l2tp: use get_next APIs for management requests and procfs/debugfs

l2tp netlink and procfs/debugfs iterate over tunnel and session lists
to obtain data. They currently use very inefficient get_nth functions
to do so. Replace these with get_next.

For netlink, use nl cb->ctx[] for passing state instead of the
obsolete cb->args[].

l2tp_tunnel_get_nth and l2tp_session_get_nth are no longer used so
they can be removed.
Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/l2tp/l2tp_core.c

@@ -241,27 +241,6 @@ struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id)
 }
 EXPORT_SYMBOL_GPL(l2tp_tunnel_get);
 
-struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth)
-{
-	struct l2tp_net *pn = l2tp_pernet(net);
-	unsigned long tunnel_id, tmp;
-	struct l2tp_tunnel *tunnel;
-	int count = 0;
-
-	rcu_read_lock_bh();
-	idr_for_each_entry_ul(&pn->l2tp_tunnel_idr, tunnel, tmp, tunnel_id) {
-		if (tunnel && ++count > nth &&
-		    refcount_inc_not_zero(&tunnel->ref_count)) {
-			rcu_read_unlock_bh();
-			return tunnel;
-		}
-	}
-	rcu_read_unlock_bh();
-
-	return NULL;
-}
-EXPORT_SYMBOL_GPL(l2tp_tunnel_get_nth);
-
 struct l2tp_tunnel *l2tp_tunnel_get_next(const struct net *net, unsigned long *key)
 {
 	struct l2tp_net *pn = l2tp_pernet(net);
@@ -355,25 +334,6 @@ struct l2tp_session *l2tp_session_get(const struct net *net, struct sock *sk, in
 }
 EXPORT_SYMBOL_GPL(l2tp_session_get);
 
-struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth)
-{
-	struct l2tp_session *session;
-	int count = 0;
-
-	rcu_read_lock_bh();
-	list_for_each_entry_rcu(session, &tunnel->session_list, list) {
-		if (++count > nth) {
-			l2tp_session_inc_refcount(session);
-			rcu_read_unlock_bh();
-			return session;
-		}
-	}
-	rcu_read_unlock_bh();
-
-	return NULL;
-}
-EXPORT_SYMBOL_GPL(l2tp_session_get_nth);
-
 static struct l2tp_session *l2tp_v2_session_get_next(const struct net *net,
 						     u16 tid,
 						     unsigned long *key)

net/l2tp/l2tp_core.h

@@ -219,14 +219,12 @@ void l2tp_session_dec_refcount(struct l2tp_session *session);
  * the caller must ensure that the reference is dropped appropriately.
  */
 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id);
-struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth);
 struct l2tp_tunnel *l2tp_tunnel_get_next(const struct net *net, unsigned long *key);
 
 struct l2tp_session *l2tp_v3_session_get(const struct net *net, struct sock *sk, u32 session_id);
 struct l2tp_session *l2tp_v2_session_get(const struct net *net, u16 tunnel_id, u16 session_id);
 struct l2tp_session *l2tp_session_get(const struct net *net, struct sock *sk, int pver,
 				      u32 tunnel_id, u32 session_id);
-struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth);
 struct l2tp_session *l2tp_session_get_next(const struct net *net, struct sock *sk, int pver,
 					   u32 tunnel_id, unsigned long *key);
 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,

net/l2tp/l2tp_debugfs.c

@@ -34,8 +34,8 @@ static struct dentry *rootdir;
 struct l2tp_dfs_seq_data {
 	struct net	*net;
 	netns_tracker	ns_tracker;
-	int tunnel_idx;			/* current tunnel */
-	int session_idx;		/* index of session within current tunnel */
+	unsigned long tkey;		/* lookup key of current tunnel */
+	unsigned long skey;		/* lookup key of current session */
 	struct l2tp_tunnel *tunnel;
 	struct l2tp_session *session;	/* NULL means get next tunnel */
 };
@@ -46,8 +46,8 @@ static void l2tp_dfs_next_tunnel(struct l2tp_dfs_seq_data *pd)
 	if (pd->tunnel)
 		l2tp_tunnel_dec_refcount(pd->tunnel);
 
-	pd->tunnel = l2tp_tunnel_get_nth(pd->net, pd->tunnel_idx);
-	pd->tunnel_idx++;
+	pd->tunnel = l2tp_tunnel_get_next(pd->net, &pd->tkey);
+	pd->tkey++;
 }
 
 static void l2tp_dfs_next_session(struct l2tp_dfs_seq_data *pd)
@@ -56,11 +56,13 @@ static void l2tp_dfs_next_session(struct l2tp_dfs_seq_data *pd)
 	if (pd->session)
 		l2tp_session_dec_refcount(pd->session);
 
-	pd->session = l2tp_session_get_nth(pd->tunnel, pd->session_idx);
-	pd->session_idx++;
+	pd->session = l2tp_session_get_next(pd->net, pd->tunnel->sock,
+					    pd->tunnel->version,
+					    pd->tunnel->tunnel_id, &pd->skey);
+	pd->skey++;
 
 	if (!pd->session) {
-		pd->session_idx = 0;
+		pd->skey = 0;
 		l2tp_dfs_next_tunnel(pd);
 	}
 }

net/l2tp/l2tp_netlink.c

@@ -491,14 +491,20 @@ static int l2tp_nl_cmd_tunnel_get(struct sk_buff *skb, struct genl_info *info)
 	return ret;
 }
 
