Re: Bug handling devices with weird names

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

Le vendredi 09 juillet 2010 à 17:41 +0200, Martín Ferrari a écrit :
> Hi,
> 
> On Fri, Jul 9, 2010 at 12:19, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> > Update user land tools ?
> >
> > No problem here :
> >
> > # ip link add name foo: type dummy
> > # ip link list foo:
> > 14: foo:: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN
> >    link/ether e6:48:a9:57:d4:1f brd ff:ff:ff:ff:ff:ff
> > # ip link del foo:
> > # ip -V
> > ip utility, iproute2-ss100519
> 
> I am using the exact same version (from Debian), and I can also
> reproduce it with fedora's iproute2-ss080725.
> The kernels are 2.6.35-rc4 and 2.6.27, respectively.. Maybe your
> version of iprout is patched as to not use ioctl?
> 
> 
> 

Well

I use the git version of iproute2, this includes following patch.

Nothing very exciting, but this avoids this ioctl() as you guessed ;)

You cannot ask old binaries to handle foo: devices very well, since
this special char (:) had special meaning in old days.

commit 62a5e0668e2920b7f09896abd884753255712a46
Author: Eric Dumazet <dada1@cosmosbay.com>
Date:   Fri Oct 23 06:25:53 2009 +0200

    ip: Support IFLA_TXQLEN in ip link show command
    
    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.

diff --git a/ip/ipaddress.c b/ip/ipaddress.c
index 267ecb3..cadc1a3 100644
--- a/ip/ipaddress.c
+++ b/ip/ipaddress.c
@@ -131,26 +131,31 @@ static void print_operstate(FILE *f, __u8 state)
 		fprintf(f, "state %s ", oper_states[state]);
 }
 
-static void print_queuelen(FILE *f, const char *name)
+static void print_queuelen(FILE *f, struct rtattr *tb[IFLA_MAX + 1])
 {
-	struct ifreq ifr;
-	int s;
-
-	s = socket(AF_INET, SOCK_STREAM, 0);
-	if (s < 0)
-		return;
-
-	memset(&ifr, 0, sizeof(ifr));
-	strcpy(ifr.ifr_name, name);
-	if (ioctl(s, SIOCGIFTXQLEN, &ifr) < 0) {
-		fprintf(f, "ioctl(SIOCGIFXQLEN) failed: %s\n", strerror(errno));
+	int qlen;
+
+	if (tb[IFLA_TXQLEN])
+		qlen = *(int *)RTA_DATA(tb[IFLA_TXQLEN]);
+	else {
+		struct ifreq ifr;
+		int s = socket(AF_INET, SOCK_STREAM, 0);
+
+		if (s < 0)
+			return;
+
+		memset(&ifr, 0, sizeof(ifr));
+		strcpy(ifr.ifr_name, (char *)RTA_DATA(tb[IFLA_IFNAME]));
+		if (ioctl(s, SIOCGIFTXQLEN, &ifr) < 0) {
+			fprintf(f, "ioctl(SIOCGIFXQLEN) failed: %s\n", strerror(errno));
+			close(s);
+			return;
+		}
 		close(s);
-		return;
+		qlen = ifr.ifr_qlen;
 	}
-	close(s);
-
-	if (ifr.ifr_qlen)
-		fprintf(f, "qlen %d", ifr.ifr_qlen);
+	if (qlen)
+		fprintf(f, "qlen %d", qlen);
 }
 
 static void print_linktype(FILE *fp, struct rtattr *tb)
@@ -253,7 +258,7 @@ int print_linkinfo(const struct sockaddr_nl *who,
 		print_operstate(fp, *(__u8 *)RTA_DATA(tb[IFLA_OPERSTATE]));
 		
 	if (filter.showqueue)
-		print_queuelen(fp, (char*)RTA_DATA(tb[IFLA_IFNAME]));
+		print_queuelen(fp, tb);
 
 	if (!filter.family || filter.family == AF_PACKET) {
 		SPRINT_BUF(b1);