netdev - [PATCH v2 1/2] ipv6: save route expiry in RTA_EXPIRES if RTF

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Message-Id: <d9679ca53d5162eaa88ac5050410e1b4fb3c2874.1471622715.git.ayourtch@gmail.com>
Date:   Fri, 19 Aug 2016 18:41:22 +0200
From:   Andrew Yourtchenko <ayourtch@...il.com>
To:     netdev@...r.kernel.org
Cc:     Andrew Yourtchenko <ayourtch@...il.com>
Subject: [PATCH v2 1/2] ipv6: save route expiry in RTA_EXPIRES if RTF_EXPIRES set

This allows "ip -6 route save" to save the expiry for the routes
that have it, such that it can be correctly restored later by
"ip -6 route restore".

If a route has RTF_EXPIRES set, generate RTA_EXPIRES value which
will be used to restore the flag and expiry value by already
existing code in rtm_to_fib6_config.

The expiry was already being saved as part of RTA_CACHEINFO
in rtnl_put_cacheinfo(), but adding code to generate RTF_EXPIRES upon save
looked more appropriate than redundant cherrypicking from
RTA_CACHEINFO upon restore.

Signed-off-by: Andrew Yourtchenko <ayourtch@...il.com>
---
Changes since v1 [1]: 
 * fixed the indentation in a multiline function call
   as per David Miller's review

[1] v1: http://marc.info/?l=linux-netdev&m=147135597422280&w=2

 net/ipv6/route.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 4981755..f5b987d 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -3244,6 +3244,14 @@ static int rt6_fill_node(struct net *net,
 	if (rtnl_put_cacheinfo(skb, &rt->dst, 0, expires, rt->dst.error) < 0)
 		goto nla_put_failure;
 
+	/* Can't rely on expires == 0. It is zero if no expires flag,
+	 * or if the timing is precisely at expiry. So, recheck the flag.
+	 */
+	if (rt->rt6i_flags & RTF_EXPIRES)
+		if (nla_put_u32(skb, RTA_EXPIRES,
+				expires > 0 ? expires / HZ : 0))
+			goto nla_put_failure;
+
 	if (nla_put_u8(skb, RTA_PREF, IPV6_EXTRACT_PREF(rt->rt6i_flags)))
 		goto nla_put_failure;
 
-- 
2.7.4