On Mon, Nov 06, 2017 at 11:51:07AM +0100, Florian Westphal wrote: > @@ -180,6 +164,12 @@ int __rtnl_register(int protocol, int msgtype, > rcu_assign_pointer(rtnl_msg_handlers[protocol], tab); > } > > + WARN_ON(tab[msgindex].owner && tab[msgindex].owner != owner); > + > + tab[msgindex].owner = owner; > + /* make sure owner is always visible first */ > + smp_wmb(); > + > if (doit) > tab[msgindex].doit = doit; > if (dumpit)
> @@ -235,6 +279,9 @@ int rtnl_unregister(int protocol, int msgtype) > handlers[msgindex].doit = NULL; > handlers[msgindex].dumpit = NULL; > handlers[msgindex].flags = 0; > + /* make sure we clear owner last */ > + smp_wmb(); > + handlers[msgindex].owner = NULL; > rtnl_unlock(); > > return 0; These wmb()'s don't make sense; and the comments are incomplete. What do they pair with? Who cares about this ordering?
