Merge branch 'for-john' of git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next

Conflicts:
	net/mac80211/chan.c

1 files changed, 500 insertions, 114 deletions

diff --git a/net/mac80211/chan.c b/net/mac80211/chan.c
index 75b5dd2c9267..48e6d6f010cd 100644
--- a/net/mac80211/chan.c
+++ b/net/mac80211/chan.c
@@ -9,6 +9,170 @@
 #include "ieee80211_i.h"
 #include "driver-ops.h"
 
+static int ieee80211_chanctx_num_assigned(struct ieee80211_local *local,
+                                          struct ieee80211_chanctx *ctx)
+{
+        struct ieee80211_sub_if_data *sdata;
+        int num = 0;
+
+        lockdep_assert_held(&local->chanctx_mtx);
+
+        list_for_each_entry(sdata, &ctx->assigned_vifs, assigned_chanctx_list)
+                num++;
+
+        return num;
+}
+
+static int ieee80211_chanctx_num_reserved(struct ieee80211_local *local,
+                                          struct ieee80211_chanctx *ctx)
+{
+        struct ieee80211_sub_if_data *sdata;
+        int num = 0;
+
+        lockdep_assert_held(&local->chanctx_mtx);
+
+        list_for_each_entry(sdata, &ctx->reserved_vifs, 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 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_sub_if_data *sdata;
+
+        lockdep_assert_held(&local->chanctx_mtx);
+
+        list_for_each_entry(sdata, &ctx->reserved_vifs,
+                            reserved_chanctx_list) {
+                if (!compat)
+                        compat = &sdata->reserved_chandef;
+
+                compat = cfg80211_chandef_compatible(&sdata->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_sub_if_data *sdata;
+
+        lockdep_assert_held(&local->chanctx_mtx);
+
+        list_for_each_entry(sdata, &ctx->assigned_vifs,
+                            assigned_chanctx_list) {
+                if (sdata->reserved_chanctx != NULL)
+                        continue;
+
+                if (!compat)
+                        compat = &sdata->vif.bss_conf.chandef;
+
+                compat = cfg80211_chandef_compatible(
+                                &sdata->vif.bss_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_vifs) &&
+            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->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 ieee80211_sta *sta)
 {
         switch (sta->bandwidth) {
@@ -190,6 +354,11 @@ ieee80211_find_chanctx(struct ieee80211_local *local,
                 if (!compat)
                         continue;
 
+                compat = ieee80211_chanctx_reserved_chandef(local, ctx,
+                                                            compat);
+                if (!compat)
+                        continue;
+
                 ieee80211_change_chanctx(local, ctx, compat);
 
                 return ctx;
@@ -217,62 +386,91 @@ static bool ieee80211_is_radar_required(struct ieee80211_local *local)
 }
 
 static struct ieee80211_chanctx *
-ieee80211_new_chanctx(struct ieee80211_local *local,
-                      const struct cfg80211_chan_def *chandef,
-                      enum ieee80211_chanctx_mode mode)
+ieee80211_alloc_chanctx(struct ieee80211_local *local,
+                        const struct cfg80211_chan_def *chandef,
+                        enum ieee80211_chanctx_mode mode)
 {
         struct ieee80211_chanctx *ctx;
-        u32 changed;
-        int err;
 
         lockdep_assert_held(&local->chanctx_mtx);
 
         ctx = kzalloc(sizeof(*ctx) + local->hw.chanctx_data_size, GFP_KERNEL);
         if (!ctx)
-                return ERR_PTR(-ENOMEM);
+                return NULL;
 
+        INIT_LIST_HEAD(&ctx->assigned_vifs);
+        INIT_LIST_HEAD(&ctx->reserved_vifs);
         ctx->conf.def = *chandef;
         ctx->conf.rx_chains_static = 1;
         ctx->conf.rx_chains_dynamic = 1;
         ctx->mode = mode;
         ctx->conf.radar_enabled = ieee80211_is_radar_required(local);
         ieee80211_recalc_chanctx_min_def(local, ctx);
+
+        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;
 
