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@@ -659,8 +659,14 @@ static void iwl_mvm_rx_tx_cmd_single(struct iwl_mvm *mvm,
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rcu_read_lock();
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sta = rcu_dereference(mvm->fw_id_to_mac_id[sta_id]);
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+ /*
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+ * sta can't be NULL otherwise it'd mean that the sta has been freed in
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+ * the firmware while we still have packets for it in the Tx queues.
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+ */
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+ if (WARN_ON_ONCE(!sta))
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+ goto out;
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- if (!IS_ERR_OR_NULL(sta)) {
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+ if (!IS_ERR(sta)) {
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mvmsta = iwl_mvm_sta_from_mac80211(sta);
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if (tid != IWL_TID_NON_QOS) {
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@@ -675,7 +681,6 @@ static void iwl_mvm_rx_tx_cmd_single(struct iwl_mvm *mvm,
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spin_unlock_bh(&mvmsta->lock);
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}
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} else {
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- sta = NULL;
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mvmsta = NULL;
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}
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@@ -683,42 +688,38 @@ static void iwl_mvm_rx_tx_cmd_single(struct iwl_mvm *mvm,
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* If the txq is not an AMPDU queue, there is no chance we freed
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* several skbs. Check that out...
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*/
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- if (txq_id < mvm->first_agg_queue && !WARN_ON(skb_freed > 1) &&
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- atomic_sub_and_test(skb_freed, &mvm->pending_frames[sta_id])) {
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- if (mvmsta) {
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- /*
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- * If there are no pending frames for this STA, notify
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- * mac80211 that this station can go to sleep in its
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- * STA table.
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- */
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- if (mvmsta->vif->type == NL80211_IFTYPE_AP)
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- ieee80211_sta_block_awake(mvm->hw, sta, false);
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- /*
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- * We might very well have taken mvmsta pointer while
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- * the station was being removed. The remove flow might
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- * have seen a pending_frame (because we didn't take
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- * the lock) even if now the queues are drained. So make
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- * really sure now that this the station is not being
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- * removed. If it is, run the drain worker to remove it.
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- */
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- spin_lock_bh(&mvmsta->lock);
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- sta = rcu_dereference(mvm->fw_id_to_mac_id[sta_id]);
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- if (!sta || PTR_ERR(sta) == -EBUSY) {
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- /*
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- * Station disappeared in the meantime:
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- * so we are draining.
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- */
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- set_bit(sta_id, mvm->sta_drained);
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- schedule_work(&mvm->sta_drained_wk);
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- }
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- spin_unlock_bh(&mvmsta->lock);
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- } else if (!mvmsta && PTR_ERR(sta) == -EBUSY) {
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- /* Tx response without STA, so we are draining */
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- set_bit(sta_id, mvm->sta_drained);
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- schedule_work(&mvm->sta_drained_wk);
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- }
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+ if (txq_id >= mvm->first_agg_queue)
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+ goto out;
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+
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+ /* We can't free more than one frame at once on a shared queue */
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+ WARN_ON(skb_freed > 1);
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+
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+ /* If we have still frames from this STA nothing to do here */
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+ if (!atomic_sub_and_test(skb_freed, &mvm->pending_frames[sta_id]))
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+ goto out;
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+
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+ if (mvmsta && mvmsta->vif->type == NL80211_IFTYPE_AP) {
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+ /*
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+ * If there are no pending frames for this STA, notify
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+ * mac80211 that this station can go to sleep in its
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+ * STA table.
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+ * If mvmsta is not NULL, sta is valid.
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+ */
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+ ieee80211_sta_block_awake(mvm->hw, sta, false);
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+ }
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+
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+ if (PTR_ERR(sta) == -EBUSY || PTR_ERR(sta) == -ENOENT) {
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+ /*
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+ * We are draining and this was the last packet - pre_rcu_remove
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+ * has been called already. We might be after the
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+ * synchronize_net already.
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+ * Don't rely on iwl_mvm_rm_sta to see the empty Tx queues.
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+ */
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+ set_bit(sta_id, mvm->sta_drained);
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+ schedule_work(&mvm->sta_drained_wk);
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}
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+out:
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rcu_read_unlock();
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}
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John W. Linville