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[NET]: Fix race condition about network device name allocation.

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Kenji Kaneshige found this race between device removal and
registration.  On unregister it is possible for the old device to
exist, because sysfs file is still open.  A new device with 'eth%d'
will select the same name, but sysfs kobject register will fial.

The following changes the shutdown order slightly. It hold a removes
the sysfs entries earlier (on unregister_netdevice), but holds a
kobject reference.  Then when todo runs the actual last put free
happens.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Stephen Hemminger 2007-05-19 15:39:25 -07:00 committed by David S. Miller
parent d8cf27287a
commit 9093bbb2d9
2 changed files with 13 additions and 5 deletions
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10
net/core/dev.c
View file

@ -3314,7 +3314,6 @@ void netdev_run_todo(void)
continue;
}
netdev_unregister_sysfs(dev);
dev->reg_state = NETREG_UNREGISTERED;
netdev_wait_allrefs(dev);
@ -3325,11 +3324,11 @@ void netdev_run_todo(void)
BUG_TRAP(!dev->ip6_ptr);
BUG_TRAP(!dev->dn_ptr);
/* It must be the very last action,
* after this 'dev' may point to freed up memory.
*/
if (dev->destructor)
dev->destructor(dev);
/* Free network device */
kobject_put(&dev->dev.kobj);
}
out:
@ -3480,6 +3479,9 @@ void unregister_netdevice(struct net_device *dev)
/* Notifier chain MUST detach us from master device. */
BUG_TRAP(!dev->master);
/* Remove entries from sysfs */
netdev_unregister_sysfs(dev);
/* Finish processing unregister after unlock */
net_set_todo(dev);

8
net/core/net-sysfs.c
View file

@ -456,9 +456,15 @@ static struct class net_class = {
#endif
};
/* Delete sysfs entries but hold kobject reference until after all
* netdev references are gone.
*/
void netdev_unregister_sysfs(struct net_device * net)
{
device_del(&(net->dev));
struct device *dev = &(net->dev);
kobject_get(&dev->kobj);
device_del(dev);
}
/* Create sysfs entries for network device. */