-        /* we hold the mutex to prevent idle from changing */
-        lockdep_assert_held(&local->mtx);
         /* turn idle off *before* setting channel -- some drivers need that */
         changed = ieee80211_idle_off(local);
         if (changed)
                 ieee80211_hw_config(local, changed);
 
         if (!local->use_chanctx) {
-                local->_oper_chandef = *chandef;
+                local->_oper_chandef = ctx->conf.def;
                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
         } else {
                 err = drv_add_chanctx(local, ctx);
                 if (err) {
-                        kfree(ctx);
                         ieee80211_recalc_idle(local);
-                        return ERR_PTR(err);
+                        return err;
                 }
         }
 
-        /* and keep the mutex held until the new chanctx is on the list */
-        list_add_rcu(&ctx->list, &local->chanctx_list);
+        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_free_chanctx(struct ieee80211_local *local,
-                                   struct ieee80211_chanctx *ctx)
+static void ieee80211_del_chanctx(struct ieee80211_local *local,
+                                  struct ieee80211_chanctx *ctx)
 {
-        bool check_single_channel = false;
         lockdep_assert_held(&local->chanctx_mtx);
 
-        WARN_ON_ONCE(ctx->refcount != 0);
-
         if (!local->use_chanctx) {
                 struct cfg80211_chan_def *chandef = &local->_oper_chandef;
                 chandef->width = NL80211_CHAN_WIDTH_20_NOHT;
@@ -282,8 +480,9 @@ static void ieee80211_free_chanctx(struct ieee80211_local *local,
                 /* NOTE: Disabling radar is only valid here for
                  * single channel context. To be sure, check it ...
                  */
-                if (local->hw.conf.radar_enabled)
-                        check_single_channel = true;
+                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);
@@ -291,39 +490,19 @@ static void ieee80211_free_chanctx(struct ieee80211_local *local,
                 drv_remove_chanctx(local, ctx);
         }
 
-        list_del_rcu(&ctx->list);
-        kfree_rcu(ctx, rcu_head);
-
-        /* throw a warning if this wasn't the only channel context. */
-        WARN_ON(check_single_channel && !list_empty(&local->chanctx_list));
-
         ieee80211_recalc_idle(local);
 }
 
-static int ieee80211_assign_vif_chanctx(struct ieee80211_sub_if_data *sdata,
-                                        struct ieee80211_chanctx *ctx)
+static void ieee80211_free_chanctx(struct ieee80211_local *local,
+                                   struct ieee80211_chanctx *ctx)
 {
-        struct ieee80211_local *local = sdata->local;
-        int ret;
-
         lockdep_assert_held(&local->chanctx_mtx);
 
-        ret = drv_assign_vif_chanctx(local, sdata, ctx);
-        if (ret)
-                return ret;
-
-        rcu_assign_pointer(sdata->vif.chanctx_conf, &ctx->conf);
-        ctx->refcount++;
-
-        ieee80211_recalc_txpower(sdata);
-        ieee80211_recalc_chanctx_min_def(local, ctx);
-        sdata->vif.bss_conf.idle = false;
+        WARN_ON_ONCE(ieee80211_chanctx_refcount(local, ctx) != 0);
 
-        if (sdata->vif.type != NL80211_IFTYPE_P2P_DEVICE &&
-            sdata->vif.type != NL80211_IFTYPE_MONITOR)
-                ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_IDLE);
-
-        return 0;
+        list_del_rcu(&ctx->list);
+        ieee80211_del_chanctx(local, ctx);
+        kfree_rcu(ctx, rcu_head);
 }
 
 static void ieee80211_recalc_chanctx_chantype(struct ieee80211_local *local,
@@ -384,30 +563,58 @@ static void ieee80211_recalc_radar_chanctx(struct ieee80211_local *local,
         drv_change_chanctx(local, chanctx, IEEE80211_CHANCTX_CHANGE_RADAR);
 }
 
-static void ieee80211_unassign_vif_chanctx(struct ieee80211_sub_if_data *sdata,
-                                           struct ieee80211_chanctx *ctx)
+static int ieee80211_assign_vif_chanctx(struct ieee80211_sub_if_data *sdata,
+                                        struct ieee80211_chanctx *new_ctx)
 {
         struct ieee80211_local *local = sdata->local;
+        struct ieee80211_chanctx_conf *conf;
+        struct ieee80211_chanctx *curr_ctx = NULL;
+        int ret = 0;
 
