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Description of problem:

iproute2 was fixed incorrectly by iproute2-2.6.32-rtnl_send-hang.patch

--- a/ip/iplink.c
+++ b/ip/iplink.c
@@ -158,8 +158,8 @@ static int iplink_have_newlink(void)
 		req.n.nlmsg_type = RTM_NEWLINK;
 		req.i.ifi_family = AF_UNSPEC;
 
-		rtnl_send(&rth, (char *)&req.n, req.n.nlmsg_len);
-		rtnl_listen(&rth, accept_msg, NULL);
+		if (rtnl_send(&rth, &req.n, req.n.nlmsg_len) == 0)
+			rtnl_listen(&rth, accept_msg, NULL);
 	}
 	return have_rtnl_newlink;
 }

Look at the rtnl_send() function
int rtnl_send(struct rtnl_handle *rth, const char *buf, int len)
{
        return send(rth->fd, buf, len, 0);
}

send() returns the number of bytes sent, so with these patch we leave a response in a socket. Each next command will get a response for a previous command.

I think we must check that rtnl_send() returns a positive value.

Version-Release number of selected component (if applicable):
iproute-2.6.32-31.el6.x86_64


How reproducible:
100%


Steps to Reproduce:
1. Install old kernel (2.6.18)
2. # ip link set up dev eth0
RTNETLINK answers: Operation not supported

Actual results:
Can't bring a network interface up

Expected results:
It works fine w/o this patch


Additional info:

https://bugzilla.redhat.com/show_bug.cgi?id=985526

You are right, the patch is wrong.

Created attachment 835274 [details]
Correct patch proposed to upstream

Just for the reference:

Corresponding Parallels issue id: PCLIN-32219

Corresponding OpenVZ bug: https://bugzilla.openvz.org/2843
Web Hosting Talk thread:  http://www.webhostingtalk.com/showthread.php?t=1327600
Fixed iproute2 packages:  http://download.openvz.org/.kir/bug2843/

Upstream is still working on fix. Current upstream sources does not provide complete fix.

I recommend to apply my patch or the latter version posted in referenced mailing list which adds a warning to error output.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2015-1331.html