// SPDX-License-Identifier: GPL-2.0-only
/*
 * mac80211 - channel management
 * Copyright 2020 - 2025 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"

struct ieee80211_chanctx_user_iter {
        struct ieee80211_chan_req *chanreq;
        struct ieee80211_sub_if_data *sdata;
        struct ieee80211_link_data *link;
        enum nl80211_iftype iftype;
        bool reserved, radar_required, done;
        enum {
                CHANCTX_ITER_POS_ASSIGNED,
                CHANCTX_ITER_POS_RESERVED,
                CHANCTX_ITER_POS_DONE,
        } per_link;
};

enum ieee80211_chanctx_iter_type {
        CHANCTX_ITER_ALL,
        CHANCTX_ITER_RESERVED,
        CHANCTX_ITER_ASSIGNED,
};

static void ieee80211_chanctx_user_iter_next(struct ieee80211_local *local,
                                             struct ieee80211_chanctx *ctx,
                                             struct ieee80211_chanctx_user_iter *iter,
                                             enum ieee80211_chanctx_iter_type type,
                                             bool start)
{
        lockdep_assert_wiphy(local->hw.wiphy);

        if (start) {
                memset(iter, 0, sizeof(*iter));
                goto next_interface;
        }

next_link:
        for (int link_id = iter->link ? iter->link->link_id : 0;
             link_id < ARRAY_SIZE(iter->sdata->link);
             link_id++) {
                struct ieee80211_link_data *link;

                link = sdata_dereference(iter->sdata->link[link_id],
                                         iter->sdata);
                if (!link)
                        continue;

                switch (iter->per_link) {
                case CHANCTX_ITER_POS_ASSIGNED:
                        iter->per_link = CHANCTX_ITER_POS_RESERVED;
                        if (type != CHANCTX_ITER_RESERVED &&
                            rcu_access_pointer(link->conf->chanctx_conf) == &ctx->conf) {
                                iter->link = link;
                                iter->reserved = false;
                                iter->radar_required = link->radar_required;
                                iter->chanreq = &link->conf->chanreq;
                                return;
                        }
                        fallthrough;
                case CHANCTX_ITER_POS_RESERVED:
                        iter->per_link = CHANCTX_ITER_POS_DONE;
                        if (type != CHANCTX_ITER_ASSIGNED &&
                            link->reserved_chanctx == ctx) {
                                iter->link = link;
                                iter->reserved = true;
                                iter->radar_required =
                                        link->reserved_radar_required;

                                iter->chanreq = &link->reserved;
                                return;
                        }
                        fallthrough;
                case CHANCTX_ITER_POS_DONE:
                        iter->per_link = CHANCTX_ITER_POS_ASSIGNED;
                        continue;
                }
        }

next_interface:
        /* next (or first) interface */
        iter->sdata = list_prepare_entry(iter->sdata, &local->interfaces, list);
        list_for_each_entry_continue(iter->sdata, &local->interfaces, list) {
                if (!ieee80211_sdata_running(iter->sdata))
                        continue;

                /* AP_VLAN has a chanctx pointer but follows AP */
                if (iter->sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
                        continue;

                iter->link = NULL;
                iter->per_link = CHANCTX_ITER_POS_ASSIGNED;
                iter->iftype = iter->sdata->vif.type;
                goto next_link;
        }

        iter->done = true;
}

#define for_each_chanctx_user_assigned(local, ctx, iter)                \
        for (ieee80211_chanctx_user_iter_next(local, ctx, iter,         \
                                              CHANCTX_ITER_ASSIGNED,    \
                                              true);                    \
             !((iter)->done);                                           \
             ieee80211_chanctx_user_iter_next(local, ctx, iter,         \
                                              CHANCTX_ITER_ASSIGNED,    \
                                              false))

#define for_each_chanctx_user_reserved(local, ctx, iter)                \
        for (ieee80211_chanctx_user_iter_next(local, ctx, iter,         \
                                              CHANCTX_ITER_RESERVED,    \
                                              true);                    \
             !((iter)->done);                                           \
             ieee80211_chanctx_user_iter_next(local, ctx, iter,         \
                                              CHANCTX_ITER_RESERVED,    \
                                              false))

#define for_each_chanctx_user_all(local, ctx, iter)                     \
        for (ieee80211_chanctx_user_iter_next(local, ctx, iter,         \
                                              CHANCTX_ITER_ALL,         \
                                              true);                    \
             !((iter)->done);                                           \
             ieee80211_chanctx_user_iter_next(local, ctx, iter,         \
                                              CHANCTX_ITER_ALL,         \
                                              false))

static int ieee80211_chanctx_num_assigned(struct ieee80211_local *local,
                                          struct ieee80211_chanctx *ctx)
{
        struct ieee80211_chanctx_user_iter iter;
        int num = 0;

        for_each_chanctx_user_assigned(local, ctx, &iter)
                num++;

        return num;
}

static int ieee80211_chanctx_num_reserved(struct ieee80211_local *local,
                                          struct ieee80211_chanctx *ctx)
{
        struct ieee80211_chanctx_user_iter iter;
        int num = 0;

        for_each_chanctx_user_reserved(local, ctx, &iter)
                num++;

        return num;
}

int ieee80211_chanctx_refcount(struct ieee80211_local *local,
                               struct ieee80211_chanctx *ctx)
{
        struct ieee80211_chanctx_user_iter iter;
        int num = 0;

        for_each_chanctx_user_all(local, ctx, &iter)
                num++;

        return num;
}

static int ieee80211_num_chanctx(struct ieee80211_local *local, int radio_idx)
{
        struct ieee80211_chanctx *ctx;
        int num = 0;

        lockdep_assert_wiphy(local->hw.wiphy);

        list_for_each_entry(ctx, &local->chanctx_list, list) {
                if (radio_idx >= 0 && ctx->conf.radio_idx != radio_idx)
                        continue;
                num++;
        }

        return num;
}

static bool ieee80211_can_create_new_chanctx(struct ieee80211_local *local,
                                             int radio_idx)
{
        lockdep_assert_wiphy(local->hw.wiphy);

        return ieee80211_num_chanctx(local, radio_idx) <
               ieee80211_max_num_channels(local, radio_idx);
}

