mac80211: set HT channel before association

Changing the channel type during operation is
confusing to some drivers and will be hard to
handle in multi-channel scenarios. Instead of
changing the channel, set it to the right HT
channel before authenticating/associating and
don't change it -- just update the 20/40 MHz
restrictions in rate control as needed when
changed by the AP.

This also fixes a problem that Paul missed in
his fix for the "regulatory makes us deaf"
issue -- when we couldn't use 40 MHz we still
associated saying we were using 40 MHz, which
could in similarly broken APs make us never
even connect successfully.

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

3 files changed, 114 insertions, 131 deletions

diff --git a/net/mac80211/ht.c b/net/mac80211/ht.c
index f25fff7607d..9b603366943 100644
--- a/net/mac80211/ht.c
+++ b/net/mac80211/ht.c
@@ -19,15 +19,6 @@
 #include "ieee80211_i.h"
 #include "rate.h"
 
-bool ieee80111_cfg_override_disables_ht40(struct ieee80211_sub_if_data *sdata)
-{
-        const __le16 flg = cpu_to_le16(IEEE80211_HT_CAP_SUP_WIDTH_20_40);
-        if ((sdata->u.mgd.ht_capa_mask.cap_info & flg) &&
-            !(sdata->u.mgd.ht_capa.cap_info & flg))
-                return true;
-        return false;
-}
-
 static void __check_htcap_disable(struct ieee80211_sub_if_data *sdata,
                                   struct ieee80211_sta_ht_cap *ht_cap,
                                   u16 flag)
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 54f5b5b299d..a67ba7c85a1 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -379,6 +379,7 @@ enum ieee80211_sta_flags {
         IEEE80211_STA_UAPSD_ENABLED     = BIT(7),
         IEEE80211_STA_NULLFUNC_ACKED    = BIT(8),
         IEEE80211_STA_RESET_SIGNAL_AVE  = BIT(9),
+        IEEE80211_STA_DISABLE_40MHZ     = BIT(10),
 };
 
 struct ieee80211_mgd_auth_data {
@@ -511,6 +512,8 @@ struct ieee80211_if_managed {
         int rssi_min_thold, rssi_max_thold;
         int last_ave_beacon_signal;
 
+        enum nl80211_channel_type tx_chantype;
+
         struct ieee80211_ht_cap ht_capa; /* configured ht-cap over-rides */
         struct ieee80211_ht_cap ht_capa_mask; /* Valid parts of ht_capa */
 };
@@ -667,12 +670,6 @@ struct ieee80211_sub_if_data {
 
         char name[IFNAMSIZ];
 
-        /*
-         * keep track of whether the HT opmode (stored in
-         * vif.bss_info.ht_operation_mode) is valid.
-         */
-        bool ht_opmode_valid;
-
         /* to detect idle changes */
         bool old_idle;
 
@@ -1300,7 +1297,6 @@ netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb,
                                        struct net_device *dev);
 
 /* HT */
-bool ieee80111_cfg_override_disables_ht40(struct ieee80211_sub_if_data *sdata);
 void ieee80211_apply_htcap_overrides(struct ieee80211_sub_if_data *sdata,
                                      struct ieee80211_sta_ht_cap *ht_cap);
 void ieee80211_ht_cap_ie_to_sta_ht_cap(struct ieee80211_sub_if_data *sdata,
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index bb7e5189e27..30259a73195 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -171,110 +171,57 @@ static int ecw2cw(int ecw)
         return (1 << ecw) - 1;
 }
 
-/*
- * ieee80211_enable_ht should be called only after the operating band
- * has been determined as ht configuration depends on the hw's
- * HT abilities for a specific band.
- */
-static u32 ieee80211_enable_ht(struct ieee80211_sub_if_data *sdata,
-                               struct ieee80211_ht_operation *ht_oper,
-                               const u8 *bssid, u16 ap_ht_cap_flags,
-                               bool beacon_htcap_ie)
+static u32 ieee80211_config_ht_tx(struct ieee80211_sub_if_data *sdata,
+                                  struct ieee80211_ht_operation *ht_oper,
+                                  const u8 *bssid, bool reconfig)
 {
         struct ieee80211_local *local = sdata->local;
         struct ieee80211_supported_band *sband;
         struct sta_info *sta;
         u32 changed = 0;
-        int ht_cfreq;
         u16 ht_opmode;
-        bool enable_ht = true;
-        enum nl80211_channel_type prev_chantype;
-        enum nl80211_channel_type rx_channel_type = NL80211_CHAN_NO_HT;
-        enum nl80211_channel_type tx_channel_type;
+        enum nl80211_channel_type channel_type;
 
         sband = local->hw.wiphy->bands[local->hw.conf.channel->band];
-        prev_chantype = sdata->vif.bss_conf.channel_type;
+        channel_type = local->hw.conf.channel_type;
 
