211_CHAN_WIDTH_20:
+	case NL80211_CHAN_WIDTH_40:
+	case NL80211_CHAN_WIDTH_80:
+	case NL80211_CHAN_WIDTH_80P80:
+	case NL80211_CHAN_WIDTH_160:
+	case NL80211_CHAN_WIDTH_320:
+		break;
+	default:
+		WARN_ON(1);
+	}
+
+	/* Check maybe BW narrowed - we do this _before_ calling recalc_chanctx_min_def
+	 * due to maybe not returning from it, e.g in case new context was added
+	 * first time with all parameters up to date.
+	 */
+	ieee80211_chan_bw_change(local, old_ctx, true);
+
+	if (cfg80211_chandef_identical(&ctx->conf.def, chandef)) {
+		ieee80211_recalc_chanctx_min_def(local, ctx, rsvd_for);
+		return;
+	}
+
+	WARN_ON(!cfg80211_chandef_compatible(&ctx->conf.def, chandef));
+
+	ctx->conf.def = *chandef;
+
+	/* check if min chanctx also changed */
+	changed = IEEE80211_CHANCTX_CHANGE_WIDTH |
+		  _ieee80211_recalc_chanctx_min_def(local, ctx, rsvd_for);
+	drv_change_chanctx(local, ctx, changed);
+
+	if (!local->use_chanctx) {
+		local->_oper_chandef = *chandef;
+		ieee80211_hw_config(local, 0);
+	}
+
+	/* check is BW wider */
+	ieee80211_chan_bw_change(local, old_ctx, false);
+}
+
+static void ieee80211_change_chanctx(struct ieee80211_local *local,
+				     struct ieee80211_chanctx *ctx,
+				     struct ieee80211_chanctx *old_ctx,
+				     const struct cfg80211_chan_def *chandef)
+{
+	_ieee80211_change_chanctx(local, ctx, old_ctx, chandef, NULL);
+}
+
+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->replace_state != IEEE80211_CHANCTX_REPLACE_NONE)
+			continue;
+
+		if (ctx->mode == IEEE80211_CHANCTX_EXCLUSIVE)
+			continue;
+
+		compat = cfg80211_chandef_compatible(&ctx->conf.def, chandef);
+		if (!compat)
+			continue;
+
+		compat = ieee80211_chanctx_reserved_chandef(local, ctx,
+							    compat);
+		if (!compat)
+			continue;
+
+		ieee80211_change_chanctx(local, ctx, ctx, compat);
+
+		return ctx;
+	}
+
+	return NULL;
+}
+
+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) {
+		unsigned int link_id;
+
+		for (link_id = 0; link_id < ARRAY_SIZE(sdata->link); link_id++) {
+			struct ieee80211_link_data *link;
+
+			link = rcu_dereference(sdata->link[link_id]);
+
+			if (link && link->radar_required) {
+				rcu_read_unlock();
+				return true;
+			}
+		}
+	}
+	rcu_read_unlock();
+
+	return false;
+}
+
+static bool
+ieee80211_chanctx_radar_required(struct ieee80211_local *local,
+				 struct ieee80211_chanctx *ctx)
+{
+	struct ieee80211_chanctx_conf *conf = &ctx->conf;
+	struct ieee80211_sub_if_data *sdata;
+	bool required = false;
+
+	lockdep_assert_held(&local->chanctx_mtx);
+	lockdep_assert_held(&local->mtx);
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
+		unsigned int link_id;
+
+		if (!ieee80211_sdata_running(sdata))
+			continue;
+		for (link_id = 0; link_id < ARRAY_SIZE(sdata->link); link_id++) {
+			struct ieee80211_link_data *link;
+
+			link = rcu_dereference(sdata->link[link_id]);
+			if (!link)
+				continue;
+
+			if (rcu_access_pointer(link->conf->chanctx_conf) != conf)
+				continue;
+			if (!link->radar_required)
+				continue;
+			required = true;
+			break;
+		}
+
+		if (required)
+			break;
+	}
+	rcu_read_unlock();
+
+	return required;
+}
+
+static struct ieee80211_chanctx *
+ieee80211_alloc_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);
+
+	ctx = kzalloc(sizeof(*ctx) + local->hw.chanctx_data_size, GFP_KERNEL);
+	if (!ctx)
+		return NULL;
+
+	INIT_LIST_HEAD(&ctx->assigned_links);
+	INIT_LIST_HEAD(&ctx->reserved_links);
+	ctx->conf.def = *chandef;
+	ctx->conf.rx_chains_static = 1;
+	ctx->conf.rx_chains_dynamic = 1;
+	ctx->mode = mode;
+	ctx->conf.radar_enabled = false;
+	_ieee80211_recalc_chanctx_min_def(local, ctx, NULL);
+
+	return ctx;
+}
+
+static int ieee80211_add_chanctx(struct ieee80211_local *local,
+				 struct ieee80211_chanctx *ctx)
+{
+	u32 changed;
+	int err;
+
+	lockdep_assert_held(&local->mtx);
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	if (!local->use_chanctx)
+		local->hw.conf.radar_enabled = ctx->conf.radar_enabled;
+
+	/* 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 = ctx->conf.def;
+		ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
+	} else {
+		err = drv_add_chanctx(local, ctx);
+		if (err) {
+			ieee80211_recalc_idle(local);
+			return err;
+		}
+	}
+
+	return 0;
+}
+
+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;
+	int err;
+
+	lockdep_assert_held(&local->mtx);
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	ctx = ieee80211_alloc_chanctx(local, chandef, mode);
+	if (!ctx)
+		return ERR_PTR(-ENOMEM);
+
+	err = ieee80211_add_chanctx(local, ctx);
+	if (err) {
+		kfree(ctx);
+		return ERR_PTR(err);
+	}
+
+	list_add_rcu(&ctx->list, &local->chanctx_list);
+	return ctx;
+}
+
+static void ieee80211_del_chanctx(struct ieee80211_local *local,
+				  struct ieee80211_chanctx *ctx)
+{
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	if (!local->use_chanctx) {
+		struct cfg80211_chan_def *chandef = &local->_oper_chandef;
+		/* S1G doesn't have 20MHz, so get the correct width for the
+		 * current channel.