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->hw.wiphy->mtx));
        if (!conf)
                return NULL;

        return container_of(conf, struct ieee80211_chanctx, conf);
}

bool ieee80211_chanreq_identical(const struct ieee80211_chan_req *a,
                                 const struct ieee80211_chan_req *b)
{
        if (!cfg80211_chandef_identical(&a->oper, &b->oper))
                return false;
        if (!a->ap.chan && !b->ap.chan)
                return true;
        return cfg80211_chandef_identical(&a->ap, &b->ap);
}

static const struct ieee80211_chan_req *
ieee80211_chanreq_compatible(const struct ieee80211_chan_req *a,
                             const struct ieee80211_chan_req *b,
                             struct ieee80211_chan_req *tmp)
{
        const struct cfg80211_chan_def *compat;

        if (a->ap.chan && b->ap.chan &&
            !cfg80211_chandef_identical(&a->ap, &b->ap))
                return NULL;

        compat = cfg80211_chandef_compatible(&a->oper, &b->oper);
        if (!compat)
                return NULL;

        /* Note: later code assumes this always fills & returns tmp if compat */
        tmp->oper = *compat;
        tmp->ap = a->ap.chan ? a->ap : b->ap;
        return tmp;
}

static const struct ieee80211_chan_req *
ieee80211_chanctx_compatible(struct ieee80211_chanctx *ctx,
                             const struct ieee80211_chan_req *req,
                             struct ieee80211_chan_req *tmp)
{
        const struct ieee80211_chan_req *ret;
        struct ieee80211_chan_req tmp2;

        *tmp = (struct ieee80211_chan_req){
                .oper = ctx->conf.def,
                .ap = ctx->conf.ap,
        };

        ret = ieee80211_chanreq_compatible(tmp, req, &tmp2);
        if (!ret)
                return NULL;
        *tmp = *ret;
        return tmp;
}

static const struct ieee80211_chan_req *
ieee80211_chanctx_reserved_chanreq(struct ieee80211_local *local,
                                   struct ieee80211_chanctx *ctx,
                                   const struct ieee80211_chan_req *req,
                                   struct ieee80211_chan_req *tmp)
{
        struct ieee80211_chanctx_user_iter iter;

        lockdep_assert_wiphy(local->hw.wiphy);

        if (WARN_ON(!req))
                return NULL;

        for_each_chanctx_user_reserved(local, ctx, &iter) {
                req = ieee80211_chanreq_compatible(iter.chanreq, req, tmp);
                if (!req)
                        break;
        }

        return req;
}

static const struct ieee80211_chan_req *
ieee80211_chanctx_non_reserved_chandef(struct ieee80211_local *local,
                                       struct ieee80211_chanctx *ctx,
                                       const struct ieee80211_chan_req *compat,
                                       struct ieee80211_chan_req *tmp)
{
        const struct ieee80211_chan_req *comp_def = compat;
        struct ieee80211_chanctx_user_iter iter;

        lockdep_assert_wiphy(local->hw.wiphy);

        for_each_chanctx_user_assigned(local, ctx, &iter) {
                if (iter.link->reserved_chanctx)
                        continue;

                comp_def = ieee80211_chanreq_compatible(iter.chanreq,
                                                        comp_def, tmp);
                if (!comp_def)
                        break;
        }

        return comp_def;
}

static bool
ieee80211_chanctx_can_reserve(struct ieee80211_local *local,
                              struct ieee80211_chanctx *ctx,
                              const struct ieee80211_chan_req *req)
{
        struct ieee80211_chan_req tmp;

        lockdep_assert_wiphy(local->hw.wiphy);

        if (!ieee80211_chanctx_reserved_chanreq(local, ctx, req, &tmp))
                return false;

        if (!ieee80211_chanctx_non_reserved_chandef(local, ctx, req, &tmp))
                return false;

        if (ieee80211_chanctx_num_reserved(local, ctx) != 0 &&
            ieee80211_chanctx_reserved_chanreq(local, ctx, req, &tmp))
                return true;

        return false;
}

static struct ieee80211_chanctx *
ieee80211_find_reservation_chanctx(struct ieee80211_local *local,
                                   const struct ieee80211_chan_req *chanreq,
                                   enum ieee80211_chanctx_mode mode)
{
        struct ieee80211_chanctx *ctx;

        lockdep_assert_wiphy(local->hw.wiphy);

        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(local, ctx, chanreq))
                        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 = wiphy_dereference(sta->local->hw.wiphy, sta->link[link_id]);

        /* no effect if this STA has no presence on this link */
        if (!link_sta)
                return NL80211_CHAN_WIDTH_20_NOHT;

        /*
         * We assume that TX/RX might be asymmetric (so e.g. VHT operating
         * mode notification changes what a STA wants to receive, but not
         * necessarily what it will transmit to us), and therefore use the
         * capabilities here. Calling it RX bandwidth capability is a bit
         * wrong though, since capabilities are in fact symmetric.
         */
        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_link_data *link)
{
        struct ieee80211_sub_if_data *sdata = link->sdata;
        unsigned int link_id = link->link_id;
        enum nl80211_chan_width max_bw = NL80211_CHAN_WIDTH_20_NOHT;
        struct sta_info *sta;

        lockdep_assert_wiphy(sdata->local->hw.wiphy);

        list_for_each_entry(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_max_required_bw(struct ieee80211_local *local,
                                      struct ieee80211_chanctx *ctx,
                                      struct ieee80211_link_data *rsvd_for,
                                      bool check_reserved)
{
        struct ieee80211_sub_if_data *sdata;
        struct ieee80211_link_data *link;
        enum nl80211_chan_width max_bw = NL80211_CHAN_WIDTH_20_NOHT;

        if (WARN_ON(check_reserved && rsvd_for))
                return ctx->conf.def.width;

        for_each_sdata_link(local, link) {
                enum nl80211_chan_width width = NL80211_CHAN_WIDTH_20_NOHT;

                if (check_reserved) {
                        if (link->reserved_chanctx != ctx)
                                continue;
                } else if (link != rsvd_for &&
                           rcu_access_pointer(link->conf->chanctx_conf) != &ctx->conf)
                        continue;

