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 17cb8ae912bc..6e149b49d4f0 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);