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authorStephen Hemminger <shemminger@linux-foundation.org>2007-06-06 22:47:07 -0700
committerChris Wright <chrisw@sous-sol.org>2007-06-11 11:36:52 -0700
commitc791b2528a1ed687f90fab0320ae7363b806435e (patch)
tree36deecc29509e6b452acf65790974f0a10ce185d
parentd4e9e959836ba3e5e754f04424ee5feb6bc16650 (diff)
[PATCH] NET: Fix race condition about network device name allocation.
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> Signed-off-by: Chris Wright <chrisw@sous-sol.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--net/core/dev.c10
-rw-r--r--net/core/net-sysfs.c8
2 files changed, 13 insertions, 5 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 4dc93cc4d5b7..0caddcf1a762 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3135,7 +3135,6 @@ void netdev_run_todo(void)
continue;
}
- netdev_unregister_sysfs(dev);
dev->reg_state = NETREG_UNREGISTERED;
netdev_wait_allrefs(dev);
@@ -3146,11 +3145,11 @@ 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:
@@ -3305,6 +3304,9 @@ 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);
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 4cbb1290a6a3..1fb7aec65169 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -451,9 +451,15 @@ 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. */