[LRO]: fix lro_gen_skb() alignment

Add a field to the lro_mgr struct so that drivers can specify how much
padding is required to align layer 3 headers when a packet is copied
into a freshly allocated skb by inet_lro.c:lro_gen_skb().  Without
padding, skbs generated by LRO will cause alignment warnings on
architectures which require strict alignment (seen on sparc64).

Myri10GE is updated to use this field.

Signed-off-by: Andrew Gallatin <gallatin@myri.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 6 insertions, 1 deletions

diff --git a/drivers/net/myri10ge/myri10ge.c b/drivers/net/myri10ge/myri10ge.c
index 0f306ddb5630..8def8657251f 100644
--- a/drivers/net/myri10ge/myri10ge.c
+++ b/drivers/net/myri10ge/myri10ge.c
@@ -1979,6 +1979,7 @@ static int myri10ge_open(struct net_device *dev)
         lro_mgr->lro_arr = mgp->rx_done.lro_desc;
         lro_mgr->get_frag_header = myri10ge_get_frag_header;
         lro_mgr->max_aggr = myri10ge_lro_max_pkts;
+        lro_mgr->frag_align_pad = 2;
         if (lro_mgr->max_aggr > MAX_SKB_FRAGS)
                 lro_mgr->max_aggr = MAX_SKB_FRAGS;
 
diff --git a/include/linux/inet_lro.h b/include/linux/inet_lro.h
index 1246d46abbc0..80335b7d77c5 100644
--- a/include/linux/inet_lro.h
+++ b/include/linux/inet_lro.h
@@ -91,6 +91,9 @@ struct net_lro_mgr {
         int max_desc; /* Max number of LRO descriptors  */
         int max_aggr; /* Max number of LRO packets to be aggregated */
 
+        int frag_align_pad; /* Padding required to properly align layer 3
+                             * headers in generated skb when using frags */
+
         struct net_lro_desc *lro_arr; /* Array of LRO descriptors */
 
         /*
diff --git a/net/ipv4/inet_lro.c b/net/ipv4/inet_lro.c
index ac3b1d3dba2e..9a96c277393d 100644
--- a/net/ipv4/inet_lro.c
+++ b/net/ipv4/inet_lro.c
@@ -401,10 +401,11 @@ static struct sk_buff *lro_gen_skb(struct net_lro_mgr *lro_mgr,
         int data_len = len;
         int hdr_len = min(len, hlen);
 
-        skb = netdev_alloc_skb(lro_mgr->dev, hlen);
+        skb = netdev_alloc_skb(lro_mgr->dev, hlen + lro_mgr->frag_align_pad);
         if (!skb)
                 return NULL;
 
+        skb_reserve(skb, lro_mgr->frag_align_pad);
         skb->len = len;
         skb->data_len = len - hdr_len;
         skb->truesize += true_size;