                switch (link->sdata->vif.type) {
                case NL80211_IFTYPE_STATION:
                        if (!link->sdata->vif.cfg.assoc) {
                                /*
                                 * The AP's sta->bandwidth may not yet be set
                                 * at this point (pre-association), so simply
                                 * take the width from the chandef. We cannot
                                 * have TDLS peers yet (only after association).
                                 */
                                width = link->conf->chanreq.oper.width;
                                break;
                        }
                        /*
                         * otherwise just use min_def like in AP, depending on what
                         * we currently think the AP STA (and possibly TDLS peers)
                         * require(s)
                         */
                        fallthrough;
                case NL80211_IFTYPE_AP:
                case NL80211_IFTYPE_AP_VLAN:
                        width = ieee80211_get_max_required_bw(link);
                        break;
                case NL80211_IFTYPE_P2P_DEVICE:
                case NL80211_IFTYPE_NAN:
                        continue;
                case NL80211_IFTYPE_MONITOR:
                        WARN_ON_ONCE(!ieee80211_hw_check(&local->hw,
                                                         NO_VIRTUAL_MONITOR));
                        fallthrough;
                case NL80211_IFTYPE_ADHOC:
                case NL80211_IFTYPE_MESH_POINT:
                case NL80211_IFTYPE_OCB:
                        width = link->conf->chanreq.oper.width;
                        break;
                case NL80211_IFTYPE_WDS:
                case NL80211_IFTYPE_UNSPECIFIED:
                case NUM_NL80211_IFTYPES:
                case NL80211_IFTYPE_P2P_CLIENT:
                case NL80211_IFTYPE_P2P_GO:
                        WARN_ON_ONCE(1);
                }

                max_bw = max(max_bw, width);
        }

        /* use the configured bandwidth in case of monitor interface */
        sdata = wiphy_dereference(local->hw.wiphy, 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);

        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,
                                   bool check_reserved)
{
        enum nl80211_chan_width max_bw;
        struct cfg80211_chan_def min_def;

        lockdep_assert_wiphy(local->hw.wiphy);

        /* 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,
                                                       check_reserved);

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

        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_DEF;
}

static void ieee80211_chan_bw_change(struct ieee80211_local *local,
                                     struct ieee80211_chanctx *ctx,
                                     bool reserved, 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;
                enum ieee80211_sta_rx_bandwidth new_sta_bw;
                unsigned int link_id;

                if (!ieee80211_sdata_running(sta->sdata))
                        continue;

                sdata = get_bss_sdata(sta->sdata);

                for (link_id = 0; link_id < ARRAY_SIZE(sdata->link); link_id++) {
                        struct ieee80211_link_data *link =
                                rcu_dereference(sdata->link[link_id]);
                        struct ieee80211_bss_conf *link_conf;
                        struct cfg80211_chan_def *new_chandef;
                        struct link_sta_info *link_sta;

                        if (!link)
                                continue;

                        link_conf = link->conf;

                        if (rcu_access_pointer(link_conf->chanctx_conf) != &ctx->conf)
                                continue;

                        link_sta = rcu_dereference(sta->link[link_id]);
                        if (!link_sta)
                                continue;

                        if (reserved)
                                new_chandef = &link->reserved.oper;
                        else
                                new_chandef = &link_conf->chanreq.oper;

                        new_sta_bw = _ieee80211_sta_cur_vht_bw(link_sta,
                                                               new_chandef);

                        /* 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 vice versa */
                        if ((new_sta_bw < link_sta->pub->bandwidth) == !narrowed)
                                continue;

                        link_sta->pub->bandwidth = new_sta_bw;
                        rate_control_rate_update(local, sband, link_sta,
                                                 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.
 */
static void
_ieee80211_recalc_chanctx_min_def(struct ieee80211_local *local,
                                  struct ieee80211_chanctx *ctx,
                                  struct ieee80211_link_data *rsvd_for,
                                  bool check_reserved)
{
        u32 changed = __ieee80211_recalc_chanctx_min_def(local, ctx, rsvd_for,
                                                         check_reserved);

        if (!changed)
                return;

        /* check is BW narrowed */
        ieee80211_chan_bw_change(local, ctx, false, true);

        drv_change_chanctx(local, ctx, changed);

        /* check is BW wider */
        ieee80211_chan_bw_change(local, ctx, false, false);
}

void ieee80211_recalc_chanctx_min_def(struct ieee80211_local *local,
                                      struct ieee80211_chanctx *ctx)
{
        _ieee80211_recalc_chanctx_min_def(local, ctx, NULL, false);
}

static void _ieee80211_change_chanctx(struct ieee80211_local *local,
                                      struct ieee80211_chanctx *ctx,
                                      struct ieee80211_chanctx *old_ctx,
                                      const struct ieee80211_chan_req *chanreq,
                                      struct ieee80211_link_data *rsvd_for)
{
        const struct cfg80211_chan_def *chandef = &chanreq->oper;
        struct ieee80211_chan_req ctx_req = {
                .oper = ctx->conf.def,
                .ap = ctx->conf.ap,
        };
        u32 changed = 0;

        /* 5/10 MHz not handled here */
        switch (chandef->width) {
        case NL80211_CHAN_WIDTH_1:
        case NL80211_CHAN_WIDTH_2:
        case NL80211_CHAN_WIDTH_4:
        case NL80211_CHAN_WIDTH_8:
        case NL80211_CHAN_WIDTH_16:
                /*
                 * mac80211 currently only supports sharing identical
                 * chanctx's for S1G interfaces.
                 */
                WARN_ON(!ieee80211_chanreq_identical(&ctx_req, chanreq));
                return;
        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, false, true);

        if (ieee80211_chanreq_identical(&ctx_req, chanreq)) {
                _ieee80211_recalc_chanctx_min_def(local, ctx, rsvd_for, false);
                return;
        }

        WARN_ON(ieee80211_chanctx_refcount(local, ctx) > 1 &&
                !cfg80211_chandef_compatible(&ctx->conf.def, &chanreq->oper));

        ieee80211_remove_wbrf(local, &ctx->conf.def);

        if (!cfg80211_chandef_identical(&ctx->conf.def, &chanreq->oper)) {
                if (ctx->conf.def.width != chanreq->oper.width)
                        changed |= IEEE80211_CHANCTX_CHANGE_WIDTH;
                if (ctx->conf.def.punctured != chanreq->oper.punctured)
                        changed |= IEEE80211_CHANCTX_CHANGE_PUNCTURING;
        }
        if (!cfg80211_chandef_identical(&ctx->conf.ap, &chanreq->ap))
                changed |= IEEE80211_CHANCTX_CHANGE_AP;
        ctx->conf.def = *chandef;
        ctx->conf.ap = chanreq->ap;

