From c15853f2c1c9baaa27bbc494cd183be96f6d9bb9 Mon Sep 17 00:00:00 2001 From: Daniel Lezcano Date: Wed, 20 Feb 2008 00:21:47 -0800 Subject: [PATCH] veth: fix dev refcount race When deleting the veth driver, veth_close calls netif_carrier_off for the two extremities of the network device. netif_carrier_off on the peer device will fire an event and hold a reference on the peer device. Just after, the peer is unregistered taking the rtnl_lock while the linkwatch_event is scheduled. If __linkwatch_run_queue does not occurs before the unregistering, unregister_netdevice will wait for the dev refcount to reach zero holding the rtnl_lock and linkwatch_event will wait for the rtnl_lock and hold the dev refcount. Signed-off-by: Daniel Lezcano Signed-off-by: David S. Miller --- drivers/net/veth.c | 53 ++++++++++++++++++++++++++++++++++------------ 1 file changed, 40 insertions(+), 13 deletions(-) diff --git a/drivers/net/veth.c b/drivers/net/veth.c index 3f67a29593..e2ad98bee6 100644 --- a/drivers/net/veth.c +++ b/drivers/net/veth.c @@ -244,18 +244,6 @@ static int veth_open(struct net_device *dev) return 0; } -static int veth_close(struct net_device *dev) -{ - struct veth_priv *priv; - - if (netif_carrier_ok(dev)) { - priv = netdev_priv(dev); - netif_carrier_off(dev); - netif_carrier_off(priv->peer); - } - return 0; -} - static int veth_dev_init(struct net_device *dev) { struct veth_net_stats *stats; @@ -286,13 +274,50 @@ static void veth_setup(struct net_device *dev) dev->hard_start_xmit = veth_xmit; dev->get_stats = veth_get_stats; dev->open = veth_open; - dev->stop = veth_close; dev->ethtool_ops = &veth_ethtool_ops; dev->features |= NETIF_F_LLTX; dev->init = veth_dev_init; dev->destructor = veth_dev_free; } +static void veth_change_state(struct net_device *dev) +{ + struct net_device *peer; + struct veth_priv *priv; + + priv = netdev_priv(dev); + peer = priv->peer; + + if (netif_carrier_ok(peer)) { + if (!netif_carrier_ok(dev)) + netif_carrier_on(dev); + } else { + if (netif_carrier_ok(dev)) + netif_carrier_off(dev); + } +} + +static int veth_device_event(struct notifier_block *unused, + unsigned long event, void *ptr) +{ + struct net_device *dev = ptr; + + if (dev->open != veth_open) + goto out; + + switch (event) { + case NETDEV_CHANGE: + veth_change_state(dev); + break; + } +out: + return NOTIFY_DONE; +} + +static struct notifier_block veth_notifier_block __read_mostly = { + .notifier_call = veth_device_event, +}; + /* * netlink interface */ @@ -454,12 +479,14 @@ static struct rtnl_link_ops veth_link_ops = { static __init int veth_init(void) { + register_netdevice_notifier(&veth_notifier_block); return rtnl_link_register(&veth_link_ops); } static __exit void veth_exit(void) { rtnl_link_unregister(&veth_link_ops); + unregister_netdevice_notifier(&veth_notifier_block); } module_init(veth_init); -- 2.39.5