netdev - [PATCH iproute2 net-next] iplink: allow configuring GSO max values

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Date:   Fri,  1 Dec 2017 12:13:08 -0800
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     netdev@...r.kernel.org
Cc:     Stephen Hemminger <stephen@...workplumber.org>,
        Stephen Hemminger <sthemmin@...rosoft.com>
Subject: [PATCH iproute2 net-next] iplink: allow configuring GSO max values

This allows sending GSO maximum values when configuring a device.
The values are advisory. Most devices will ignore them but for some
pseudo devices such as veth pairs they can be set.

Example:
	# ip link add dev vm1 type veth peer name vm2 gso_max_size 32768

Signed-off-by: Stephen Hemminger <sthemmin@...rosoft.com>
---
 ip/iplink.c           | 19 ++++++++++++++++++-
 man/man8/ip-link.8.in | 13 +++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/ip/iplink.c b/ip/iplink.c
index 0a8eb56fb252..6379b16a14f5 100644
--- a/ip/iplink.c
+++ b/ip/iplink.c
@@ -97,7 +97,8 @@ void iplink_usage(void)
 		"			  [ master DEVICE ][ vrf NAME ]\n"
 		"			  [ nomaster ]\n"
 		"			  [ addrgenmode { eui64 | none | stable_secret | random } ]\n"
-		"	                  [ protodown { on | off } ]\n"
+		"			  [ protodown { on | off } ]\n"
+		"			  [ gso_max_size BYTES ] | [ gso_max_segs PACKETS ]\n"
 		"\n"
 		"       ip link show [ DEVICE | group GROUP ] [up] [master DEV] [vrf NAME] [type TYPE]\n");
 
@@ -848,6 +849,22 @@ int iplink_parse(int argc, char **argv, struct iplink_req *req,
 				return on_off("protodown", *argv);
 			addattr8(&req->n, sizeof(*req), IFLA_PROTO_DOWN,
 				 proto_down);
+		} else if (strcmp(*argv, "gso_max_size") == 0) {
+			unsigned int max_size;
+
+			NEXT_ARG();
+			if (get_unsigned(&max_size, *argv, 0) || max_size > UINT16_MAX)
+				invarg("Invalid \"gso_max_size\" value\n",
+				       *argv);
+			addattr32(&req->n, sizeof(*req), IFLA_GSO_MAX_SIZE, max_size);
+		} else if (strcmp(*argv, "gso_max_segs") == 0) {
+			unsigned int max_segs;
+
+			NEXT_ARG();
+			if (get_unsigned(&max_segs, *argv, 0) || max_segs > UINT16_MAX)
+				invarg("Invalid \"gso_max_segs\" value\n",
+				       *argv);
+			addattr32(&req->n, sizeof(*req), IFLA_GSO_MAX_SEGS, max_segs);
 		} else {
 			if (matches(*argv, "help") == 0)
 				usage();
diff --git a/man/man8/ip-link.8.in b/man/man8/ip-link.8.in
index a6a10e577b1f..0db2582e19f7 100644
--- a/man/man8/ip-link.8.in
+++ b/man/man8/ip-link.8.in
@@ -36,6 +36,11 @@ ip-link \- network device configuration
 .RB "[ " numrxqueues
 .IR QUEUE_COUNT " ]"
 .br
+.BR "[" gso_max_size
+.IR BYTES " ]"
+.RB "[ " gso_max_segs
+.IR SEGMENTS " ]"
+.br
 .BI type " TYPE"
 .RI "[ " ARGS " ]"
 
@@ -343,6 +348,14 @@ specifies the number of transmit queues for new device.
 specifies the number of receive queues for new device.
 
 .TP
+.BI gso_max_size " BYTES "
+specifies the recommended maximum size of a Generic Segment Offload packet the new device should accept.
+
+.TP
+.BI gso_max_segs " SEGMENTS "
+specifies the recommended maximum number of a Generic Segment Offload segments the new device should accept.
+
+.TP
 .BI index " IDX "
 specifies the desired index of the new virtual device. The link creation fails, if the index is busy.
 
-- 
2.11.0