inet: Hide route peer accesses behind helpers.

We encode the pointer(s) into an unsigned long with one state bit.

The state bit is used so we can store the inetpeer tree root to use
when resolving the peer later.

Later the peer roots will be per-FIB table, and this change works to
facilitate that.

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

4 files changed, 126 insertions, 8 deletions

diff --git a/include/net/inetpeer.h b/include/net/inetpeer.h
index b84b32f..d432489 100644
--- a/include/net/inetpeer.h
+++ b/include/net/inetpeer.h
@@ -71,6 +71,60 @@ struct inet_peer_base {
 	int			total;
 };
 
+#define INETPEER_BASE_BIT	0x1UL
+
+static inline struct inet_peer *inetpeer_ptr(unsigned long val)
+{
+	BUG_ON(val & INETPEER_BASE_BIT);
+	return (struct inet_peer *) val;
+}
+
+static inline struct inet_peer_base *inetpeer_base_ptr(unsigned long val)
+{
+	if (!(val & INETPEER_BASE_BIT))
+		return NULL;
+	val &= ~INETPEER_BASE_BIT;
+	return (struct inet_peer_base *) val;
+}
+
+static inline bool inetpeer_ptr_is_peer(unsigned long val)
+{
+	return !(val & INETPEER_BASE_BIT);
+}
+
+static inline void __inetpeer_ptr_set_peer(unsigned long *val, struct inet_peer *peer)
+{
+	/* This implicitly clears INETPEER_BASE_BIT */
+	*val = (unsigned long) peer;
+}
+
+static inline bool inetpeer_ptr_set_peer(unsigned long *ptr, struct inet_peer *peer)
+{
+	unsigned long val = (unsigned long) peer;
+	unsigned long orig = *ptr;
+
+	if (!(orig & INETPEER_BASE_BIT) || !val ||
+	    cmpxchg(ptr, orig, val) != orig)
+		return false;
+	return true;
+}
+
+static inline void inetpeer_init_ptr(unsigned long *ptr, struct inet_peer_base *base)
+{
+	*ptr = (unsigned long) base | INETPEER_BASE_BIT;
+}
+
+static inline void inetpeer_transfer_peer(unsigned long *to, unsigned long *from)
+{
+	unsigned long val = *from;
+
+	*to = val;
+	if (inetpeer_ptr_is_peer(val)) {
+		struct inet_peer *peer = inetpeer_ptr(val);
+		atomic_inc(&peer->refcnt);
+	}
+}
+
 extern void inet_peer_base_init(struct inet_peer_base *);
 
 void			inet_initpeers(void) __init;
diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 0ae759a..3ac5f15 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -107,7 +107,7 @@ struct rt6_info {
 	u32				rt6i_peer_genid;
 
 	struct inet6_dev		*rt6i_idev;
-	struct inet_peer		*rt6i_peer;
+	unsigned long			_rt6i_peer;
 
 #ifdef CONFIG_XFRM
 	u32				rt6i_flow_cache_genid;
@@ -118,6 +118,36 @@ struct rt6_info {
 	u8				rt6i_protocol;
 };
 
+static inline struct inet_peer *rt6_peer_ptr(struct rt6_info *rt)
+{
+	return inetpeer_ptr(rt->_rt6i_peer);
+}
+
+static inline bool rt6_has_peer(struct rt6_info *rt)
+{
+	return inetpeer_ptr_is_peer(rt->_rt6i_peer);
+}
+
+static inline void __rt6_set_peer(struct rt6_info *rt, struct inet_peer *peer)
+{
+	__inetpeer_ptr_set_peer(&rt->_rt6i_peer, peer);
+}
+
+static inline bool rt6_set_peer(struct rt6_info *rt, struct inet_peer *peer)
+{
+	return inetpeer_ptr_set_peer(&rt->_rt6i_peer, peer);
+}
+
+static inline void rt6_init_peer(struct rt6_info *rt, struct inet_peer_base *base)
+{
+	inetpeer_init_ptr(&rt->_rt6i_peer, base);
+}
+
+static inline void rt6_transfer_peer(struct rt6_info *rt, struct rt6_info *ort)
+{
+	inetpeer_transfer_peer(&rt->_rt6i_peer, &ort->_rt6i_peer);
+}
+
 static inline struct inet6_dev *ip6_dst_idev(struct dst_entry *dst)
 {
 	return ((struct rt6_info *)dst)->rt6i_idev;
diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 73d7502..f88a85c 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -57,11 +57,11 @@ extern void rt6_bind_peer(struct rt6_info *rt, int create);
 
 static inline struct inet_peer *__rt6_get_peer(struct rt6_info *rt, int create)
 {
-	if (rt->rt6i_peer)
-		return rt->rt6i_peer;
+	if (rt6_has_peer(rt))
+		return rt6_peer_ptr(rt);
 
 	rt6_bind_peer(rt, create);
-	return rt->rt6i_peer;
+	return rt6_peer_ptr(rt);
 }
 
 static inline struct inet_peer *rt6_get_peer(struct rt6_info *rt)
diff --git a/include/net/route.h b/include/net/route.h
index 433fc6c..6340c37 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -67,10 +67,44 @@ struct rtable {
 	/* Miscellaneous cached information */
 	__be32			rt_spec_dst; /* RFC1122 specific destination */
 	u32			rt_peer_genid;
-	struct inet_peer	*peer; /* long-living peer info */
+	unsigned long		_peer; /* long-living peer info */
 	struct fib_info		*fi; /* for client ref to shared metrics */
 };
 
+static inline struct inet_peer *rt_peer_ptr(struct rtable *rt)
+{
+	return inetpeer_ptr(rt->_peer);
+}
+
+static inline bool rt_has_peer(struct rtable *rt)
+{
+	return inetpeer_ptr_is_peer(rt->_peer);
+}
+
+static inline void __rt_set_peer(struct rtable *rt, struct inet_peer *peer)
+{
+	__inetpeer_ptr_set_peer(&rt->_peer, peer);
+}
+
+static inline bool rt_set_peer(struct rtable *rt, struct inet_peer *peer)
+{
+	return inetpeer_ptr_set_peer(&rt->_peer, peer);
+}
+
+static inline void rt_init_peer(struct rtable *rt, struct inet_peer_base *base)
+{
+	inetpeer_init_ptr(&rt->_peer, base);
+}
+
+static inline void rt_transfer_peer(struct rtable *rt, struct rtable *ort)
+{
+	rt->_peer = ort->_peer;
+	if (rt_has_peer(ort)) {
+		struct inet_peer *peer = rt_peer_ptr(ort);
+		atomic_inc(&peer->refcnt);
+	}
+}
+
 static inline bool rt_is_input_route(const struct rtable *rt)
 {
 	return rt->rt_route_iif != 0;
@@ -298,11 +332,11 @@ extern void rt_bind_peer(struct rtable *rt, __be32 daddr, int create);
 
 static inline struct inet_peer *__rt_get_peer(struct rtable *rt, __be32 daddr, int create)
 {
-	if (rt->peer)
-		return rt->peer;
+	if (rt_has_peer(rt))
+		return rt_peer_ptr(rt);
 
 	rt_bind_peer(rt, daddr, create);
-	return rt->peer;
+	return rt_peer_ptr(rt);
 }
 
 static inline struct inet_peer *rt_get_peer(struct rtable *rt, __be32 daddr)