GSO: Support partial segmentation offload
This patch adds support for something I am referring to as GSO partial.
The basic idea is that we can support a broader range of devices for
segmentation if we use fixed outer headers and have the hardware only
really deal with segmenting the inner header. The idea behind the naming
is due to the fact that everything before csum_start will be fixed headers,
and everything after will be the region that is handled by hardware.
With the current implementation it allows us to add support for the
following GSO types with an inner TSO_MANGLEID or TSO6 offload:
NETIF_F_GSO_GRE
NETIF_F_GSO_GRE_CSUM
NETIF_F_GSO_IPIP
NETIF_F_GSO_SIT
NETIF_F_UDP_TUNNEL
NETIF_F_UDP_TUNNEL_CSUM
In the case of hardware that already supports tunneling we may be able to
extend this further to support TSO_TCPV4 without TSO_MANGLEID if the
hardware can support updating inner IPv4 headers.
Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
index d1ffd55..02737b6 100644
--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -109,6 +109,12 @@
goto out;
}
+ /* GSO partial only requires splitting the frame into an MSS
+ * multiple and possibly a remainder. So update the mss now.
+ */
+ if (features & NETIF_F_GSO_PARTIAL)
+ mss = skb->len - (skb->len % mss);
+
copy_destructor = gso_skb->destructor == tcp_wfree;
ooo_okay = gso_skb->ooo_okay;
/* All segments but the first should have ooo_okay cleared */
@@ -133,7 +139,7 @@
newcheck = ~csum_fold((__force __wsum)((__force u32)th->check +
(__force u32)delta));
- do {
+ while (skb->next) {
th->fin = th->psh = 0;
th->check = newcheck;
@@ -153,7 +159,7 @@
th->seq = htonl(seq);
th->cwr = 0;
- } while (skb->next);
+ }
/* Following permits TCP Small Queues to work well with GSO :
* The callback to TCP stack will be called at the time last frag