[PATCH 1/2] ipv6: Store ndisc_nodeid in IP6CB().

[PATCH 1/2] ipv6: Store ndisc_nodeid in IP6CB().

[David Miller]

There is no reason we need to use up space in the generic
SKB area for this.  All packet input paths in ipv6 explicitly
clear out the IP6CB() area and therefore the default value
for ndisc_nodeid will be correct.

Signed-off-by: David S. Miller <davem@davemloft.net>
---
 include/linux/ipv6.h   |    2 +-
 include/linux/skbuff.h |    9 ++-------
 net/ipv6/ndisc.c       |   11 ++++++-----
 net/ipv6/sit.c         |    9 ++++++---
 4 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index e0cc9a7..fc39add 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -247,7 +247,7 @@ struct inet6_skb_parm {
 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 	__u16			dsthao;
 #endif
-
+	__u8			ndisc_nodetype;
 #define IP6SKB_XFRM_TRANSFORMED	1
 #define IP6SKB_FORWARDED	2
 };
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 124f90c..7c16f24 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -369,14 +369,9 @@ struct sk_buff {
 #endif
 #endif
 
-	kmemcheck_bitfield_begin(flags2);
-	__u16			queue_mapping:16;
-#ifdef CONFIG_IPV6_NDISC_NODETYPE
-	__u8			ndisc_nodetype:2;
-#endif
-	kmemcheck_bitfield_end(flags2);
+	__u16			queue_mapping;
 
-	/* 0/14 bit hole */
+	/* 16 bit hole */
 
 #ifdef CONFIG_NET_DMA
 	dma_cookie_t		dma_cookie;
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index da0a4d2..e7c0897 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1134,7 +1134,7 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 	}
 
 #ifdef CONFIG_IPV6_NDISC_NODETYPE
-	if (skb->ndisc_nodetype == NDISC_NODETYPE_HOST) {
+	if (IP6CB(skb)->ndisc_nodetype == NDISC_NODETYPE_HOST) {
 		ND_PRINTK2(KERN_WARNING
 			   "ICMPv6 RA: from host or unauthorized router\n");
 		return;
@@ -1166,7 +1166,7 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 
 #ifdef CONFIG_IPV6_NDISC_NODETYPE
 	/* skip link-specific parameters from interior routers */
-	if (skb->ndisc_nodetype == NDISC_NODETYPE_NODEFAULT)
+	if (IP6CB(skb)->ndisc_nodetype == NDISC_NODETYPE_NODEFAULT)
 		goto skip_linkparms;
 #endif
 
@@ -1323,7 +1323,8 @@ skip_linkparms:
 		     p = ndisc_next_option(p, ndopts.nd_opts_ri_end)) {
 			struct route_info *ri = (struct route_info *)p;
 #ifdef CONFIG_IPV6_NDISC_NODETYPE
-			if (skb->ndisc_nodetype == NDISC_NODETYPE_NODEFAULT &&
+			if (IP6CB(skb)->ndisc_nodetype ==
+			    NDISC_NODETYPE_NODEFAULT &&
 			    ri->prefix_len == 0)
 				continue;
 #endif
@@ -1337,7 +1338,7 @@ skip_linkparms:
 
 #ifdef CONFIG_IPV6_NDISC_NODETYPE
 	/* skip link-specific ndopts from interior routers */
-	if (skb->ndisc_nodetype == NDISC_NODETYPE_NODEFAULT)
+	if (IP6CB(skb)->ndisc_nodetype == NDISC_NODETYPE_NODEFAULT)
 		goto out;
 #endif
 
@@ -1405,7 +1406,7 @@ static void ndisc_redirect_rcv(struct sk_buff *skb)
 	u8 *lladdr = NULL;
 
 #ifdef CONFIG_IPV6_NDISC_NODETYPE
-	switch (skb->ndisc_nodetype) {
+	switch (IP6CB(skb)->ndisc_nodetype) {
 	case NDISC_NODETYPE_HOST:
 	case NDISC_NODETYPE_NODEFAULT:
 		ND_PRINTK2(KERN_WARNING
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 5abae10..ac014e0 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -427,21 +427,24 @@ static int
 isatap_chksrc(struct sk_buff *skb, struct iphdr *iph, struct ip_tunnel *t)
 {
 	struct ip_tunnel_prl_entry *p;
+	struct inet6_skb_parm *cb;
 	int ok = 1;
 
+	cb = IP6CB(skb);
+
 	rcu_read_lock();
 	p = __ipip6_tunnel_locate_prl(t, iph->saddr);
 	if (p) {
 		if (p->flags & PRL_DEFAULT)
-			skb->ndisc_nodetype = NDISC_NODETYPE_DEFAULT;
+			cb->ndisc_nodetype = NDISC_NODETYPE_DEFAULT;
 		else
-			skb->ndisc_nodetype = NDISC_NODETYPE_NODEFAULT;
+			cb->ndisc_nodetype = NDISC_NODETYPE_NODEFAULT;
 	} else {
 		struct in6_addr *addr6 = &ipv6_hdr(skb)->saddr;
 		if (ipv6_addr_is_isatap(addr6) &&
 		    (addr6->s6_addr32[3] == iph->saddr) &&
 		    ipv6_chk_prefix(addr6, t->dev))
-			skb->ndisc_nodetype = NDISC_NODETYPE_HOST;
+			cb->ndisc_nodetype = NDISC_NODETYPE_HOST;
 		else
 			ok = 0;
 	}
-- 
1.7.0.4

Re: [PATCH 1/2] ipv6: Store ndisc_nodeid in IP6CB().

[Herbert Xu]

On Wed, May 19, 2010 at 07:55:36PM -0700, David Miller wrote:
> 
> There is no reason we need to use up space in the generic
> SKB area for this.  All packet input paths in ipv6 explicitly
> clear out the IP6CB() area and therefore the default value
> for ndisc_nodeid will be correct.
> 
> Signed-off-by: David S. Miller <davem@davemloft.net>

Looks good to me.  Thanks!
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [PATCH 1/2] ipv6: Store ndisc_nodeid in IP6CB().

[David Miller]

From: David Miller <davem@davemloft.net>
Date: Wed, 19 May 2010 19:55:36 -0700 (PDT)

> 
> There is no reason we need to use up space in the generic
> SKB area for this.  All packet input paths in ipv6 explicitly
> clear out the IP6CB() area and therefore the default value
> for ndisc_nodeid will be correct.
> 
> Signed-off-by: David S. Miller <davem@davemloft.net>

Turns out the patch doesn't build, because it throws the
DCCP control block beyond the skb->cb[] size of 48 bytes
with ipv6 enabled on 64-bit.

Ho hum...