-        lockdep_assert_held(&local->chanctx_mtx);
+        conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
+                                         lockdep_is_held(&local->chanctx_mtx));
 
-        ctx->refcount--;
-        rcu_assign_pointer(sdata->vif.chanctx_conf, NULL);
+        if (conf) {
+                curr_ctx = container_of(conf, struct ieee80211_chanctx, conf);
 
-        sdata->vif.bss_conf.idle = true;
+                drv_unassign_vif_chanctx(local, sdata, curr_ctx);
+                conf = NULL;
+                list_del(&sdata->assigned_chanctx_list);
+        }
 
-        if (sdata->vif.type != NL80211_IFTYPE_P2P_DEVICE &&
-            sdata->vif.type != NL80211_IFTYPE_MONITOR)
-                ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_IDLE);
+        if (new_ctx) {
+                ret = drv_assign_vif_chanctx(local, sdata, new_ctx);
+                if (ret)
+                        goto out;
 
-        drv_unassign_vif_chanctx(local, sdata, ctx);
+                conf = &new_ctx->conf;
+                list_add(&sdata->assigned_chanctx_list,
+                         &new_ctx->assigned_vifs);
+        }
 
-        if (ctx->refcount > 0) {
-                ieee80211_recalc_chanctx_chantype(sdata->local, ctx);
-                ieee80211_recalc_smps_chanctx(local, ctx);
-                ieee80211_recalc_radar_chanctx(local, ctx);
-                ieee80211_recalc_chanctx_min_def(local, ctx);
+out:
+        rcu_assign_pointer(sdata->vif.chanctx_conf, conf);
+
+        sdata->vif.bss_conf.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);
         }
+
+        if (new_ctx && ieee80211_chanctx_num_assigned(local, new_ctx) > 0) {
+                ieee80211_recalc_txpower(sdata);
+                ieee80211_recalc_chanctx_min_def(local, new_ctx);
+        }
+
+        if (sdata->vif.type != NL80211_IFTYPE_P2P_DEVICE &&
+            sdata->vif.type != NL80211_IFTYPE_MONITOR)
+                ieee80211_bss_info_change_notify(sdata,
+                                                 BSS_CHANGED_IDLE);
+
+        return ret;
 }
 
 static void __ieee80211_vif_release_channel(struct ieee80211_sub_if_data *sdata)
@@ -425,8 +632,11 @@ static void __ieee80211_vif_release_channel(struct ieee80211_sub_if_data *sdata)
 
         ctx = container_of(conf, struct ieee80211_chanctx, conf);
 
-        ieee80211_unassign_vif_chanctx(sdata, ctx);
-        if (ctx->refcount == 0)
+        if (sdata->reserved_chanctx)
+                ieee80211_vif_unreserve_chanctx(sdata);
+
+        ieee80211_assign_vif_chanctx(sdata, NULL);
+        if (ieee80211_chanctx_refcount(local, ctx) == 0)
                 ieee80211_free_chanctx(local, ctx);
 }
 
@@ -526,6 +736,7 @@ int ieee80211_vif_use_channel(struct ieee80211_sub_if_data *sdata,
 {
         struct ieee80211_local *local = sdata->local;
         struct ieee80211_chanctx *ctx;
+        u8 radar_detect_width = 0;
         int ret;
 
         lockdep_assert_held(&local->mtx);
@@ -533,6 +744,22 @@ int ieee80211_vif_use_channel(struct ieee80211_sub_if_data *sdata,
         WARN_ON(sdata->dev && netif_carrier_ok(sdata->dev));
 