+		 */
+		if (chandef->chan->band == NL80211_BAND_S1GHZ)
+			chandef->width =
+				ieee80211_s1g_channel_width(chandef->chan);
+		else
+			chandef->width = NL80211_CHAN_WIDTH_20_NOHT;
+		chandef->center_freq1 = chandef->chan->center_freq;
+		chandef->freq1_offset = chandef->chan->freq_offset;
+		chandef->center_freq2 = 0;
+
+		/* NOTE: Disabling radar is only valid here for
+		 * single channel context. To be sure, check it ...
+		 */
+		WARN_ON(local->hw.conf.radar_enabled &&
+			!list_empty(&local->chanctx_list));
+
+		local->hw.conf.radar_enabled = false;
+
+		ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
+	} else {
+		drv_remove_chanctx(local, ctx);
+	}
+
+	ieee80211_recalc_idle(local);
+}
+
+static void ieee80211_free_chanctx(struct ieee80211_local *local,
+				   struct ieee80211_chanctx *ctx)
+{
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	WARN_ON_ONCE(ieee80211_chanctx_refcount(local, ctx) != 0);
+
+	list_del_rcu(&ctx->list);
+	ieee80211_del_chanctx(local, ctx);
+	kfree_rcu(ctx, rcu_head);
+}
+
+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;
+	struct sta_info *sta;
+
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
+		int link_id;
+
+		if (!ieee80211_sdata_running(sdata))
+			continue;
+
+		if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
+			continue;
+
+		for (link_id = 0; link_id < ARRAY_SIZE(sdata->link); link_id++) {
+			struct ieee80211_bss_conf *link_conf =
+				rcu_dereference(sdata->vif.link_conf[link_id]);
+
+			if (!link_conf)
+				continue;
+
+			if (rcu_access_pointer(link_conf->chanctx_conf) != conf)
+				continue;
+
+			if (!compat)
+				compat = &link_conf->chandef;
+
+			compat = cfg80211_chandef_compatible(&link_conf->chandef,
+							     compat);
+			if (WARN_ON_ONCE(!compat))
+				break;
+		}
+	}
+
+	if (WARN_ON_ONCE(!compat)) {
+		rcu_read_unlock();
+		return;
+	}
+
+	/* TDLS peers can sometimes affect the chandef width */
+	list_for_each_entry_rcu(sta, &local->sta_list, list) {
+		if (!sta->uploaded ||
+		    !test_sta_flag(sta, WLAN_STA_TDLS_WIDER_BW) ||
+		    !test_sta_flag(sta, WLAN_STA_AUTHORIZED) ||
+		    !sta->tdls_chandef.chan)
+			continue;
+
+		compat = cfg80211_chandef_compatible(&sta->tdls_chandef,
+						     compat);
+		if (WARN_ON_ONCE(!compat))
+			break;
+	}
+	rcu_read_unlock();
+
+	if (!compat)
+		return;
+
+	ieee80211_change_chanctx(local, ctx, 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 ieee80211_is_radar_required */
+	lockdep_assert_held(&local->mtx);
+
+	radar_enabled = ieee80211_chanctx_radar_required(local, chanctx);
+
+	if (radar_enabled == chanctx->conf.radar_enabled)
+		return;
+
+	chanctx->conf.radar_enabled = 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 int ieee80211_assign_link_chanctx(struct ieee80211_link_data *link,
+					 struct ieee80211_chanctx *new_ctx)
+{
+	struct ieee80211_sub_if_data *sdata = link->sdata;
+	struct ieee80211_local *local = sdata->local;
+	struct ieee80211_chanctx_conf *conf;
+	struct ieee80211_chanctx *curr_ctx = NULL;
+	int ret = 0;
+
+	if (WARN_ON(sdata->vif.type == NL80211_IFTYPE_NAN))
+		return -ENOTSUPP;
+
+	conf = rcu_dereference_protected(link->conf->chanctx_conf,
+					 lockdep_is_held(&local->chanctx_mtx));
+
+	if (conf) {
+		curr_ctx = container_of(conf, struct ieee80211_chanctx, conf);
+
+		drv_unassign_vif_chanctx(local, sdata, link->conf, curr_ctx);
+		conf = NULL;
+		list_del(&link->assigned_chanctx_list);
+	}
+
+	if (new_ctx) {
+		/* recalc considering the link we'll use it for now */
+		ieee80211_recalc_chanctx_min_def(local, new_ctx, link);
+
+		ret = drv_assign_vif_chanctx(local, sdata, link->conf, new_ctx);
+		if (ret)
+			goto out;
+
+		conf = &new_ctx->conf;
+		list_add(&link->assigned_chanctx_list,
+			 &new_ctx->assigned_links);
+	}
+
+out:
+	rcu_assign_pointer(link->conf->chanctx_conf, conf);
+
+	sdata->vif.cfg.idle = !conf;
+
+	if (curr_ctx && ieee80211_chanctx_num_assigned(local, curr_ctx) > 0) {
+		ieee80211_recalc_chanctx_chantype(local, curr_ctx);
+		ieee80211_recalc_smps_chanctx(local, curr_ctx);
+		ieee80211_recalc_radar_chanctx(local, curr_ctx);
+		ieee80211_recalc_chanctx_min_def(local, curr_ctx, NULL);
+	}
+
+	if (new_ctx && ieee80211_chanctx_num_assigned(local, new_ctx) > 0) {
+		ieee80211_recalc_txpower(sdata, false);
+		ieee80211_recalc_chanctx_min_def(local, new_ctx, NULL);
+	}
+
+	if (sdata->vif.type != NL80211_IFTYPE_P2P_DEVICE &&
+	    sdata->vif.type != NL80211_IFTYPE_MONITOR)
+		ieee80211_vif_cfg_change_notify(sdata, BSS_CHANGED_IDLE);
+
+	ieee80211_check_fast_xmit_iface(sdata);
+
+	return ret;
+}
+
+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;
+		unsigned int link_id;
+
+		if (!ieee80211_sdata_running(sdata))
+			continue;
+
+		switch (sdata->vif.type) {
+		case NL80211_IFTYPE_STATION:
+			if (!sdata->u.mgd.associated)
