rhashtable: Convert bucket iterators to take table and index

This patch is in preparation to introduce per bucket spinlocks. It
extends all iterator macros to take the bucket table and bucket
index. It also introduces a new rht_dereference_bucket() to
handle protected accesses to buckets.

It introduces a barrier() to the RCU iterators to the prevent
the compiler from caching the first element.

The lockdep verifier is introduced as stub which always succeeds
and properly implement in the next patch when the locks are
introduced.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netfilter/nft_hash.c b/net/netfilter/nft_hash.c
index 614ee09..d93f1f4 100644
--- a/net/netfilter/nft_hash.c
+++ b/net/netfilter/nft_hash.c
@@ -142,7 +142,9 @@
 
 	tbl = rht_dereference_rcu(priv->tbl, priv);
 	for (i = 0; i < tbl->size; i++) {
-		rht_for_each_entry_rcu(he, tbl->buckets[i], node) {
+		struct rhash_head *pos;
+
+		rht_for_each_entry_rcu(he, pos, tbl, i, node) {
 			if (iter->count < iter->skip)
 				goto cont;
 
@@ -197,15 +199,13 @@
 {
 	const struct rhashtable *priv = nft_set_priv(set);
 	const struct bucket_table *tbl = priv->tbl;
-	struct nft_hash_elem *he, *next;
+	struct nft_hash_elem *he;
+	struct rhash_head *pos, *next;
 	unsigned int i;
 
 	for (i = 0; i < tbl->size; i++) {
-		for (he = rht_entry(tbl->buckets[i], struct nft_hash_elem, node);
-		     he != NULL; he = next) {
-			next = rht_entry(he->node.next, struct nft_hash_elem, node);
+		rht_for_each_entry_safe(he, pos, next, tbl, i, node)
 			nft_hash_elem_destroy(set, he);
-		}
 	}
 	rhashtable_destroy(priv);
 }
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index a5d7ed6..57449b6 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2898,7 +2898,9 @@
 		const struct bucket_table *tbl = rht_dereference_rcu(ht->tbl, ht);
 
 		for (j = 0; j < tbl->size; j++) {
-			rht_for_each_entry_rcu(nlk, tbl->buckets[j], node) {
+			struct rhash_head *node;
+
+			rht_for_each_entry_rcu(nlk, node, tbl, j, node) {
 				s = (struct sock *)nlk;
 
 				if (sock_net(s) != seq_file_net(seq))
@@ -2926,6 +2928,8 @@
 static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 {
 	struct rhashtable *ht;
+	const struct bucket_table *tbl;
+	struct rhash_head *node;
 	struct netlink_sock *nlk;
 	struct nl_seq_iter *iter;
 	struct net *net;
@@ -2942,17 +2946,17 @@
 
 	i = iter->link;
 	ht = &nl_table[i].hash;
-	rht_for_each_entry(nlk, nlk->node.next, ht, node)
+	tbl = rht_dereference_rcu(ht->tbl, ht);
+	rht_for_each_entry_rcu_continue(nlk, node, nlk->node.next, tbl, iter->hash_idx, node)
 		if (net_eq(sock_net((struct sock *)nlk), net))
 			return nlk;
 
 	j = iter->hash_idx + 1;
 
 	do {
-		const struct bucket_table *tbl = rht_dereference_rcu(ht->tbl, ht);
 
 		for (; j < tbl->size; j++) {
-			rht_for_each_entry(nlk, tbl->buckets[j], ht, node) {
+			rht_for_each_entry_rcu(nlk, node, tbl, j, node) {
 				if (net_eq(sock_net((struct sock *)nlk), net)) {
 					iter->link = i;
 					iter->hash_idx = j;
diff --git a/net/netlink/diag.c b/net/netlink/diag.c
index de8c74a..fcca36d 100644
--- a/net/netlink/diag.c
+++ b/net/netlink/diag.c
@@ -113,7 +113,9 @@
 	req = nlmsg_data(cb->nlh);
 
 	for (i = 0; i < htbl->size; i++) {
-		rht_for_each_entry(nlsk, htbl->buckets[i], ht, node) {
+		struct rhash_head *pos;
+
+		rht_for_each_entry(nlsk, pos, htbl, i, node) {
 			sk = (struct sock *)nlsk;
 
 			if (!net_eq(sock_net(sk), net))