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Date: Wed, 19 Aug 2015 08:44:08 +0200
From: Vincent Bernat <vincent@...nat.im>
To: "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
Nicolas Dichtel <nicolas.dichtel@...nd.com>
Cc: Vincent Bernat <vincent@...nat.im>
Subject: [PATCH] veth: replace iflink by a dedicated symlink in sysfs
While the documentation doesn't say exactly what kind of relationship
iflink should represent, until a45253, only lower devices were
advertised this way. While veth cannot have a lower device, using iflink
to advertise the peer may create infinite loops in programs using iflink
to discover device topology.
Instead of advertising the peer link with iflink, a symbolic link "peer"
is added to each peer.
Signed-off-by: Vincent Bernat <vincent@...nat.im>
---
drivers/net/veth.c | 40 +++++++++++++++++++++++++---------------
1 file changed, 25 insertions(+), 15 deletions(-)
diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index c8186ffda1a3..47f165bc3107 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -105,6 +105,17 @@ static const struct ethtool_ops veth_ethtool_ops = {
.get_ethtool_stats = veth_get_ethtool_stats,
};
+static int veth_peer_sysfs_add(struct net_device *dev,
+ struct net_device *peer_dev)
+{
+ return sysfs_create_link(&(dev->dev.kobj), &(peer_dev->dev.kobj),
+ "peer");
+}
+static void veth_peer_sysfs_del(struct net_device *dev)
+{
+ sysfs_remove_link(&(dev->dev.kobj), "peer");
+}
+
static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct veth_priv *priv = netdev_priv(dev);
@@ -263,20 +274,6 @@ static void veth_poll_controller(struct net_device *dev)
}
#endif /* CONFIG_NET_POLL_CONTROLLER */
-static int veth_get_iflink(const struct net_device *dev)
-{
- struct veth_priv *priv = netdev_priv(dev);
- struct net_device *peer;
- int iflink;
-
- rcu_read_lock();
- peer = rcu_dereference(priv->peer);
- iflink = peer ? peer->ifindex : 0;
- rcu_read_unlock();
-
- return iflink;
-}
-
static const struct net_device_ops veth_netdev_ops = {
.ndo_init = veth_dev_init,
.ndo_open = veth_open,
@@ -289,7 +286,6 @@ static const struct net_device_ops veth_netdev_ops = {
#ifdef CONFIG_NET_POLL_CONTROLLER
.ndo_poll_controller = veth_poll_controller,
#endif
- .ndo_get_iflink = veth_get_iflink,
};
#define VETH_FEATURES (NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_ALL_TSO | \
@@ -436,6 +432,13 @@ static int veth_newlink(struct net *src_net, struct net_device *dev,
netif_carrier_off(dev);
+ err = veth_peer_sysfs_add(dev, peer);
+ if (err < 0)
+ goto err_configure_dev;
+ err = veth_peer_sysfs_add(peer, dev);
+ if (err < 0)
+ goto err_configure_dev;
+
/*
* tie the deviced together
*/
@@ -447,9 +450,13 @@ static int veth_newlink(struct net *src_net, struct net_device *dev,
rcu_assign_pointer(priv->peer, dev);
return 0;
+err_configure_dev:
+ veth_peer_sysfs_del(dev);
+ veth_peer_sysfs_del(peer);
err_register_dev:
/* nothing to do */
err_configure_peer:
+ veth_peer_sysfs_del(dev);
unregister_netdevice(peer);
return err;
@@ -466,6 +473,9 @@ static void veth_dellink(struct net_device *dev, struct list_head *head)
priv = netdev_priv(dev);
peer = rtnl_dereference(priv->peer);
+ veth_peer_sysfs_del(dev);
+ if (peer) veth_peer_sysfs_del(dev);
+
/* Note : dellink() is called from default_device_exit_batch(),
* before a rcu_synchronize() point. The devices are guaranteed
* not being freed before one RCU grace period.
--
2.5.0
--
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