openvswitch: Add packet len info to upcall.

The commit f2a4d086ed4c ("openvswitch: Add packet truncation support.")
introduces packet truncation before sending to userspace upcall receiver.
This patch passes up the skb->len before truncation so that the upcall
receiver knows the original packet size. Potentially this will be used
by sFlow, where OVS translates sFlow config header=N to a sample action,
truncating packet to N byte in kernel datapath. Thus, only N bytes instead
of full-packet size is copied from kernel to userspace, saving the
kernel-to-userspace bandwidth.

Signed-off-by: William Tu <u9012063@gmail.com>
Cc: Pravin Shelar <pshelar@nicira.com>
Acked-by: Pravin B Shelar <pshelar@ovn.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/uapi/linux/openvswitch.h b/include/uapi/linux/openvswitch.h
index 8274675ba9a3..d95a3018f6a1 100644
--- a/include/uapi/linux/openvswitch.h
+++ b/include/uapi/linux/openvswitch.h
@@ -166,6 +166,7 @@ enum ovs_packet_cmd {
  * output port is actually a tunnel port. Contains the output tunnel key
  * extracted from the packet as nested %OVS_TUNNEL_KEY_ATTR_* attributes.
  * @OVS_PACKET_ATTR_MRU: Present for an %OVS_PACKET_CMD_ACTION and
+ * @OVS_PACKET_ATTR_LEN: Packet size before truncation.
  * %OVS_PACKET_ATTR_USERSPACE action specify the Maximum received fragment
  * size.
  *
@@ -185,6 +186,7 @@ enum ovs_packet_attr {
         OVS_PACKET_ATTR_PROBE,      /* Packet operation is a feature probe,
                                        error logging should be suppressed. */
         OVS_PACKET_ATTR_MRU,        /* Maximum received IP fragment size. */
+        OVS_PACKET_ATTR_LEN,            /* Packet size before truncation. */
         __OVS_PACKET_ATTR_MAX
 };