mac80211: improve HT channel handling

Currently, when one interface switches HT mode,
all others will follow along. This is clearly
undesirable, since the new one might switch to
no-HT while another one is operating in HT.

Address this issue by keeping track of the HT
mode per interface, and allowing only changes
that are compatible, i.e. switching into HT40+
is not possible when another interface is in
HT40-, in that case the second one needs to
fall back to HT20.

Also, to allow drivers to know what's going on,
store the per-interface HT mode (channel type)
in the virtual interface's bss_conf.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 23 insertions, 21 deletions

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 17cb8ae912b..6e149b49d4f 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -136,11 +136,14 @@ static u32 ieee80211_enable_ht(struct ieee80211_sub_if_data *sdata,
 	struct sta_info *sta;
 	u32 changed = 0;
 	u16 ht_opmode;
-	bool enable_ht = true, ht_changed;
+	bool enable_ht = true;
+	enum nl80211_channel_type prev_chantype;
 	enum nl80211_channel_type channel_type = NL80211_CHAN_NO_HT;
 
 	sband = local->hw.wiphy->bands[local->hw.conf.channel->band];
 
+	prev_chantype = sdata->vif.bss_conf.channel_type;
+
 	/* HT is not supported */
 	if (!sband->ht_cap.ht_supported)
 		enable_ht = false;
@@ -171,38 +174,37 @@ static u32 ieee80211_enable_ht(struct ieee80211_sub_if_data *sdata,
 		}
 	}
 
-	ht_changed = conf_is_ht(&local->hw.conf) != enable_ht ||
-		     channel_type != local->hw.conf.channel_type;
-
 	if (local->tmp_channel)
 		local->tmp_channel_type = channel_type;
-	local->oper_channel_type = channel_type;
 
-	if (ht_changed) {
-                /* channel_type change automatically detected */
-		ieee80211_hw_config(local, 0);
+	if (!ieee80211_set_channel_type(local, sdata, channel_type)) {
+		/* can only fail due to HT40+/- mismatch */
+		channel_type = NL80211_CHAN_HT20;
+		WARN_ON(!ieee80211_set_channel_type(local, sdata, channel_type));
+	}
 
+	/* channel_type change automatically detected */
+	ieee80211_hw_config(local, 0);
+
+	if (prev_chantype != channel_type) {
 		rcu_read_lock();
 		sta = sta_info_get(sdata, bssid);
 		if (sta)
 			rate_control_rate_update(local, sband, sta,
 						 IEEE80211_RC_HT_CHANGED,
-						 local->oper_channel_type);
+						 channel_type);
 		rcu_read_unlock();
-        }
-
-	/* disable HT */
-	if (!enable_ht)
-		return 0;
+	}
 
 	ht_opmode = le16_to_cpu(hti->operation_mode);
 
 	/* if bss configuration changed store the new one */
-	if (!sdata->ht_opmode_valid ||
-	    sdata->vif.bss_conf.ht_operation_mode != ht_opmode) {
+	if (sdata->ht_opmode_valid != enable_ht ||
+	    sdata->vif.bss_conf.ht_operation_mode != ht_opmode ||
+	    prev_chantype != channel_type) {
 		changed |= BSS_CHANGED_HT;
 		sdata->vif.bss_conf.ht_operation_mode = ht_opmode;
-		sdata->ht_opmode_valid = true;
+		sdata->ht_opmode_valid = enable_ht;
 	}
 
 	return changed;
@@ -865,7 +867,7 @@ static void ieee80211_set_disassoc(struct ieee80211_sub_if_data *sdata,
 	ieee80211_set_wmm_default(sdata);
 
 	/* channel(_type) changes are handled by ieee80211_hw_config */
-	local->oper_channel_type = NL80211_CHAN_NO_HT;
+	WARN_ON(!ieee80211_set_channel_type(local, sdata, NL80211_CHAN_NO_HT));
 
 	/* on the next assoc, re-program HT parameters */
 	sdata->ht_opmode_valid = false;
@@ -882,8 +884,8 @@ static void ieee80211_set_disassoc(struct ieee80211_sub_if_data *sdata,
 
 	ieee80211_hw_config(local, config_changed);
 
-	/* And the BSSID changed -- not very interesting here */
-	changed |= BSS_CHANGED_BSSID;
+	/* The BSSID (not really interesting) and HT changed */
+	changed |= BSS_CHANGED_BSSID | BSS_CHANGED_HT;
 	ieee80211_bss_info_change_notify(sdata, changed);
 
 	if (remove_sta)
@@ -2265,7 +2267,7 @@ int ieee80211_mgd_action(struct ieee80211_sub_if_data *sdata,
 	if ((chan != local->tmp_channel ||
 	     channel_type != local->tmp_channel_type) &&
 	    (chan != local->oper_channel ||
-	     channel_type != local->oper_channel_type))
+	     channel_type != local->_oper_channel_type))
 		return -EBUSY;
 
 	skb = dev_alloc_skb(local->hw.extra_tx_headroom + len);