+				continue;
+			break;
+		case NL80211_IFTYPE_AP:
+		case NL80211_IFTYPE_ADHOC:
+		case NL80211_IFTYPE_MESH_POINT:
+		case NL80211_IFTYPE_OCB:
+			break;
+		default:
+			continue;
+		}
+
+		for (link_id = 0; link_id < ARRAY_SIZE(sdata->link); link_id++) {
+			struct ieee80211_link_data *link;
+
+			link = rcu_dereference(sdata->link[link_id]);
+
+			if (!link)
+				continue;
+
+			if (rcu_access_pointer(link->conf->chanctx_conf) != &chanctx->conf)
+				continue;
+
+			switch (link->smps_mode) {
+			default:
+				WARN_ONCE(1, "Invalid SMPS mode %d\n",
+					  link->smps_mode);
+				fallthrough;
+			case IEEE80211_SMPS_OFF:
+				needed_static = link->needed_rx_chains;
+				needed_dynamic = link->needed_rx_chains;
+				break;
+			case IEEE80211_SMPS_DYNAMIC:
+				needed_static = 1;
+				needed_dynamic = link->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);
+		}
+	}
+
+	/* Disable SMPS for the monitor interface */
+	sdata = rcu_dereference(local->monitor_sdata);
+	if (sdata &&
+	    rcu_access_pointer(sdata->vif.bss_conf.chanctx_conf) == &chanctx->conf)
+		rx_chains_dynamic = rx_chains_static = local->rx_chains;
+
+	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);
+}
+
+static void
+__ieee80211_link_copy_chanctx_to_vlans(struct ieee80211_link_data *link,
+				       bool clear)
+{
+	struct ieee80211_sub_if_data *sdata = link->sdata;
+	unsigned int link_id = link->link_id;
+	struct ieee80211_bss_conf *link_conf = link->conf;
+	struct ieee80211_local *local __maybe_unused = sdata->local;
+	struct ieee80211_sub_if_data *vlan;
+	struct ieee80211_chanctx_conf *conf;
+
+	if (WARN_ON(sdata->vif.type != NL80211_IFTYPE_AP))
+		return;
+
+	lockdep_assert_held(&local->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(link_conf->chanctx_conf,
+					 lockdep_is_held(&local->chanctx_mtx));
+	WARN_ON(!conf);
+
+	if (clear)
+		conf = NULL;
+
+	rcu_read_lock();
+	list_for_each_entry(vlan, &sdata->u.ap.vlans, u.vlan.list) {
+		struct ieee80211_bss_conf *vlan_conf;
+
+		vlan_conf = rcu_dereference(vlan->vif.link_conf[link_id]);
+		if (WARN_ON(!vlan_conf))
+			continue;
+
+		rcu_assign_pointer(vlan_conf->chanctx_conf, conf);
+	}
+	rcu_read_unlock();
+}
+
+void ieee80211_link_copy_chanctx_to_vlans(struct ieee80211_link_data *link,
+					  bool clear)
+{
+	struct ieee80211_local *local = link->sdata->local;
+
+	mutex_lock(&local->chanctx_mtx);
+
+	__ieee80211_link_copy_chanctx_to_vlans(link, clear);
+
+	mutex_unlock(&local->chanctx_mtx);
+}
+
+int ieee80211_link_unreserve_chanctx(struct ieee80211_link_data *link)
+{
+	struct ieee80211_sub_if_data *sdata = link->sdata;
+	struct ieee80211_chanctx *ctx = link->reserved_chanctx;
+
+	lockdep_assert_held(&sdata->local->chanctx_mtx);
+
+	if (WARN_ON(!ctx))
+		return -EINVAL;
+
+	list_del(&link->reserved_chanctx_list);
+	link->reserved_chanctx = NULL;
+
+	if (ieee80211_chanctx_refcount(sdata->local, ctx) == 0) {
+		if (ctx->replace_state == IEEE80211_CHANCTX_REPLACES_OTHER) {
+			if (WARN_ON(!ctx->replace_ctx))
+				return -EINVAL;
+
+			WARN_ON(ctx->replace_ctx->replace_state !=
+			        IEEE80211_CHANCTX_WILL_BE_REPLACED);
+			WARN_ON(ctx->replace_ctx->replace_ctx != ctx);
+
+			ctx->replace_ctx->replace_ctx = NULL;
+			ctx->replace_ctx->replace_state =
+					IEEE80211_CHANCTX_REPLACE_NONE;
+
+			list_del_rcu(&ctx->list);
+			kfree_rcu(ctx, rcu_head);
+		} else {
+			ieee80211_free_chanctx(sdata->local, ctx);
+		}
+	}
+
+	return 0;
+}
+
+int ieee80211_link_reserve_chanctx(struct ieee80211_link_data *link,
+				   const struct cfg80211_chan_def *chandef,
+				   enum ieee80211_chanctx_mode mode,
+				   bool radar_required)
+{
+	struct ieee80211_sub_if_data *sdata = link->sdata;
+	struct ieee80211_local *local = sdata->local;
+	struct ieee80211_chanctx *new_ctx, *curr_ctx, *ctx;
+
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	curr_ctx = ieee80211_link_get_chanctx(link);
+	if (curr_ctx && local->use_chanctx && !local->ops->switch_vif_chanctx)
+		return -ENOTSUPP;
+
+	new_ctx = ieee80211_find_reservation_chanctx(local, chandef, mode);
+	if (!new_ctx) {
+		if (ieee80211_can_create_new_chanctx(local)) {
+			new_ctx = ieee80211_new_chanctx(local, chandef, mode);
+			if (IS_ERR(new_ctx))
+				return PTR_ERR(new_ctx);
+		} else {
+			if (!curr_ctx ||
+			    (curr_ctx->replace_state ==
+			     IEEE80211_CHANCTX_WILL_BE_REPLACED) ||
+			    !list_empty(&curr_ctx->reserved_links)) {
+				/*
+				 * Another link already requested this context
+				 * for a reservation. Find another one hoping
+				 * all links assigned to it will also switch
+				 * soon enough.
+				 *
+				 * TODO: This needs a little more work as some
+				 * cases (more than 2 chanctx capable devices)
+				 * may fail which could otherwise succeed
+				 * provided some channel context juggling was
+				 * performed.
