1 files changed, 37 insertions, 36 deletions

diff --git a/drivers/net/wireless/iwlwifi/mvm/tx.c b/drivers/net/wireless/iwlwifi/mvm/tx.c
index 90378c217bc7..4df12fa9d336 100644
--- a/drivers/net/wireless/iwlwifi/mvm/tx.c
+++ b/drivers/net/wireless/iwlwifi/mvm/tx.c
@@ -659,8 +659,14 @@ static void iwl_mvm_rx_tx_cmd_single(struct iwl_mvm *mvm,
         rcu_read_lock();
 
         sta = rcu_dereference(mvm->fw_id_to_mac_id[sta_id]);
+        /*
+         * sta can't be NULL otherwise it'd mean that the sta has been freed in
+         * the firmware while we still have packets for it in the Tx queues.
+         */
+        if (WARN_ON_ONCE(!sta))
+                goto out;
 
-        if (!IS_ERR_OR_NULL(sta)) {
+        if (!IS_ERR(sta)) {
                 mvmsta = iwl_mvm_sta_from_mac80211(sta);
 
                 if (tid != IWL_TID_NON_QOS) {
@@ -675,7 +681,6 @@ static void iwl_mvm_rx_tx_cmd_single(struct iwl_mvm *mvm,
                         spin_unlock_bh(&mvmsta->lock);
                 }
         } else {
-                sta = NULL;
                 mvmsta = NULL;
         }
 
@@ -683,42 +688,38 @@ 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 (txq_id < 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 (!sta || PTR_ERR(sta) == -EBUSY) {
-                                /*
-                                 * 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 && PTR_ERR(sta) == -EBUSY) {
-                        /* Tx response without STA, so we are draining */
-                        set_bit(sta_id, mvm->sta_drained);
-                        schedule_work(&mvm->sta_drained_wk);
-                }
+        if (txq_id >= mvm->first_agg_queue)
+                goto out;
+
+        /* We can't free more than one frame at once on a shared queue */
+        WARN_ON(skb_freed > 1);
+
+        /* If we have still frames from this STA nothing to do here */
+        if (!atomic_sub_and_test(skb_freed, &mvm->pending_frames[sta_id]))
+                goto out;
+
+        if (mvmsta && mvmsta->vif->type == NL80211_IFTYPE_AP) {
+                /*
+                 * If there are no pending frames for this STA, notify
+                 * mac80211 that this station can go to sleep in its
+                 * STA table.
+                 * If mvmsta is not NULL, sta is valid.
+                 */
+                ieee80211_sta_block_awake(mvm->hw, sta, false);
+        }
+
+        if (PTR_ERR(sta) == -EBUSY || PTR_ERR(sta) == -ENOENT) {
+                /*
+                 * We are draining and this was the last packet - pre_rcu_remove
+                 * has been called already. We might be after the
+                 * synchronize_net already.
+                 * Don't rely on iwl_mvm_rm_sta to see the empty Tx queues.
+                 */
+                set_bit(sta_id, mvm->sta_drained);
+                schedule_work(&mvm->sta_drained_wk);
         }
 
+out:
         rcu_read_unlock();
 }