Subject: Re: [PATCH v3 2/2] macvtap: restore vlan header on user read

From: [email-masked] (Eric W. Biederman)
Date: Wed, 25 Apr 2012 22:31:25 -0700

Basil Gor <[email-masked]> writes:

> Vlan tag is restored during buffer transmit to a network device (bridge
> port) in bridging code in case of tun/tap driver. In case of macvtap it
> has to be done explicitly. Otherwise vlan_tci is ignored and user always
> gets untagged packets.

We could quibble about efficiencies but this looks good except for
macvtap_recvmsg which isn't setting the auxdata for the vlan header.

Eric

> Signed-off-by: Basil Gor <[email-masked]>
> ---
>  drivers/net/macvtap.c |   11 ++++++++++-
>  1 files changed, 10 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
> index 0427c65..28d2678 100644
> --- a/drivers/net/macvtap.c
> +++ b/drivers/net/macvtap.c
> @@ -1,6 +1,7 @@
>  #include <linux/etherdevice.h>
>  #include <linux/if_macvlan.h>
>  #include <linux/interrupt.h>
> +#include <linux/if_vlan.h>
>  #include <linux/nsproxy.h>
>  #include <linux/compat.h>
>  #include <linux/if_tun.h>
> @@ -753,13 +754,21 @@ static ssize_t macvtap_aio_write(struct kiocb *iocb, const struct iovec *iv,
>  
>  /* Put packet to the user space buffer */
>  static ssize_t macvtap_put_user(struct macvtap_queue *q,
> -				const struct sk_buff *skb,
> +				struct sk_buff *skb,
>  				const struct iovec *iv, int len)
>  {
>  	struct macvlan_dev *vlan;
>  	int ret;
>  	int vnet_hdr_len = 0;
>  
> +	if (vlan_tx_tag_present(skb)) {
> +		skb = __vlan_put_tag(skb, vlan_tx_tag_get(skb));
> +		if (unlikely(!skb))
> +			return -ENOMEM;
> +
> +		skb->vlan_tci = 0;
> +	}
> +
>  	if (q->flags & IFF_VNET_HDR) {
>  		struct virtio_net_hdr vnet_hdr;
>  		vnet_hdr_len = q->vnet_hdr_sz;