+				 *
+				 * Consider ctx1..3, link1..6, each ctx has 2
+				 * links. link1 and link2 from ctx1 request new
+				 * different chandefs starting 2 in-place
+				 * reserations with ctx4 and ctx5 replacing
+				 * ctx1 and ctx2 respectively. Next link5 and
+				 * link6 from ctx3 reserve ctx4. If link3 and
+				 * link4 remain on ctx2 as they are then this
+				 * fails unless `replace_ctx` from ctx5 is
+				 * replaced with ctx3.
+				 */
+				list_for_each_entry(ctx, &local->chanctx_list,
+						    list) {
+					if (ctx->replace_state !=
+					    IEEE80211_CHANCTX_REPLACE_NONE)
+						continue;
+
+					if (!list_empty(&ctx->reserved_links))
+						continue;
+
+					curr_ctx = ctx;
+					break;
+				}
+			}
+
+			/*
+			 * If that's true then all available contexts already
+			 * have reservations and cannot be used.
+			 */
+			if (!curr_ctx ||
+			    (curr_ctx->replace_state ==
+			     IEEE80211_CHANCTX_WILL_BE_REPLACED) ||
+			    !list_empty(&curr_ctx->reserved_links))
+				return -EBUSY;
+
+			new_ctx = ieee80211_alloc_chanctx(local, chandef, mode);
+			if (!new_ctx)
+				return -ENOMEM;
+
+			new_ctx->replace_ctx = curr_ctx;
+			new_ctx->replace_state =
+					IEEE80211_CHANCTX_REPLACES_OTHER;
+
+			curr_ctx->replace_ctx = new_ctx;
+			curr_ctx->replace_state =
+					IEEE80211_CHANCTX_WILL_BE_REPLACED;
+
+			list_add_rcu(&new_ctx->list, &local->chanctx_list);
+		}
+	}
+
+	list_add(&link->reserved_chanctx_list, &new_ctx->reserved_links);
+	link->reserved_chanctx = new_ctx;
+	link->reserved_chandef = *chandef;
+	link->reserved_radar_required = radar_required;
+	link->reserved_ready = false;
+
+	return 0;
+}
+
+static void
+ieee80211_link_chanctx_reservation_complete(struct ieee80211_link_data *link)
+{
+	struct ieee80211_sub_if_data *sdata = link->sdata;
+
+	switch (sdata->vif.type) {
+	case NL80211_IFTYPE_ADHOC:
+	case NL80211_IFTYPE_AP:
+	case NL80211_IFTYPE_MESH_POINT:
+	case NL80211_IFTYPE_OCB:
+		ieee80211_queue_work(&sdata->local->hw,
+				     &link->csa_finalize_work);
+		break;
+	case NL80211_IFTYPE_STATION:
+		wiphy_delayed_work_queue(sdata->local->hw.wiphy,
+					 &link->u.mgd.chswitch_work, 0);
+		break;
+	case NL80211_IFTYPE_UNSPECIFIED:
+	case NL80211_IFTYPE_AP_VLAN:
+	case NL80211_IFTYPE_WDS:
+	case NL80211_IFTYPE_MONITOR:
+	case NL80211_IFTYPE_P2P_CLIENT:
+	case NL80211_IFTYPE_P2P_GO:
+	case NL80211_IFTYPE_P2P_DEVICE:
+	case NL80211_IFTYPE_NAN:
+	case NUM_NL80211_IFTYPES:
+		WARN_ON(1);
+		break;
+	}
+}
+
+static void
+ieee80211_link_update_chandef(struct ieee80211_link_data *link,
+			      const struct cfg80211_chan_def *chandef)
+{
+	struct ieee80211_sub_if_data *sdata = link->sdata;
+	unsigned int link_id = link->link_id;
+	struct ieee80211_sub_if_data *vlan;
+
+	link->conf->chandef = *chandef;
+
+	if (sdata->vif.type != NL80211_IFTYPE_AP)
+		return;
+
+	rcu_read_lock();
+	list_for_each_entry(vlan, &sdata->u.ap.vlans, u.vlan.list) {
+		struct ieee80211_bss_conf *vlan_conf;
+
+		vlan_conf = rcu_dereference(vlan->vif.link_conf[link_id]);
+		if (WARN_ON(!vlan_conf))
+			continue;
+
+		vlan_conf->chandef = *chandef;
+	}
+	rcu_read_unlock();
+}
+
+static int
+ieee80211_link_use_reserved_reassign(struct ieee80211_link_data *link)
+{
+	struct ieee80211_sub_if_data *sdata = link->sdata;
+	struct ieee80211_bss_conf *link_conf = link->conf;
+	struct ieee80211_local *local = sdata->local;
+	struct ieee80211_vif_chanctx_switch vif_chsw[1] = {};
+	struct ieee80211_chanctx *old_ctx, *new_ctx;
+	const struct cfg80211_chan_def *chandef;
+	u64 changed = 0;
+	int err;
+
+	lockdep_assert_held(&local->mtx);
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	new_ctx = link->reserved_chanctx;
+	old_ctx = ieee80211_link_get_chanctx(link);
+
+	if (WARN_ON(!link->reserved_ready))
+		return -EBUSY;
+
+	if (WARN_ON(!new_ctx))
+		return -EINVAL;
+
+	if (WARN_ON(!old_ctx))
+		return -EINVAL;
+
+	if (WARN_ON(new_ctx->replace_state ==
+		    IEEE80211_CHANCTX_REPLACES_OTHER))
+		return -EINVAL;
+
+	chandef = ieee80211_chanctx_non_reserved_chandef(local, new_ctx,
+				&link->reserved_chandef);
+	if (WARN_ON(!chandef))
+		return -EINVAL;
+
+	if (link_conf->chandef.width != link->reserved_chandef.width)
+		changed = BSS_CHANGED_BANDWIDTH;
+
+	ieee80211_link_update_chandef(link, &link->reserved_chandef);
+
+	_ieee80211_change_chanctx(local, new_ctx, old_ctx, chandef, link);
+
+	vif_chsw[0].vif = &sdata->vif;
+	vif_chsw[0].old_ctx = &old_ctx->conf;
+	vif_chsw[0].new_ctx = &new_ctx->conf;
+	vif_chsw[0].link_conf = link->conf;
+
+	list_del(&link->reserved_chanctx_list);
+	link->reserved_chanctx = NULL;
+
+	err = drv_switch_vif_chanctx(local, vif_chsw, 1,
+				     CHANCTX_SWMODE_REASSIGN_VIF);
+	if (err) {
+		if (ieee80211_chanctx_refcount(local, new_ctx) == 0)
+			ieee80211_free_chanctx(local, new_ctx);
+
+		goto out;
+	}
+
+	list_move(&link->assigned_chanctx_list, &new_ctx->assigned_links);
+	rcu_assign_pointer(link_conf->chanctx_conf, &new_ctx->conf);
+
+	if (sdata->vif.type == NL80211_IFTYPE_AP)
+		__ieee80211_link_copy_chanctx_to_vlans(link, false);
+
+	ieee80211_check_fast_xmit_iface(sdata);
+
+	if (ieee80211_chanctx_refcount(local, old_ctx) == 0)
+		ieee80211_free_chanctx(local, old_ctx);
+
+	ieee80211_recalc_chanctx_min_def(local, new_ctx, NULL);
+	ieee80211_recalc_smps_chanctx(local, new_ctx);
