IPoIB: Stop lying about hard_header_len and use skb->cb to stash LL addresses

Commit a0417fa3a18a ("net: Make qdisc_skb_cb upper size bound
explicit.") made it possible for a netdev driver to use skb->cb
between its header_ops.create method and its .ndo_start_xmit
method.  Use this in ipoib_hard_header() to stash away the LL address
(GID + QPN), instead of the "ipoib_pseudoheader" hack.  This allows
IPoIB to stop lying about its hard_header_len, which will let us fix
the L2 check for GRO.

Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 24 insertions, 47 deletions

diff --git a/drivers/infiniband/ulp/ipoib/ipoib.h b/drivers/infiniband/ulp/ipoib/ipoib.h
index b3cc1e062b17..86df632ea612 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib.h
+++ b/drivers/infiniband/ulp/ipoib/ipoib.h
@@ -44,6 +44,7 @@
 #include <linux/mutex.h>
 
 #include <net/neighbour.h>
+#include <net/sch_generic.h>
 
 #include <linux/atomic.h>
 
@@ -117,8 +118,9 @@ struct ipoib_header {
         u16     reserved;
 };
 
-struct ipoib_pseudoheader {
-        u8  hwaddr[INFINIBAND_ALEN];
+struct ipoib_cb {
+        struct qdisc_skb_cb     qdisc_cb;
+        u8                      hwaddr[INFINIBAND_ALEN];
 };
 
 /* Used for all multicast joins (broadcast, IPv4 mcast and IPv6 mcast) */
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c b/drivers/infiniband/ulp/ipoib/ipoib_main.c
index 3514ca05deea..3974c290b667 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_main.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c
@@ -653,7 +653,7 @@ static void ipoib_path_lookup(struct sk_buff *skb, struct neighbour *n, struct n
 }
 
 static void unicast_arp_send(struct sk_buff *skb, struct net_device *dev,
-                             struct ipoib_pseudoheader *phdr)
+                             struct ipoib_cb *cb)
 {
         struct ipoib_dev_priv *priv = netdev_priv(dev);
         struct ipoib_path *path;
@@ -661,17 +661,15 @@ static void unicast_arp_send(struct sk_buff *skb, struct net_device *dev,
 
         spin_lock_irqsave(&priv->lock, flags);
 
-        path = __path_find(dev, phdr->hwaddr + 4);
+        path = __path_find(dev, cb->hwaddr + 4);
         if (!path || !path->valid) {
                 int new_path = 0;
 
                 if (!path) {
-                        path = path_rec_create(dev, phdr->hwaddr + 4);
+                        path = path_rec_create(dev, cb->hwaddr + 4);
                         new_path = 1;
                 }
                 if (path) {
-                        /* put pseudoheader back on for next time */
-                        skb_push(skb, sizeof *phdr);
                         __skb_queue_tail(&path->queue, skb);
 
                         if (!path->query && path_rec_start(dev, path)) {
@@ -695,12 +693,10 @@ static void unicast_arp_send(struct sk_buff *skb, struct net_device *dev,
                           be16_to_cpu(path->pathrec.dlid));
 
                 spin_unlock_irqrestore(&priv->lock, flags);
-                ipoib_send(dev, skb, path->ah, IPOIB_QPN(phdr->hwaddr));
+                ipoib_send(dev, skb, path->ah, IPOIB_QPN(cb->hwaddr));
                 return;
         } else if ((path->query || !path_rec_start(dev, path)) &&
                    skb_queue_len(&path->queue) < IPOIB_MAX_PATH_REC_QUEUE) {
-                /* put pseudoheader back on for next time */
-                skb_push(skb, sizeof *phdr);
                 __skb_queue_tail(&path->queue, skb);
         } else {
                 ++dev->stats.tx_dropped;
@@ -774,16 +770,14 @@ static int ipoib_start_xmit(struct sk_buff *skb, struct net_device *dev)
                         dev_kfree_skb_any(skb);
                 }
         } else {
-                struct ipoib_pseudoheader *phdr =
-                        (struct ipoib_pseudoheader *) skb->data;
-                skb_pull(skb, sizeof *phdr);
+                struct ipoib_cb *cb = (struct ipoib_cb *) skb->cb;
 
-                if (phdr->hwaddr[4] == 0xff) {
+                if (cb->hwaddr[4] == 0xff) {
                         /* Add in the P_Key for multicast*/
-                        phdr->hwaddr[8] = (priv->pkey >> 8) & 0xff;
-                        phdr->hwaddr[9] = priv->pkey & 0xff;
+                        cb->hwaddr[8] = (priv->pkey >> 8) & 0xff;
+                        cb->hwaddr[9] = priv->pkey & 0xff;
 
