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>

6 files changed, 118 insertions, 31 deletions

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 414b7dd7d7fd..ab166c6d9399 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -1166,23 +1166,34 @@ static int ieee80211_set_channel(struct wiphy *wiphy,
                                  enum nl80211_channel_type channel_type)
 {
         struct ieee80211_local *local = wiphy_priv(wiphy);
+        struct ieee80211_sub_if_data *sdata = NULL;
+
+        if (netdev)
+                sdata = IEEE80211_DEV_TO_SUB_IF(netdev);
 
         switch (ieee80211_get_channel_mode(local, NULL)) {
         case CHAN_MODE_HOPPING:
                 return -EBUSY;
         case CHAN_MODE_FIXED:
-                if (local->oper_channel == chan &&
-                    local->oper_channel_type == channel_type)
+                if (local->oper_channel != chan)
+                        return -EBUSY;
+                if (!sdata && local->_oper_channel_type == channel_type)
                         return 0;
-                return -EBUSY;
+                break;
         case CHAN_MODE_UNDEFINED:
                 break;
         }
 
         local->oper_channel = chan;
-        local->oper_channel_type = channel_type;
 
-        return ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
+        if (!ieee80211_set_channel_type(local, sdata, channel_type))
+                return -EBUSY;
+
+        ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
+        if (sdata && sdata->vif.type != NL80211_IFTYPE_MONITOR)
+                ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_HT);
+
+        return 0;
 }
 
 #ifdef CONFIG_PM
@@ -1406,7 +1417,7 @@ int __ieee80211_request_smps(struct ieee80211_sub_if_data *sdata,
          * association, there's no need to send an action frame.
          */
         if (!sdata->u.mgd.associated ||
-            sdata->local->oper_channel_type == NL80211_CHAN_NO_HT) {
+            sdata->vif.bss_conf.channel_type == NL80211_CHAN_NO_HT) {
                 mutex_lock(&sdata->local->iflist_mtx);
                 ieee80211_recalc_smps(sdata->local, sdata);
                 mutex_unlock(&sdata->local->iflist_mtx);
diff --git a/net/mac80211/chan.c b/net/mac80211/chan.c
index 08f3832661a5..5d218c530a4e 100644
--- a/net/mac80211/chan.c
+++ b/net/mac80211/chan.c
@@ -2,6 +2,7 @@
  * mac80211 - channel management
  */
 
+#include <linux/nl80211.h>
 #include "ieee80211_i.h"
 
 enum ieee80211_chan_mode
@@ -55,3 +56,72 @@ ieee80211_get_channel_mode(struct ieee80211_local *local,
 
         return mode;
 }
+
+bool ieee80211_set_channel_type(struct ieee80211_local *local,
+                                struct ieee80211_sub_if_data *sdata,
+                                enum nl80211_channel_type chantype)
+{
+        struct ieee80211_sub_if_data *tmp;
+        enum nl80211_channel_type superchan = NL80211_CHAN_NO_HT;
+        bool result;
+
+        mutex_lock(&local->iflist_mtx);
+
+        list_for_each_entry(tmp, &local->interfaces, list) {
+                if (tmp == sdata)
+                        continue;
+
+                if (!ieee80211_sdata_running(tmp))
+                        continue;
+
+                switch (tmp->vif.bss_conf.channel_type) {
+                case NL80211_CHAN_NO_HT:
+                case NL80211_CHAN_HT20:
+                        superchan = tmp->vif.bss_conf.channel_type;
+                        break;
+                case NL80211_CHAN_HT40PLUS:
+                        WARN_ON(superchan == NL80211_CHAN_HT40MINUS);
+                        superchan = NL80211_CHAN_HT40PLUS;
+                        break;
+                case NL80211_CHAN_HT40MINUS:
+                        WARN_ON(superchan == NL80211_CHAN_HT40PLUS);
+                        superchan = NL80211_CHAN_HT40MINUS;
+                        break;
+                }
+        }
+
+        switch (superchan) {
+        case NL80211_CHAN_NO_HT:
+        case NL80211_CHAN_HT20:
+                /*
+                 * allow any change that doesn't go to no-HT
+                 * (if it already is no-HT no change is needed)
+                 */
+                if (chantype == NL80211_CHAN_NO_HT)
+                        break;
+                superchan = chantype;
+                break;
+        case NL80211_CHAN_HT40PLUS:
+        case NL80211_CHAN_HT40MINUS:
+                /* allow smaller bandwidth and same */
+                if (chantype == NL80211_CHAN_NO_HT)
+                        break;
+                if (chantype == NL80211_CHAN_HT20)
+                        break;
+                if (superchan == chantype)
+                        break;
+                result = false;
+                goto out;
+        }
+
+        local->_oper_channel_type = superchan;
+
+        if (sdata)
+                sdata->vif.bss_conf.channel_type = chantype;
+
+        result = true;
+ out:
+        mutex_unlock(&local->iflist_mtx);
+
+        return result;
+}
diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
index d5855ae387e8..36745f494f63 100644
--- a/net/mac80211/ibss.c
+++ b/net/mac80211/ibss.c
@@ -102,7 +102,7 @@ static void __ieee80211_sta_join_ibss(struct ieee80211_sub_if_data *sdata,
         sdata->drop_unencrypted = capability & WLAN_CAPABILITY_PRIVACY ? 1 : 0;
 
         local->oper_channel = chan;
-        local->oper_channel_type = NL80211_CHAN_NO_HT;
+        WARN_ON(!ieee80211_set_channel_type(local, sdata, NL80211_CHAN_NO_HT));
         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
 
         sband = local->hw.wiphy->bands[chan->band];
@@ -910,7 +910,8 @@ int ieee80211_ibss_join(struct ieee80211_sub_if_data *sdata,
         /* fix ourselves to that channel now already */
         if (params->channel_fixed) {
                 sdata->local->oper_channel = params->channel;
-                sdata->local->oper_channel_type = NL80211_CHAN_NO_HT;
+                WARN_ON(!ieee80211_set_channel_type(sdata->local, sdata,
+                                                    NL80211_CHAN_NO_HT));
         }
 
         if (params->ie) {
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 359edff31471..69e7f4131f46 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -768,7 +768,7 @@ struct ieee80211_local {
         enum mac80211_scan_state next_scan_state;
         struct delayed_work scan_work;
         struct ieee80211_sub_if_data *scan_sdata;
-        enum nl80211_channel_type oper_channel_type;
+        enum nl80211_channel_type _oper_channel_type;
         struct ieee80211_channel *oper_channel, *csa_channel;
 
         /* Temporary remain-on-channel for off-channel operations */
@@ -1239,6 +1239,9 @@ enum ieee80211_chan_mode {
 enum ieee80211_chan_mode
 ieee80211_get_channel_mode(struct ieee80211_local *local,
                            struct ieee80211_sub_if_data *ignore);
+bool ieee80211_set_channel_type(struct ieee80211_local *local,
+                                struct ieee80211_sub_if_data *sdata,
+                                enum nl80211_channel_type chantype);
 
 #ifdef CONFIG_MAC80211_NOINLINE
 #define debug_noinline noinline
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 353b6b42d9c5..d763d76e809f 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -111,7 +111,7 @@ int ieee80211_hw_config(struct ieee80211_local *local, u32 changed)
                 channel_type = local->tmp_channel_type;
         } else {
                 chan = local->oper_channel;
-                channel_type = local->oper_channel_type;
+                channel_type = local->_oper_channel_type;
         }
 
         if (chan != local->hw.conf.channel ||
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);