+	ieee80211_recalc_radar_chanctx(local, new_ctx);
+
+	if (changed)
+		ieee80211_link_info_change_notify(sdata, link, changed);
+
+out:
+	ieee80211_link_chanctx_reservation_complete(link);
+	return err;
+}
+
+static int
+ieee80211_link_use_reserved_assign(struct ieee80211_link_data *link)
+{
+	struct ieee80211_sub_if_data *sdata = link->sdata;
+	struct ieee80211_local *local = sdata->local;
+	struct ieee80211_chanctx *old_ctx, *new_ctx;
+	const struct cfg80211_chan_def *chandef;
+	int err;
+
+	old_ctx = ieee80211_link_get_chanctx(link);
+	new_ctx = link->reserved_chanctx;
+
+	if (WARN_ON(!link->reserved_ready))
+		return -EINVAL;
+
+	if (WARN_ON(old_ctx))
+		return -EINVAL;
+
+	if (WARN_ON(!new_ctx))
+		return -EINVAL;
+
+	if (WARN_ON(new_ctx->replace_state ==
+		    IEEE80211_CHANCTX_REPLACES_OTHER))
+		return -EINVAL;
+
+	chandef = ieee80211_chanctx_non_reserved_chandef(local, new_ctx,
+				&link->reserved_chandef);
+	if (WARN_ON(!chandef))
+		return -EINVAL;
+
+	ieee80211_change_chanctx(local, new_ctx, new_ctx, chandef);
+
+	list_del(&link->reserved_chanctx_list);
+	link->reserved_chanctx = NULL;
+
+	err = ieee80211_assign_link_chanctx(link, new_ctx);
+	if (err) {
+		if (ieee80211_chanctx_refcount(local, new_ctx) == 0)
+			ieee80211_free_chanctx(local, new_ctx);
+
+		goto out;
+	}
+
+out:
+	ieee80211_link_chanctx_reservation_complete(link);
+	return err;
+}
+
+static bool
+ieee80211_link_has_in_place_reservation(struct ieee80211_link_data *link)
+{
+	struct ieee80211_sub_if_data *sdata = link->sdata;
+	struct ieee80211_chanctx *old_ctx, *new_ctx;
+
+	lockdep_assert_held(&sdata->local->chanctx_mtx);
+
+	new_ctx = link->reserved_chanctx;
+	old_ctx = ieee80211_link_get_chanctx(link);
+
+	if (!old_ctx)
+		return false;
+
+	if (WARN_ON(!new_ctx))
+		return false;
+
+	if (old_ctx->replace_state != IEEE80211_CHANCTX_WILL_BE_REPLACED)
+		return false;
+
+	if (new_ctx->replace_state != IEEE80211_CHANCTX_REPLACES_OTHER)
+		return false;
+
+	return true;
+}
+
+static int ieee80211_chsw_switch_hwconf(struct ieee80211_local *local,
+					struct ieee80211_chanctx *new_ctx)
+{
+	const struct cfg80211_chan_def *chandef;
+
+	lockdep_assert_held(&local->mtx);
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	chandef = ieee80211_chanctx_reserved_chandef(local, new_ctx, NULL);
+	if (WARN_ON(!chandef))
+		return -EINVAL;
+
+	local->hw.conf.radar_enabled = new_ctx->conf.radar_enabled;
+	local->_oper_chandef = *chandef;
+	ieee80211_hw_config(local, 0);
+
+	return 0;
+}
+
+static int ieee80211_chsw_switch_vifs(struct ieee80211_local *local,
+				      int n_vifs)
+{
+	struct ieee80211_vif_chanctx_switch *vif_chsw;
+	struct ieee80211_link_data *link;
+	struct ieee80211_chanctx *ctx, *old_ctx;
+	int i, err;
+
+	lockdep_assert_held(&local->mtx);
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	vif_chsw = kcalloc(n_vifs, sizeof(vif_chsw[0]), GFP_KERNEL);
+	if (!vif_chsw)
+		return -ENOMEM;
+
+	i = 0;
+	list_for_each_entry(ctx, &local->chanctx_list, list) {
+		if (ctx->replace_state != IEEE80211_CHANCTX_REPLACES_OTHER)
+			continue;
+
+		if (WARN_ON(!ctx->replace_ctx)) {
+			err = -EINVAL;
+			goto out;
+		}
+
+		list_for_each_entry(link, &ctx->reserved_links,
+				    reserved_chanctx_list) {
+			if (!ieee80211_link_has_in_place_reservation(link))
+				continue;
+
+			old_ctx = ieee80211_link_get_chanctx(link);
+			vif_chsw[i].vif = &link->sdata->vif;
+			vif_chsw[i].old_ctx = &old_ctx->conf;
+			vif_chsw[i].new_ctx = &ctx->conf;
+			vif_chsw[i].link_conf = link->conf;
+
+			i++;
+		}
+	}
+
+	err = drv_switch_vif_chanctx(local, vif_chsw, n_vifs,
+				     CHANCTX_SWMODE_SWAP_CONTEXTS);
+
+out:
+	kfree(vif_chsw);
+	return err;
+}
+
+static int ieee80211_chsw_switch_ctxs(struct ieee80211_local *local)
+{
+	struct ieee80211_chanctx *ctx;
+	int err;
+
+	lockdep_assert_held(&local->mtx);
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	list_for_each_entry(ctx, &local->chanctx_list, list) {
+		if (ctx->replace_state != IEEE80211_CHANCTX_REPLACES_OTHER)
+			continue;
+
+		if (!list_empty(&ctx->replace_ctx->assigned_links))
+			continue;
+
+		ieee80211_del_chanctx(local, ctx->replace_ctx);
+		err = ieee80211_add_chanctx(local, ctx);
+		if (err)
+			goto err;
+	}
+
+	return 0;
+
+err:
+	WARN_ON(ieee80211_add_chanctx(local, ctx));
+	list_for_each_entry_continue_reverse(ctx, &local->chanctx_list, list) {
+		if (ctx->replace_state != IEEE80211_CHANCTX_REPLACES_OTHER)
+			continue;
+
+		if (!list_empty(&ctx->replace_ctx->assigned_links))
+			continue;
+
+		ieee80211_del_chanctx(local, ctx);
+		WARN_ON(ieee80211_add_chanctx(local, ctx->replace_ctx));
+	}
+
+	return err;
+}
+
+static int ieee80211_vif_use_reserved_switch(struct ieee80211_local *local)
+{
+	struct ieee80211_chanctx *ctx, *ctx_tmp, *old_ctx;
+	struct ieee80211_chanctx *new_ctx = NULL;
+	int err, n_assigned, n_reserved, n_ready;
+	int n_ctx = 0, n_vifs_switch = 0, n_vifs_assign = 0, n_vifs_ctxless = 0;
+
+	lockdep_assert_held(&local->mtx);
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	/*
+	 * If there are 2 independent pairs of channel contexts performing
+	 * cross-switch of their vifs this code will still wait until both are
+	 * ready even though it could be possible to switch one before the
+	 * other is ready.
