netdev - [PATCH net-next 1/2] vlan: use xarray iterator to implement /proc/net/vlan/config

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Date: Fri,  9 Feb 2024 14:56:14 +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 1/2] vlan: use xarray iterator to implement /proc/net/vlan/config

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

Not only this removes quadratic behavior, it also makes sure
an existing vlan device is always visible in the dump,
regardless of concurrent net->dev_base_head changes.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/8021q/vlanproc.c | 46 +++++++++++++++-----------------------------
 1 file changed, 16 insertions(+), 30 deletions(-)

diff --git a/net/8021q/vlanproc.c b/net/8021q/vlanproc.c
index 7825c129742a0f334bd8404bc3dc26547eb69083..87b959da00cd3844de1b56b45045e88e6a0293ba 100644
--- a/net/8021q/vlanproc.c
+++ b/net/8021q/vlanproc.c
@@ -163,48 +163,34 @@ void vlan_proc_rem_dev(struct net_device *vlandev)
  * The following few functions build the content of /proc/net/vlan/config
  */
 
-/* start read of /proc/net/vlan/config */
-static void *vlan_seq_start(struct seq_file *seq, loff_t *pos)
-	__acquires(rcu)
+static void *vlan_seq_from_index(struct seq_file *seq, loff_t *pos)
 {
+	unsigned long ifindex = *pos;
 	struct net_device *dev;
-	struct net *net = seq_file_net(seq);
-	loff_t i = 1;
-
-	rcu_read_lock();
-	if (*pos == 0)
-		return SEQ_START_TOKEN;
 
-	for_each_netdev_rcu(net, dev) {
+	for_each_netdev_dump(seq_file_net(seq), dev, ifindex) {
 		if (!is_vlan_dev(dev))
 			continue;
-
-		if (i++ == *pos)
-			return dev;
+		*pos = dev->ifindex;
+		return dev;
 	}
+	return NULL;
+}
+
+static void *vlan_seq_start(struct seq_file *seq, loff_t *pos)
+	__acquires(rcu)
+{
+	rcu_read_lock();
+	if (*pos == 0)
+		return SEQ_START_TOKEN;
 
-	return  NULL;
+	return vlan_seq_from_index(seq, pos);
 }
 
 static void *vlan_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 {
-	struct net_device *dev;
-	struct net *net = seq_file_net(seq);
-
 	++*pos;
-
-	dev = v;
-	if (v == SEQ_START_TOKEN)
-		dev = net_device_entry(&net->dev_base_head);
-
-	for_each_netdev_continue_rcu(net, dev) {
-		if (!is_vlan_dev(dev))
-			continue;
-
-		return dev;
-	}
-
-	return NULL;
+	return vlan_seq_from_index(seq, pos);
 }
 
 static void vlan_seq_stop(struct seq_file *seq, void *v)
-- 
2.43.0.687.g38aa6559b0-goog