Re: [PATCH] net: ipv6: Make address flushing on ifdown optional

[David Miller]

From: David Ahern <d...@cumulusnetworks.com>
Date: Sat, 13 Feb 2016 14:23:27 -0800

> @@ -3427,31 +3493,52 @@ static int addrconf_ifdown(struct net_device *dev, 
> int how)
>               write_lock_bh(&idev->lock);
>       }
>  
> -     while (!list_empty(&idev->addr_list)) {
> -             ifa = list_first_entry(&idev->addr_list,
> -                                    struct inet6_ifaddr, if_list);
> -             addrconf_del_dad_work(ifa);
> +     INIT_LIST_HEAD(&del_list);
> +     list_for_each_entry_safe(ifa, tmp, &idev->addr_list, if_list) {
> +             bool keep_ifa = false;
>  
> -             list_del(&ifa->if_list);
> +             if (!how && keep_addr && ifa->user_managed)
> +                     keep_ifa = true;

I think it would make sense to evaluate "!how && keep_addr" outside the
loop.  The only thing that changes is ifa->user_managed on each iteration.

But I also want some more documentation in what you are doing here.

I understand the address flushing on ifdown avoidance, but all of this
user_managed logic is not mentioned at all.  Why do you need it?  What
role does it play in achieving your goal?

Thanks.