sctp: add the rhashtable apis for sctp global transport hashtable

tranport hashtbale will replace the association hashtable to do the
lookup for transport, and then get association by t->assoc, rhashtable
apis will be used because of it's resizable, scalable and using rcu.

lport + rport + paddr will be the base hashkey to locate the chain,
with net to protect one netns from another, then plus the laddr to
compare to get the target.

this patch will provider the lookup functions:
- sctp_epaddr_lookup_transport
- sctp_addrs_lookup_transport

hash/unhash functions:
- sctp_hash_transport
- sctp_unhash_transport

init/destroy functions:
- sctp_transport_hashtable_init
- sctp_transport_hashtable_destroy

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sctp/sctp.h

@@ -143,6 +143,17 @@ void sctp_icmp_proto_unreachable(struct sock *sk,
 				 struct sctp_transport *t);
 void sctp_backlog_migrate(struct sctp_association *assoc,
 			  struct sock *oldsk, struct sock *newsk);
+int sctp_transport_hashtable_init(void);
+void sctp_transport_hashtable_destroy(void);
+void sctp_hash_transport(struct sctp_transport *t);
+void sctp_unhash_transport(struct sctp_transport *t);
+struct sctp_transport *sctp_addrs_lookup_transport(
+				struct net *net,
+				const union sctp_addr *laddr,
+				const union sctp_addr *paddr);
+struct sctp_transport *sctp_epaddr_lookup_transport(
+				const struct sctp_endpoint *ep,
+				const union sctp_addr *paddr);
 
 /*
  * sctp/proc.c

include/net/sctp/structs.h

@@ -48,6 +48,7 @@
 #define __sctp_structs_h__
 
 #include <linux/ktime.h>
+#include <linux/rhashtable.h>
 #include <linux/socket.h>	/* linux/in.h needs this!!    */
 #include <linux/in.h>		/* We get struct sockaddr_in. */
 #include <linux/in6.h>		/* We get struct in6_addr     */
@@ -123,6 +124,8 @@ extern struct sctp_globals {
 	struct sctp_hashbucket *assoc_hashtable;
 	/* This is the sctp port control hash.	*/
 	struct sctp_bind_hashbucket *port_hashtable;
+	/* This is the hash of all transports. */
+	struct rhashtable transport_hashtable;
 
 	/* Sizes of above hashtables. */
 	int ep_hashsize;
@@ -147,6 +150,7 @@ extern struct sctp_globals {
 #define sctp_assoc_hashtable		(sctp_globals.assoc_hashtable)
 #define sctp_port_hashsize		(sctp_globals.port_hashsize)
 #define sctp_port_hashtable		(sctp_globals.port_hashtable)
+#define sctp_transport_hashtable	(sctp_globals.transport_hashtable)
 #define sctp_checksum_disable		(sctp_globals.checksum_disable)
 
 /* SCTP Socket type: UDP or TCP style. */
@@ -753,6 +757,7 @@ static inline int sctp_packet_empty(struct sctp_packet *packet)
 struct sctp_transport {
 	/* A list of transports. */
 	struct list_head transports;
+	struct rhash_head node;
 
 	/* Reference counting. */
 	atomic_t refcnt;

net/sctp/input.c

@@ -782,6 +782,137 @@ static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(struct net *net,
 	return ep;
 }
 
