Re: [PATCH] wext: fix message delay/ordering

[Johannes Berg <johannes@sipsolutions.net>]

On Wed, 2016-01-27 at 13:14 +0100, Johannes Berg wrote:
> 
> +static int wext_netdev_notifier_call(struct notifier_block *nb,
> +				     unsigned long state, void *ptr)
> +{
> +	/*
> +	 * When a netdev is unregistered, flush all pending messages
> +	 * to avoid them going out after the RTM_DELLINK, which can
> +	 * happen due to the schedule_work().
> +	 */
> +	if (state == NETDEV_UNREGISTER)
> +		wireless_nlevent_flush();
> 
It could be argued that the state check isn't really necessary and
should be removed to avoid ordering issues with up/down vs. wext, but
this fixes the really strange issue where you get an RTM_NEWLINK after
RTM_DELLINK (with the same ifidx), and I don't see how any software
would care much about the ordering otherwise.

johannes