[net-next,6/6] ibmvnic: Improve TX buffer accounting

Message ID 1520987663-26056-7-git-send-email-tlfalcon@linux.vnet.ibm.com
State Changes Requested
Delegated to: David Miller
Headers show
Series
  • ibmvnic: Update TX pool and TX routines
Related show

Commit Message

Thomas Falcon March 14, 2018, 12:34 a.m.
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: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
---
 drivers/net/ethernet/ibm/ibmvnic.c | 30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

Patch

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index 3b752e3..f599dad 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -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;