netdev - Re: [PATCH v2] net IPv6 : Fix broken IPv6 routing table after loopback down-up

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Date:	Thu, 28 Mar 2013 06:44:25 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Balakumaran Kannan <kumaran.4353@...il.com>
Cc:	yoshfuji@...ux-ipv6.org, davem@...emloft.net,
	Patrick McHardy <kaber@...sh.net>,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>, jmorris@...ei.org,
	Balakumaran.Kannan@...sony.com, maruthi.thotad@...sony.com,
	netdev@...r.kernel.org, jamshed.a@...sony.com,
	amit.agarwal@...sony.com, takuzo.ohara@...sony.com,
	aaditya.kumar@...sony.com
Subject: Re: [PATCH v2] net IPv6 : Fix broken IPv6 routing table after
 loopback down-up

On Thu, 2013-03-28 at 18:57 +0530, Balakumaran Kannan wrote:
> IPv6 Routing table becomes broken once we do ifdown, ifup of the loopback(lo)
> interface. After down-up, routes of other interface's IPv6 addresses through
> 'lo' are lost.
> 

>  	add_addr(idev, &in6addr_loopback, 128, IFA_HOST);
> +
> +	/* Add routes to other interface's IPv6 addresses */
> +	rcu_read_lock();
> +	for_each_netdev_rcu(dev_net(dev), sp_dev) {
> +

We hold RTNL at this point, so why use RCU at all, and adding potential
long latencies ?

Just use for_each_netdev()

This way, a preemption is still allowed.

Also, I am not sure we need ipv6_find_idev()

__in6_dev_get() should be OK.



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