net: Fix possible wrong checksum generation.

Patch cef401de7be8c4e (net: fix possible wrong checksum
generation) fixed wrong checksum calculation but it broke TSO by
defining new GSO type but not a netdev feature for that type.
net_gso_ok() would not allow hardware checksum/segmentation
offload of such packets without the feature.

Following patch fixes TSO and wrong checksum. This patch uses
same logic that Eric Dumazet used. Patch introduces new flag
SKBTX_SHARED_FRAG if at least one frag can be modified by
the user. but SKBTX_SHARED_FRAG flag is kept in skb shared
info tx_flags rather than gso_type.

tx_flags is better compared to gso_type since we can have skb with
shared frag without gso packet. It does not link SHARED_FRAG to
GSO, So there is no need to define netdev feature for this.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index b181dfb3d6d6..97243011d319 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -543,7 +543,6 @@ static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,
                 skb->data_len += len;
                 skb->len += len;
                 skb->truesize += truesize;
-                skb_shinfo(skb)->gso_type |= SKB_GSO_SHARED_FRAG;
                 atomic_add(truesize, &skb->sk->sk_wmem_alloc);
                 while (len) {
                         int off = base & ~PAGE_MASK;
@@ -599,7 +598,7 @@ static int macvtap_skb_from_vnet_hdr(struct sk_buff *skb,
 
         if (vnet_hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
                 skb_shinfo(skb)->gso_size = vnet_hdr->gso_size;
-                skb_shinfo(skb)->gso_type |= gso_type;
+                skb_shinfo(skb)->gso_type = gso_type;
 
                 /* Header must be checked, and gso_segs computed. */
                 skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
@@ -743,6 +742,7 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
         if (zerocopy) {
                 skb_shinfo(skb)->destructor_arg = m->msg_control;
                 skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
+                skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
         }
         if (vlan)
                 macvlan_start_xmit(skb, vlan->dev);