+struct l2tp_nl_cb_data {
+	unsigned long tkey;
+	unsigned long skey;
+};
+
 static int l2tp_nl_cmd_tunnel_dump(struct sk_buff *skb, struct netlink_callback *cb)
 {
-	int ti = cb->args[0];
+	struct l2tp_nl_cb_data *cbd = (void *)&cb->ctx[0];
+	unsigned long key = cbd->tkey;
 	struct l2tp_tunnel *tunnel;
 	struct net *net = sock_net(skb->sk);
 
 	for (;;) {
-		tunnel = l2tp_tunnel_get_nth(net, ti);
+		tunnel = l2tp_tunnel_get_next(net, &key);
 		if (!tunnel)
 			goto out;
 
@@ -510,11 +516,11 @@ static int l2tp_nl_cmd_tunnel_dump(struct sk_buff *skb, struct netlink_callback
 		}
 		l2tp_tunnel_dec_refcount(tunnel);
 
-		ti++;
+		key++;
 	}
 
 out:
-	cb->args[0] = ti;
+	cbd->tkey = key;
 
 	return skb->len;
 }
@@ -832,25 +838,27 @@ static int l2tp_nl_cmd_session_get(struct sk_buff *skb, struct genl_info *info)
 
 static int l2tp_nl_cmd_session_dump(struct sk_buff *skb, struct netlink_callback *cb)
 {
+	struct l2tp_nl_cb_data *cbd = (void *)&cb->ctx[0];
 	struct net *net = sock_net(skb->sk);
 	struct l2tp_session *session;
 	struct l2tp_tunnel *tunnel = NULL;
-	int ti = cb->args[0];
-	int si = cb->args[1];
+	unsigned long tkey = cbd->tkey;
+	unsigned long skey = cbd->skey;
 
 	for (;;) {
 		if (!tunnel) {
-			tunnel = l2tp_tunnel_get_nth(net, ti);
+			tunnel = l2tp_tunnel_get_next(net, &tkey);
 			if (!tunnel)
 				goto out;
 		}
 
-		session = l2tp_session_get_nth(tunnel, si);
+		session = l2tp_session_get_next(net, tunnel->sock, tunnel->version,
+						tunnel->tunnel_id, &skey);
 		if (!session) {
-			ti++;
+			tkey++;
 			l2tp_tunnel_dec_refcount(tunnel);
 			tunnel = NULL;
-			si = 0;
+			skey = 0;
 			continue;
 		}
 
@@ -863,12 +871,12 @@ static int l2tp_nl_cmd_session_dump(struct sk_buff *skb, struct netlink_callback
 		}
 		l2tp_session_dec_refcount(session);
 
-		si++;
+		skey++;
 	}
 
 out:
-	cb->args[0] = ti;
-	cb->args[1] = si;
+	cbd->tkey = tkey;
+	cbd->skey = skey;
 
 	return skb->len;
 }

net/l2tp/l2tp_ppp.c

@@ -1397,8 +1397,8 @@ static int pppol2tp_getsockopt(struct socket *sock, int level, int optname,
 
 struct pppol2tp_seq_data {
 	struct seq_net_private p;
-	int tunnel_idx;			/* current tunnel */
-	int session_idx;		/* index of session within current tunnel */
+	unsigned long tkey;		/* lookup key of current tunnel */
+	unsigned long skey;		/* lookup key of current session */
 	struct l2tp_tunnel *tunnel;
 	struct l2tp_session *session;	/* NULL means get next tunnel */
 };
@@ -1410,8 +1410,8 @@ static void pppol2tp_next_tunnel(struct net *net, struct pppol2tp_seq_data *pd)
 		l2tp_tunnel_dec_refcount(pd->tunnel);
 
 	for (;;) {
-		pd->tunnel = l2tp_tunnel_get_nth(net, pd->tunnel_idx);
-		pd->tunnel_idx++;
+		pd->tunnel = l2tp_tunnel_get_next(net, &pd->tkey);
+		pd->tkey++;
 
 		/* Only accept L2TPv2 tunnels */
 		if (!pd->tunnel || pd->tunnel->version == 2)
@@ -1427,11 +1427,13 @@ static void pppol2tp_next_session(struct net *net, struct pppol2tp_seq_data *pd)
 	if (pd->session)
 		l2tp_session_dec_refcount(pd->session);
 
-	pd->session = l2tp_session_get_nth(pd->tunnel, pd->session_idx);
-	pd->session_idx++;
+	pd->session = l2tp_session_get_next(net, pd->tunnel->sock,
+					    pd->tunnel->version,
+					    pd->tunnel->tunnel_id, &pd->skey);
+	pd->skey++;
 
 	if (!pd->session) {
-		pd->session_idx = 0;
+		pd->skey = 0;
 		pppol2tp_next_tunnel(net, pd);
 	}
 }