-                        ipoib_mcast_send(dev, phdr->hwaddr + 4, skb);
+                        ipoib_mcast_send(dev, cb->hwaddr + 4, skb);
                 } else {
                         /* unicast GID -- should be ARP or RARP reply */
 
@@ -792,14 +786,14 @@ static int ipoib_start_xmit(struct sk_buff *skb, struct net_device *dev)
                                 ipoib_warn(priv, "Unicast, no %s: type %04x, QPN %06x %pI6\n",
                                            skb_dst(skb) ? "neigh" : "dst",
                                            be16_to_cpup((__be16 *) skb->data),
-                                           IPOIB_QPN(phdr->hwaddr),
-                                           phdr->hwaddr + 4);
+                                           IPOIB_QPN(cb->hwaddr),
+                                           cb->hwaddr + 4);
                                 dev_kfree_skb_any(skb);
                                 ++dev->stats.tx_dropped;
                                 goto unlock;
                         }
 
-                        unicast_arp_send(skb, dev, phdr);
+                        unicast_arp_send(skb, dev, cb);
                 }
         }
 unlock:
@@ -825,8 +819,6 @@ static int ipoib_hard_header(struct sk_buff *skb,
                              const void *daddr, const void *saddr, unsigned len)
 {
         struct ipoib_header *header;
-        struct dst_entry *dst;
-        struct neighbour *n;
 
         header = (struct ipoib_header *) skb_push(skb, sizeof *header);
 
@@ -834,18 +826,13 @@ static int ipoib_hard_header(struct sk_buff *skb,
         header->reserved = 0;
 
         /*
-         * If we don't have a neighbour structure, stuff the
-         * destination address onto the front of the skb so we can
-         * figure out where to send the packet later.
+         * If we don't have a dst_entry structure, stuff the
+         * destination address into skb->cb so we can figure out where
+         * to send the packet later.
          */
-        dst = skb_dst(skb);
-        n = NULL;
-        if (dst)
-                n = dst_get_neighbour_noref_raw(dst);
-        if ((!dst || !n) && daddr) {
-                struct ipoib_pseudoheader *phdr =
-                        (struct ipoib_pseudoheader *) skb_push(skb, sizeof *phdr);
-                memcpy(phdr->hwaddr, daddr, INFINIBAND_ALEN);
+        if (!skb_dst(skb)) {
+                struct ipoib_cb *cb = (struct ipoib_cb *) skb->cb;
+                memcpy(cb->hwaddr, daddr, INFINIBAND_ALEN);
         }
 
         return 0;
@@ -1021,11 +1008,7 @@ static void ipoib_setup(struct net_device *dev)
 
         dev->flags              |= IFF_BROADCAST | IFF_MULTICAST;
 
-        /*
-         * We add in INFINIBAND_ALEN to allow for the destination
-         * address "pseudoheader" for skbs without neighbour struct.
-         */
-        dev->hard_header_len     = IPOIB_ENCAP_LEN + INFINIBAND_ALEN;
+        dev->hard_header_len     = IPOIB_ENCAP_LEN;
         dev->addr_len            = INFINIBAND_ALEN;
         dev->type                = ARPHRD_INFINIBAND;
         dev->tx_queue_len        = ipoib_sendq_size * 2;
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
index f7ff9dd66cda..20ebc6fd1bb9 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
@@ -262,21 +262,13 @@ static int ipoib_mcast_join_finish(struct ipoib_mcast *mcast,
         netif_tx_lock_bh(dev);
         while (!skb_queue_empty(&mcast->pkt_queue)) {
                 struct sk_buff *skb = skb_dequeue(&mcast->pkt_queue);
-                struct dst_entry *dst = skb_dst(skb);
-                struct neighbour *n = NULL;
 
                 netif_tx_unlock_bh(dev);
 
                 skb->dev = dev;
-                if (dst)
-                        n = dst_get_neighbour_noref_raw(dst);
-                if (!dst || !n) {
-                        /* put pseudoheader back on for next time */
-                        skb_push(skb, sizeof (struct ipoib_pseudoheader));
-                }
-
                 if (dev_queue_xmit(skb))
                         ipoib_warn(priv, "dev_queue_xmit failed to requeue packet\n");
+
                 netif_tx_lock_bh(dev);
         }
         netif_tx_unlock_bh(dev);