netdev - [PATCH net-next 04/13] ipv6: use xarray iterator to implement inet6_dump

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Message-ID: <20240221105915.829140-5-edumazet@google.com>
Date: Wed, 21 Feb 2024 10:59:06 +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>, Ido Schimmel <idosch@...dia.com>
Subject: [PATCH net-next 04/13] ipv6: use xarray iterator to implement inet6_dump_ifinfo()

Prepare inet6_dump_ifinfo() to run with RCU protection
instead of RTNL and use for_each_netdev_dump() interface.

Also properly return 0 at the end of a dump, avoiding
an extra recvmsg() system call and RTNL acquisition.

Note that RTNL-less dumps need core changes, yet to come.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Ido Schimmel <idosch@...dia.com>
---
 net/ipv6/addrconf.c | 46 +++++++++++++++++++--------------------------
 1 file changed, 19 insertions(+), 27 deletions(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index df3c6feea74e2d95144140eceb6df5cef2dce1f4..8994ddc6c859e6bc68303e6e61663baf330aee00 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -6117,50 +6117,42 @@ static int inet6_valid_dump_ifinfo(const struct nlmsghdr *nlh,
 static int inet6_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
 {
 	struct net *net = sock_net(skb->sk);
-	int h, s_h;
-	int idx = 0, s_idx;
+	struct {
+		unsigned long ifindex;
+	} *ctx = (void *)cb->ctx;
 	struct net_device *dev;
 	struct inet6_dev *idev;
-	struct hlist_head *head;
+	int err;
 
 	/* only requests using strict checking can pass data to
 	 * influence the dump
 	 */
 	if (cb->strict_check) {
-		int err = inet6_valid_dump_ifinfo(cb->nlh, cb->extack);
+		err = inet6_valid_dump_ifinfo(cb->nlh, cb->extack);
 
 		if (err < 0)
 			return err;
 	}
 
-	s_h = cb->args[0];
-	s_idx = cb->args[1];
-
+	err = 0;
 	rcu_read_lock();
-	for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
-		idx = 0;
-		head = &net->dev_index_head[h];
-		hlist_for_each_entry_rcu(dev, head, index_hlist) {
-			if (idx < s_idx)
-				goto cont;
-			idev = __in6_dev_get(dev);
-			if (!idev)
-				goto cont;
-			if (inet6_fill_ifinfo(skb, idev,
-					      NETLINK_CB(cb->skb).portid,
-					      cb->nlh->nlmsg_seq,
-					      RTM_NEWLINK, NLM_F_MULTI) < 0)
-				goto out;
-cont:
-			idx++;
+	for_each_netdev_dump(net, dev, ctx->ifindex) {
+		idev = __in6_dev_get(dev);
+		if (!idev)
+			continue;
+		err = inet6_fill_ifinfo(skb, idev,
+					NETLINK_CB(cb->skb).portid,
+					cb->nlh->nlmsg_seq,
+					RTM_NEWLINK, NLM_F_MULTI);
+		if (err < 0) {
+			if (likely(skb->len))
+				err = skb->len;
+			break;
 		}
 	}
-out:
 	rcu_read_unlock();
-	cb->args[1] = idx;
-	cb->args[0] = h;
 
-	return skb->len;
+	return err;
 }
 
 void inet6_ifinfo_notify(int event, struct inet6_dev *idev)
-- 
2.44.0.rc0.258.g7320e95886-goog