netdev - Re: [PATCH] net_namespace: fixed net

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Date:   Thu, 08 Sep 2016 16:37:41 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Jojy Varghese <jojy.varghese@...il.com>
Cc:     netdev@...r.kernel.org, davem@...emloft.net
Subject: Re: [PATCH] net_namespace: fixed net_device reference leak

On Thu, 2016-09-08 at 16:16 -0700, Jojy Varghese wrote:
> The dst's do disappear but the net device does not. A better solution
> is to only hold reference to dst's net device ONLY if it is not a
> loopback device. In the case of the loopback device, we want to do
> only a "put" on it and skip the "hold".
> 
> Updating the patch below:
> 
> ---
>  net/core/dst.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/net/core/dst.c b/net/core/dst.c
> index 7e45593..f63027e 100644
> --- a/net/core/dst.c
> +++ b/net/core/dst.c
> @@ -433,12 +433,11 @@ static void dst_ifdown(struct dst_entry *dst,
> struct net_device *dev,
>                 dst->input = dst_discard;
>                 dst->output = dst_discard_out;
>         } else {
> -               if (dst->dev == dev_net(dst->dev)->loopback_dev)

On which tree are you working exactly ?
Current code is not looking like that.

> -                       dst->dev = init_net.loopback_dev;
> -               else
> +               if (dst->dev != dev_net(dst->dev)->loopback_dev) {
>                         dst->dev = dev_net(dst->dev)->loopback_dev;
> +                       dev_hold(dst->dev);
> +               }
> 
> -               dev_hold(dst->dev);
>                 dev_put(dev);
>         }
>  }


I appreciate your desperate efforts, but I am telling you the bug is
elsewhere.

Do you have a reproducer of the bug, on latest David Miller tree
( https://git.kernel.org/cgit/linux/kernel/git/davem/net.git )

Thanks.