        /* check if min chanctx also changed */
        changed |= __ieee80211_recalc_chanctx_min_def(local, ctx, rsvd_for,
                                                      false);

        ieee80211_add_wbrf(local, &ctx->conf.def);

        drv_change_chanctx(local, ctx, changed);

        /* check if BW is wider */
        ieee80211_chan_bw_change(local, old_ctx, false, false);
}

static void ieee80211_change_chanctx(struct ieee80211_local *local,
                                     struct ieee80211_chanctx *ctx,
                                     struct ieee80211_chanctx *old_ctx,
                                     const struct ieee80211_chan_req *chanreq)
{
        _ieee80211_change_chanctx(local, ctx, old_ctx, chanreq, NULL);
}

/* Note: if successful, the returned chanctx is reserved for the link */
static struct ieee80211_chanctx *
ieee80211_find_chanctx(struct ieee80211_local *local,
                       struct ieee80211_link_data *link,
                       const struct ieee80211_chan_req *chanreq,
                       enum ieee80211_chanctx_mode mode)
{
        struct ieee80211_chan_req tmp;
        struct ieee80211_chanctx *ctx;

        lockdep_assert_wiphy(local->hw.wiphy);

        if (mode == IEEE80211_CHANCTX_EXCLUSIVE)
                return NULL;

        if (WARN_ON(link->reserved_chanctx))
                return NULL;

        list_for_each_entry(ctx, &local->chanctx_list, list) {
                const struct ieee80211_chan_req *compat;

                if (ctx->replace_state != IEEE80211_CHANCTX_REPLACE_NONE)
                        continue;

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

                compat = ieee80211_chanctx_compatible(ctx, chanreq, &tmp);
                if (!compat)
                        continue;

                compat = ieee80211_chanctx_reserved_chanreq(local, ctx,
                                                            compat, &tmp);
                if (!compat)
                        continue;

                /*
                 * Reserve the chanctx temporarily, as the driver might change
                 * active links during callbacks we make into it below and/or
                 * later during assignment, which could (otherwise) cause the
                 * context to actually be removed.
                 */
                link->reserved_chanctx = ctx;

                ieee80211_change_chanctx(local, ctx, ctx, compat);

                return ctx;
        }

        return NULL;
}

bool ieee80211_is_radar_required(struct ieee80211_local *local,
                                 struct cfg80211_scan_request *req)
{
        struct wiphy *wiphy = local->hw.wiphy;
        struct ieee80211_link_data *link;
        struct ieee80211_channel *chan;
        int radio_idx;

        lockdep_assert_wiphy(local->hw.wiphy);

        if (!req)
                return false;

        for_each_sdata_link(local, link) {
                if (link->radar_required) {
                        chan = link->conf->chanreq.oper.chan;
                        radio_idx = cfg80211_get_radio_idx_by_chan(wiphy, chan);

                        if (ieee80211_is_radio_idx_in_scan_req(wiphy, req,
                                                               radio_idx))
                                return true;
                }
        }

        return false;
}

static bool
ieee80211_chanctx_radar_required(struct ieee80211_local *local,
                                 struct ieee80211_chanctx *ctx)
{
        struct ieee80211_chanctx_user_iter iter;

        lockdep_assert_wiphy(local->hw.wiphy);

        for_each_chanctx_user_assigned(local, ctx, &iter) {
                if (iter.radar_required)
                        return true;
        }

        return false;
}

static struct ieee80211_chanctx *
ieee80211_alloc_chanctx(struct ieee80211_local *local,
                        const struct ieee80211_chan_req *chanreq,
                        enum ieee80211_chanctx_mode mode,
                        int radio_idx)
{
        struct ieee80211_chanctx *ctx;

        lockdep_assert_wiphy(local->hw.wiphy);

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

        ctx->conf.def = chanreq->oper;
        ctx->conf.ap = chanreq->ap;
        ctx->conf.rx_chains_static = 1;
        ctx->conf.rx_chains_dynamic = 1;
        ctx->mode = mode;
        ctx->conf.radar_enabled = false;
        ctx->conf.radio_idx = radio_idx;
        ctx->radar_detected = false;
        __ieee80211_recalc_chanctx_min_def(local, ctx, NULL, false);

        return ctx;
}

static int ieee80211_add_chanctx(struct ieee80211_local *local,
                                 struct ieee80211_chanctx *ctx)
{
        u32 changed;
        int err;

        lockdep_assert_wiphy(local->hw.wiphy);

        ieee80211_add_wbrf(local, &ctx->conf.def);

        /* turn idle off *before* setting channel -- some drivers need that */
        changed = ieee80211_idle_off(local);
        if (changed)
                ieee80211_hw_config(local, -1, changed);

        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 ieee80211_chan_req *chanreq,
                      enum ieee80211_chanctx_mode mode,
                      bool assign_on_failure,
                      int radio_idx)
{
        struct ieee80211_chanctx *ctx;
        int err;

        lockdep_assert_wiphy(local->hw.wiphy);

        ctx = ieee80211_alloc_chanctx(local, chanreq, mode, radio_idx);
        if (!ctx)
                return ERR_PTR(-ENOMEM);

        err = ieee80211_add_chanctx(local, ctx);
        if (!assign_on_failure && err) {
                kfree(ctx);
                return ERR_PTR(err);
        }
        /* We ignored a driver error, see _ieee80211_set_active_links */
        WARN_ON_ONCE(err && !local->in_reconfig);

        list_add_rcu(&ctx->list, &local->chanctx_list);
        return ctx;
}

static void ieee80211_del_chanctx(struct ieee80211_local *local,
                                  struct ieee80211_chanctx *ctx,
                                  bool skip_idle_recalc)
{
        lockdep_assert_wiphy(local->hw.wiphy);

        drv_remove_chanctx(local, ctx);

        if (!skip_idle_recalc)
                ieee80211_recalc_idle(local);

        ieee80211_remove_wbrf(local, &ctx->conf.def);
}

static void ieee80211_free_chanctx(struct ieee80211_local *local,
                                   struct ieee80211_chanctx *ctx,
                                   bool skip_idle_recalc)
{
        lockdep_assert_wiphy(local->hw.wiphy);

