Subject: [PATCH iproute2] ip link: Do not call ll_name_to_index when creating a new link

From: [email-masked]
Date: Thu, 17 May 2018 16:22:37 -0600

From: David Ahern <[email-masked]>

Using iproute2 to create a bridge and add 4094 vlans to it can take from
2 to 3 *minutes*. The reason is the extraneous call to ll_name_to_index.
ll_name_to_index results in an ioctl(SIOCGIFINDEX) call which in turn
invokes dev_load. If the index does not exist, which it won't when
creating a new link, dev_load calls modprobe twice -- once for
netdev-NAME and again for NAME. This is unnecessary overhead for each
link create.

When ip link is invoked for a new device, there is no reason to
call ll_name_to_index for the new device. With this patch, creating
a bridge and adding 4094 vlans takes less than 3 *seconds*.

Signed-off-by: David Ahern <[email-masked]>
---
 ip/ip_common.h    |  3 ++-
 ip/iplink.c       | 22 +++++++++++++---------
 ip/iplink_vxcan.c |  3 ++-
 ip/link_veth.c    |  3 ++-
 4 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/ip/ip_common.h b/ip/ip_common.h
index 1b89795caa58..67f413474631 100644
--- a/ip/ip_common.h
+++ b/ip/ip_common.h
@@ -132,7 +132,8 @@ struct link_util {
 
 struct link_util *get_link_kind(const char *kind);
 
-int iplink_parse(int argc, char **argv, struct iplink_req *req, char **type);
+int iplink_parse(int argc, char **argv, struct iplink_req *req,
+		 char **type, bool is_add_cmd);
 
 /* iplink_bridge.c */
 void br_dump_bridge_id(const struct ifla_bridge_id *id, char *buf, size_t len);
diff --git a/ip/iplink.c b/ip/iplink.c
index e6bb4493120e..c8bf49ed3d24 100644
--- a/ip/iplink.c
+++ b/ip/iplink.c
@@ -571,7 +571,8 @@ static int iplink_parse_vf(int vf, int *argcp, char ***argvp,
 	return 0;
 }
 
-int iplink_parse(int argc, char **argv, struct iplink_req *req, char **type)
+int iplink_parse(int argc, char **argv, struct iplink_req *req, char **type,
+		 bool is_add_cmd)
 {
 	char *name = NULL;
 	char *dev = NULL;
@@ -610,7 +611,8 @@ int iplink_parse(int argc, char **argv, struct iplink_req *req, char **type)
 			name = *argv;
 			if (!dev) {
 				dev = name;
-				dev_index = ll_name_to_index(dev);
+				if (!is_add_cmd)
+					dev_index = ll_name_to_index(dev);
 			}
 		} else if (strcmp(*argv, "index") == 0) {
 			NEXT_ARG();
@@ -919,7 +921,8 @@ int iplink_parse(int argc, char **argv, struct iplink_req *req, char **type)
 			if (check_ifname(*argv))
 				invarg("\"dev\" not a valid ifname", *argv);
 			dev = *argv;
-			dev_index = ll_name_to_index(dev);
+			if (!is_add_cmd)
+				dev_index = ll_name_to_index(dev);
 		}
 		argc--; argv++;
 	}
@@ -1011,7 +1014,8 @@ int iplink_parse(int argc, char **argv, struct iplink_req *req, char **type)
 	return ret;
 }
 
-static int iplink_modify(int cmd, unsigned int flags, int argc, char **argv)
+static int iplink_modify(int cmd, unsigned int flags, int argc, char **argv,
+			 bool is_add_cmd)
 {
 	char *type = NULL;
 	struct iplink_req req = {
@@ -1022,7 +1026,7 @@ static int iplink_modify(int cmd, unsigned int flags, int argc, char **argv)
 	};
 	int ret;
 
-	ret = iplink_parse(argc, argv, &req, &type);
+	ret = iplink_parse(argc, argv, &req, &type, is_add_cmd);
 	if (ret < 0)
 		return ret;
 
@@ -1630,18 +1634,18 @@ int do_iplink(int argc, char **argv)
 		if (matches(*argv, "add") == 0)
 			return iplink_modify(RTM_NEWLINK,
 					     NLM_F_CREATE|NLM_F_EXCL,
-					     argc-1, argv+1);
+					     argc-1, argv+1, true);
 		if (matches(*argv, "set") == 0 ||
 		    matches(*argv, "change") == 0)
 			return iplink_modify(RTM_NEWLINK, 0,
-					     argc-1, argv+1);
+					     argc-1, argv+1, false);
 		if (matches(*argv, "replace") == 0)
 			return iplink_modify(RTM_NEWLINK,
 					     NLM_F_CREATE|NLM_F_REPLACE,
-					     argc-1, argv+1);
+					     argc-1, argv+1, false);
 		if (matches(*argv, "delete") == 0)
 			return iplink_modify(RTM_DELLINK, 0,
-					     argc-1, argv+1);
+					     argc-1, argv+1, false);
 	} else {
 #if IPLINK_IOCTL_COMPAT
 		if (matches(*argv, "set") == 0)
diff --git a/ip/iplink_vxcan.c b/ip/iplink_vxcan.c
index 8b08c9a70c65..e30a784d9851 100644
--- a/ip/iplink_vxcan.c
+++ b/ip/iplink_vxcan.c
@@ -56,7 +56,8 @@ static int vxcan_parse_opt(struct link_util *lu, int argc, char **argv,
 
 	n->nlmsg_len += sizeof(struct ifinfomsg);
 
-	err = iplink_parse(argc - 1, argv + 1, (struct iplink_req *)n, &type);
+	err = iplink_parse(argc - 1, argv + 1, (struct iplink_req *)n, &type,
+			   false);
 	if (err < 0)
 		return err;
 
diff --git a/ip/link_veth.c b/ip/link_veth.c
index 33e8f2b102e7..68823931c0ec 100644
--- a/ip/link_veth.c
+++ b/ip/link_veth.c
@@ -54,7 +54,8 @@ static int veth_parse_opt(struct link_util *lu, int argc, char **argv,
 
 	n->nlmsg_len += sizeof(struct ifinfomsg);
 
-	err = iplink_parse(argc - 1, argv + 1, (struct iplink_req *)n, &type);
+	err = iplink_parse(argc - 1, argv + 1, (struct iplink_req *)n, &type,
+			   false);
 	if (err < 0)
 		return err;
 
-- 
2.11.0