Merge branch 'net-dst_entry-shrink'

David Miller says:

====================
net: Significantly shrink the size of routes.

Through a combination of several things, our route structures are
larger than they need to be.

Mostly this stems from having members in dst_entry which are only used
by one class of routes.  So the majority of the work in this series is
about "un-commoning" these members and pushing them into the type
specific structures.

Unfortunately, IPSEC needed the most surgery.  The majority of the
changes here had to do with bundle creation and management.

The other issue is the refcount alignment in dst_entry.  Once we get
rid of the not-so-common members, it really opens the door to removing
that alignment entirely.

I think the new layout looks really nice, so I'll reproduce it here:

	struct net_device       *dev;
	struct  dst_ops	        *ops;
	unsigned long		_metrics;
	unsigned long           expires;
	struct xfrm_state	*xfrm;
	int			(*input)(struct sk_buff *);
	int			(*output)(struct net *net, struct sock *sk, struct sk_buff *skb);
	unsigned short		flags;
	short			obsolete;
	unsigned short		header_len;
	unsigned short		trailer_len;
	atomic_t		__refcnt;
	int			__use;
	unsigned long		lastuse;
	struct lwtunnel_state   *lwtstate;
	struct rcu_head		rcu_head;
	short			error;
	short			__pad;
	__u32			tclassid;

(This is for 64-bit, on 32-bit the __refcnt comes at the very end)

So, the good news:

1) struct dst_entry shrinks from 160 to 112 bytes.

2) struct rtable shrinks from 216 to 168 bytes.

3) struct rt6_info shrinks from 384 to 320 bytes.

Enjoy.

v2:
	Collapse some patches logically based upon feedback.
	Fix the strange patch #7.

v3:	xfrm_dst_path() needs inline keyword
	Properly align __refcnt on 32-bit.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 35 insertions, 3 deletions

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index dc28a98ce97c..1ec0c4760646 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -968,7 +968,7 @@ static inline bool xfrm_sec_ctx_match(struct xfrm_sec_ctx *s1, struct xfrm_sec_c
 
 /* A struct encoding bundle of transformations to apply to some set of flow.
  *
- * dst->child points to the next element of bundle.
+ * xdst->child points to the next element of bundle.
  * dst->xfrm  points to an instanse of transformer.
  *
  * Due to unfortunate limitations of current routing cache, which we
@@ -984,6 +984,8 @@ struct xfrm_dst {
 		struct rt6_info		rt6;
 	} u;
 	struct dst_entry *route;
+	struct dst_entry *child;
+	struct dst_entry *path;
 	struct xfrm_policy *pols[XFRM_POLICY_TYPE_MAX];
 	int num_pols, num_xfrms;
 	u32 xfrm_genid;
@@ -994,7 +996,35 @@ struct xfrm_dst {
 	u32 path_cookie;
 };
 
+static inline struct dst_entry *xfrm_dst_path(const struct dst_entry *dst)
+{
 #ifdef CONFIG_XFRM
+	if (dst->xfrm) {
+		const struct xfrm_dst *xdst = (const struct xfrm_dst *) dst;
+
+		return xdst->path;
+	}
+#endif
+	return (struct dst_entry *) dst;
+}
+
+static inline struct dst_entry *xfrm_dst_child(const struct dst_entry *dst)
+{
+#ifdef CONFIG_XFRM
+	if (dst->xfrm) {
+		struct xfrm_dst *xdst = (struct xfrm_dst *) dst;
+		return xdst->child;
+	}
+#endif
+	return NULL;
+}
+
+#ifdef CONFIG_XFRM
+static inline void xfrm_dst_set_child(struct xfrm_dst *xdst, struct dst_entry *child)
+{
+	xdst->child = child;
+}
+
 static inline void xfrm_dst_destroy(struct xfrm_dst *xdst)
 {
 	xfrm_pols_put(xdst->pols, xdst->num_pols);
@@ -1866,12 +1896,14 @@ bool xfrm_dev_offload_ok(struct sk_buff *skb, struct xfrm_state *x);
 static inline bool xfrm_dst_offload_ok(struct dst_entry *dst)
 {
 	struct xfrm_state *x = dst->xfrm;
+	struct xfrm_dst *xdst;
 
 	if (!x || !x->type_offload)
 		return false;
 
-	if (x->xso.offload_handle && (x->xso.dev == dst->path->dev) &&
-	    !dst->child->xfrm)
+	xdst = (struct xfrm_dst *) dst;
+	if (x->xso.offload_handle && (x->xso.dev == xfrm_dst_path(dst)->dev) &&
+	    !xdst->child->xfrm)
 		return true;
 
 	return false;