        WARN_ON_ONCE(ieee80211_chanctx_refcount(local, ctx) != 0);

        list_del_rcu(&ctx->list);
        ieee80211_del_chanctx(local, ctx, skip_idle_recalc);
        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;
        const struct ieee80211_chan_req *compat = NULL;
        struct ieee80211_chanctx_user_iter iter;
        struct ieee80211_chan_req tmp;
        struct sta_info *sta;

        lockdep_assert_wiphy(local->hw.wiphy);

        for_each_chanctx_user_assigned(local, ctx, &iter) {
                if (!compat)
                        compat = iter.chanreq;

                compat = ieee80211_chanreq_compatible(iter.chanreq,
                                                      compat, &tmp);
                if (WARN_ON_ONCE(!compat))
                        return;
        }

        if (WARN_ON_ONCE(!compat))
                return;

        /* TDLS peers can sometimes affect the chandef width */
        list_for_each_entry(sta, &local->sta_list, list) {
                struct ieee80211_sub_if_data *sdata = sta->sdata;
                struct ieee80211_chan_req tdls_chanreq = {};
                struct ieee80211_link_data *link;
                int tdls_link_id;

                if (!sta->uploaded ||
                    !test_sta_flag(sta, WLAN_STA_TDLS_WIDER_BW) ||
                    !test_sta_flag(sta, WLAN_STA_AUTHORIZED) ||
                    !sta->tdls_chandef.chan)
                        continue;

                tdls_link_id = ieee80211_tdls_sta_link_id(sta);
                link = sdata_dereference(sdata->link[tdls_link_id], sdata);
                if (!link)
                        continue;

                if (rcu_access_pointer(link->conf->chanctx_conf) != conf)
                        continue;

                tdls_chanreq.oper = sta->tdls_chandef;

                /* note this always fills and returns &tmp if compat */
                compat = ieee80211_chanreq_compatible(&tdls_chanreq,
                                                      compat, &tmp);
                if (WARN_ON_ONCE(!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_wiphy(local->hw.wiphy);

        radar_enabled = ieee80211_chanctx_radar_required(local, chanctx);

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

        chanctx->conf.radar_enabled = radar_enabled;

        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,
                                         bool assign_on_failure)
{
        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;
        bool new_idle;
        int ret;

        if (WARN_ON(sdata->vif.type == NL80211_IFTYPE_NAN))
                return -EOPNOTSUPP;

        conf = rcu_dereference_protected(link->conf->chanctx_conf,
                                         lockdep_is_held(&local->hw.wiphy->mtx));

        if (conf && !local->in_reconfig) {
                curr_ctx = container_of(conf, struct ieee80211_chanctx, conf);

                drv_unassign_vif_chanctx(local, sdata, link->conf, curr_ctx);
                conf = NULL;
        }

        if (new_ctx) {
                /* recalc considering the link we'll use it for now */
                _ieee80211_recalc_chanctx_min_def(local, new_ctx, link, false);

                ret = drv_assign_vif_chanctx(local, sdata, link->conf, new_ctx);
                if (assign_on_failure || !ret) {
                        /* Need to continue, see _ieee80211_set_active_links */
                        WARN_ON_ONCE(ret && !local->in_reconfig);
                        ret = 0;

                        /* succeeded, so commit it to the data structures */
                        conf = &new_ctx->conf;
                }
        } else {
                ret = 0;
        }

        rcu_assign_pointer(link->conf->chanctx_conf, 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);
        }

        if (new_ctx && ieee80211_chanctx_num_assigned(local, new_ctx) > 0) {
                ieee80211_recalc_txpower(link, false);
                ieee80211_recalc_chanctx_min_def(local, new_ctx);
        }

        if (conf) {
                new_idle = false;
        } else {
                struct ieee80211_link_data *tmp;

                new_idle = true;
                for_each_sdata_link(local, tmp) {
                        if (rcu_access_pointer(tmp->conf->chanctx_conf)) {
                                new_idle = false;
                                break;
                        }
                }
        }

        if (new_idle != sdata->vif.cfg.idle) {
                sdata->vif.cfg.idle = new_idle;

                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_chanctx_user_iter iter;
        struct ieee80211_sub_if_data *sdata;
        u8 rx_chains_static, rx_chains_dynamic;

        lockdep_assert_wiphy(local->hw.wiphy);

        rx_chains_static = 1;
        rx_chains_dynamic = 1;

        for_each_chanctx_user_assigned(local, chanctx, &iter) {
                u8 needed_static, needed_dynamic;

                switch (iter.iftype) {
                case NL80211_IFTYPE_STATION:
                        if (!iter.sdata->u.mgd.associated)
                                continue;
                        break;
                case NL80211_IFTYPE_MONITOR:
                        if (!ieee80211_hw_check(&local->hw, NO_VIRTUAL_MONITOR))
                                continue;
                        break;
                case NL80211_IFTYPE_AP:
                case NL80211_IFTYPE_ADHOC:
                case NL80211_IFTYPE_MESH_POINT:
                case NL80211_IFTYPE_OCB:
                        break;
                default:
                        continue;
                }

                if (iter.iftype == NL80211_IFTYPE_MONITOR) {
                        rx_chains_dynamic = rx_chains_static = local->rx_chains;
                        break;
                }

                switch (iter.link->smps_mode) {
                default:
                        WARN_ONCE(1, "Invalid SMPS mode %d\n",
                                  iter.link->smps_mode);
                        fallthrough;
                case IEEE80211_SMPS_OFF:
                        needed_static = iter.link->needed_rx_chains;
                        needed_dynamic = iter.link->needed_rx_chains;
                        break;
                case IEEE80211_SMPS_DYNAMIC:
                        needed_static = 1;
                        needed_dynamic = iter.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 = wiphy_dereference(local->hw.wiphy, 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;

        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_wiphy(local->hw.wiphy);

        /* 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->hw.wiphy->mtx));
        WARN_ON(!conf);

        if (clear)
                conf = NULL;

        list_for_each_entry(vlan, &sdata->u.ap.vlans, u.vlan.list) {
                struct ieee80211_bss_conf *vlan_conf;

                vlan_conf = wiphy_dereference(local->hw.wiphy,
                                              vlan->vif.link_conf[link_id]);
                if (WARN_ON(!vlan_conf))
                        continue;

                rcu_assign_pointer(vlan_conf->chanctx_conf, conf);
        }
}

void ieee80211_link_copy_chanctx_to_vlans(struct ieee80211_link_data *link,
                                          bool clear)
{
        struct ieee80211_local *local = link->sdata->local;

        lockdep_assert_wiphy(local->hw.wiphy);

