netdev - [PATCH net-next 2/2] rtnetlink: use xarray iterator to implement rtnl_dump

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Date: Fri,  9 Feb 2024 14:56:15 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 2/2] rtnetlink: use xarray iterator to implement rtnl_dump_ifinfo()

Adopt net->dev_by_index as I did in commit 0e0939c0adf9
("net-procfs: use xarray iterator to implement /proc/net/dev")

This makes sure an existing device is always visible in the dump,
regardless of concurrent insertions/deletions.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/core/rtnetlink.c | 59 ++++++++++++++------------------------------
 1 file changed, 19 insertions(+), 40 deletions(-)

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 31f433950c8dc953bcb65cc0469f7df962314b87..68a224bbf1dd6118526329782362a4bfc192d6b1 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -2188,25 +2188,20 @@ static int rtnl_valid_dump_ifinfo_req(const struct nlmsghdr *nlh,
 
 static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
 {
+	const struct rtnl_link_ops *kind_ops = NULL;
 	struct netlink_ext_ack *extack = cb->extack;
 	const struct nlmsghdr *nlh = cb->nlh;
 	struct net *net = sock_net(skb->sk);
-	struct net *tgt_net = net;
-	int h, s_h;
-	int idx = 0, s_idx;
-	struct net_device *dev;
-	struct hlist_head *head;
+	unsigned long ifindex = cb->args[0];
+	unsigned int flags = NLM_F_MULTI;
 	struct nlattr *tb[IFLA_MAX+1];
+	struct net *tgt_net = net;
 	u32 ext_filter_mask = 0;
-	const struct rtnl_link_ops *kind_ops = NULL;
-	unsigned int flags = NLM_F_MULTI;
+	struct net_device *dev;
 	int master_idx = 0;
 	int netnsid = -1;
 	int err, i;
 
-	s_h = cb->args[0];
-	s_idx = cb->args[1];
-
 	err = rtnl_valid_dump_ifinfo_req(nlh, cb->strict_check, tb, extack);
 	if (err < 0) {
 		if (cb->strict_check)
@@ -2250,42 +2245,26 @@ static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
 		flags |= NLM_F_DUMP_FILTERED;
 
 walk_entries:
-	for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
-		idx = 0;
-		head = &tgt_net->dev_index_head[h];
-		hlist_for_each_entry(dev, head, index_hlist) {
-			if (link_dump_filtered(dev, master_idx, kind_ops))
-				goto cont;
-			if (idx < s_idx)
-				goto cont;
-			err = rtnl_fill_ifinfo(skb, dev, net,
-					       RTM_NEWLINK,
-					       NETLINK_CB(cb->skb).portid,
-					       nlh->nlmsg_seq, 0, flags,
-					       ext_filter_mask, 0, NULL, 0,
-					       netnsid, GFP_KERNEL);
-
-			if (err < 0) {
-				if (likely(skb->len))
-					goto out;
-
-				goto out_err;
-			}
-cont:
-			idx++;
-		}
-	}
-out:
 	err = skb->len;
-out_err:
-	cb->args[1] = idx;
-	cb->args[0] = h;
+	for_each_netdev_dump(tgt_net, dev, ifindex) {
+		if (link_dump_filtered(dev, master_idx, kind_ops))
+			continue;
+		err = rtnl_fill_ifinfo(skb, dev, net, RTM_NEWLINK,
+				       NETLINK_CB(cb->skb).portid,
+				       nlh->nlmsg_seq, 0, flags,
+				       ext_filter_mask, 0, NULL, 0,
+				       netnsid, GFP_KERNEL);
+
+		if (err < 0)
+			break;
+		cb->args[0] = ifindex + 1;
+	}
 	cb->seq = tgt_net->dev_base_seq;
 	nl_dump_check_consistent(cb, nlmsg_hdr(skb));
 	if (netnsid >= 0)
 		put_net(tgt_net);
 
-	return err;
+	return skb->len ?: err;
 }
 
 int rtnl_nla_parse_ifinfomsg(struct nlattr **tb, const struct nlattr *nla_peer,
-- 
2.43.0.687.g38aa6559b0-goog