Re: [PATCH v6 40/46] tun: TUN_VNET_LE support, fix sparse warnings for virtio headers

[Jason Wang <jasowang@redhat.com>]

On Fri, Nov 28, 2014 at 4:11 AM, Michael S. Tsirkin <mst@redhat.com> 
wrote:
> Pretty straight-forward: convert all fields to/from
> virtio endian-ness.
> 
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>  drivers/net/tun.c | 48 
> +++++++++++++++++++++++++++++-------------------
>  1 file changed, 29 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 61c000c..f411ffd 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -111,7 +111,7 @@ do {								\
>  #define TUN_FASYNC	IFF_ATTACH_QUEUE
>  
>  #define TUN_FEATURES (IFF_NO_PI | IFF_ONE_QUEUE | IFF_VNET_HDR | \
> -		      IFF_MULTI_QUEUE)
> +		      IFF_VNET_LE | IFF_MULTI_QUEUE)
>  #define GOODCOPY_LEN 128
>  
>  #define FLT_EXACT_COUNT 8
> @@ -205,6 +205,16 @@ struct tun_struct {
>  	u32 flow_count;
>  };
>  
> +static inline u16 tun16_to_cpu(struct tun_struct *tun, __virtio16 
> val)
> +{
> +	return __virtio16_to_cpu(tun->flags & IFF_VNET_LE, val);
> +}
> +
> +static inline __virtio16 cpu_to_tun16(struct tun_struct *tun, u16 
> val)
> +{
> +	return __cpu_to_virtio16(tun->flags & IFF_VNET_LE, val);
> +}
> +
>  static inline u32 tun_hashfn(u32 rxhash)
>  {
>  	return rxhash & 0x3ff;
> @@ -1053,10 +1063,10 @@ static ssize_t tun_get_user(struct tun_struct 
> *tun, struct tun_file *tfile,
>  			return -EFAULT;
>  
>  		if ((gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
> -		    gso.csum_start + gso.csum_offset + 2 > gso.hdr_len)
> -			gso.hdr_len = gso.csum_start + gso.csum_offset + 2;
> +		    tun16_to_cpu(tun, gso.csum_start) + tun16_to_cpu(tun, 
> gso.csum_offset) + 2 > tun16_to_cpu(tun, gso.hdr_len))
> +			gso.hdr_len = cpu_to_tun16(tun, tun16_to_cpu(tun, gso.csum_start) 
> + tun16_to_cpu(tun, gso.csum_offset) + 2);
>  
> -		if (gso.hdr_len > len)
> +		if (tun16_to_cpu(tun, gso.hdr_len) > len)
>  			return -EINVAL;
>  		offset += tun->vnet_hdr_sz;
>  	}
> @@ -1064,7 +1074,7 @@ static ssize_t tun_get_user(struct tun_struct 
> *tun, struct tun_file *tfile,
>  	if ((tun->flags & TUN_TYPE_MASK) == IFF_TAP) {
>  		align += NET_IP_ALIGN;
>  		if (unlikely(len < ETH_HLEN ||
> -			     (gso.hdr_len && gso.hdr_len < ETH_HLEN)))
> +			     (gso.hdr_len && tun16_to_cpu(tun, gso.hdr_len) < ETH_HLEN)))
>  			return -EINVAL;
>  	}
>  
> @@ -1075,7 +1085,7 @@ static ssize_t tun_get_user(struct tun_struct 
> *tun, struct tun_file *tfile,
>  		 * enough room for skb expand head in case it is used.
>  		 * The rest of the buffer is mapped from userspace.
>  		 */
> -		copylen = gso.hdr_len ? gso.hdr_len : GOODCOPY_LEN;
> +		copylen = gso.hdr_len ? tun16_to_cpu(tun, gso.hdr_len) : 
> GOODCOPY_LEN;
>  		if (copylen > good_linear)
>  			copylen = good_linear;
>  		linear = copylen;
> @@ -1085,10 +1095,10 @@ static ssize_t tun_get_user(struct tun_struct 
> *tun, struct tun_file *tfile,
>  
>  	if (!zerocopy) {
>  		copylen = len;
> -		if (gso.hdr_len > good_linear)
