Re: [PATCH net-next] tun: fix csum generation for tap devices

[Mike Rapoport <rppt@linux.vnet.ibm.com>]

On Tue, Jun 14, 2016 at 12:00:04AM +0200, Paolo Abeni wrote:
> The commit 34166093639b ("tuntap: use common code for virtio_net_hdr
> and skb GSO conversion") replaced the tun code for header manipulation
> with the generic helpers. While doing so, it implictly moved the
> skb_partial_csum_set() invocation after eth_type_trans(), which
> invalidate the current gso start/offset values.
> Fix it by moving the helper invocation before the mac pulling.
> 
> Fixes: 34166093639 ("tuntap: use common code for virtio_net_hdr and skb GSO conversion")
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Acked-by: Mike Rapoport <rppt@linux.vnet.ibm.com>

> ---
>  drivers/net/tun.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 8cc6bf4..4884802 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -1254,6 +1254,13 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
>  		return -EFAULT;
>  	}
> 
> +	err = virtio_net_hdr_to_skb(skb, &gso, tun_is_little_endian(tun));
> +	if (err) {
> +		this_cpu_inc(tun->pcpu_stats->rx_frame_errors);
> +		kfree_skb(skb);
> +		return -EINVAL;
> +	}
> +
>  	switch (tun->flags & TUN_TYPE_MASK) {
>  	case IFF_TUN:
>  		if (tun->flags & IFF_NO_PI) {
> @@ -1280,13 +1287,6 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
>  		break;
>  	}
> 
> -	err = virtio_net_hdr_to_skb(skb, &gso, tun_is_little_endian(tun));
> -	if (err) {
> -		this_cpu_inc(tun->pcpu_stats->rx_frame_errors);
> -		kfree_skb(skb);
> -		return -EINVAL;
> -	}
> -
>  	/* copy skb_ubuf_info for callback when skb has no error */
>  	if (zerocopy) {
>  		skb_shinfo(skb)->destructor_arg = msg_control;
> -- 
> 1.8.3.1
>