+/* rhashtable for transport */
+struct sctp_hash_cmp_arg {
+	const union sctp_addr		*laddr;
+	const union sctp_addr		*paddr;
+	const struct net		*net;
+};
+
+static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg,
+				const void *ptr)
+{
+	const struct sctp_hash_cmp_arg *x = arg->key;
+	const struct sctp_transport *t = ptr;
+	struct sctp_association *asoc = t->asoc;
+	const struct net *net = x->net;
+
+	if (x->laddr->v4.sin_port != htons(asoc->base.bind_addr.port))
+		return 1;
+	if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr))
+		return 1;
+	if (!net_eq(sock_net(asoc->base.sk), net))
+		return 1;
+	if (!sctp_bind_addr_match(&asoc->base.bind_addr,
+				  x->laddr, sctp_sk(asoc->base.sk)))
+		return 1;
+
+	return 0;
+}
+
+static inline u32 sctp_hash_obj(const void *data, u32 len, u32 seed)
+{
+	const struct sctp_transport *t = data;
+	const union sctp_addr *paddr = &t->ipaddr;
+	const struct net *net = sock_net(t->asoc->base.sk);
+	u16 lport = htons(t->asoc->base.bind_addr.port);
+	u32 addr;
+
+	if (paddr->sa.sa_family == AF_INET6)
+		addr = jhash(&paddr->v6.sin6_addr, 16, seed);
+	else
+		addr = paddr->v4.sin_addr.s_addr;
+
+	return  jhash_3words(addr, ((__u32)paddr->v4.sin_port) << 16 |
+			     (__force __u32)lport, net_hash_mix(net), seed);
+}
+
+static inline u32 sctp_hash_key(const void *data, u32 len, u32 seed)
+{
+	const struct sctp_hash_cmp_arg *x = data;
+	const union sctp_addr *paddr = x->paddr;
+	const struct net *net = x->net;
+	u16 lport = x->laddr->v4.sin_port;
+	u32 addr;
+
+	if (paddr->sa.sa_family == AF_INET6)
+		addr = jhash(&paddr->v6.sin6_addr, 16, seed);
+	else
+		addr = paddr->v4.sin_addr.s_addr;
+
+	return  jhash_3words(addr, ((__u32)paddr->v4.sin_port) << 16 |
+			     (__force __u32)lport, net_hash_mix(net), seed);
+}
+
+static const struct rhashtable_params sctp_hash_params = {
+	.head_offset		= offsetof(struct sctp_transport, node),
+	.hashfn			= sctp_hash_key,
+	.obj_hashfn		= sctp_hash_obj,
+	.obj_cmpfn		= sctp_hash_cmp,
+	.automatic_shrinking	= true,
+};
+
+int sctp_transport_hashtable_init(void)
+{
+	return rhashtable_init(&sctp_transport_hashtable, &sctp_hash_params);
+}
+
+void sctp_transport_hashtable_destroy(void)
+{
+	rhashtable_destroy(&sctp_transport_hashtable);
+}
+
+void sctp_hash_transport(struct sctp_transport *t)
+{
+	struct sctp_sockaddr_entry *addr;
+	struct sctp_hash_cmp_arg arg;
+
+	addr = list_entry(t->asoc->base.bind_addr.address_list.next,
+			  struct sctp_sockaddr_entry, list);
+	arg.laddr = &addr->a;
+	arg.paddr = &t->ipaddr;
+	arg.net   = sock_net(t->asoc->base.sk);
+
+reinsert:
+	if (rhashtable_lookup_insert_key(&sctp_transport_hashtable, &arg,
+					 &t->node, sctp_hash_params) == -EBUSY)
+		goto reinsert;
+}
+
+void sctp_unhash_transport(struct sctp_transport *t)
+{
+	rhashtable_remove_fast(&sctp_transport_hashtable, &t->node,
+			       sctp_hash_params);
+}
+
+struct sctp_transport *sctp_addrs_lookup_transport(
+				struct net *net,
+				const union sctp_addr *laddr,
+				const union sctp_addr *paddr)
+{
+	struct sctp_hash_cmp_arg arg = {
+		.laddr = laddr,
+		.paddr = paddr,
+		.net   = net,
+	};
+
+	return rhashtable_lookup_fast(&sctp_transport_hashtable, &arg,
+				      sctp_hash_params);
+}
+
+struct sctp_transport *sctp_epaddr_lookup_transport(
+				const struct sctp_endpoint *ep,
+				const union sctp_addr *paddr)
+{
+	struct sctp_sockaddr_entry *addr;
+	struct net *net = sock_net(ep->base.sk);
+
+	addr = list_entry(ep->base.bind_addr.address_list.next,
+			  struct sctp_sockaddr_entry, list);
+
+	return sctp_addrs_lookup_transport(net, &addr->a, paddr);
+}
+
 /* Insert association into the hash table.  */
 static void __sctp_hash_established(struct sctp_association *asoc)
 {