net: convert some netlink netdev iterators to depend on the xarray

Reap the benefits of easier iteration thanks to the xarray.
Convert just the genetlink ones, those are easier to test.

Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Link: https://lore.kernel.org/r/20230726185530.2247698-3-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

4 files changed, 54 insertions, 122 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 32a4cdf37dd4..84c36a7f873f 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3016,6 +3016,9 @@ extern rwlock_t				dev_base_lock;		/* Device list lock */
 			if (netdev_master_upper_dev_get_rcu(slave) == (bond))
 #define net_device_entry(lh)	list_entry(lh, struct net_device, dev_list)
 
+#define for_each_netdev_dump(net, d, ifindex)				\
+	xa_for_each_start(&(net)->dev_by_index, (ifindex), (d), (ifindex))
+
 static inline struct net_device *next_net_device(struct net_device *dev)
 {
 	struct list_head *lh;
diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index 65ef4867fc49..797c813c7c77 100644
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -101,43 +101,22 @@ int netdev_nl_dev_get_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 {
 	struct net *net = sock_net(skb->sk);
 	struct net_device *netdev;
-	int idx = 0, s_idx;
-	int h, s_h;
-	int err;
-
-	s_h = cb->args[0];
-	s_idx = cb->args[1];
+	int err = 0;
 
 	rtnl_lock();
-
-	for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
-		struct hlist_head *head;
-
-		idx = 0;
-		head = &net->dev_index_head[h];
-		hlist_for_each_entry(netdev, head, index_hlist) {
-			if (idx < s_idx)
-				goto cont;
-			err = netdev_nl_dev_fill(netdev, skb,
-						 NETLINK_CB(cb->skb).portid,
-						 cb->nlh->nlmsg_seq, 0,
-						 NETDEV_CMD_DEV_GET);
-			if (err < 0)
-				break;
-cont:
-			idx++;
-		}
+	for_each_netdev_dump(net, netdev, cb->args[0]) {
+		err = netdev_nl_dev_fill(netdev, skb,
+					 NETLINK_CB(cb->skb).portid,
+					 cb->nlh->nlmsg_seq, 0,
+					 NETDEV_CMD_DEV_GET);
+		if (err < 0)
+			break;
 	}
-
 	rtnl_unlock();
 
 	if (err != -EMSGSIZE)
 		return err;
 
-	cb->args[1] = idx;
-	cb->args[0] = h;
-	cb->seq = net->dev_base_seq;
-
 	return skb->len;
 }
 
diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c
index 39a459b0111b..ae344f1b0bbd 100644
--- a/net/ethtool/netlink.c
+++ b/net/ethtool/netlink.c
@@ -252,8 +252,7 @@ int ethnl_multicast(struct sk_buff *skb, struct net_device *dev)
  * @ops:        request ops of currently processed message type
  * @req_info:   parsed request header of processed request
  * @reply_data: data needed to compose the reply
- * @pos_hash:   saved iteration position - hashbucket
- * @pos_idx:    saved iteration position - index
+ * @pos_ifindex: saved iteration position - ifindex
  *
  * These parameters are kept in struct netlink_callback as context preserved
  * between iterations. They are initialized by ethnl_default_start() and used
@@ -263,8 +262,7 @@ struct ethnl_dump_ctx {
 	const struct ethnl_request_ops	*ops;
 	struct ethnl_req_info		*req_info;
 	struct ethnl_reply_data		*reply_data;
-	int				pos_hash;
-	int				pos_idx;
+	unsigned long			pos_ifindex;
 };
 
 static const struct ethnl_request_ops *
@@ -490,55 +488,27 @@ static int ethnl_default_dumpit(struct sk_buff *skb,
 {
 	struct ethnl_dump_ctx *ctx = ethnl_dump_context(cb);
 	struct net *net = sock_net(skb->sk);
-	int s_idx = ctx->pos_idx;
-	int h, idx = 0;
+	struct net_device *dev;
 	int ret = 0;
 
 	rtnl_lock();
-	for (h = ctx->pos_hash; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
-		struct hlist_head *head;
-		struct net_device *dev;
-		unsigned int seq;
-
-		head = &net->dev_index_head[h];
-
-restart_chain:
-		seq = net->dev_base_seq;
-		cb->seq = seq;
-		idx = 0;
-		hlist_for_each_entry(dev, head, index_hlist) {
-			if (idx < s_idx)
-				goto cont;
-			dev_hold(dev);
-			rtnl_unlock();
-
-			ret = ethnl_default_dump_one(skb, dev, ctx, cb);
-			dev_put(dev);
-			if (ret < 0) {
-				if (ret == -EOPNOTSUPP)
-					goto lock_and_cont;
-				if (likely(skb->len))
-					ret = skb->len;
-				goto out;
-			}
-lock_and_cont:
-			rtnl_lock();
-			if (net->dev_base_seq != seq) {
-				s_idx = idx + 1;
-				goto restart_chain;
-			}
-cont:
-			idx++;
-		}
+	for_each_netdev_dump(net, dev, ctx->pos_ifindex) {
+		dev_hold(dev);
+		rtnl_unlock();
+
+		ret = ethnl_default_dump_one(skb, dev, ctx, cb);
+
+		rtnl_lock();
+		dev_put(dev);
 
