gro: Add page frag support

This patch allows GRO to merge page frags (skb_shinfo(skb)->frags)
in one skb, rather than using the less efficient frag_list.

It also adds a new interface, napi_gro_frags to allow drivers
to inject page frags directly into the stack without allocating
an skb.  This is intended to be the GRO equivalent for LRO's
lro_receive_frags interface.

The existing GSO interface can already handle page frags with
or without an appended frag_list so nothing needs to be changed
there.

The merging itself is rather simple.  We store any new frag entries
after the last existing entry, without checking whether the first
new entry can be merged with the last existing entry.  Making this
check would actually be easy but since no existing driver can
produce contiguous frags anyway it would just be mental masturbation.

If the total number of entries would exceed the capacity of a
single skb, we simply resort to using frag_list as we do now.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 1 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 41e1224..c28bbba 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -313,10 +313,11 @@ struct napi_struct {
 #ifdef CONFIG_NETPOLL
 	spinlock_t		poll_lock;
 	int			poll_owner;
-	struct net_device	*dev;
 #endif
+	struct net_device	*dev;
 	struct list_head	dev_list;
 	struct sk_buff		*gro_list;
+	struct sk_buff		*skb;
 };
 
 enum
@@ -990,6 +991,9 @@ struct napi_gro_cb {
 
 	/* Number of segments aggregated. */
 	int count;
+
+	/* Free the skb? */
+	int free;
 };
 
 #define NAPI_GRO_CB(skb) ((struct napi_gro_cb *)(skb)->cb)
@@ -1011,6 +1015,14 @@ struct packet_type {
 	struct list_head	list;
 };
 
+struct napi_gro_fraginfo {
+	skb_frag_t frags[MAX_SKB_FRAGS];
+	unsigned int nr_frags;
+	unsigned int ip_summed;
+	unsigned int len;
+	__wsum csum;
+};
+
 #include <linux/interrupt.h>
 #include <linux/notifier.h>
 
@@ -1363,6 +1375,8 @@ extern int		netif_receive_skb(struct sk_buff *skb);
 extern void		napi_gro_flush(struct napi_struct *napi);
 extern int		napi_gro_receive(struct napi_struct *napi,
 					 struct sk_buff *skb);
+extern int		napi_gro_frags(struct napi_struct *napi,
+				       struct napi_gro_fraginfo *info);
 extern void		netif_nit_deliver(struct sk_buff *skb);
 extern int		dev_valid_name(const char *name);
 extern int		dev_ioctl(struct net *net, unsigned int cmd, void __user *);