iwlwifi: mvm: fix aggregation drain flow

Move the counter for non-AMPDU frames to mvm. It is needed
for the drain flow which happens once the ieee80211_sta has
been freed, so keeping it in iwl_mvm_sta which is embed into
ieee80211_sta is not a good idea.

Also, since its purpose it to remove the STA in the fw only
after all the frames for this station have exited the shared
Tx queues, we need to decrement it in the reclaim flow. This
flow can happen after ieee80211_sta has been removed, which
means that we have no iwl_mvm_sta there. So we can't know
what is the vif type. Hence, we know audit these frames for
all the vif types.
In order to avoid spawning sta_drained_wk all the time, we
now check that we are in a flow in which draining might
happen - only when mvmsta is NULL. This is better than
previous code that would spawn sta_drained_wk all the time
in AP mode.

Cc: stable@vger.kernel.org [3.9]
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Reviewed-by: Ilan Peer <ilan.peer@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>

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

1 files changed, 36 insertions, 12 deletions

diff --git a/drivers/net/wireless/iwlwifi/mvm/tx.c b/drivers/net/wireless/iwlwifi/mvm/tx.c
index 479074303bd7..f212f16502ff 100644
--- a/drivers/net/wireless/iwlwifi/mvm/tx.c
+++ b/drivers/net/wireless/iwlwifi/mvm/tx.c
@@ -416,9 +416,8 @@ int iwl_mvm_tx_skb(struct iwl_mvm *mvm, struct sk_buff *skb,
 
         spin_unlock(&mvmsta->lock);
 
-        if (mvmsta->vif->type == NL80211_IFTYPE_AP &&
-            txq_id < IWL_MVM_FIRST_AGG_QUEUE)
-                atomic_inc(&mvmsta->pending_frames);
+        if (txq_id < IWL_MVM_FIRST_AGG_QUEUE)
+                atomic_inc(&mvm->pending_frames[mvmsta->sta_id]);
 
         return 0;
 
@@ -680,16 +679,41 @@ static void iwl_mvm_rx_tx_cmd_single(struct iwl_mvm *mvm,
         /*
          * If the txq is not an AMPDU queue, there is no chance we freed
          * several skbs. Check that out...
-         * If there are no pending frames for this STA, notify mac80211 that
-         * this station can go to sleep in its STA table.
          */
-        if (txq_id < IWL_MVM_FIRST_AGG_QUEUE && mvmsta &&
-            !WARN_ON(skb_freed > 1) &&
-            mvmsta->vif->type == NL80211_IFTYPE_AP &&
-            atomic_sub_and_test(skb_freed, &mvmsta->pending_frames)) {
-                ieee80211_sta_block_awake(mvm->hw, sta, false);
-                set_bit(sta_id, mvm->sta_drained);
-                schedule_work(&mvm->sta_drained_wk);
+        if (txq_id < IWL_MVM_FIRST_AGG_QUEUE && !WARN_ON(skb_freed > 1) &&
+            atomic_sub_and_test(skb_freed, &mvm->pending_frames[sta_id])) {
+                if (mvmsta) {
+                        /*
+                         * If there are no pending frames for this STA, notify
+                         * mac80211 that this station can go to sleep in its
+                         * STA table.
+                         */
+                        if (mvmsta->vif->type == NL80211_IFTYPE_AP)
+                                ieee80211_sta_block_awake(mvm->hw, sta, false);
+                        /*
+                         * We might very well have taken mvmsta pointer while
+                         * the station was being removed. The remove flow might
+                         * have seen a pending_frame (because we didn't take
+                         * the lock) even if now the queues are drained. So make
+                         * really sure now that this the station is not being
+                         * removed. If it is, run the drain worker to remove it.
+                         */
+                        spin_lock_bh(&mvmsta->lock);
+                        sta = rcu_dereference(mvm->fw_id_to_mac_id[sta_id]);
+                        if (IS_ERR_OR_NULL(sta)) {
+                                /*
+                                 * Station disappeared in the meantime:
+                                 * so we are draining.
+                                 */
+                                set_bit(sta_id, mvm->sta_drained);
+                                schedule_work(&mvm->sta_drained_wk);
+                        }
+                        spin_unlock_bh(&mvmsta->lock);
+                } else if (!mvmsta) {
+                        /* Tx response without STA, so we are draining */
+                        set_bit(sta_id, mvm->sta_drained);
+                        schedule_work(&mvm->sta_drained_wk);
+                }
         }
 
         rcu_read_unlock();