+	 *
+	 * For practical reasons and code simplicity just do a single huge
+	 * switch.
+	 */
+
+	/*
+	 * Verify if the reservation is still feasible.
+	 *  - if it's not then disconnect
+	 *  - if it is but not all vifs necessary are ready then defer
+	 */
+
+	list_for_each_entry(ctx, &local->chanctx_list, list) {
+		struct ieee80211_link_data *link;
+
+		if (ctx->replace_state != IEEE80211_CHANCTX_REPLACES_OTHER)
+			continue;
+
+		if (WARN_ON(!ctx->replace_ctx)) {
+			err = -EINVAL;
+			goto err;
+		}
+
+		if (!local->use_chanctx)
+			new_ctx = ctx;
+
+		n_ctx++;
+
+		n_assigned = 0;
+		n_reserved = 0;
+		n_ready = 0;
+
+		list_for_each_entry(link, &ctx->replace_ctx->assigned_links,
+				    assigned_chanctx_list) {
+			n_assigned++;
+			if (link->reserved_chanctx) {
+				n_reserved++;
+				if (link->reserved_ready)
+					n_ready++;
+			}
+		}
+
+		if (n_assigned != n_reserved) {
+			if (n_ready == n_reserved) {
+				wiphy_info(local->hw.wiphy,
+					   "channel context reservation cannot be finalized because some interfaces aren't switching\n");
+				err = -EBUSY;
+				goto err;
+			}
+
+			return -EAGAIN;
+		}
+
+		ctx->conf.radar_enabled = false;
+		list_for_each_entry(link, &ctx->reserved_links,
+				    reserved_chanctx_list) {
+			if (ieee80211_link_has_in_place_reservation(link) &&
+			    !link->reserved_ready)
+				return -EAGAIN;
+
+			old_ctx = ieee80211_link_get_chanctx(link);
+			if (old_ctx) {
+				if (old_ctx->replace_state ==
+				    IEEE80211_CHANCTX_WILL_BE_REPLACED)
+					n_vifs_switch++;
+				else
+					n_vifs_assign++;
+			} else {
+				n_vifs_ctxless++;
+			}
+
+			if (link->reserved_radar_required)
+				ctx->conf.radar_enabled = true;
+		}
+	}
+
+	if (WARN_ON(n_ctx == 0) ||
+	    WARN_ON(n_vifs_switch == 0 &&
+		    n_vifs_assign == 0 &&
+		    n_vifs_ctxless == 0) ||
+	    WARN_ON(n_ctx > 1 && !local->use_chanctx) ||
+	    WARN_ON(!new_ctx && !local->use_chanctx)) {
+		err = -EINVAL;
+		goto err;
+	}
+
+	/*
+	 * All necessary vifs are ready. Perform the switch now depending on
+	 * reservations and driver capabilities.
+	 */
+
+	if (local->use_chanctx) {
+		if (n_vifs_switch > 0) {
+			err = ieee80211_chsw_switch_vifs(local, n_vifs_switch);
+			if (err)
+				goto err;
+		}
+
+		if (n_vifs_assign > 0 || n_vifs_ctxless > 0) {
+			err = ieee80211_chsw_switch_ctxs(local);
+			if (err)
+				goto err;
+		}
+	} else {
+		err = ieee80211_chsw_switch_hwconf(local, new_ctx);
+		if (err)
+			goto err;
+	}
+
+	/*
+	 * Update all structures, values and pointers to point to new channel
+	 * context(s).
