netdev - Re: unregister_netdevice: waiting for eth0 to become free. Usage count = 1

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Message-ID: <5a4e7562-49f7-a91f-5776-5a0efe9161c7@gmail.com>
Date:   Sun, 13 Aug 2017 17:08:03 -0600
From:   David Ahern <dsahern@...il.com>
To:     Wei Wang <weiwan@...gle.com>
Cc:     Ido Schimmel <idosch@...sch.org>,
        Cong Wang <xiyou.wangcong@...il.com>,
        John Stultz <john.stultz@...aro.org>,
        Martin KaFai Lau <kafai@...com>,
        lkml <linux-kernel@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        Linux USB List <linux-usb@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>
Subject: Re: unregister_netdevice: waiting for eth0 to become free. Usage
 count = 1

On 8/13/17 2:56 PM, Wei Wang wrote:
>> Looking at my patch to move host routes from loopback to device with the
>> address, I have this:
>>
>> @@ -2789,7 +2808,8 @@ static int fib6_ifdown(struct rt6_info *rt, void *arg)
>>         const struct arg_dev_net *adn = arg;
>>         const struct net_device *dev = adn->dev;
>>
>> -       if ((rt->dst.dev == dev || !dev) &&
>> +       if ((rt->dst.dev == dev || !dev ||
>> +            (netdev_unregistering(dev) && rt->rt6i_idev->dev == dev)) &&
>>             rt != adn->net->ipv6.ip6_null_entry &&
>>             (rt->rt6i_nsiblings == 0 ||
>>              (dev && netdev_unregistering(dev)) ||
> 
> As you explained earlier, after your patch, all entries in the fib6
> tree will have rt->dst.dev be the same as rt->rt6i_idev->dev except
> those ones created by p6_rt_cache_alloc() and ip6_rt_pcpu_alloc().
> Then the above newly added check is mainly to catch those cached dst
> entries (created by ip6_rt_cached_alloc()). right?
> And it is required because __ipv6_ifa_notify() -> ip6_del_rt() won't
> take care of those cached dst entries.
> 
> Then I think I should wait for your patches to get merged before
> submitting my patch?

no. your patch will need to go back to 4.12; my changes will not be
appropriate for that.