+        if (WARN_ON_ONCE(channel_type == NL80211_CHAN_NO_HT))
+                return 0;
 
-        ht_cfreq = ieee80211_channel_to_frequency(ht_oper->primary_chan,
-                                                  sband->band);
-        /* check that channel matches the right operating channel */
-        if (local->hw.conf.channel->center_freq != ht_cfreq) {
-                /* Some APs mess this up, evidently.
-                 * Netgear WNDR3700 sometimes reports 4 higher than
-                 * the actual channel, for instance.
-                 */
-                printk(KERN_DEBUG
-                       "%s: Wrong control channel in association"
-                       " response: configured center-freq: %d"
-                       " ht-cfreq: %d  ht->control_chan: %d"
-                       " band: %d.  Disabling HT.\n",
-                       sdata->name,
-                       local->hw.conf.channel->center_freq,
-                       ht_cfreq, ht_oper->primary_chan,
-                       sband->band);
-                enable_ht = false;
-        }
-
-        if (enable_ht) {
-                rx_channel_type = NL80211_CHAN_HT20;
-
-                if (!(ap_ht_cap_flags & IEEE80211_HT_CAP_40MHZ_INTOLERANT) &&
-                    !ieee80111_cfg_override_disables_ht40(sdata) &&
-                    (sband->ht_cap.cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40) &&
-                    (ht_oper->ht_param & IEEE80211_HT_PARAM_CHAN_WIDTH_ANY)) {
-                        switch (ht_oper->ht_param &
-                                        IEEE80211_HT_PARAM_CHA_SEC_OFFSET) {
-                        case IEEE80211_HT_PARAM_CHA_SEC_ABOVE:
-                                rx_channel_type = NL80211_CHAN_HT40PLUS;
-                                break;
-                        case IEEE80211_HT_PARAM_CHA_SEC_BELOW:
-                                rx_channel_type = NL80211_CHAN_HT40MINUS;
-                                break;
-                        }
-                }
-        }
-
-        tx_channel_type = ieee80211_get_tx_channel_type(local, rx_channel_type);
-
-        if (local->tmp_channel)
-                local->tmp_channel_type = rx_channel_type;
+        channel_type = ieee80211_get_tx_channel_type(local, channel_type);
 
-        if (!ieee80211_set_channel_type(local, sdata, rx_channel_type)) {
-                /* can only fail due to HT40+/- mismatch */
-                rx_channel_type = NL80211_CHAN_HT20;
-                WARN_ON(!ieee80211_set_channel_type(local, sdata,
-                                                    rx_channel_type));
-        }
+        /* This can change during the lifetime of the BSS */
+        if (!(ht_oper->ht_param & IEEE80211_HT_PARAM_CHAN_WIDTH_ANY))
+                channel_type = NL80211_CHAN_HT20;
 
-        if (beacon_htcap_ie && (prev_chantype != rx_channel_type)) {
-                /*
-                 * Whenever the AP announces the HT mode change that can be
-                 * 40MHz intolerant or etc., it would be safer to stop tx
-                 * queues before doing hw config to avoid buffer overflow.
-                 */
-                ieee80211_stop_queues_by_reason(&sdata->local->hw,
+        if (!reconfig || (sdata->u.mgd.tx_chantype != channel_type)) {
+                if (reconfig) {
+                        /*
+                         * Whenever the AP announces the HT mode changed
+                         * (e.g. 40 MHz intolerant) stop queues to avoid
+                         * sending out frames while the rate control is
+                         * reconfiguring.
+                         */
+                        ieee80211_stop_queues_by_reason(&sdata->local->hw,
                                 IEEE80211_QUEUE_STOP_REASON_CHTYPE_CHANGE);
 
-                /* flush out all packets */
-                synchronize_net();
-
-                drv_flush(local, false);
-        }
+                        /* flush out all packets */
+                        synchronize_net();
 
-        /* channel_type change automatically detected */
-        ieee80211_hw_config(local, 0);
+                        drv_flush(local, false);
+                }
 
-        if (prev_chantype != tx_channel_type) {
                 rcu_read_lock();
                 sta = sta_info_get(sdata, bssid);
                 if (sta)
                         rate_control_rate_update(local, sband, sta,
                                                  IEEE80211_RC_HT_CHANGED,
-                                                 tx_channel_type);
+                                                 channel_type);
                 rcu_read_unlock();
 
