[RFC PATCH 2/5] driver/net/tun: Added features for USO.

[Andrew Melnychenko <andrew@daynix.com>]

Added support for USO4 and USO6, also added code for new ioctl TUNGETSUPPORTEDOFFLOADS.
For now, to "enable" USO, it's required to set both USO4 and USO6 simultaneously.
USO enables NETIF_F_GSO_UDP_L4.

Signed-off-by: Andrew Melnychenko <andrew@daynix.com>
---
 drivers/net/tap.c | 18 ++++++++++++++++--
 drivers/net/tun.c | 15 ++++++++++++++-
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index 8e3a28ba6b28..82d742ba78b1 100644
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -940,6 +940,10 @@ static int set_offload(struct tap_queue *q, unsigned long arg)
 			if (arg & TUN_F_TSO6)
 				feature_mask |= NETIF_F_TSO6;
 		}
+
+		/* TODO: for now USO4 and USO6 should work simultaneously */
+		if (arg & (TUN_F_USO4 | TUN_F_USO6) == (TUN_F_USO4 | TUN_F_USO6))
+			features |= NETIF_F_GSO_UDP_L4;
 	}
 
 	/* tun/tap driver inverts the usage for TSO offloads, where
@@ -950,7 +954,8 @@ static int set_offload(struct tap_queue *q, unsigned long arg)
 	 * When user space turns off TSO, we turn off GSO/LRO so that
 	 * user-space will not receive TSO frames.
 	 */
-	if (feature_mask & (NETIF_F_TSO | NETIF_F_TSO6))
+	if (feature_mask & (NETIF_F_TSO | NETIF_F_TSO6) ||
+	    feature_mask & (TUN_F_USO4 | TUN_F_USO6) == (TUN_F_USO4 | TUN_F_USO6))
 		features |= RX_OFFLOADS;
 	else
 		features &= ~RX_OFFLOADS;
@@ -979,6 +984,7 @@ static long tap_ioctl(struct file *file, unsigned int cmd,
 	unsigned short u;
 	int __user *sp = argp;
 	struct sockaddr sa;
+	unsigned int supported_offloads;
 	int s;
 	int ret;
 
@@ -1074,7 +1080,8 @@ static long tap_ioctl(struct file *file, unsigned int cmd,
 	case TUNSETOFFLOAD:
 		/* let the user check for future flags */
 		if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
-			    TUN_F_TSO_ECN | TUN_F_UFO))
+			    TUN_F_TSO_ECN | TUN_F_UFO |
+			    TUN_F_USO4 | TUN_F_USO6))
 			return -EINVAL;
 
 		rtnl_lock();
@@ -1082,6 +1089,13 @@ static long tap_ioctl(struct file *file, unsigned int cmd,
 		rtnl_unlock();
 		return ret;
 
+	case TUNGETSUPPORTEDOFFLOADS:
+		supported_offloads = TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
+						TUN_F_TSO_ECN | TUN_F_UFO | TUN_F_USO4 | TUN_F_USO6;
+		if (copy_to_user(&arg, &supported_offloads, sizeof(supported_offloads)))
+			return -EFAULT;
+		return 0;
+
 	case SIOCGIFHWADDR:
 		rtnl_lock();
 		tap = tap_get_tap_dev(q);
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index fed85447701a..4f2105d1e6f1 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -185,7 +185,7 @@ struct tun_struct {
 	struct net_device	*dev;
 	netdev_features_t	set_features;
 #define TUN_USER_FEATURES (NETIF_F_HW_CSUM|NETIF_F_TSO_ECN|NETIF_F_TSO| \
-			  NETIF_F_TSO6)
+			  NETIF_F_TSO6 | NETIF_F_GSO_UDP_L4)
 
 	int			align;
 	int			vnet_hdr_sz;
@@ -2821,6 +2821,12 @@ static int set_offload(struct tun_struct *tun, unsigned long arg)
 		}
 
 		arg &= ~TUN_F_UFO;
+
+		/* TODO: for now USO4 and USO6 should work simultaneously */
+		if (arg & TUN_F_USO4 && arg & TUN_F_USO6) {
+			features |= NETIF_F_GSO_UDP_L4;
+			arg &= ~(TUN_F_USO4 | TUN_F_USO6);
+		}
 	}
 
 	/* This gives the user a way to test for new features in future by
@@ -2991,6 +2997,7 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
 	int sndbuf;
 	int vnet_hdr_sz;
 	int le;
+	unsigned int supported_offloads;
 	int ret;
 	bool do_notify = false;
 
@@ -3154,6 +3161,12 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
 	case TUNSETOFFLOAD:
 		ret = set_offload(tun, arg);
 		break;
+	case TUNGETSUPPORTEDOFFLOADS:
+		supported_offloads = TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
+				TUN_F_TSO_ECN | TUN_F_UFO | TUN_F_USO4 | TUN_F_USO6;
+		if (copy_to_user(&arg, &supported_offloads, sizeof(supported_offloads)))
+			ret = -EFAULT;
+		break;
 
 	case TUNSETTXFILTER:
 		/* Can be set only for TAPs */
-- 
2.34.1