Subject: Re: [PATCH 01/10] core: Split out UFO6 support

From: "Michael S. Tsirkin" <[email-masked]>
Date: Thu, 18 Dec 2014 00:45:53 +0200

On Wed, Dec 17, 2014 at 01:20:46PM -0500, Vladislav Yasevich wrote:
> Split IPv6 support for UFO into its own feature similiar to TSO.
> This will later allow us to re-enable UFO support for virtio-net
> devices.
> 
> Signed-off-by: Vladislav Yasevich <[email-masked]>
> ---
>  include/linux/netdev_features.h |  7 +++++--
>  include/linux/netdevice.h       |  1 +
>  include/linux/skbuff.h          |  1 +
>  net/core/dev.c                  | 35 +++++++++++++++++++----------------
>  net/core/ethtool.c              |  2 +-
>  5 files changed, 27 insertions(+), 19 deletions(-)
> 
> diff --git a/include/linux/netdev_features.h b/include/linux/netdev_features.h
> index dcfdecb..a078945 100644
> --- a/include/linux/netdev_features.h
> +++ b/include/linux/netdev_features.h
> @@ -48,8 +48,9 @@ enum {
>  	NETIF_F_GSO_UDP_TUNNEL_BIT,	/* ... UDP TUNNEL with TSO */
>  	NETIF_F_GSO_UDP_TUNNEL_CSUM_BIT,/* ... UDP TUNNEL with TSO & CSUM */
>  	NETIF_F_GSO_MPLS_BIT,		/* ... MPLS segmentation */
> +	NETIF_F_UFO6_BIT,		/* ... UDPv6 fragmentation */
>  	/**/NETIF_F_GSO_LAST =		/* last bit, see GSO_MASK */
> -		NETIF_F_GSO_MPLS_BIT,
> +		NETIF_F_UFO6_BIT,
>  
>  	NETIF_F_FCOE_CRC_BIT,		/* FCoE CRC32 */
>  	NETIF_F_SCTP_CSUM_BIT,		/* SCTP checksum offload */
> @@ -109,6 +110,7 @@ enum {
>  #define NETIF_F_TSO_ECN		__NETIF_F(TSO_ECN)
>  #define NETIF_F_TSO		__NETIF_F(TSO)
>  #define NETIF_F_UFO		__NETIF_F(UFO)
> +#define NETIF_F_UFO6		__NETIF_F(UFO6)
>  #define NETIF_F_VLAN_CHALLENGED	__NETIF_F(VLAN_CHALLENGED)
>  #define NETIF_F_RXFCS		__NETIF_F(RXFCS)
>  #define NETIF_F_RXALL		__NETIF_F(RXALL)
> @@ -141,7 +143,7 @@ enum {
>  
>  /* List of features with software fallbacks. */
>  #define NETIF_F_GSO_SOFTWARE	(NETIF_F_TSO | NETIF_F_TSO_ECN | \
> -				 NETIF_F_TSO6 | NETIF_F_UFO)
> +				 NETIF_F_TSO6 | NETIF_F_UFO | NETIF_F_UFO6)
>  
>  #define NETIF_F_GEN_CSUM	NETIF_F_HW_CSUM
>  #define NETIF_F_V4_CSUM		(NETIF_F_GEN_CSUM | NETIF_F_IP_CSUM)
> @@ -149,6 +151,7 @@ enum {
>  #define NETIF_F_ALL_CSUM	(NETIF_F_V4_CSUM | NETIF_F_V6_CSUM)
>  
>  #define NETIF_F_ALL_TSO 	(NETIF_F_TSO | NETIF_F_TSO6 | NETIF_F_TSO_ECN)
> +#define NETIF_F_ALL_UFO		(NETIF_F_UFO | NETIF_F_UFO6)
>  
>  #define NETIF_F_ALL_FCOE	(NETIF_F_FCOE_CRC | NETIF_F_FCOE_MTU | \
>  				 NETIF_F_FSO)
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index 74fd5d3..86af10a 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -3559,6 +3559,7 @@ static inline bool net_gso_ok(netdev_features_t features, int gso_type)
>  	/* check flags correspondence */
>  	BUILD_BUG_ON(SKB_GSO_TCPV4   != (NETIF_F_TSO >> NETIF_F_GSO_SHIFT));
>  	BUILD_BUG_ON(SKB_GSO_UDP     != (NETIF_F_UFO >> NETIF_F_GSO_SHIFT));
> +	BUILD_BUG_ON(SKB_GSO_UDP6    != (NETIF_F_UFO6 >> NETIF_F_GSO_SHIFT));
>  	BUILD_BUG_ON(SKB_GSO_DODGY   != (NETIF_F_GSO_ROBUST >> NETIF_F_GSO_SHIFT));
>  	BUILD_BUG_ON(SKB_GSO_TCP_ECN != (NETIF_F_TSO_ECN >> NETIF_F_GSO_SHIFT));
>  	BUILD_BUG_ON(SKB_GSO_TCPV6   != (NETIF_F_TSO6 >> NETIF_F_GSO_SHIFT));
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 6c8b6f6..8538b67 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -372,6 +372,7 @@ enum {
>  
>  	SKB_GSO_MPLS = 1 << 12,
>  
> +	SKB_GSO_UDP6 = 1 << 13
>  };
>  
>  #if BITS_PER_LONG > 32

