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Commit b95e5928 authored by William Tu's avatar William Tu Committed by David S. Miller
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openvswitch: Add packet len info to upcall. 



The commit f2a4d086 ("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: default avatarWilliam Tu <u9012063@gmail.com>
Cc: Pravin Shelar <pshelar@nicira.com>
Acked-by: default avatarPravin B Shelar <pshelar@ovn.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 904632a2

include/uapi/linux/openvswitch.h

+2 −0
Original line number Diff line number Diff line
@@ -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

};

net/openvswitch/datapath.c

+12 −1
Original line number Diff line number Diff line
@@ -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))) {