mac80211: wait for the first beacon on the new channel after CSA

Instead of immediately reopening the queues (in case of block_tx),
calling the post_channel_switch operation and sending the
notification, wait for the first beacon on the new channel.  This
makes sure that we don't lose packets if the AP/GO is not on the new
channel yet.

Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

3 files changed, 36 insertions, 13 deletions

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index a9cc49128980..78d6121eb372 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -434,6 +434,8 @@ struct ieee80211_if_managed {
 
         unsigned int flags;
 
+        bool csa_waiting_bcn;
+
         bool beacon_crc_valid;
         u32 beacon_crc;
 
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index af237223a8cd..e469b3390f2a 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -842,6 +842,8 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
         sdata_lock(sdata);
         mutex_lock(&local->mtx);
         sdata->vif.csa_active = false;
+        if (sdata->vif.type == NL80211_IFTYPE_STATION)
+                sdata->u.mgd.csa_waiting_bcn = false;
         if (sdata->csa_block_tx) {
                 ieee80211_wake_vif_queues(local, sdata,
                                           IEEE80211_QUEUE_STOP_REASON_CSA);
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index cb1a8c3bc73f..148253c1bd78 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -1001,31 +1001,44 @@ static void ieee80211_chswitch_work(struct work_struct *work)
         /* XXX: shouldn't really modify cfg80211-owned data! */
         ifmgd->associated->channel = sdata->csa_chandef.chan;
 
-        sdata->vif.csa_active = false;
+        ifmgd->csa_waiting_bcn = true;
+
+        ieee80211_sta_reset_beacon_monitor(sdata);
+        ieee80211_sta_reset_conn_monitor(sdata);
+
+out:
+        mutex_unlock(&local->chanctx_mtx);
+        mutex_unlock(&local->mtx);
+        sdata_unlock(sdata);
+}
+
+static void ieee80211_chswitch_post_beacon(struct ieee80211_sub_if_data *sdata)
+{
+        struct ieee80211_local *local = sdata->local;
+        struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
+        int ret;
+
+        sdata_assert_lock(sdata);
+
+        WARN_ON(!sdata->vif.csa_active);
 
-        /* XXX: wait for a beacon first? */
         if (sdata->csa_block_tx) {
                 ieee80211_wake_vif_queues(local, sdata,
                                           IEEE80211_QUEUE_STOP_REASON_CSA);
                 sdata->csa_block_tx = false;
         }
 
+        sdata->vif.csa_active = false;
+        ifmgd->csa_waiting_bcn = false;
+
         ret = drv_post_channel_switch(sdata);
         if (ret) {
                 sdata_info(sdata,
                            "driver post channel switch failed, disconnecting\n");
                 ieee80211_queue_work(&local->hw,
                                      &ifmgd->csa_connection_drop_work);
-                goto out;
+                return;
         }
-
-        ieee80211_sta_reset_beacon_monitor(sdata);
-        ieee80211_sta_reset_conn_monitor(sdata);
-
-out:
-        mutex_unlock(&local->chanctx_mtx);
-        mutex_unlock(&local->mtx);
-        sdata_unlock(sdata);
 }
 
 void ieee80211_chswitch_done(struct ieee80211_vif *vif, bool success)
@@ -1943,6 +1956,7 @@ static void ieee80211_set_disassoc(struct ieee80211_sub_if_data *sdata,
         ieee80211_vif_release_channel(sdata);
 
         sdata->vif.csa_active = false;
+        ifmgd->csa_waiting_bcn = false;
         if (sdata->csa_block_tx) {
                 ieee80211_wake_vif_queues(local, sdata,
                                           IEEE80211_QUEUE_STOP_REASON_CSA);
@@ -2191,6 +2205,7 @@ static void __ieee80211_disconnect(struct ieee80211_sub_if_data *sdata)
                                true, frame_buf);
         mutex_lock(&local->mtx);
         sdata->vif.csa_active = false;
+        ifmgd->csa_waiting_bcn = false;
         if (sdata->csa_block_tx) {
                 ieee80211_wake_vif_queues(local, sdata,
                                           IEEE80211_QUEUE_STOP_REASON_CSA);
@@ -3215,6 +3230,9 @@ static void ieee80211_rx_mgmt_beacon(struct ieee80211_sub_if_data *sdata,
                 }
         }
 
+        if (ifmgd->csa_waiting_bcn)
+                ieee80211_chswitch_post_beacon(sdata);
+
         if (ncrc == ifmgd->beacon_crc && ifmgd->beacon_crc_valid)
                 return;
         ifmgd->beacon_crc = ncrc;
@@ -3687,11 +3705,12 @@ static void ieee80211_sta_bcn_mon_timer(unsigned long data)
         struct ieee80211_sub_if_data *sdata =
                 (struct ieee80211_sub_if_data *) data;
         struct ieee80211_local *local = sdata->local;
+        struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
 
         if (local->quiescing)
                 return;
 
-        if (sdata->vif.csa_active)
+        if (sdata->vif.csa_active && !ifmgd->csa_waiting_bcn)
                 return;
 
         sdata->u.mgd.connection_loss = false;
@@ -3709,7 +3728,7 @@ static void ieee80211_sta_conn_mon_timer(unsigned long data)
         if (local->quiescing)
                 return;
 
-        if (sdata->vif.csa_active)
+        if (sdata->vif.csa_active && !ifmgd->csa_waiting_bcn)
                 return;
 
         ieee80211_queue_work(&local->hw, &ifmgd->monitor_work);