         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);
+
+        sdata->radar_required = ret;
+
+        ret = ieee80211_check_combinations(sdata, chandef, mode,
+                                           radar_detect_width);
+        if (ret < 0)
+                goto out;
+
         __ieee80211_vif_release_channel(sdata);
 
         ctx = ieee80211_find_chanctx(local, chandef, mode);
@@ -548,7 +775,7 @@ int ieee80211_vif_use_channel(struct ieee80211_sub_if_data *sdata,
         ret = ieee80211_assign_vif_chanctx(sdata, ctx);
         if (ret) {
                 /* if assign fails refcount stays the same */
-                if (ctx->refcount == 0)
+                if (ieee80211_chanctx_refcount(local, ctx) == 0)
                         ieee80211_free_chanctx(local, ctx);
                 goto out;
         }
@@ -560,15 +787,47 @@ int ieee80211_vif_use_channel(struct ieee80211_sub_if_data *sdata,
         return ret;
 }
 
+static int __ieee80211_vif_change_channel(struct ieee80211_sub_if_data *sdata,
+                                          struct ieee80211_chanctx *ctx,
+                                          u32 *changed)
+{
+        struct ieee80211_local *local = sdata->local;
+        const struct cfg80211_chan_def *chandef = &sdata->csa_chandef;
+        u32 chanctx_changed = 0;
+
+        if (!cfg80211_chandef_usable(sdata->local->hw.wiphy, chandef,
+                                     IEEE80211_CHAN_DISABLED))
+                return -EINVAL;
+
+        if (ieee80211_chanctx_refcount(local, ctx) != 1)
+                return -EINVAL;
+
+        if (sdata->vif.bss_conf.chandef.width != chandef->width) {
+                chanctx_changed = IEEE80211_CHANCTX_CHANGE_WIDTH;
+                *changed |= BSS_CHANGED_BANDWIDTH;
+        }
+
+        sdata->vif.bss_conf.chandef = *chandef;
+        ctx->conf.def = *chandef;
+
+        chanctx_changed |= IEEE80211_CHANCTX_CHANGE_CHANNEL;
+        drv_change_chanctx(local, ctx, chanctx_changed);
+
+        ieee80211_recalc_chanctx_chantype(local, ctx);
+        ieee80211_recalc_smps_chanctx(local, ctx);
+        ieee80211_recalc_radar_chanctx(local, ctx);
+        ieee80211_recalc_chanctx_min_def(local, ctx);
+
+        return 0;
+}
+
 int ieee80211_vif_change_channel(struct ieee80211_sub_if_data *sdata,
                                  u32 *changed)
 {
         struct ieee80211_local *local = sdata->local;
         struct ieee80211_chanctx_conf *conf;
         struct ieee80211_chanctx *ctx;
-        const struct cfg80211_chan_def *chandef = &sdata->csa_chandef;
         int ret;
-        u32 chanctx_changed = 0;
 
         lockdep_assert_held(&local->mtx);
 
@@ -576,11 +835,94 @@ int ieee80211_vif_change_channel(struct ieee80211_sub_if_data *sdata,
         if (WARN_ON(!sdata->vif.csa_active))
                 return -EINVAL;
 
-        if (!cfg80211_chandef_usable(sdata->local->hw.wiphy, chandef,
-                                     IEEE80211_CHAN_DISABLED))
+        mutex_lock(&local->chanctx_mtx);
+        conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
+                                         lockdep_is_held(&local->chanctx_mtx));
+        if (!conf) {
+                ret = -EINVAL;
+                goto out;
+        }
+
+        ctx = container_of(conf, struct ieee80211_chanctx, conf);
+
+        ret = __ieee80211_vif_change_channel(sdata, ctx, changed);
+ out:
+        mutex_unlock(&local->chanctx_mtx);
+        return ret;
+}
+
+static void
+__ieee80211_vif_copy_chanctx_to_vlans(struct ieee80211_sub_if_data *sdata,
+                                      bool clear)
+{
+        struct ieee80211_local *local = sdata->local;
+        struct ieee80211_sub_if_data *vlan;
+        struct ieee80211_chanctx_conf *conf;
+
+        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(sdata->vif.chanctx_conf,
+                                lockdep_is_held(&local->chanctx_mtx));
+        WARN_ON(!conf);
+
+        if (clear)
+                conf = NULL;
+
+        list_for_each_entry(vlan, &sdata->u.ap.vlans, u.vlan.list)
+                rcu_assign_pointer(vlan->vif.chanctx_conf, conf);
+}
+
+void ieee80211_vif_copy_chanctx_to_vlans(struct ieee80211_sub_if_data *sdata,
+                                         bool clear)
+{
+        struct ieee80211_local *local = sdata->local;
+
+        mutex_lock(&local->chanctx_mtx);
+
+        __ieee80211_vif_copy_chanctx_to_vlans(sdata, clear);
+
+        mutex_unlock(&local->chanctx_mtx);
+}
+
+int ieee80211_vif_unreserve_chanctx(struct ieee80211_sub_if_data *sdata)
+{
+        struct ieee80211_chanctx *ctx = sdata->reserved_chanctx;
+
+        lockdep_assert_held(&sdata->local->chanctx_mtx);
+
+        if (WARN_ON(!ctx))
                 return -EINVAL;
 
