Messages in this thread | | | Date | Mon, 14 May 2007 08:41:57 -0700 | From | Stephen Hemminger <> | Subject | Re: [BUG][PATCH] Fix race condition about network device name allocation |
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On Mon, 14 May 2007 10:33:01 +0900 Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com> wrote:
> Hi Stephen, > > Thank you for comments. I'll try your patch. > > I have one concern about your patch, though I don't know very much > about netdev codes. > > @@ -3411,6 +3410,9 @@ void unregister_netdevice(struct net_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); > > > > With your patch, the netdev_unregister_sysfs() will be called > earlier than now. Does it have no side effect? I'm worrying > about if there are somebody that depend on sysfs entry until > net_run_todo() is called.
The unregister_sysfs() removes the entry in /sys/class/net and then decrements the reference count. When ref count goes to zero, the kobject_release callback gets called and which does kfree().
Changing the shutdown order makes the /sys/class/net entry disappear sooner. In order to prevent the free from happening until after all the dev_put() calls have happened, the reference count for the kobject needs to be increased.
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