From f498afc5b130da3d23a2c86729368c64e487e6d8 Mon Sep 17 00:00:00 2001
From: Evelyn Tsai <evelyn.tsai@mediatek.com>
Date: Fri, 16 Dec 2022 03:31:06 +0800
Subject: [PATCH 10/15] mac80211: mtk: check the control channel before
 downgrading the bandwidth

---
 net/mac80211/mlme.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index d8484cd..8ab5c52 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -4582,6 +4582,26 @@ ieee80211_verify_sta_he_mcs_support(struct ieee80211_sub_if_data *sdata,
 	return false;
 }
 
+static bool ieee80211_check_same_ctrl_channel(struct ieee80211_sub_if_data *sdata,
+					      const struct cfg80211_chan_def *chandef)
+{
+	struct ieee80211_local *local = sdata->local;
+	struct ieee80211_chanctx *ctx;
+
+	mutex_lock(&local->chanctx_mtx);
+	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 (chandef->chan == ctx->conf.def.chan)
+			return true;
+	}
+
+	mutex_unlock(&local->chanctx_mtx);
+	return false;
+}
+
 static int ieee80211_prep_channel(struct ieee80211_sub_if_data *sdata,
 				  struct ieee80211_link_data *link,
 				  struct cfg80211_bss *cbss,
@@ -4808,6 +4828,9 @@ static int ieee80211_prep_channel(struct ieee80211_sub_if_data *sdata,
 	    chandef.width == NL80211_CHAN_WIDTH_10)
 		goto out;
 
+	if (!ret || !ieee80211_check_same_ctrl_channel(sdata, &chandef))
+		goto out;
+
 	while (ret && chandef.width != NL80211_CHAN_WIDTH_20_NOHT) {
 		*conn_flags |=
 			ieee80211_chandef_downgrade(&chandef);
-- 
2.18.0