+        list_del(&sdata->reserved_chanctx_list);
+        sdata->reserved_chanctx = NULL;
+
+        if (ieee80211_chanctx_refcount(sdata->local, ctx) == 0)
+                ieee80211_free_chanctx(sdata->local, ctx);
+
+        return 0;
+}
+
+int ieee80211_vif_reserve_chanctx(struct ieee80211_sub_if_data *sdata,
+                                  const struct cfg80211_chan_def *chandef,
+                                  enum ieee80211_chanctx_mode mode,
+                                  bool radar_required)
+{
+        struct ieee80211_local *local = sdata->local;
+        struct ieee80211_chanctx_conf *conf;
+        struct ieee80211_chanctx *new_ctx, *curr_ctx;
+        int ret = 0;
+
         mutex_lock(&local->chanctx_mtx);
+
         conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
                                          lockdep_is_held(&local->chanctx_mtx));
         if (!conf) {
@@ -588,30 +930,108 @@ int ieee80211_vif_change_channel(struct ieee80211_sub_if_data *sdata,
                 goto out;
         }
 
-        ctx = container_of(conf, struct ieee80211_chanctx, conf);
-        if (ctx->refcount != 1) {
+        curr_ctx = container_of(conf, struct ieee80211_chanctx, conf);
+
+        new_ctx = ieee80211_find_reservation_chanctx(local, chandef, mode);
+        if (!new_ctx) {
+                if (ieee80211_chanctx_refcount(local, curr_ctx) == 1 &&
+                    (local->hw.flags & IEEE80211_HW_CHANGE_RUNNING_CHANCTX)) {
+                        /* if we're the only users of the chanctx and
+                         * the driver supports changing a running
+                         * context, reserve our current context
+                         */
+                        new_ctx = curr_ctx;
+                } else if (ieee80211_can_create_new_chanctx(local)) {
+                        /* create a new context and reserve it */
+                        new_ctx = ieee80211_new_chanctx(local, chandef, mode);
+                        if (IS_ERR(new_ctx)) {
+                                ret = PTR_ERR(new_ctx);
+                                goto out;
+                        }
+                } else {
+                        ret = -EBUSY;
+                        goto out;
+                }
+        }
+
+        list_add(&sdata->reserved_chanctx_list, &new_ctx->reserved_vifs);
+        sdata->reserved_chanctx = new_ctx;
+        sdata->reserved_chandef = *chandef;
+        sdata->reserved_radar_required = radar_required;
+out:
+        mutex_unlock(&local->chanctx_mtx);
+        return ret;
+}
+
+int ieee80211_vif_use_reserved_context(struct ieee80211_sub_if_data *sdata,
+                                       u32 *changed)
+{
+        struct ieee80211_local *local = sdata->local;
+        struct ieee80211_chanctx *ctx;
+        struct ieee80211_chanctx *old_ctx;
+        struct ieee80211_chanctx_conf *conf;
+        int ret;
+        u32 tmp_changed = *changed;
+
+        /* TODO: need to recheck if the chandef is usable etc.? */
+
+        lockdep_assert_held(&local->mtx);
+
+        mutex_lock(&local->chanctx_mtx);
+
+        ctx = sdata->reserved_chanctx;
+        if (WARN_ON(!ctx)) {
                 ret = -EINVAL;
                 goto out;
         }
 
