[PATCH 1/3 net] ibmvnic: Modify buffer size on failover

[John Allen <jallen@linux.vnet.ibm.com>]

Using newer backing devices can cause the required padding at the end of
rx buffers to change. Currently we assume that the size of buffers will
never change, but in the case that we failover from a backing device with
smaller padding requirement to a backing device with a larger padding
requirement, the vnic server will fail to post rx buffers due to
inadequate space in our rx pool. This patch fixes the issue by checking
whether or not the buffer size has changed on a reset and if it has,
reallocate the buffer.

Signed-off-by: John Allen <jallen@linux.vnet.ibm.com>
---
diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index b676fa9..5b68a28 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -412,13 +412,25 @@ static int reset_rx_pools(struct ibmvnic_adapter *adapter)
 	int rx_scrqs;
 	int i, j, rc;

+	size_array = (u64 *)((u8 *)(adapter->login_rsp_buf) +
+		be32_to_cpu(adapter->login_rsp_buf->off_rxadd_buff_size));
+
 	rx_scrqs = be32_to_cpu(adapter->login_rsp_buf->num_rxadd_subcrqs);
 	for (i = 0; i < rx_scrqs; i++) {
 		rx_pool = &adapter->rx_pool[i];

 		netdev_dbg(adapter->netdev, "Re-setting rx_pool[%d]\n", i);

-		rc = reset_long_term_buff(adapter, &rx_pool->long_term_buff);
+		if (rx_pool->buff_size != be64_to_cpu(size_array[i])) {
+			rx_pool->buff_size = be64_to_cpu(size_array[i]);
+			rc = alloc_long_term_buff(adapter,
+						  &rx_pool->long_term_buff,
+						  rx_pool->size *
+						  rx_pool->buff_size);
+		} else {
+			rc = reset_long_term_buff(adapter,
+						  &rx_pool->long_term_buff);
+		}
 		if (rc)
 			return rc;