netdev - Re: sctp netns "unregister_netdevice: waiting for lo to become free. Usage count = 1"

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Message-ID: <aba6d3c5-4b26-5e61-e4c4-e5925749cd1e@nokia.com>
Date:   Wed, 31 Jan 2018 19:51:58 +0200
From:   Tommi Rantala <tommi.t.rantala@...ia.com>
To:     Neil Horman <nhorman@...driver.com>
Cc:     Vlad Yasevich <vyasevich@...il.com>, linux-sctp@...r.kernel.org,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Subject: Re: sctp netns "unregister_netdevice: waiting for lo to become free.
 Usage count = 1"

On 31.01.2018 14:31, Neil Horman wrote:
> On Wed, Jan 31, 2018 at 11:42:24AM +0200, Tommi Rantala wrote:
>> I think there's a problem in the dst refcounting in sctp_v4_get_dst()
>>
>> There's a dst_entry struct that has >0 refcnt after running the testcase,
>> which makes it impossible to delete the loopback device, as that dst is
>> never freed.
>>
>> I'll try to make a patch.
>>
> Are you looking at the second for loop there, which uses ip_route_output_key,
> but discards the result if dst is already set?  That does look a bit wonky, and
> the same problem may exist in the ipv6 path.  Let me know what the result is.

Yes, that was it. Did you receive the email I sent with the patch?
(I'm not seeing that message e.g. at spinics.net linux-sctp archive, so 
just wondering if that email got lost somehow...)

I'll check the ipv6 case, did not try it yet.

Tommi