mac80211: Update rate control on channel change

A channel change or a channel bandwidth change can impact the
rate control logic. However, the rate control logic was not updated
before/after such a change, which might result in unexpected
behavior.

Fix this by updating the stations rate control logic when the
corresponding channel context changes.

Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20201206145305.600d967fe3c9.I48305f25cfcc9c032c77c51396e9e9b882748a86@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/chan.c

@@ -9,6 +9,7 @@
 #include <net/cfg80211.h>
 #include "ieee80211_i.h"
 #include "driver-ops.h"
+#include "rate.h"
 
 static int ieee80211_chanctx_num_assigned(struct ieee80211_local *local,
 					  struct ieee80211_chanctx *ctx)
@@ -345,10 +346,42 @@ void ieee80211_recalc_chanctx_min_def(struct ieee80211_local *local,
 	drv_change_chanctx(local, ctx, IEEE80211_CHANCTX_CHANGE_MIN_WIDTH);
 }
 
+static void ieee80211_chan_bw_change(struct ieee80211_local *local,
+				     struct ieee80211_chanctx *ctx)
+{
+	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) {
+		enum ieee80211_sta_rx_bandwidth new_sta_bw;
+
+		if (!ieee80211_sdata_running(sta->sdata))
+			continue;
+
+		if (rcu_access_pointer(sta->sdata->vif.chanctx_conf) !=
+		    &ctx->conf)
+			continue;
+
+		new_sta_bw = ieee80211_sta_cur_vht_bw(sta);
+		if (new_sta_bw == sta->sta.bandwidth)
+			continue;
+
+		sta->sta.bandwidth = new_sta_bw;
+		rate_control_rate_update(local, sband, sta,
+					 IEEE80211_RC_BW_CHANGED);
+	}
+	rcu_read_unlock();
+}
+
 static void ieee80211_change_chanctx(struct ieee80211_local *local,
 				     struct ieee80211_chanctx *ctx,
 				     const struct cfg80211_chan_def *chandef)
 {
+	enum nl80211_chan_width width;
+
 	if (cfg80211_chandef_identical(&ctx->conf.def, chandef)) {
 		ieee80211_recalc_chanctx_min_def(local, ctx);
 		return;
@@ -356,7 +389,25 @@ static void ieee80211_change_chanctx(struct ieee80211_local *local,
 
 	WARN_ON(!cfg80211_chandef_compatible(&ctx->conf.def, chandef));
 
+	width = ctx->conf.def.width;
 	ctx->conf.def = *chandef;
+
+	/* expected to handle only 20/40/80/160 channel widths */
+	switch (chandef->width) {
+	case NL80211_CHAN_WIDTH_20_NOHT:
+	case NL80211_CHAN_WIDTH_20:
+	case NL80211_CHAN_WIDTH_40:
+	case NL80211_CHAN_WIDTH_80:
+	case NL80211_CHAN_WIDTH_80P80:
+	case NL80211_CHAN_WIDTH_160:
+		break;
+	default:
+		WARN_ON(1);
+	}
+
+	if (chandef->width < width)
+		ieee80211_chan_bw_change(local, ctx);
+
 	drv_change_chanctx(local, ctx, IEEE80211_CHANCTX_CHANGE_WIDTH);
 	ieee80211_recalc_chanctx_min_def(local, ctx);
 
@@ -364,6 +415,9 @@ static void ieee80211_change_chanctx(struct ieee80211_local *local,
 		local->_oper_chandef = *chandef;
 		ieee80211_hw_config(local, 0);
 	}
+
+	if (chandef->width > width)
+		ieee80211_chan_bw_change(local, ctx);
 }
 
 static struct ieee80211_chanctx *
@@ -1053,8 +1107,14 @@ ieee80211_vif_use_reserved_reassign(struct ieee80211_sub_if_data *sdata)
 	if (WARN_ON(!chandef))
 		return -EINVAL;
 
+	if (old_ctx->conf.def.width > new_ctx->conf.def.width)
+		ieee80211_chan_bw_change(local, new_ctx);
+
 	ieee80211_change_chanctx(local, new_ctx, chandef);
 
+	if (old_ctx->conf.def.width < new_ctx->conf.def.width)
+		ieee80211_chan_bw_change(local, new_ctx);
+
 	vif_chsw[0].vif = &sdata->vif;
 	vif_chsw[0].old_ctx = &old_ctx->conf;
 	vif_chsw[0].new_ctx = &new_ctx->conf;
@@ -1445,6 +1505,7 @@ static int ieee80211_vif_use_reserved_switch(struct ieee80211_local *local)
 		ieee80211_recalc_smps_chanctx(local, ctx);
 		ieee80211_recalc_radar_chanctx(local, ctx);
 		ieee80211_recalc_chanctx_min_def(local, ctx);
+		ieee80211_chan_bw_change(local, ctx);
 
 		list_for_each_entry_safe(sdata, sdata_tmp, &ctx->reserved_vifs,
 					 reserved_chanctx_list) {