> +		if (tun16_to_cpu(tun, gso.hdr_len) > good_linear)
>  			linear = good_linear;
>  		else
> -			linear = gso.hdr_len;
> +			linear = tun16_to_cpu(tun, gso.hdr_len);
>  	}
>  
>  	skb = tun_alloc_skb(tfile, align, copylen, linear, noblock);
> @@ -1115,8 +1125,8 @@ static ssize_t tun_get_user(struct tun_struct 
> *tun, struct tun_file *tfile,
>  	}
>  
>  	if (gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
> -		if (!skb_partial_csum_set(skb, gso.csum_start,
> -					  gso.csum_offset)) {
> +		if (!skb_partial_csum_set(skb, tun16_to_cpu(tun, gso.csum_start),
> +					  tun16_to_cpu(tun, gso.csum_offset))) {
>  			tun->dev->stats.rx_frame_errors++;
>  			kfree_skb(skb);
>  			return -EINVAL;
> @@ -1184,7 +1194,7 @@ static ssize_t tun_get_user(struct tun_struct 
> *tun, struct tun_file *tfile,
>  		if (gso.gso_type & VIRTIO_NET_HDR_GSO_ECN)
>  			skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
>  
> -		skb_shinfo(skb)->gso_size = gso.gso_size;
> +		skb_shinfo(skb)->gso_size = tun16_to_cpu(tun, gso.gso_size);
>  		if (skb_shinfo(skb)->gso_size == 0) {
>  			tun->dev->stats.rx_frame_errors++;
>  			kfree_skb(skb);
> @@ -1276,8 +1286,8 @@ static ssize_t tun_put_user(struct tun_struct 
> *tun,
>  			struct skb_shared_info *sinfo = skb_shinfo(skb);
>  
>  			/* This is a hint as to how much should be linear. */
> -			gso.hdr_len = skb_headlen(skb);
> -			gso.gso_size = sinfo->gso_size;
> +			gso.hdr_len = cpu_to_tun16(tun, skb_headlen(skb));
> +			gso.gso_size = cpu_to_tun16(tun, sinfo->gso_size);
>  			if (sinfo->gso_type & SKB_GSO_TCPV4)
>  				gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
>  			else if (sinfo->gso_type & SKB_GSO_TCPV6)
> @@ -1285,12 +1295,12 @@ static ssize_t tun_put_user(struct tun_struct 
> *tun,
>  			else {
>  				pr_err("unexpected GSO type: "
>  				       "0x%x, gso_size %d, hdr_len %d\n",
> -				       sinfo->gso_type, gso.gso_size,
> -				       gso.hdr_len);
> +				       sinfo->gso_type, tun16_to_cpu(tun, gso.gso_size),
> +				       tun16_to_cpu(tun, gso.hdr_len));
>  				print_hex_dump(KERN_ERR, "tun: ",
>  					       DUMP_PREFIX_NONE,
>  					       16, 1, skb->head,
> -					       min((int)gso.hdr_len, 64), true);
> +					       min((int)tun16_to_cpu(tun, gso.hdr_len), 64), true);
>  				WARN_ON_ONCE(1);
>  				return -EINVAL;
>  			}
> @@ -1301,9 +1311,9 @@ static ssize_t tun_put_user(struct tun_struct 
> *tun,
>  
>  		if (skb->ip_summed == CHECKSUM_PARTIAL) {
>  			gso.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
> -			gso.csum_start = skb_checksum_start_offset(skb) +
> -					 vlan_hlen;
> -			gso.csum_offset = skb->csum_offset;
> +			gso.csum_start = cpu_to_tun16(tun, skb_checksum_start_offset(skb) 
> +
> +						      vlan_hlen);
> +			gso.csum_offset = cpu_to_tun16(tun, skb->csum_offset);
>  		} else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
>  			gso.flags = VIRTIO_NET_HDR_F_DATA_VALID;
>  		} /* else everything is zero */
> -- 
> MST

Reviewed-by: Jason Wang <jasowang@redhat.com>