So this implies anything getting GSO packets e.g.
from userspace now needs to check IP version to
set GSO type correctly.

I think you missed some places that do this, e.g. af_packet
sockets.

> diff --git a/net/core/dev.c b/net/core/dev.c
> index 945bbd0..fa4d2ee 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -5929,6 +5929,12 @@ static netdev_features_t netdev_fix_features(struct net_device *dev,
>  		features &= ~NETIF_F_ALL_TSO;
>  	}
>  
> +	/* UFO requires that SG is present as well */
> +	if ((features & NETIF_F_ALL_UFO) && !(features & NETIF_F_SG)) {
> +		netdev_dbg(dev, "Dropping UFO features since no SG feature.\n");
> +		features &= ~NETIF_F_ALL_UFO;
> +	}
> +
>  	if ((features & NETIF_F_TSO) && !(features & NETIF_F_HW_CSUM) &&
>  					!(features & NETIF_F_IP_CSUM)) {
>  		netdev_dbg(dev, "Dropping TSO features since no CSUM feature.\n");
> @@ -5952,24 +5958,21 @@ static netdev_features_t netdev_fix_features(struct net_device *dev,
>  		features &= ~NETIF_F_GSO;
>  	}
>  
> -	/* UFO needs SG and checksumming */
> -	if (features & NETIF_F_UFO) {
> -		/* maybe split UFO into V4 and V6? */
> -		if (!((features & NETIF_F_GEN_CSUM) ||
> -		    (features & (NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM))
> -			    == (NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM))) {
> -			netdev_dbg(dev,
> -				"Dropping NETIF_F_UFO since no checksum offload features.\n");
> -			features &= ~NETIF_F_UFO;
> -		}
> -
> -		if (!(features & NETIF_F_SG)) {
> -			netdev_dbg(dev,
> -				"Dropping NETIF_F_UFO since no NETIF_F_SG feature.\n");
> -			features &= ~NETIF_F_UFO;
> -		}
> +	/* UFO also needs checksumming */
> +	if ((features & NETIF_F_UFO) && !(features & NETIF_F_GEN_CSUM) &&
> +					!(features & NETIF_F_IP_CSUM)) {
> +		netdev_dbg(dev,
> +			   "Dropping NETIF_F_UFO since no checksum offload features.\n");
> +		features &= ~NETIF_F_UFO;
> +	}
> +	if ((features & NETIF_F_UFO6) && !(features & NETIF_F_GEN_CSUM) &&
> +					 !(features & NETIF_F_IPV6_CSUM)) {
> +		netdev_dbg(dev,
> +			   "Dropping NETIF_F_UFO6 since no checksum offload features.\n");
> +		features &= ~NETIF_F_UFO6;
>  	}
>  
> +
>  #ifdef CONFIG_NET_RX_BUSY_POLL
>  	if (dev->netdev_ops->ndo_busy_poll)
>  		features |= NETIF_F_BUSY_POLL;
> diff --git a/net/core/ethtool.c b/net/core/ethtool.c
> index 06dfb29..93eff41 100644
> --- a/net/core/ethtool.c
> +++ b/net/core/ethtool.c
> @@ -223,7 +223,7 @@ static netdev_features_t ethtool_get_feature_mask(u32 eth_cmd)
>  		return NETIF_F_ALL_TSO;
>  	case ETHTOOL_GUFO:
>  	case ETHTOOL_SUFO:
> -		return NETIF_F_UFO;
> +		return NETIF_F_ALL_UFO;
>  	case ETHTOOL_GGSO:
>  	case ETHTOOL_SGSO:
>  		return NETIF_F_GSO;
> -- 
> 1.9.3