[PATCH (resubmit)]: fix lro_gen_skb() alignment

[PATCH (resubmit)]: fix lro_gen_skb() alignment

[Andrew Gallatin]

[-- Attachment #1: Type: text/plain, Size: 429 bytes --]


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>


[-- Attachment #2: lro_align.diff --]
[-- Type: text/plain, Size: 1566 bytes --]

diff --git a/drivers/net/myri10ge/myri10ge.c b/drivers/net/myri10ge/myri10ge.c
index 0f306dd..8def865 100644
--- a/drivers/net/myri10ge/myri10ge.c
+++ b/drivers/net/myri10ge/myri10ge.c
@@ -1979,6 +1979,7 @@ static int myri10ge_open(struct net_devi
 	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 1246d46..80335b7 100644
--- a/include/linux/inet_lro.h
+++ b/include/linux/inet_lro.h
@@ -91,6 +91,9 @@ #define LRO_F_EXTRACT_VLAN_ID 2  /* Set 
 	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 ac3b1d3..9a96c27 100644
--- a/net/ipv4/inet_lro.c
+++ b/net/ipv4/inet_lro.c
@@ -401,10 +401,11 @@ static struct sk_buff *lro_gen_skb(struc
 	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;

Re: [PATCH (resubmit)]: fix lro_gen_skb() alignment

[David Miller]

From: Andrew Gallatin <gallatin@myri.com>
Date: Tue, 04 Dec 2007 14:55:06 -0500

> 
> 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>

Applied, thanks Andrew.