netdev - [PATCH 2/2] ibmveth: Automatically enable larger rx buffer pools for larger mtu

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Date:	Fri, 08 Jun 2007 14:05:17 -0500
From:	Brian King <brking@...ux.vnet.ibm.com>
To:	santil@...ux.vnet.ibm.com
Cc:	rcjenn@...ux.vnet.ibm.com, netdev@...r.kernel.org,
	brking@...ux.vnet.ibm.com
Subject: [PATCH 2/2] ibmveth: Automatically enable larger rx buffer pools for larger mtu


Currently, ibmveth maintains several rx buffer pools, which can
be modified through sysfs. By default, pools are not allocated by
default such that jumbo frames cannot be supported without first
activating larger rx buffer pools. This results in failures when attempting
to change the mtu. This patch makes ibmveth automatically allocate
these larger buffer pools when the mtu is changed.

Signed-off-by: Brian King <brking@...ux.vnet.ibm.com>
---

 linux-2.6-bjking1/drivers/net/ibmveth.c |   27 +++++++++++++++++++++++----
 1 file changed, 23 insertions(+), 4 deletions(-)

diff -puN drivers/net/ibmveth.c~ibmveth_large_mtu drivers/net/ibmveth.c
--- linux-2.6/drivers/net/ibmveth.c~ibmveth_large_mtu	2007-05-16 10:47:54.000000000 -0500
+++ linux-2.6-bjking1/drivers/net/ibmveth.c	2007-05-16 10:47:54.000000000 -0500
@@ -915,17 +915,36 @@ static int ibmveth_change_mtu(struct net
 {
 	struct ibmveth_adapter *adapter = dev->priv;
 	int new_mtu_oh = new_mtu + IBMVETH_BUFF_OH;
-	int i;
+	int reinit = 0;
+	int i, rc;
 
 	if (new_mtu < IBMVETH_MAX_MTU)
 		return -EINVAL;
 
+	for (i = 0; i < IbmVethNumBufferPools; i++)
+		if (new_mtu_oh < adapter->rx_buff_pool[i].buff_size)
+			break;
+
+	if (i == IbmVethNumBufferPools)
+		return -EINVAL;
+
 	/* Look for an active buffer pool that can hold the new MTU */
 	for(i = 0; i<IbmVethNumBufferPools; i++) {
-		if (!adapter->rx_buff_pool[i].active)
-			continue;
+		if (!adapter->rx_buff_pool[i].active) {
+			adapter->rx_buff_pool[i].active = 1;
+			reinit = 1;
+		}
+
 		if (new_mtu_oh < adapter->rx_buff_pool[i].buff_size) {
-			dev->mtu = new_mtu;
+			if (reinit && netif_running(adapter->netdev)) {
+				adapter->pool_config = 1;
+				ibmveth_close(adapter->netdev);
+				adapter->pool_config = 0;
+				dev->mtu = new_mtu;
+				if ((rc = ibmveth_open(adapter->netdev)))
+					return rc;
+			} else
+				dev->mtu = new_mtu;
 			return 0;
 		}
 	}
_
-
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