mac80211: fix CSA tx queue stopping

It was possible for tx queues to be stuck stopped
if AP CSA finalization failed. In that case
neither stop_ap nor do_stop woke the queues up.
This means it was impossible to perform tx at all
until driver was reloaded or a successful CSA was
performed later.

It was possible to solve this in a simpler manner
however this is more robust and future proof
(having multi-vif CSA in mind).

New sdata->csa_block_tx is introduced to keep
track of which interfaces requested tx to be
blocked for CSA. This is required because mac80211
stops all tx queues for that purpose. This means
queues must be awoken only when last tx-blocking
CSA interface is finished.

It is still possible to have tx queues stopped
after CSA failure but as soon as offending
interfaces are stopped from userspace (stop_ap or
ifdown) tx queues are woken up properly.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 28 insertions, 9 deletions

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 488826f188a7..d68e73cbdcd6 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -975,16 +975,20 @@ static void ieee80211_chswitch_work(struct work_struct *work)
         /* XXX: shouldn't really modify cfg80211-owned data! */
         ifmgd->associated->channel = sdata->csa_chandef.chan;
 
+        ieee80211_bss_info_change_notify(sdata, changed);
+
+        mutex_lock(&local->mtx);
+        sdata->vif.csa_active = false;
         /* XXX: wait for a beacon first? */
-        ieee80211_wake_queues_by_reason(&local->hw,
+        if (!ieee80211_csa_needs_block_tx(local))
+                ieee80211_wake_queues_by_reason(&local->hw,
                                         IEEE80211_MAX_QUEUE_MAP,
                                         IEEE80211_QUEUE_STOP_REASON_CSA);
+        mutex_unlock(&local->mtx);
 
-        ieee80211_bss_info_change_notify(sdata, changed);
-
- out:
-        sdata->vif.csa_active = false;
         ifmgd->flags &= ~IEEE80211_STA_CSA_RECEIVED;
+
+out:
         sdata_unlock(sdata);
 }
 
@@ -1100,12 +1104,16 @@ ieee80211_sta_process_chanswitch(struct ieee80211_sub_if_data *sdata,
         mutex_unlock(&local->chanctx_mtx);
 
         sdata->csa_chandef = csa_ie.chandef;
+
+        mutex_lock(&local->mtx);
         sdata->vif.csa_active = true;
+        sdata->csa_block_tx = csa_ie.mode;
 
-        if (csa_ie.mode)
+        if (sdata->csa_block_tx)
                 ieee80211_stop_queues_by_reason(&local->hw,
-                                IEEE80211_MAX_QUEUE_MAP,
-                                IEEE80211_QUEUE_STOP_REASON_CSA);
+                                        IEEE80211_MAX_QUEUE_MAP,
+                                        IEEE80211_QUEUE_STOP_REASON_CSA);
+        mutex_unlock(&local->mtx);
 
         if (local->ops->channel_switch) {
                 /* use driver's channel switch callback */
@@ -1817,6 +1825,12 @@ static void ieee80211_set_disassoc(struct ieee80211_sub_if_data *sdata,
         ifmgd->flags = 0;
         mutex_lock(&local->mtx);
         ieee80211_vif_release_channel(sdata);
+
+        sdata->vif.csa_active = false;
+        if (!ieee80211_csa_needs_block_tx(local))
+                ieee80211_wake_queues_by_reason(&local->hw,
+                                        IEEE80211_MAX_QUEUE_MAP,
+                                        IEEE80211_QUEUE_STOP_REASON_CSA);
         mutex_unlock(&local->mtx);
 
         sdata->encrypt_headroom = IEEE80211_ENCRYPT_HEADROOM;
@@ -2045,6 +2059,7 @@ EXPORT_SYMBOL(ieee80211_ap_probereq_get);
 
 static void __ieee80211_disconnect(struct ieee80211_sub_if_data *sdata)
 {
+        struct ieee80211_local *local = sdata->local;
         struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
         u8 frame_buf[IEEE80211_DEAUTH_FRAME_LEN];
 
@@ -2058,10 +2073,14 @@ static void __ieee80211_disconnect(struct ieee80211_sub_if_data *sdata)
                                WLAN_REASON_DISASSOC_DUE_TO_INACTIVITY,
                                true, frame_buf);
         ifmgd->flags &= ~IEEE80211_STA_CSA_RECEIVED;
+
+        mutex_lock(&local->mtx);
         sdata->vif.csa_active = false;
-        ieee80211_wake_queues_by_reason(&sdata->local->hw,
+        if (!ieee80211_csa_needs_block_tx(local))
+                ieee80211_wake_queues_by_reason(&local->hw,
                                         IEEE80211_MAX_QUEUE_MAP,
                                         IEEE80211_QUEUE_STOP_REASON_CSA);
+        mutex_unlock(&local->mtx);
 
         cfg80211_tx_mlme_mgmt(sdata->dev, frame_buf,
                               IEEE80211_DEAUTH_FRAME_LEN);