-                if (beacon_htcap_ie)
+                sdata->u.mgd.tx_chantype = channel_type;
+
+                if (reconfig)
                         ieee80211_wake_queues_by_reason(&sdata->local->hw,
                                 IEEE80211_QUEUE_STOP_REASON_CHTYPE_CHANGE);
         }
@@ -282,12 +229,9 @@ static u32 ieee80211_enable_ht(struct ieee80211_sub_if_data *sdata,
         ht_opmode = le16_to_cpu(ht_oper->operation_mode);
 
         /* if bss configuration changed store the new one */
-        if (sdata->ht_opmode_valid != enable_ht ||
-            sdata->vif.bss_conf.ht_operation_mode != ht_opmode ||
-            prev_chantype != rx_channel_type) {
+        if (!reconfig || (sdata->vif.bss_conf.ht_operation_mode != ht_opmode)) {
                 changed |= BSS_CHANGED_HT;
                 sdata->vif.bss_conf.ht_operation_mode = ht_opmode;
-                sdata->ht_opmode_valid = enable_ht;
         }
 
         return changed;
@@ -359,6 +303,16 @@ static void ieee80211_add_ht_ie(struct ieee80211_sub_if_data *sdata,
                 break;
         }
 
+        /*
+         * If 40 MHz was disabled associate as though we weren't
+         * capable of 40 MHz -- some broken APs will never fall
+         * back to trying to transmit in 20 MHz.
+         */
+        if (sdata->u.mgd.flags & IEEE80211_STA_DISABLE_40MHZ) {
+                cap &= ~IEEE80211_HT_CAP_SUP_WIDTH_20_40;
+                cap &= ~IEEE80211_HT_CAP_SGI_40;
+        }
+
         /* set SM PS mode properly */
         cap &= ~IEEE80211_HT_CAP_SM_PS;
         switch (smps) {
@@ -1436,7 +1390,6 @@ static void ieee80211_set_disassoc(struct ieee80211_sub_if_data *sdata,
         sdata->vif.bss_conf.assoc = false;
 
         /* on the next assoc, re-program HT parameters */
-        sdata->ht_opmode_valid = false;
         memset(&ifmgd->ht_capa, 0, sizeof(ifmgd->ht_capa));
         memset(&ifmgd->ht_capa_mask, 0, sizeof(ifmgd->ht_capa_mask));
 
@@ -2003,7 +1956,6 @@ static bool ieee80211_assoc_success(struct ieee80211_sub_if_data *sdata,
         struct ieee80211_bss_conf *bss_conf = &sdata->vif.bss_conf;
         u32 changed = 0;
         int err;
-        u16 ap_ht_cap_flags;
 
         /* AssocResp and ReassocResp have identical structure */
 
@@ -2054,8 +2006,6 @@ static bool ieee80211_assoc_success(struct ieee80211_sub_if_data *sdata,
                 ieee80211_ht_cap_ie_to_sta_ht_cap(sdata, sband,
                                 elems.ht_cap_elem, &sta->sta.ht_cap);
 
-        ap_ht_cap_flags = sta->sta.ht_cap.cap;
-
         rate_control_rate_init(sta);
 
         if (ifmgd->flags & IEEE80211_STA_MFP_ENABLED)
@@ -2097,9 +2047,8 @@ static bool ieee80211_assoc_success(struct ieee80211_sub_if_data *sdata,
 
         if (elems.ht_operation && elems.wmm_param &&
             !(ifmgd->flags & IEEE80211_STA_DISABLE_11N))
-                changed |= ieee80211_enable_ht(sdata, elems.ht_operation,
-                                               cbss->bssid, ap_ht_cap_flags,
-                                               false);
+                changed |= ieee80211_config_ht_tx(sdata, elems.ht_operation,
+                                                  cbss->bssid, false);
 
         /* set AID and assoc capability,
          * ieee80211_set_associated() will tell the driver */
@@ -2511,29 +2460,12 @@ static void ieee80211_rx_mgmt_beacon(struct ieee80211_sub_if_data *sdata,
 
         if (elems.ht_cap_elem && elems.ht_operation && elems.wmm_param &&
             !(ifmgd->flags & IEEE80211_STA_DISABLE_11N)) {
-                struct sta_info *sta;
                 struct ieee80211_supported_band *sband;
-                u16 ap_ht_cap_flags;
-
-                rcu_read_lock();
-
-                sta = sta_info_get(sdata, bssid);
-                if (WARN_ON(!sta)) {
-                        rcu_read_unlock();
-                        return;
-                }
 
                 sband = local->hw.wiphy->bands[local->hw.conf.channel->band];
 