-        if (sdata->vif.bss_conf.chandef.width != chandef->width) {
-                chanctx_changed = IEEE80211_CHANCTX_CHANGE_WIDTH;
-                *changed |= BSS_CHANGED_BANDWIDTH;
+        conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
+                                         lockdep_is_held(&local->chanctx_mtx));
+        if (!conf) {
+                ret = -EINVAL;
+                goto out;
         }
 
-        sdata->vif.bss_conf.chandef = *chandef;
-        ctx->conf.def = *chandef;
+        old_ctx = container_of(conf, struct ieee80211_chanctx, conf);
 
-        chanctx_changed |= IEEE80211_CHANCTX_CHANGE_CHANNEL;
-        drv_change_chanctx(local, ctx, chanctx_changed);
+        if (sdata->vif.bss_conf.chandef.width != sdata->reserved_chandef.width)
+                tmp_changed |= BSS_CHANGED_BANDWIDTH;
+
+        sdata->vif.bss_conf.chandef = sdata->reserved_chandef;
+
+        /* unref our reservation */
+        sdata->reserved_chanctx = NULL;
+        sdata->radar_required = sdata->reserved_radar_required;
+        list_del(&sdata->reserved_chanctx_list);
+
+        if (old_ctx == ctx) {
+                /* This is our own context, just change it */
+                ret = __ieee80211_vif_change_channel(sdata, old_ctx,
+                                                     &tmp_changed);
+                if (ret)
+                        goto out;
+        } else {
+                ret = ieee80211_assign_vif_chanctx(sdata, ctx);
+                if (ieee80211_chanctx_refcount(local, old_ctx) == 0)
+                        ieee80211_free_chanctx(local, old_ctx);
+                if (ret) {
+                        /* if assign fails refcount stays the same */
+                        if (ieee80211_chanctx_refcount(local, ctx) == 0)
+                                ieee80211_free_chanctx(local, ctx);
+                        goto out;
+                }
+
+                if (sdata->vif.type == NL80211_IFTYPE_AP)
+                        __ieee80211_vif_copy_chanctx_to_vlans(sdata, false);
+        }
+
+        *changed = tmp_changed;
 
         ieee80211_recalc_chanctx_chantype(local, ctx);
         ieee80211_recalc_smps_chanctx(local, ctx);
         ieee80211_recalc_radar_chanctx(local, ctx);
         ieee80211_recalc_chanctx_min_def(local, ctx);
-
-        ret = 0;
- out:
+out:
         mutex_unlock(&local->chanctx_mtx);
         return ret;
 }
@@ -695,40 +1115,6 @@ void ieee80211_vif_vlan_copy_chanctx(struct ieee80211_sub_if_data *sdata)
         mutex_unlock(&local->chanctx_mtx);
 }
 
-void ieee80211_vif_copy_chanctx_to_vlans(struct ieee80211_sub_if_data *sdata,
-                                         bool clear)
-{
-        struct ieee80211_local *local = sdata->local;
-        struct ieee80211_sub_if_data *vlan;
-        struct ieee80211_chanctx_conf *conf;
-
-        ASSERT_RTNL();
-
-        if (WARN_ON(sdata->vif.type != NL80211_IFTYPE_AP))
-                return;
-
-        mutex_lock(&local->chanctx_mtx);
-
-        /*
-         * Check that conf exists, even when clearing this function
-         * must be called with the AP's channel context still there
-         * as it would otherwise cause VLANs to have an invalid
-         * channel context pointer for a while, possibly pointing
-         * to a channel context that has already been freed.
-         */
-        conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
-                                lockdep_is_held(&local->chanctx_mtx));
-        WARN_ON(!conf);
-
-        if (clear)
-                conf = NULL;
-
-        list_for_each_entry(vlan, &sdata->u.ap.vlans, u.vlan.list)
-                rcu_assign_pointer(vlan->vif.chanctx_conf, conf);
-
-        mutex_unlock(&local->chanctx_mtx);
-}
-
 void ieee80211_iter_chan_contexts_atomic(
         struct ieee80211_hw *hw,
         void (*iter)(struct ieee80211_hw *hw,