IPoIB: Handle 4K IB MTU for UD (datagram) mode

This patch enables IPoIB to use 4K UD messages (when the underlying
device and fabrics support a 4K MTU) by using two scatter buffers when
PAGE_SIZE is less than or equal to thhe HCA IB MTU size.  The first
buffer is for IPoIB header + GRH header, and the second buffer is the
IPoIB payload, which is 4K-4.

Signed-off-by: Shirley Ma <xma@us.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 14 insertions, 5 deletions

diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c b/drivers/infiniband/ulp/ipoib/ipoib_main.c
index bd07f02cf02b..7a4ed9d3d844 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_main.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c
@@ -195,7 +195,7 @@ static int ipoib_change_mtu(struct net_device *dev, int new_mtu)
                 return 0;
         }
 
-        if (new_mtu > IPOIB_PACKET_SIZE - IPOIB_ENCAP_LEN)
+        if (new_mtu > IPOIB_UD_MTU(priv->max_ib_mtu))
                 return -EINVAL;
 
         priv->admin_mtu = new_mtu;
@@ -971,10 +971,6 @@ static void ipoib_setup(struct net_device *dev)
                                     NETIF_F_LLTX                |
                                     NETIF_F_HIGHDMA);
 
-        /* MTU will be reset when mcast join happens */
-        dev->mtu                 = IPOIB_PACKET_SIZE - IPOIB_ENCAP_LEN;
-        priv->mcast_mtu          = priv->admin_mtu = dev->mtu;
-
         memcpy(dev->broadcast, ipv4_bcast_addr, INFINIBAND_ALEN);
 
         netif_carrier_off(dev);
@@ -1107,6 +1103,7 @@ static struct net_device *ipoib_add_port(const char *format,
 {
         struct ipoib_dev_priv *priv;
         struct ib_device_attr *device_attr;
+        struct ib_port_attr attr;
         int result = -ENOMEM;
 
         priv = ipoib_intf_alloc(format);
@@ -1115,6 +1112,18 @@ static struct net_device *ipoib_add_port(const char *format,
 
         SET_NETDEV_DEV(priv->dev, hca->dma_device);
 
+        if (!ib_query_port(hca, port, &attr))
+                priv->max_ib_mtu = ib_mtu_enum_to_int(attr.max_mtu);
+        else {
+                printk(KERN_WARNING "%s: ib_query_port %d failed\n",
+                       hca->name, port);
+                goto device_init_failed;
+        }
+
+        /* MTU will be reset when mcast join happens */
+        priv->dev->mtu  = IPOIB_UD_MTU(priv->max_ib_mtu);
+        priv->mcast_mtu  = priv->admin_mtu = priv->dev->mtu;
+
         result = ib_query_pkey(hca, port, 0, &priv->pkey);
         if (result) {
                 printk(KERN_WARNING "%s: ib_query_pkey port %d failed (ret = %d)\n",