[PATCH iproute2] ip: Support IFLA_TXQLEN in ip link command

[Eric Dumazet <eric.dumazet@gmail.com>]

We currently use an expensive ioctl() to get device txqueuelen, while
rtnetlink gave it to us for free. This patch speeds up ip link operation
when many devices are registered.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
---

diff --git a/ip/ipaddress.c b/ip/ipaddress.c
index 267ecb3..f06a3f7 100644
--- a/ip/ipaddress.c
+++ b/ip/ipaddress.c
@@ -252,9 +252,12 @@ int print_linkinfo(const struct sockaddr_nl *who,
 	if (tb[IFLA_OPERSTATE])
 		print_operstate(fp, *(__u8 *)RTA_DATA(tb[IFLA_OPERSTATE]));
 		
-	if (filter.showqueue)
-		print_queuelen(fp, (char*)RTA_DATA(tb[IFLA_IFNAME]));
-
+	if (filter.showqueue) {
+		if (tb[IFLA_TXQLEN])
+			fprintf(fp, "qlen %d ", *(int *)RTA_DATA(tb[IFLA_TXQLEN]));
+		else
+			print_queuelen(fp, (char *)RTA_DATA(tb[IFLA_IFNAME]));
+	}
 	if (!filter.family || filter.family == AF_PACKET) {
 		SPRINT_BUF(b1);
 		fprintf(fp, "%s", _SL_);