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 <u9012...@gmail.com>
Cc: Pravin Shelar <pshe...@nicira.com>
---
v3->v4:
- Add OVS_PACKET_ATTR_LEN only when packet is truncated,
This avoid sending extra attribute in the case of miss flow.
v2->v3:
- Remove platform specific name.
- Fix issue when receiving GSO packet
- Remove skblen in struct dp_upcall_info
v1->v2:
- Pass skb->len to userspace instead of cutlen
---
include/uapi/linux/openvswitch.h | 2 ++
net/openvswitch/datapath.c | 13 ++++++++++++-
2 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/include/uapi/linux/openvswitch.h b/include/uapi/linux/openvswitch.h
index 8274675..d95a301 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
};
diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 6739342..524c0fd 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -387,7 +387,8 @@ static size_t upcall_msg_size(const struct dp_upcall_info
*upcall_info,
{
size_t size = NLMSG_ALIGN(sizeof(struct ovs_header))
+ nla_total_size(hdrlen) /* OVS_PACKET_ATTR_PACKET */
- + nla_total_size(ovs_key_attr_size()); /* OVS_PACKET_ATTR_KEY */
+ + nla_total_size(ovs_key_attr_size()) /* OVS_PACKET_ATTR_KEY */
+ + nla_total_size(sizeof(unsigned int)); /* OVS_PACKET_ATTR_LEN
*/
/* OVS_PACKET_ATTR_USERDATA */
if (upcall_info->userdata)
@@ -514,6 +515,16 @@ static int queue_userspace_packet(struct datapath *dp,
struct sk_buff *skb,
pad_packet(dp, user_skb);
}
+ /* Add OVS_PACKET_ATTR_LEN when packet is truncated */
+ if (cutlen > 0) {
+ if (nla_put_u32(user_skb, OVS_PACKET_ATTR_LEN,
+ skb->len)) {
+ err = -ENOBUFS;
+ goto out;
+ }
+ pad_packet(dp, user_skb);
+ }
+
/* Only reserve room for attribute header, packet data is added
* in skb_zerocopy() */
if (!(nla = nla_reserve(user_skb, OVS_PACKET_ATTR_PACKET, 0))) {
--
2.5.0