-                ieee80211_ht_cap_ie_to_sta_ht_cap(sdata, sband,
-                                elems.ht_cap_elem, &sta->sta.ht_cap);
-
-                ap_ht_cap_flags = sta->sta.ht_cap.cap;
-
-                rcu_read_unlock();
-
-                changed |= ieee80211_enable_ht(sdata, elems.ht_operation,
-                                               bssid, ap_ht_cap_flags, true);
+                changed |= ieee80211_config_ht_tx(sdata, elems.ht_operation,
+                                                  bssid, true);
         }
 
         /* Note: country IE parsing is done for us by cfg80211 */
@@ -3065,6 +2997,11 @@ static int ieee80211_prep_connection(struct ieee80211_sub_if_data *sdata,
         struct sta_info *sta;
         bool have_sta = false;
         int err;
+        int ht_cfreq;
+        enum nl80211_channel_type channel_type = NL80211_CHAN_NO_HT;
+        const u8 *ht_oper_ie;
+        const struct ieee80211_ht_operation *ht_oper = NULL;
+        struct ieee80211_supported_band *sband;
 
         if (WARN_ON(!ifmgd->auth_data && !ifmgd->assoc_data))
                 return -EINVAL;
@@ -3086,17 +3023,76 @@ static int ieee80211_prep_connection(struct ieee80211_sub_if_data *sdata,
         mutex_unlock(&local->mtx);
 
         /* switch to the right channel */
+        sband = local->hw.wiphy->bands[cbss->channel->band];
+
+        ifmgd->flags &= ~IEEE80211_STA_DISABLE_40MHZ;
+
+        if (sband->ht_cap.ht_supported) {
+                ht_oper_ie = cfg80211_find_ie(WLAN_EID_HT_OPERATION,
+                                              cbss->information_elements,
+                                              cbss->len_information_elements);
+                if (ht_oper_ie && ht_oper_ie[1] >= sizeof(*ht_oper))
+                        ht_oper = (void *)(ht_oper_ie + 2);
+        }
+
+        if (ht_oper) {
+                ht_cfreq = ieee80211_channel_to_frequency(ht_oper->primary_chan,
+                                                          cbss->channel->band);
+                /* check that channel matches the right operating channel */
+                if (cbss->channel->center_freq != ht_cfreq) {
+                        /*
+                         * It's possible that some APs are confused here;
+                         * Netgear WNDR3700 sometimes reports 4 higher than
+                         * the actual channel in association responses, but
+                         * since we look at probe response/beacon data here
+                         * it should be OK.
+                         */
+                        printk(KERN_DEBUG
+                               "%s: Wrong control channel: center-freq: %d"
+                               " ht-cfreq: %d ht->primary_chan: %d"
+                               " band: %d. Disabling HT.\n",
+                               sdata->name, cbss->channel->center_freq,
+                               ht_cfreq, ht_oper->primary_chan,
+                               cbss->channel->band);
+                        ht_oper = NULL;
+                }
+        }
+
+        if (ht_oper) {
+                channel_type = NL80211_CHAN_HT20;
+
+                if (sband->ht_cap.cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40) {
+                        switch (ht_oper->ht_param &
+                                        IEEE80211_HT_PARAM_CHA_SEC_OFFSET) {
+                        case IEEE80211_HT_PARAM_CHA_SEC_ABOVE:
+                                channel_type = NL80211_CHAN_HT40PLUS;
+                                break;
+                        case IEEE80211_HT_PARAM_CHA_SEC_BELOW:
+                                channel_type = NL80211_CHAN_HT40MINUS;
+                                break;
+                        }
+                }
+        }
+
+        if (!ieee80211_set_channel_type(local, sdata, channel_type)) {
+                /* can only fail due to HT40+/- mismatch */
+                channel_type = NL80211_CHAN_HT20;
+                printk(KERN_DEBUG
+                       "%s: disabling 40 MHz due to multi-vif mismatch\n",
+                       sdata->name);
+                ifmgd->flags |= IEEE80211_STA_DISABLE_40MHZ;
+                WARN_ON(!ieee80211_set_channel_type(local, sdata,
+                                                    channel_type));
+        }
+
         local->oper_channel = cbss->channel;
-        ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
+        ieee80211_hw_config(local, 0);
 
         if (!have_sta) {
-                struct ieee80211_supported_band *sband;
                 u32 rates = 0, basic_rates = 0;
                 bool have_higher_than_11mbit;
                 int min_rate = INT_MAX, min_rate_index = -1;
 
-                sband = sdata->local->hw.wiphy->bands[cbss->channel->band];
-
                 ieee80211_get_rates(sband, bss->supp_rates,
                                     bss->supp_rates_len,
                                     &rates, &basic_rates,