+	 */
+	list_for_each_entry(ctx, &local->chanctx_list, list) {
+		struct ieee80211_link_data *link, *link_tmp;
+
+		if (ctx->replace_state != IEEE80211_CHANCTX_REPLACES_OTHER)
+			continue;
+
+		if (WARN_ON(!ctx->replace_ctx)) {
+			err = -EINVAL;
+			goto err;
+		}
+
+		list_for_each_entry(link, &ctx->reserved_links,
+				    reserved_chanctx_list) {
+			struct ieee80211_sub_if_data *sdata = link->sdata;
+			struct ieee80211_bss_conf *link_conf = link->conf;
+			u64 changed = 0;
+
+			if (!ieee80211_link_has_in_place_reservation(link))
+				continue;
+
+			rcu_assign_pointer(link_conf->chanctx_conf,
+					   &ctx->conf);
+
+			if (sdata->vif.type == NL80211_IFTYPE_AP)
+				__ieee80211_link_copy_chanctx_to_vlans(link,
+								       false);
+
+			ieee80211_check_fast_xmit_iface(sdata);
+
+			link->radar_required = link->reserved_radar_required;
+
+			if (link_conf->chandef.width != link->reserved_chandef.width)
+				changed = BSS_CHANGED_BANDWIDTH;
+
+			ieee80211_link_update_chandef(link, &link->reserved_chandef);
+			if (changed)
+				ieee80211_link_info_change_notify(sdata,
+								  link,
+								  changed);
+
+			ieee80211_recalc_txpower(sdata, false);
+		}
+
+		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, NULL);
+
+		list_for_each_entry_safe(link, link_tmp, &ctx->reserved_links,
+					 reserved_chanctx_list) {
+			if (ieee80211_link_get_chanctx(link) != ctx)
+				continue;
+
+			list_del(&link->reserved_chanctx_list);
+			list_move(&link->assigned_chanctx_list,
+				  &ctx->assigned_links);
+			link->reserved_chanctx = NULL;
+
+			ieee80211_link_chanctx_reservation_complete(link);
+		}
+
+		/*
+		 * This context might have been a dependency for an already
+		 * ready re-assign reservation interface that was deferred. Do
+		 * not propagate error to the caller though. The in-place
+		 * reservation for originally requested interface has already
+		 * succeeded at this point.
+		 */
+		list_for_each_entry_safe(link, link_tmp, &ctx->reserved_links,
+					 reserved_chanctx_list) {
+			if (WARN_ON(ieee80211_link_has_in_place_reservation(link)))
+				continue;
+
+			if (WARN_ON(link->reserved_chanctx != ctx))
+				continue;
+
+			if (!link->reserved_ready)
+				continue;
+
+			if (ieee80211_link_get_chanctx(link))
+				err = ieee80211_link_use_reserved_reassign(link);
+			else
+				err = ieee80211_link_use_reserved_assign(link);
+
+			if (err) {
+				link_info(link,
+					  "failed to finalize (re-)assign reservation (err=%d)\n",
+					  err);
+				ieee80211_link_unreserve_chanctx(link);
+				cfg80211_stop_iface(local->hw.wiphy,
+						    &link->sdata->wdev,
+						    GFP_KERNEL);
+			}
+		}
+	}
+
+	/*
+	 * Finally free old contexts
+	 */
+
+	list_for_each_entry_safe(ctx, ctx_tmp, &local->chanctx_list, list) {
+		if (ctx->replace_state != IEEE80211_CHANCTX_WILL_BE_REPLACED)
+			continue;
+
+		ctx->replace_ctx->replace_ctx = NULL;
+		ctx->replace_ctx->replace_state =
+				IEEE80211_CHANCTX_REPLACE_NONE;
+
+		list_del_rcu(&ctx->list);
+		kfree_rcu(ctx, rcu_head);
+	}
+
+	return 0;
+
+err:
+	list_for_each_entry(ctx, &local->chanctx_list, list) {
+		struct ieee80211_link_data *link, *link_tmp;
+
+		if (ctx->replace_state != IEEE80211_CHANCTX_REPLACES_OTHER)
+			continue;
+
+		list_for_each_entry_safe(link, link_tmp, &ctx->reserved_links,
+					 reserved_chanctx_list) {
+			ieee80211_link_unreserve_chanctx(link);
+			ieee80211_link_chanctx_reservation_complete(link);
+		}
+	}
+
+	return err;
+}
+
+static void __ieee80211_link_release_channel(struct ieee80211_link_data *link)
+{
+	struct ieee80211_sub_if_data *sdata = link->sdata;
+	struct ieee80211_bss_conf *link_conf = link->conf;
+	struct ieee80211_local *local = sdata->local;
+	struct ieee80211_chanctx_conf *conf;
+	struct ieee80211_chanctx *ctx;
+	bool use_reserved_switch = false;
+
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	conf = rcu_dereference_protected(link_conf->chanctx_conf,
+					 lockdep_is_held(&local->chanctx_mtx));
+	if (!conf)
+		return;
+
+	ctx = container_of(conf, struct ieee80211_chanctx, conf);
+
+	if (link->reserved_chanctx) {
+		if (link->reserved_chanctx->replace_state == IEEE80211_CHANCTX_REPLACES_OTHER &&
+		    ieee80211_chanctx_num_reserved(local, link->reserved_chanctx) > 1)
+			use_reserved_switch = true;
+
+		ieee80211_link_unreserve_chanctx(link);
+	}
+
+	ieee80211_assign_link_chanctx(link, NULL);
+	if (ieee80211_chanctx_refcount(local, ctx) == 0)
+		ieee80211_free_chanctx(local, ctx);
+
+	link->radar_required = false;
+
+	/* Unreserving may ready an in-place reservation. */
+	if (use_reserved_switch)
+		ieee80211_vif_use_reserved_switch(local);
+}
+
+int ieee80211_link_use_channel(struct ieee80211_link_data *link,
+			       const struct cfg80211_chan_def *chandef,
+			       enum ieee80211_chanctx_mode mode)
+{
+	struct ieee80211_sub_if_data *sdata = link->sdata;
+	struct ieee80211_local *local = sdata->local;
+	struct ieee80211_chanctx *ctx;
+	u8 radar_detect_width = 0;
+	int ret;
+
+	lockdep_assert_held(&local->mtx);
+
+	if (sdata->vif.active_links &&
+	    !(sdata->vif.active_links & BIT(link->link_id))) {
+		ieee80211_link_update_chandef(link, chandef);
+		return 0;
+	}
+
+	mutex_lock(&local->chanctx_mtx);
+
+	ret = cfg80211_chandef_dfs_required(local->hw.wiphy,
+					    chandef,
+					    sdata->wdev.iftype);
+	if (ret < 0)
+		goto out;
+	if (ret > 0)
+		radar_detect_width = BIT(chandef->width);
+
