linux-kernel - Re: [PATCHv2] tun: fix carrier on/off status

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Date:	Mon, 28 Jan 2013 19:00:20 +0800
From:	Jason Wang <jasowang@...hat.com>
To:	"Michael S. Tsirkin" <mst@...hat.com>
CC:	Toralf Förster <toralf.foerster@....de>,
	netdev@...r.kernel.org,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	David Miller <davem@...emloft.net>
Subject: Re: [PATCHv2] tun: fix carrier on/off status

On 01/28/2013 06:38 PM, Michael S. Tsirkin wrote:
> Commit c8d68e6be1c3b242f1c598595830890b65cea64a removed carrier off call
> from tun_detach since it's now called on queue disable and not only on
> tun close.  This confuses userspace which used this flag to detect a
> free tun. To fix, put this back but under if (clean).
>
> Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
>
> ---
>
> Changes from v1:
> 	Don't set carrier off unless all queues are closed.
>
> Note: didn't test in MQ mode - Jason, care checking this does the
> right thing there?

Tested-by: Jason Wang <jasowang@...hat.com>
Acked-by: Jason Wang <jasowang@...hat.com>
>
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index af372d0..06b2723 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -434,10 +434,13 @@ static void __tun_detach(struct tun_file *tfile, bool clean)
>  	}
>  
>  	if (clean) {
> -		if (tun && tun->numqueues == 0 && tun->numdisabled == 0 &&
> -		    !(tun->flags & TUN_PERSIST))
> -			if (tun->dev->reg_state == NETREG_REGISTERED)
> +		if (tun && tun->numqueues == 0 && tun->numdisabled == 0) {
> +			netif_carrier_off(tun->dev);
> +
> +			if (!(tun->flags & TUN_PERSIST) &&
> +			    tun->dev->reg_state == NETREG_REGISTERED)
>  				unregister_netdevice(tun->dev);
> +		}
>  
>  		BUG_ON(!test_bit(SOCK_EXTERNALLY_ALLOCATED,
>  				 &tfile->socket.flags));
> @@ -1644,10 +1647,10 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
>  		    device_create_file(&tun->dev->dev, &dev_attr_owner) ||
>  		    device_create_file(&tun->dev->dev, &dev_attr_group))
>  			pr_err("Failed to create tun sysfs files\n");
> -
> -		netif_carrier_on(tun->dev);
>  	}
>  
> +	netif_carrier_on(tun->dev);
> +
>  	tun_debug(KERN_INFO, tun, "tun_set_iff\n");
>  
>  	if (ifr->ifr_flags & IFF_NO_PI)
> --
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