+static void __ieee80211_vif_release_channel(struct ieee80211_sub_if_data *sdata)
+{
+ struct ieee80211_local *local = sdata->local;
+ struct ieee80211_chanctx_conf *conf;
+ struct ieee80211_chanctx *ctx;
+ bool use_reserved_switch = false;
+
+ lockdep_assert_held(&local->chanctx_mtx);
+
+ conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
+ lockdep_is_held(&local->chanctx_mtx));
+ if (!conf)
+ return;
+
+ ctx = container_of(conf, struct ieee80211_chanctx, conf);
+
+ if (sdata->reserved_chanctx) {
+ if (sdata->reserved_chanctx->replace_state ==
+ IEEE80211_CHANCTX_REPLACES_OTHER &&
+ ieee80211_chanctx_num_reserved(local,
+ sdata->reserved_chanctx) > 1)
+ use_reserved_switch = true;
+
+ ieee80211_vif_unreserve_chanctx(sdata);
+ }
+
+ ieee80211_assign_vif_chanctx(sdata, NULL);
+ if (ieee80211_chanctx_refcount(local, ctx) == 0)
+ ieee80211_free_chanctx(local, ctx);
+
+ /* Unreserving may ready an in-place reservation. */
+ if (use_reserved_switch)
+ ieee80211_vif_use_reserved_switch(local);
+}
+
+int ieee80211_vif_use_channel(struct ieee80211_sub_if_data *sdata,
+ const struct cfg80211_chan_def *chandef,
+ enum ieee80211_chanctx_mode mode)
+{
+ struct ieee80211_local *local = sdata->local;
+ struct ieee80211_chanctx *ctx;
+ u8 radar_detect_width = 0;
+ int ret;
+
+ lockdep_assert_held(&local->mtx);
+
+ 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);
+ if (!ctx)
+ ctx = ieee80211_new_chanctx(local, chandef, mode);
+ if (IS_ERR(ctx)) {
+ ret = PTR_ERR(ctx);
+ goto out;
+ }
+
+ sdata->vif.bss_conf.chandef = *chandef;
+
+ ret = ieee80211_assign_vif_chanctx(sdata, ctx);
+ if (ret) {
+ /* if assign fails refcount stays the same */
+ if (ieee80211_chanctx_refcount(local, ctx) == 0)
+ ieee80211_free_chanctx(local, ctx);
+ goto out;
+ }
+
+ ieee80211_recalc_smps_chanctx(local, ctx);
+ ieee80211_recalc_radar_chanctx(local, ctx);
+ out:
+ mutex_unlock(&local->chanctx_mtx);
+ return ret;
+}
+