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>

diff --git a/include/uapi/linux/openvswitch.h b/include/uapi/linux/openvswitch.h
index 8274675ba9a32eb338dc92872b94fab6617a9c46..d95a3018f6a1e7018f2b8774c4513387a270b3fd 100644 (file)
--- 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 6739342953338f7bfaeb6a121cd9ef958c12fc98..524c0fd3078e7d4a7358118d9cfe93be5f64b052 100644 (file)
--- 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))) {