rtnetlink: switch rtnl_fdb_dump() to for_each_netdev_dump()

This is the last netdev iterator still using net->dev_index_head[].

Convert to modern for_each_netdev_dump() for better scalability,
and use common patterns in our stack.

Following patch in this series removes the pad field
in struct ndo_fdb_dump_context.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20241209100747.2269613-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 35 insertions, 57 deletions

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 453cc8bf18fb..8fe252c298a2 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -4914,13 +4914,10 @@ static int rtnl_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb)
 	struct ndo_fdb_dump_context *ctx = (void *)cb->ctx;
 	struct net_device *dev, *br_dev = NULL;
 	struct net *net = sock_net(skb->sk);
-	struct hlist_head *head;
 	int brport_idx = 0;
 	int br_idx = 0;
-	int h, s_h;
-	int idx = 0, s_idx;
-	int err = 0;
 	int fidx = 0;
+	int err;
 
 	NL_ASSERT_CTX_FITS(struct ndo_fdb_dump_context);
 
@@ -4941,69 +4938,50 @@ static int rtnl_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb)
 		ops = br_dev->netdev_ops;
 	}
 
-	s_h = ctx->s_h;
-	s_idx = ctx->s_idx;
-
-	for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
-		idx = 0;
-		head = &net->dev_index_head[h];
-		hlist_for_each_entry(dev, head, index_hlist) {
-
-			if (brport_idx && (dev->ifindex != brport_idx))
-				continue;
-
-			if (!br_idx) { /* user did not specify a specific bridge */
-				if (netif_is_bridge_port(dev)) {
-					br_dev = netdev_master_upper_dev_get(dev);
-					cops = br_dev->netdev_ops;
-				}
-			} else {
-				if (dev != br_dev &&
-				    !netif_is_bridge_port(dev))
-					continue;
+	for_each_netdev_dump(net, dev, ctx->ifindex) {
+		if (brport_idx && (dev->ifindex != brport_idx))
+			continue;
 
-				if (br_dev != netdev_master_upper_dev_get(dev) &&
-				    !netif_is_bridge_master(dev))
-					continue;
-				cops = ops;
+		if (!br_idx) { /* user did not specify a specific bridge */
+			if (netif_is_bridge_port(dev)) {
+				br_dev = netdev_master_upper_dev_get(dev);
+				cops = br_dev->netdev_ops;
 			}
+		} else {
+			if (dev != br_dev &&
+			    !netif_is_bridge_port(dev))
+				continue;
 
-			if (idx < s_idx)
-				goto cont;
+			if (br_dev != netdev_master_upper_dev_get(dev) &&
+			    !netif_is_bridge_master(dev))
+				continue;
+			cops = ops;
+		}
 
-			if (netif_is_bridge_port(dev)) {
-				if (cops && cops->ndo_fdb_dump) {
-					err = cops->ndo_fdb_dump(skb, cb,
-								br_dev, dev,
-								&fidx);
-					if (err == -EMSGSIZE)
-						goto out;
-				}
+		if (netif_is_bridge_port(dev)) {
+			if (cops && cops->ndo_fdb_dump) {
+				err = cops->ndo_fdb_dump(skb, cb, br_dev, dev,
+							&fidx);
+				if (err == -EMSGSIZE)
+					break;
 			}
+		}
 
-			if (dev->netdev_ops->ndo_fdb_dump)
-				err = dev->netdev_ops->ndo_fdb_dump(skb, cb,
-								    dev, NULL,
-								    &fidx);
-			else
-				err = ndo_dflt_fdb_dump(skb, cb, dev, NULL,
-							&fidx);
-			if (err == -EMSGSIZE)
-				goto out;
+		if (dev->netdev_ops->ndo_fdb_dump)
+			err = dev->netdev_ops->ndo_fdb_dump(skb, cb, dev, NULL,
+							    &fidx);
+		else
+			err = ndo_dflt_fdb_dump(skb, cb, dev, NULL, &fidx);
+		if (err == -EMSGSIZE)
+			break;
 
-			cops = NULL;
+		cops = NULL;
 
-			/* reset fdb offset to 0 for rest of the interfaces */
-			ctx->fdb_idx = 0;
-			fidx = 0;
-cont:
-			idx++;
-		}
+		/* reset fdb offset to 0 for rest of the interfaces */
+		ctx->fdb_idx = 0;
+		fidx = 0;
 	}
 
-out:
-	ctx->s_h = h;
-	ctx->s_idx = idx;
 	ctx->fdb_idx = fidx;
 
 	return skb->len;