From cbc0484a42adf93bdd6897f93b15b0eaeb3077f6 Mon Sep 17 00:00:00 2001
From: Richard Maw <richard.maw@codethink.co.uk>
Date: Thu, 12 Mar 2015 18:14:58 +0000
Subject: [PATCH] networkd: Begin with serial number 1 for netlink requests

"Notifications are of informal nature and no reply is expected, therefore the
sequence number is typically set to 0."[1]

If networkd is started soon after recent netlink activity, then there
will be messages with sequence number 0 in the buffer.

The first thing networkd does is to request a dump of all the links. If
it uses sequence number 0 for this, then it may confuse the dump request's
response with that of a notification.

This will result in it failing to properly enumerate all the links,
but more importantly, when it comes to enumerate all the addresses, it
will still have the link dump in progress, so the address enumeration
will fail with -EBUSY.

[1]: http://www.infradead.org/~tgr/libnl/doc/core.html#core_msg_types

[tomegun: sequence -> serial]

(cherry picked from commit d422e52a3523ad0955bec4f9fbed46e234d28590)
---
 src/libsystemd/sd-rtnl/sd-rtnl.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/libsystemd/sd-rtnl/sd-rtnl.c b/src/libsystemd/sd-rtnl/sd-rtnl.c
index ae49c77e01..7cdcc5d96a 100644
--- a/src/libsystemd/sd-rtnl/sd-rtnl.c
+++ b/src/libsystemd/sd-rtnl/sd-rtnl.c
@@ -61,6 +61,11 @@ static int sd_rtnl_new(sd_rtnl **ret) {
                             sizeof(struct nlmsghdr), sizeof(uint8_t)))
                 return -ENOMEM;
 
+        /* Change notification responses have sequence 0, so we must
+         * start our request sequence numbers at 1, or we may confuse our
+         * responses with notifications from the kernel */
+        rtnl->serial = 1;
+
         *ret = rtnl;
         rtnl = NULL;