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Commit 86b61a5f authored by Thomas Falcon's avatar Thomas Falcon Committed by David S. Miller
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ibmvnic: Improve TX buffer accounting 



Improve TX pool buffer accounting to prevent the producer
index from overruning the consumer. First, set the next free
index to an invalid value if it is in use. If next buffer
to be consumed is in use, drop the packet.

Finally, if the transmit fails for some other reason, roll
back the consumer index and set the free map entry to its original
value. This should also be done if the DMA map fails.

Signed-off-by: default avatarThomas Falcon <tlfalcon@linux.vnet.ibm.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 06b3e357

drivers/net/ethernet/ibm/ibmvnic.c

+21 −9
Original line number Diff line number Diff line
@@ -1426,6 +1426,16 @@ static int ibmvnic_xmit(struct sk_buff *skb, struct net_device *netdev) 


	index = tx_pool->free_map[tx_pool->consumer_index];



	if (index == IBMVNIC_INVALID_MAP) {

		dev_kfree_skb_any(skb);

		tx_send_failed++;

		tx_dropped++;

		ret = NETDEV_TX_OK;

		goto out;

	}



	tx_pool->free_map[tx_pool->consumer_index] = IBMVNIC_INVALID_MAP;



	offset = index * tx_pool->buf_size;

	dst = tx_pool->long_term_buff.buff + offset;

	memset(dst, 0, tx_pool->buf_size);
@@ -1522,7 +1532,7 @@ static int ibmvnic_xmit(struct sk_buff *skb, struct net_device *netdev) 
			tx_map_failed++;

			tx_dropped++;

			ret = NETDEV_TX_OK;

			goto out;

			goto tx_err_out;

		}

		lpar_rc = send_subcrq_indirect(adapter, handle_array[queue_num],

					       (u64)tx_buff->indir_dma,
@@ -1534,13 +1544,6 @@ static int ibmvnic_xmit(struct sk_buff *skb, struct net_device *netdev) 
	}

	if (lpar_rc != H_SUCCESS) {

		dev_err(dev, "tx failed with code %ld\n", lpar_rc);



		if (tx_pool->consumer_index == 0)

			tx_pool->consumer_index =

				tx_pool->num_buffers - 1;

		else

			tx_pool->consumer_index--;



		dev_kfree_skb_any(skb);

		tx_buff->skb = NULL;
@@ -1556,7 +1559,7 @@ static int ibmvnic_xmit(struct sk_buff *skb, struct net_device *netdev) 
		tx_send_failed++;

		tx_dropped++;

		ret = NETDEV_TX_OK;

		goto out;

		goto tx_err_out;

	}



	if (atomic_add_return(num_entries, &tx_scrq->used)
@@ -1569,7 +1572,16 @@ static int ibmvnic_xmit(struct sk_buff *skb, struct net_device *netdev) 
	tx_bytes += skb->len;

	txq->trans_start = jiffies;

	ret = NETDEV_TX_OK;

	goto out;



tx_err_out:

	/* roll back consumer index and map array*/

	if (tx_pool->consumer_index == 0)

		tx_pool->consumer_index =

			tx_pool->num_buffers - 1;

	else

		tx_pool->consumer_index--;

	tx_pool->free_map[tx_pool->consumer_index] = index;

out:

	netdev->stats.tx_dropped += tx_dropped;

	netdev->stats.tx_bytes += tx_bytes;