mac80211: ignore CSA to same channel

If the AP is confused and starts doing a CSA to the same channel,
just ignore that request instead of trying to act it out since it
was likely sent in error anyway.

In the case of the bug I was investigating the GO was misbehaving
and sending out a beacon with CSA IEs still included after having
actually done the channel switch.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

2 files changed, 14 insertions, 0 deletions

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index c0e089c194f1..8d53d65bd2ab 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -464,6 +464,7 @@ struct ieee80211_if_managed {
         unsigned int flags;
 
         bool csa_waiting_bcn;
+        bool csa_ignored_same_chan;
 
         bool beacon_crc_valid;
         u32 beacon_crc;
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index cde8cd3d6595..142f66aece18 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -1150,6 +1150,17 @@ ieee80211_sta_process_chanswitch(struct ieee80211_sub_if_data *sdata,
                 return;
         }
 
+        if (cfg80211_chandef_identical(&csa_ie.chandef,
+                                       &sdata->vif.bss_conf.chandef)) {
+                if (ifmgd->csa_ignored_same_chan)
+                        return;
+                sdata_info(sdata,
+                           "AP %pM tries to chanswitch to same channel, ignore\n",
+                           ifmgd->associated->bssid);
+                ifmgd->csa_ignored_same_chan = true;
+                return;
+        }
+
         mutex_lock(&local->mtx);
         mutex_lock(&local->chanctx_mtx);
         conf = rcu_dereference_protected(sdata->vif.chanctx_conf,
@@ -1210,6 +1221,7 @@ ieee80211_sta_process_chanswitch(struct ieee80211_sub_if_data *sdata,
         sdata->vif.csa_active = true;
         sdata->csa_chandef = csa_ie.chandef;
         sdata->csa_block_tx = csa_ie.mode;
+        ifmgd->csa_ignored_same_chan = false;
 
         if (sdata->csa_block_tx)
                 ieee80211_stop_vif_queues(local, sdata,
@@ -2090,6 +2102,7 @@ static void ieee80211_set_disassoc(struct ieee80211_sub_if_data *sdata,
 
         sdata->vif.csa_active = false;
         ifmgd->csa_waiting_bcn = false;
+        ifmgd->csa_ignored_same_chan = false;
         if (sdata->csa_block_tx) {
                 ieee80211_wake_vif_queues(local, sdata,
                                           IEEE80211_QUEUE_STOP_REASON_CSA);