        __ieee80211_link_copy_chanctx_to_vlans(link, clear);
}

void 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_wiphy(sdata->local->hw.wiphy);

        if (WARN_ON(!ctx))
                return;

        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;

                        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, false);
                }
        }
}

static struct ieee80211_chanctx *
ieee80211_replace_chanctx(struct ieee80211_local *local,
                          const struct ieee80211_chan_req *chanreq,
                          enum ieee80211_chanctx_mode mode,
                          struct ieee80211_chanctx *curr_ctx)
{
        struct ieee80211_chanctx *new_ctx, *ctx;
        struct wiphy *wiphy = local->hw.wiphy;
        const struct wiphy_radio *radio;

        if (!curr_ctx ||
            curr_ctx->replace_state == IEEE80211_CHANCTX_WILL_BE_REPLACED ||
            ieee80211_chanctx_num_reserved(local, curr_ctx) != 0) {
                /*
                 * 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 reservations 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 (ieee80211_chanctx_num_reserved(local, ctx) != 0)
                                continue;

                        if (ctx->conf.radio_idx >= 0) {
                                radio = &wiphy->radio[ctx->conf.radio_idx];
                                if (!cfg80211_radio_chandef_valid(radio, &chanreq->oper))
                                        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 ||
            ieee80211_chanctx_num_reserved(local, curr_ctx) != 0)
                return ERR_PTR(-EBUSY);

        new_ctx = ieee80211_alloc_chanctx(local, chanreq, mode, -1);
        if (!new_ctx)
                return ERR_PTR(-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);

        return new_ctx;
}

static bool
ieee80211_find_available_radio(struct ieee80211_local *local,
                               const struct ieee80211_chan_req *chanreq,
                               u32 radio_mask, int *radio_idx)
{
        struct wiphy *wiphy = local->hw.wiphy;
        const struct wiphy_radio *radio;
        int i;

        *radio_idx = -1;
        if (!wiphy->n_radio)
                return true;

        for (i = 0; i < wiphy->n_radio; i++) {
                if (!(radio_mask & BIT(i)))
                        continue;

                radio = &wiphy->radio[i];
                if (!cfg80211_radio_chandef_valid(radio, &chanreq->oper))
                        continue;

                if (!ieee80211_can_create_new_chanctx(local, i))
                        continue;

                *radio_idx = i;
                return true;
        }

        return false;
}

int ieee80211_link_reserve_chanctx(struct ieee80211_link_data *link,
                                   const struct ieee80211_chan_req *chanreq,
                                   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;
        int radio_idx;

        lockdep_assert_wiphy(local->hw.wiphy);

        curr_ctx = ieee80211_link_get_chanctx(link);
        if (curr_ctx && !local->ops->switch_vif_chanctx)
                return -EOPNOTSUPP;

        new_ctx = ieee80211_find_reservation_chanctx(local, chanreq, mode);
        if (!new_ctx) {
                if (ieee80211_can_create_new_chanctx(local, -1) &&
                    ieee80211_find_available_radio(local, chanreq,
                                                   sdata->wdev.radio_mask,
                                                   &radio_idx))
                        new_ctx = ieee80211_new_chanctx(local, chanreq, mode,
                                                        false, radio_idx);
                else
                        new_ctx = ieee80211_replace_chanctx(local, chanreq,
                                                            mode, curr_ctx);
                if (IS_ERR(new_ctx))
                        return PTR_ERR(new_ctx);
        }

        link->reserved_chanctx = new_ctx;
        link->reserved = *chanreq;
        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:
                wiphy_work_queue(sdata->local->hw.wiphy,
                                 &link->csa.finalize_work);
                break;
        case NL80211_IFTYPE_STATION:
                wiphy_hrtimer_work_queue(sdata->local->hw.wiphy,
                                         &link->u.mgd.csa.switch_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_chanreq(struct ieee80211_link_data *link,
                              const struct ieee80211_chan_req *chanreq)
{
        struct ieee80211_sub_if_data *sdata = link->sdata;
        unsigned int link_id = link->link_id;
        struct ieee80211_sub_if_data *vlan;

        link->conf->chanreq = *chanreq;

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

        list_for_each_entry(vlan, &sdata->u.ap.vlans, u.vlan.list) {
                struct ieee80211_bss_conf *vlan_conf;

                vlan_conf = wiphy_dereference(sdata->local->hw.wiphy,
                                              vlan->vif.link_conf[link_id]);
                if (WARN_ON(!vlan_conf))
                        continue;

                vlan_conf->chanreq = *chanreq;
        }
}

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 ieee80211_chan_req *chanreq;
        struct ieee80211_chan_req tmp;
        u64 changed = 0;
        int err;

        lockdep_assert_wiphy(local->hw.wiphy);

        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;

        chanreq = ieee80211_chanctx_non_reserved_chandef(local, new_ctx,
                                                         &link->reserved,
                                                         &tmp);
        if (WARN_ON(!chanreq))
                return -EINVAL;

        if (link_conf->chanreq.oper.width != link->reserved.oper.width)
                changed = BSS_CHANGED_BANDWIDTH;

        ieee80211_link_update_chanreq(link, &link->reserved);

        _ieee80211_change_chanctx(local, new_ctx, old_ctx, chanreq, 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;

        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, false);

                goto out;
        }

        link->radar_required = link->reserved_radar_required;
        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, false);

        ieee80211_recalc_chanctx_min_def(local, new_ctx);
        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 ieee80211_chan_req *chanreq;
        struct ieee80211_chan_req tmp;
        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;

        chanreq = ieee80211_chanctx_non_reserved_chandef(local, new_ctx,
                                                         &link->reserved,
                                                         &tmp);
        if (WARN_ON(!chanreq))
                return -EINVAL;

        ieee80211_change_chanctx(local, new_ctx, new_ctx, chanreq);

        link->reserved_chanctx = NULL;

        err = ieee80211_assign_link_chanctx(link, new_ctx, false);
        if (err) {
                if (ieee80211_chanctx_refcount(local, new_ctx) == 0)
                        ieee80211_free_chanctx(local, new_ctx, false);

                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_wiphy(sdata->local->hw.wiphy);