+	link->radar_required = ret;
+
+	ret = ieee80211_check_combinations(sdata, chandef, mode,
+					   radar_detect_width);
+	if (ret < 0)
+		goto out;
+
+	__ieee80211_link_release_channel(link);
+
+	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;
+	}
+
+	ieee80211_link_update_chandef(link, chandef);
+
+	ret = ieee80211_assign_link_chanctx(link, ctx);
+	if (ret) {
+		/* if assign fails refcount stays the same */
+		if (ieee80211_chanctx_refcount(local, ctx) == 0)
+			ieee80211_free_chanctx(local, ctx);
+		goto out;
+	}
+
+	ieee80211_recalc_smps_chanctx(local, ctx);
+	ieee80211_recalc_radar_chanctx(local, ctx);
+ out:
+	if (ret)
+		link->radar_required = false;
+
+	mutex_unlock(&local->chanctx_mtx);
+	return ret;
+}
+
+int ieee80211_link_use_reserved_context(struct ieee80211_link_data *link)
+{
+	struct ieee80211_sub_if_data *sdata = link->sdata;
+	struct ieee80211_local *local = sdata->local;
+	struct ieee80211_chanctx *new_ctx;
+	struct ieee80211_chanctx *old_ctx;
+	int err;
+
+	lockdep_assert_held(&local->mtx);
+	lockdep_assert_held(&local->chanctx_mtx);
+
+	new_ctx = link->reserved_chanctx;
+	old_ctx = ieee80211_link_get_chanctx(link);
+
+	if (WARN_ON(!new_ctx))
+		return -EINVAL;
+
+	if (WARN_ON(new_ctx->replace_state ==
+		    IEEE80211_CHANCTX_WILL_BE_REPLACED))
+		return -EINVAL;
+
+	if (WARN_ON(link->reserved_ready))
+		return -EINVAL;
+
+	link->reserved_ready = true;
+
+	if (new_ctx->replace_state == IEEE80211_CHANCTX_REPLACE_NONE) {
+		if (old_ctx)
+			return ieee80211_link_use_reserved_reassign(link);
+
+		return ieee80211_link_use_reserved_assign(link);
+	}
+
+	/*
+	 * In-place reservation may need to be finalized now either if:
+	 *  a) sdata is taking part in the swapping itself and is the last one
+	 *  b) sdata has switched with a re-assign reservation to an existing
+	 *     context readying in-place switching of old_ctx
+	 *
+	 * In case of (b) do not propagate the error up because the requested
+	 * sdata already switched successfully. Just spill an extra warning.
+	 * The ieee80211_vif_use_reserved_switch() already stops all necessary
+	 * interfaces upon failure.
+	 */
+	if ((old_ctx &&
+	     old_ctx->replace_state == IEEE80211_CHANCTX_WILL_BE_REPLACED) ||
+	    new_ctx->replace_state == IEEE80211_CHANCTX_REPLACES_OTHER) {
+		err = ieee80211_vif_use_reserved_switch(local);
+		if (err && err != -EAGAIN) {
+			if (new_ctx->replace_state ==
+			    IEEE80211_CHANCTX_REPLACES_OTHER)
+				return err;
+
+			wiphy_info(local->hw.wiphy,
+				   "depending in-place reservation failed (err=%d)\n",
+				   err);
+		}
+	}
+
+	return 0;
+}
+
+int ieee80211_link_change_bandwidth(struct ieee80211_link_data *link,
+				    const struct cfg80211_chan_def *chandef,
+				    u64 *changed)
+{
+	struct ieee80211_sub_if_data *sdata = link->sdata;
+	struct ieee80211_bss_conf *link_conf = link->conf;
+	struct ieee80211_local *local = sdata->local;
+	struct ieee80211_chanctx_conf *conf;
+	struct ieee80211_chanctx *ctx;
+	const struct cfg80211_chan_def *compat;
+	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, &link_conf->chandef)) {
+		ret = 0;
+		goto out;
+	}
+
+	if (chandef->width == NL80211_CHAN_WIDTH_20_NOHT ||
+	    link_conf->chandef.width == NL80211_CHAN_WIDTH_20_NOHT) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	conf = rcu_dereference_protected(link_conf->chanctx_conf,
+					 lockdep_is_held(&local->chanctx_mtx));
+	if (!conf) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	ctx = container_of(conf, struct ieee80211_chanctx, conf);
+
+	compat = cfg80211_chandef_compatible(&conf->def, chandef);
+	if (!compat) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	switch (ctx->replace_state) {
+	case IEEE80211_CHANCTX_REPLACE_NONE:
+		if (!ieee80211_chanctx_reserved_chandef(local, ctx, compat)) {
+			ret = -EBUSY;
+			goto out;
+		}
+		break;
+	case IEEE80211_CHANCTX_WILL_BE_REPLACED:
+		/* TODO: Perhaps the bandwidth change could be treated as a
+		 * reservation itself? */
+		ret = -EBUSY;
+		goto out;
+	case IEEE80211_CHANCTX_REPLACES_OTHER:
+		/* channel context that is going to replace another channel
+		 * context doesn't really exist and shouldn't be assigned
+		 * anywhere yet */
+		WARN_ON(1);
+		break;
+	}
+
+	ieee80211_link_update_chandef(link, chandef);
+
+	ieee80211_recalc_chanctx_chantype(local, ctx);
+
+	*changed |= BSS_CHANGED_BANDWIDTH;
+	ret = 0;
+ out:
+	mutex_unlock(&local->chanctx_mtx);
+	return ret;
+}
+
+void ieee80211_link_release_channel(struct ieee80211_link_data *link)
+{
+	struct ieee80211_sub_if_data *sdata = link->sdata;
+
+	mutex_lock(&sdata->local->chanctx_mtx);
+	if (rcu_access_pointer(link->conf->chanctx_conf)) {
+		lockdep_assert_held(&sdata->local->mtx);
+		__ieee80211_link_release_channel(link);
+	}
+	mutex_unlock(&sdata->local->chanctx_mtx);
+}
+
+void ieee80211_link_vlan_copy_chanctx(struct ieee80211_link_data *link)
+{
+	struct ieee80211_sub_if_data *sdata = link->sdata;
+	unsigned int link_id = link->link_id;
+	struct ieee80211_bss_conf *link_conf = link->conf;
+	struct ieee80211_bss_conf *ap_conf;
+	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);
+
+	rcu_read_lock();
+	ap_conf = rcu_dereference(ap->vif.link_conf[link_id]);
+	conf = rcu_dereference_protected(ap_conf->chanctx_conf,
+					 lockdep_is_held(&local->chanctx_mtx));
+	rcu_assign_pointer(link_conf->chanctx_conf, conf);
+	rcu_read_unlock();
+	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);