ibmvnic: Keep track of supplementary TX descriptors

Supplementary TX descriptors were not being accounted for, which
was resulting in an overflow of the hardware device's transmit
queue. Keep track of those descriptors now when determining
how many entries remain on the TX queue.
Signed-off-by: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ibm/ibmvnic.c

@@ -1467,6 +1467,7 @@ static int ibmvnic_xmit(struct sk_buff *skb, struct net_device *netdev)
 	if ((*hdrs >> 7) & 1) {
 		build_hdr_descs_arr(tx_buff, &num_entries, *hdrs);
 		tx_crq.v1.n_crq_elem = num_entries;
+		tx_buff->num_entries = num_entries;
 		tx_buff->indir_arr[0] = tx_crq;
 		tx_buff->indir_dma = dma_map_single(dev, tx_buff->indir_arr,
 						    sizeof(tx_buff->indir_arr),
@@ -1515,7 +1516,7 @@ static int ibmvnic_xmit(struct sk_buff *skb, struct net_device *netdev)
 		goto out;
 	}
 
-	if (atomic_inc_return(&tx_scrq->used)
+	if (atomic_add_return(num_entries, &tx_scrq->used)
 					>= adapter->req_tx_entries_per_subcrq) {
 		netdev_info(netdev, "Stopping queue %d\n", queue_num);
 		netif_stop_subqueue(netdev, queue_num);
@@ -2468,6 +2469,7 @@ static int ibmvnic_complete_tx(struct ibmvnic_adapter *adapter,
 restart_loop:
 	while (pending_scrq(adapter, scrq)) {
 		unsigned int pool = scrq->pool_index;
+		int num_entries = 0;
 
 		next = ibmvnic_next_scrq(adapter, scrq);
 		for (i = 0; i < next->tx_comp.num_comps; i++) {
@@ -2498,6 +2500,8 @@ static int ibmvnic_complete_tx(struct ibmvnic_adapter *adapter,
 				txbuff->skb = NULL;
 			}
 
+			num_entries += txbuff->num_entries;
+
 			adapter->tx_pool[pool].free_map[adapter->tx_pool[pool].
 						     producer_index] = index;
 			adapter->tx_pool[pool].producer_index =
@@ -2507,7 +2511,7 @@ static int ibmvnic_complete_tx(struct ibmvnic_adapter *adapter,
 		/* remove tx_comp scrq*/
 		next->tx_comp.first = 0;
 
-		if (atomic_sub_return(next->tx_comp.num_comps, &scrq->used) <=
+		if (atomic_sub_return(num_entries, &scrq->used) <=
 		    (adapter->req_tx_entries_per_subcrq / 2) &&
 		    __netif_subqueue_stopped(adapter->netdev,
 					     scrq->pool_index)) {

drivers/net/ethernet/ibm/ibmvnic.h

@@ -909,6 +909,7 @@ struct ibmvnic_tx_buff {
 	union sub_crq indir_arr[6];
 	u8 hdr_data[140];
 	dma_addr_t indir_dma;
+	int num_entries;
 };
 
 struct ibmvnic_tx_pool {