        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_vifs(struct ieee80211_local *local,
                                      int n_vifs)
{
        struct ieee80211_vif_chanctx_switch *vif_chsw;
        struct ieee80211_chanctx *ctx, *old_ctx;
        int i, err;

        lockdep_assert_wiphy(local->hw.wiphy);

        vif_chsw = kzalloc_objs(vif_chsw[0], n_vifs);
        if (!vif_chsw)
                return -ENOMEM;

        i = 0;
        list_for_each_entry(ctx, &local->chanctx_list, list) {
                struct ieee80211_chanctx_user_iter iter;

                if (ctx->replace_state != IEEE80211_CHANCTX_REPLACES_OTHER)
                        continue;

                if (WARN_ON(!ctx->replace_ctx)) {
                        err = -EINVAL;
                        goto out;
                }

                for_each_chanctx_user_reserved(local, ctx, &iter) {
                        if (!ieee80211_link_has_in_place_reservation(iter.link))
                                continue;

                        old_ctx = ieee80211_link_get_chanctx(iter.link);
                        vif_chsw[i].vif = &iter.sdata->vif;
                        vif_chsw[i].old_ctx = &old_ctx->conf;
                        vif_chsw[i].new_ctx = &ctx->conf;
                        vif_chsw[i].link_conf = iter.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_wiphy(local->hw.wiphy);

        list_for_each_entry(ctx, &local->chanctx_list, list) {
                if (ctx->replace_state != IEEE80211_CHANCTX_REPLACES_OTHER)
                        continue;

                if (ieee80211_chanctx_num_assigned(local, ctx) != 0)
                        continue;

                ieee80211_del_chanctx(local, ctx->replace_ctx, false);
                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 (ieee80211_chanctx_num_assigned(local, ctx) != 0)
                        continue;

                ieee80211_del_chanctx(local, ctx, false);
                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;
        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_wiphy(local->hw.wiphy);

        /*
         * 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_chanctx_user_iter iter;

                if (ctx->replace_state != IEEE80211_CHANCTX_REPLACES_OTHER)
                        continue;

                if (WARN_ON(!ctx->replace_ctx)) {
                        err = -EINVAL;
                        goto err;
                }

                n_ctx++;

                n_assigned = 0;
                n_reserved = 0;
                n_ready = 0;

                for_each_chanctx_user_assigned(local, ctx->replace_ctx, &iter) {
                        n_assigned++;
                        if (iter.link->reserved_chanctx) {
                                n_reserved++;
                                if (iter.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;
                for_each_chanctx_user_reserved(local, ctx, &iter) {
                        if (ieee80211_link_has_in_place_reservation(iter.link) &&
                            !iter.link->reserved_ready)
                                return -EAGAIN;

                        old_ctx = ieee80211_link_get_chanctx(iter.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 (iter.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)) {
                err = -EINVAL;
                goto err;
        }

        /* update station rate control and min width before switch */
        list_for_each_entry(ctx, &local->chanctx_list, list) {
                struct ieee80211_chanctx_user_iter iter;

                if (ctx->replace_state != IEEE80211_CHANCTX_REPLACES_OTHER)
                        continue;

                if (WARN_ON(!ctx->replace_ctx)) {
                        err = -EINVAL;
                        goto err;
                }

                for_each_chanctx_user_reserved(local, ctx, &iter) {
                        if (!ieee80211_link_has_in_place_reservation(iter.link))
                                continue;

                        ieee80211_chan_bw_change(local,
                                                 ieee80211_link_get_chanctx(iter.link),
                                                 true, true);
                }

                _ieee80211_recalc_chanctx_min_def(local, ctx, NULL, true);
        }

        /*
         * All necessary vifs are ready. Perform the switch now depending on
         * reservations and driver capabilities.
         */

        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;
        }

        /*
         * Update all structures, values and pointers to point to new channel
         * context(s).
         */
        list_for_each_entry(ctx, &local->chanctx_list, list) {
                struct ieee80211_chanctx_user_iter iter;

                if (ctx->replace_state != IEEE80211_CHANCTX_REPLACES_OTHER)
                        continue;

                if (WARN_ON(!ctx->replace_ctx)) {
                        err = -EINVAL;
                        goto err;
                }

                for_each_chanctx_user_reserved(local, ctx, &iter) {
                        struct ieee80211_link_data *link = iter.link;
                        struct ieee80211_sub_if_data *sdata = iter.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 = iter.radar_required;

                        if (link_conf->chanreq.oper.width != iter.chanreq->oper.width)
                                changed = BSS_CHANGED_BANDWIDTH;

                        ieee80211_link_update_chanreq(link, &link->reserved);
                        if (changed)
                                ieee80211_link_info_change_notify(sdata,
                                                                  link,
                                                                  changed);

                        ieee80211_recalc_txpower(link, 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);

                for_each_chanctx_user_reserved(local, ctx, &iter) {
                        if (ieee80211_link_get_chanctx(iter.link) != ctx)
                                continue;

                        iter.link->reserved_chanctx = NULL;

                        ieee80211_link_chanctx_reservation_complete(iter.link);
                        ieee80211_chan_bw_change(local, ctx, false, false);
                }

                /*
                 * 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.
                 */
                for_each_chanctx_user_reserved(local, ctx, &iter) {
                        struct ieee80211_link_data *link = iter.link;

                        if (WARN_ON(ieee80211_link_has_in_place_reservation(link)))
                                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_chanctx_user_iter iter;

                if (ctx->replace_state != IEEE80211_CHANCTX_REPLACES_OTHER)
                        continue;

                for_each_chanctx_user_reserved(local, ctx, &iter) {
                        ieee80211_link_unreserve_chanctx(iter.link);
                        ieee80211_link_chanctx_reservation_complete(iter.link);
                }
        }

        return err;
}

void __ieee80211_link_release_channel(struct ieee80211_link_data *link,
                                      bool skip_idle_recalc)
{
        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_wiphy(local->hw.wiphy);

        conf = rcu_dereference_protected(link_conf->chanctx_conf,
                                         lockdep_is_held(&local->hw.wiphy->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, false);
        if (ieee80211_chanctx_refcount(local, ctx) == 0)
                ieee80211_free_chanctx(local, ctx, skip_idle_recalc);

