linux-kernel - [PATCH 3.2 28/74] ipv6: always add flag an address that failed DAD with DADFAILED

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Date:   Mon, 09 Oct 2017 13:30:34 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Hannes Frederic Sowa" <hannes@...essinduktion.org>,
        "David S. Miller" <davem@...emloft.net>,
        "Lubomir Rintel" <lkundrak@...sk>
Subject: [PATCH 3.2 28/74] ipv6: always add flag an address that failed
 DAD with DADFAILED

3.2.94-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Lubomir Rintel <lkundrak@...sk>

commit 3d171f3907329d4b1ce31d5ec9c852c5f0269578 upstream.

The userspace needs to know why is the address being removed so that it can
perhaps obtain a new address.

Without the DADFAILED flag it's impossible to distinguish removal of a
temporary and tentative address due to DAD failure from other reasons (device
removed, manual address removal).

Signed-off-by: Lubomir Rintel <lkundrak@...sk>
Acked-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
Signed-off-by: David S. Miller <davem@...emloft.net>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/ipv6/addrconf.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1382,12 +1382,13 @@ struct inet6_ifaddr *ipv6_get_ifaddr(str
 
 static void addrconf_dad_stop(struct inet6_ifaddr *ifp, int dad_failed)
 {
+	if (dad_failed)
+		ifp->flags |= IFA_F_DADFAILED;
+
 	if (ifp->flags&IFA_F_PERMANENT) {
 		spin_lock_bh(&ifp->lock);
 		addrconf_del_timer(ifp);
 		ifp->flags |= IFA_F_TENTATIVE;
-		if (dad_failed)
-			ifp->flags |= IFA_F_DADFAILED;
 		spin_unlock_bh(&ifp->lock);
 		if (dad_failed)
 			ipv6_ifa_notify(0, ifp);