+		if (ret < 0 && ret != -EOPNOTSUPP) {
+			if (likely(skb->len))
+				ret = skb->len;
+			break;
+		}
 	}
 	rtnl_unlock();
 
-out:
-	ctx->pos_hash = h;
-	ctx->pos_idx = idx;
-	nl_dump_check_consistent(cb, nlmsg_hdr(skb));
-
 	return ret;
 }
 
@@ -584,8 +554,7 @@ static int ethnl_default_start(struct netlink_callback *cb)
 	ctx->ops = ops;
 	ctx->req_info = req_info;
 	ctx->reply_data = reply_data;
-	ctx->pos_hash = 0;
-	ctx->pos_idx = 0;
+	ctx->pos_ifindex = 0;
 
 	return 0;
 
diff --git a/net/ethtool/tunnels.c b/net/ethtool/tunnels.c
index 67fb414ca859..05f752557b5e 100644
--- a/net/ethtool/tunnels.c
+++ b/net/ethtool/tunnels.c
@@ -212,8 +212,7 @@ err_unlock_rtnl:
 
 struct ethnl_tunnel_info_dump_ctx {
 	struct ethnl_req_info	req_info;
-	int			pos_hash;
-	int			pos_idx;
+	unsigned long		ifindex;
 };
 
 int ethnl_tunnel_info_start(struct netlink_callback *cb)
@@ -243,57 +242,39 @@ int ethnl_tunnel_info_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
 {
 	struct ethnl_tunnel_info_dump_ctx *ctx = (void *)cb->ctx;
 	struct net *net = sock_net(skb->sk);
-	int s_idx = ctx->pos_idx;
-	int h, idx = 0;
+	struct net_device *dev;
 	int ret = 0;
 	void *ehdr;
 
 	rtnl_lock();
-	cb->seq = net->dev_base_seq;
-	for (h = ctx->pos_hash; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
-		struct hlist_head *head;
-		struct net_device *dev;
-
-		head = &net->dev_index_head[h];
-		idx = 0;
-		hlist_for_each_entry(dev, head, index_hlist) {
-			if (idx < s_idx)
-				goto cont;
-
-			ehdr = ethnl_dump_put(skb, cb,
-					      ETHTOOL_MSG_TUNNEL_INFO_GET_REPLY);
-			if (!ehdr) {
-				ret = -EMSGSIZE;
-				goto out;
-			}
-
-			ret = ethnl_fill_reply_header(skb, dev, ETHTOOL_A_TUNNEL_INFO_HEADER);
-			if (ret < 0) {
-				genlmsg_cancel(skb, ehdr);
-				goto out;
-			}
-
-			ctx->req_info.dev = dev;
-			ret = ethnl_tunnel_info_fill_reply(&ctx->req_info, skb);
-			ctx->req_info.dev = NULL;
-			if (ret < 0) {
-				genlmsg_cancel(skb, ehdr);
-				if (ret == -EOPNOTSUPP)
-					goto cont;
-				goto out;
-			}
-			genlmsg_end(skb, ehdr);
-cont:
-			idx++;
+	for_each_netdev_dump(net, dev, ctx->ifindex) {
+		ehdr = ethnl_dump_put(skb, cb,
+				      ETHTOOL_MSG_TUNNEL_INFO_GET_REPLY);
+		if (!ehdr) {
+			ret = -EMSGSIZE;
+			break;
 		}
+
+		ret = ethnl_fill_reply_header(skb, dev,
+					      ETHTOOL_A_TUNNEL_INFO_HEADER);
+		if (ret < 0) {
+			genlmsg_cancel(skb, ehdr);
+			break;
+		}
+
+		ctx->req_info.dev = dev;
+		ret = ethnl_tunnel_info_fill_reply(&ctx->req_info, skb);
+		ctx->req_info.dev = NULL;
+		if (ret < 0) {
+			genlmsg_cancel(skb, ehdr);
+			if (ret == -EOPNOTSUPP)
+				continue;
+			break;
+		}
+		genlmsg_end(skb, ehdr);
 	}
-out:
 	rtnl_unlock();
 
-	ctx->pos_hash = h;
-	ctx->pos_idx = idx;
-	nl_dump_check_consistent(cb, nlmsg_hdr(skb));
-
 	if (ret == -EMSGSIZE && skb->len)
 		return skb->len;
 	return ret;