iwlwifi: pcie: implement the overlow queue for Gen2 devices

When we enable TSO, we can have a lot of packets in the
operation mode that will be pushed to the transport
no matter what is the queue's fullness state.

To cope with that the transport can buffer those packets
and add them to the ring later when there is more room.
This implementation was missing in the Gen2 devices'
code.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>

drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c

@@ -488,6 +488,23 @@ int iwl_trans_pcie_gen2_tx(struct iwl_trans *trans, struct sk_buff *skb,
 
 	spin_lock(&txq->lock);
 
+	if (iwl_queue_space(txq) < txq->high_mark) {
+		iwl_stop_queue(trans, txq);
+
+		/* don't put the packet on the ring, if there is no room */
+		if (unlikely(iwl_queue_space(txq) < 3)) {
+			struct iwl_device_cmd **dev_cmd_ptr;
+
+			dev_cmd_ptr = (void *)((u8 *)skb->cb +
+					       trans_pcie->dev_cmd_offs);
+
+			*dev_cmd_ptr = dev_cmd;
+			__skb_queue_tail(&txq->overflow_q, skb);
+			spin_unlock(&txq->lock);
+			return 0;
+		}
+	}
+
 	idx = iwl_pcie_get_cmd_index(txq, txq->write_ptr);
 
 	/* Set up driver data for this TFD */
@@ -523,9 +540,6 @@ int iwl_trans_pcie_gen2_tx(struct iwl_trans *trans, struct sk_buff *skb,
 	/* Tell device the write index *just past* this latest filled TFD */
 	txq->write_ptr = iwl_queue_inc_wrap(txq->write_ptr);
 	iwl_pcie_gen2_txq_inc_wr_ptr(trans, txq);
-	if (iwl_queue_space(txq) < txq->high_mark)
-		iwl_stop_queue(trans, txq);
-
 	/*
 	 * At this point the frame is "transmitted" successfully
 	 * and we will get a TX status notification eventually.
@@ -957,6 +971,13 @@ void iwl_pcie_gen2_txq_unmap(struct iwl_trans *trans, int txq_id)
 			spin_unlock_irqrestore(&trans_pcie->reg_lock, flags);
 		}
 	}
+
+	while (!skb_queue_empty(&txq->overflow_q)) {
+		struct sk_buff *skb = __skb_dequeue(&txq->overflow_q);
+
+		iwl_op_mode_free_skb(trans->op_mode, skb);
+	}
+
 	spin_unlock_bh(&txq->lock);
 
 	/* just in case - this queue may have been stopped */

drivers/net/wireless/intel/iwlwifi/pcie/tx.c

@@ -1166,7 +1166,7 @@ void iwl_trans_pcie_reclaim(struct iwl_trans *trans, int txq_id, int ssn,
 			 * In that case, iwl_queue_space will be small again
 			 * and we won't wake mac80211's queue.
 			 */
-			iwl_trans_pcie_tx(trans, skb, dev_cmd_ptr, txq_id);
+			iwl_trans_tx(trans, skb, dev_cmd_ptr, txq_id);
 		}
 		spin_lock_bh(&txq->lock);