        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 ieee80211_chan_req *chanreq,
                                enum ieee80211_chanctx_mode mode,
                                bool assign_on_failure)
{
        struct ieee80211_sub_if_data *sdata = link->sdata;
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_chanctx *ctx;
        u8 radar_detect_width = 0;
        bool reserved = false;
        int radio_idx;
        int ret;

        lockdep_assert_wiphy(local->hw.wiphy);

        if (!ieee80211_vif_link_active(&sdata->vif, link->link_id)) {
                ieee80211_link_update_chanreq(link, chanreq);
                return 0;
        }

        ret = cfg80211_chandef_dfs_required(local->hw.wiphy,
                                            &chanreq->oper,
                                            sdata->wdev.iftype);
        if (ret < 0)
                goto out;
        if (ret > 0)
                radar_detect_width = BIT(chanreq->oper.width);

        link->radar_required = ret;

        ret = ieee80211_check_combinations(sdata, &chanreq->oper, mode,
                                           radar_detect_width, -1);
        if (ret < 0)
                goto out;

        if (!local->in_reconfig)
                __ieee80211_link_release_channel(link, false);

        ctx = ieee80211_find_chanctx(local, link, chanreq, mode);
        /* Note: context is now reserved */
        if (ctx)
                reserved = true;
        else if (!ieee80211_find_available_radio(local, chanreq,
                                                 sdata->wdev.radio_mask,
                                                 &radio_idx))
                ctx = ERR_PTR(-EBUSY);
        else
                ctx = ieee80211_new_chanctx(local, chanreq, mode,
                                            assign_on_failure, radio_idx);
        if (IS_ERR(ctx)) {
                ret = PTR_ERR(ctx);
                goto out;
        }

        ieee80211_link_update_chanreq(link, chanreq);

        ret = ieee80211_assign_link_chanctx(link, ctx, assign_on_failure);

        if (reserved) {
                /* remove reservation */
                WARN_ON(link->reserved_chanctx != ctx);
                link->reserved_chanctx = NULL;
        }

        if (ret) {
                /* if assign fails refcount stays the same */
                if (ieee80211_chanctx_refcount(local, ctx) == 0)
                        ieee80211_free_chanctx(local, ctx, false);
                goto out;
        }

        ieee80211_recalc_smps_chanctx(local, ctx);
        ieee80211_recalc_radar_chanctx(local, ctx);
 out:
        if (ret)
                link->radar_required = false;

        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_wiphy(local->hw.wiphy);

        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;
}

/*
 * This is similar to ieee80211_chanctx_compatible(), but rechecks
 * against all the links actually using it (except the one that's
 * passed, since that one is changing).
 * This is done in order to allow changes to the AP's bandwidth for
 * wider bandwidth OFDMA purposes, which wouldn't be treated as
 * compatible by ieee80211_chanctx_recheck() but is OK if the link
 * requesting the update is the only one using it.
 */
static const struct ieee80211_chan_req *
ieee80211_chanctx_recheck(struct ieee80211_local *local,
                          struct ieee80211_link_data *skip_link,
                          struct ieee80211_chanctx *ctx,
                          const struct ieee80211_chan_req *req,
                          struct ieee80211_chan_req *tmp)
{
        const struct ieee80211_chan_req *ret = req;
        struct ieee80211_chanctx_user_iter iter;

        lockdep_assert_wiphy(local->hw.wiphy);

        for_each_chanctx_user_all(local, ctx, &iter) {
                if (iter.link == skip_link)
                        continue;

                ret = ieee80211_chanreq_compatible(ret, iter.chanreq, tmp);
                if (!ret)
                        return NULL;
        }

        *tmp = *ret;
        return tmp;
}

int ieee80211_link_change_chanreq(struct ieee80211_link_data *link,
                                  const struct ieee80211_chan_req *chanreq,
                                  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 ieee80211_chan_req *compat;
        struct ieee80211_chan_req tmp;

        lockdep_assert_wiphy(local->hw.wiphy);

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

        /* for non-HT 20 MHz the rest doesn't matter */
        if (chanreq->oper.width == NL80211_CHAN_WIDTH_20_NOHT &&
            cfg80211_chandef_identical(&chanreq->oper, &link_conf->chanreq.oper))
                return 0;

        /* but you cannot switch to/from it */
        if (chanreq->oper.width == NL80211_CHAN_WIDTH_20_NOHT ||
            link_conf->chanreq.oper.width == NL80211_CHAN_WIDTH_20_NOHT)
                return -EINVAL;

        conf = rcu_dereference_protected(link_conf->chanctx_conf,
                                         lockdep_is_held(&local->hw.wiphy->mtx));
        if (!conf)
                return -EINVAL;

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

        compat = ieee80211_chanctx_recheck(local, link, ctx, chanreq, &tmp);
        if (!compat)
                return -EINVAL;

        switch (ctx->replace_state) {
        case IEEE80211_CHANCTX_REPLACE_NONE:
                if (!ieee80211_chanctx_reserved_chanreq(local, ctx, compat,
                                                        &tmp))
                        return -EBUSY;
                break;
        case IEEE80211_CHANCTX_WILL_BE_REPLACED:
                /* TODO: Perhaps the bandwidth change could be treated as a
                 * reservation itself? */
                return -EBUSY;
        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_chanreq(link, chanreq);

        ieee80211_recalc_chanctx_chantype(local, ctx);

        *changed |= BSS_CHANGED_BANDWIDTH;
        return 0;
}

void ieee80211_link_release_channel(struct ieee80211_link_data *link)
{
        struct ieee80211_sub_if_data *sdata = link->sdata;

        if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
                return;

        lockdep_assert_wiphy(sdata->local->hw.wiphy);

        if (rcu_access_pointer(link->conf->chanctx_conf))
                __ieee80211_link_release_channel(link, false);
}

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;

        lockdep_assert_wiphy(local->hw.wiphy);

        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);

        ap_conf = wiphy_dereference(local->hw.wiphy,
                                    ap->vif.link_conf[link_id]);
        conf = wiphy_dereference(local->hw.wiphy,
                                 ap_conf->chanctx_conf);
        rcu_assign_pointer(link_conf->chanctx_conf, conf);
}

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);

void ieee80211_iter_chan_contexts_mtx(
        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;

        lockdep_assert_wiphy(hw->wiphy);

        list_for_each_entry(ctx, &local->chanctx_list, list)
                if (ctx->driver_present)
                        iter(hw, &ctx->conf, iter_data);
}
EXPORT_SYMBOL_GPL(ieee80211_iter_chan_contexts_mtx);