linux-kernel - Re: [PATCH] tun: don't hold network namespace by tun sockets

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Message-ID: <1331486969.2449.15.camel@edumazet-laptop>
Date:	Sun, 11 Mar 2012 10:29:29 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Stanislav Kinsbursky <skinsbursky@...allels.com>
Cc:	davem@...emloft.net, ebiederm@...stanetworks.com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	xemul@...allel.com, shemminger@...tta.com, devel@...nvz.org
Subject: Re: [PATCH] tun: don't hold network namespace by tun sockets

Le dimanche 11 mars 2012 à 19:21 +0400, Stanislav Kinsbursky a écrit :
> TUN was designed to destroy it's socket on network namesapce shutdown. But this
> will never happen for persistent device, because it's socket holds network
> namespace.
> This patch removes of holding network namespace by TUN socket and replaces it
> by creating socket in init_net and then changing it's net it to desired one. On
> shutdown socket is moved back to init_net prior to final put.
> 
> Signed-off-by: Stanislav Kinsbursky <skinsbursky@...allels.com>
> 
> ---
>  drivers/net/tun.c |   10 +++++++---
>  1 files changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 2c5d349..92ef539 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -358,8 +358,11 @@ static void tun_net_uninit(struct net_device *dev)
>  static void tun_free_netdev(struct net_device *dev)
>  {
>  	struct tun_struct *tun = netdev_priv(dev);
> +	struct sock *sk = tun->socket.sk;
>  
> -	sock_put(tun->socket.sk);
> +	release_net(sock_net(sk));
> +	sock_net_set(sk, get_net(&init_net));
> +	sock_put(sk);


Hmm, maybe use sk_release_kernel(), as its should be the thing
associated with sk_change_net().

Or at least make intent clear, since its not obvious.



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