[Devel] [PATCH RHEL7 COMMIT] ms/ipv6: reorder ip6_route_dev_notifier after ipv6_dev_notf

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-514.26.1.vz7.33.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-514.26.1.vz7.33.9
------>
commit e00c100739440ff23be2a3f59af233ea9f2d369b
Author: WANG Cong <xiyou.wangcong at gmail.com>
Date:   Mon May 8 10:12:13 2017 -0700

    ms/ipv6: reorder ip6_route_dev_notifier after ipv6_dev_notf
    
    For each netns (except init_net), we initialize its null entry
    in 3 places:
    
    1) The template itself, as we use kmemdup()
    2) Code around dst_init_metrics() in ip6_route_net_init()
    3) ip6_route_dev_notify(), which is supposed to initialize it after
       loopback registers
    
    Unfortunately the last one still happens in a wrong order because
    we expect to initialize net->ipv6.ip6_null_entry->rt6i_idev to
    net->loopback_dev's idev, thus we have to do that after we add
    idev to loopback. However, this notifier has priority == 0 same as
    ipv6_dev_notf, and ipv6_dev_notf is registered after
    ip6_route_dev_notifier so it is called actually after
    ip6_route_dev_notifier. This is similar to commit 2f460933f58e
    ("ipv6: initialize route null entry in addrconf_init()") which
    fixes init_net.
    
    Fix it by picking a smaller priority for ip6_route_dev_notifier.
    Also, we have to release the refcnt accordingly when unregistering
    loopback_dev because device exit functions are called before subsys
    exit functions.
    
    Acked-by: David Ahern <dsahern at gmail.com>
    Tested-by: David Ahern <dsahern at gmail.com>
    Signed-off-by: Cong Wang <xiyou.wangcong at gmail.com>
    Signed-off-by: David S. Miller <davem at davemloft.net>
    
    https://jira.sw.ru/browse/PSBM-66197
    
    (cherry picked from commit 242d3a49a2a1a71d8eb9f953db1bcaa9d698ce00)
    Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
---
 include/net/addrconf.h |  2 ++
 net/ipv6/addrconf.c    |  1 +
 net/ipv6/route.c       | 13 +++++++++++--
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index a17d6b9..2905c15 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -19,6 +19,8 @@
 #define ADDRCONF_TIMER_FUZZ		(HZ / 4)
 #define ADDRCONF_TIMER_FUZZ_MAX		(HZ)
 
+#define ADDRCONF_NOTIFY_PRIORITY	0
+
 #include <linux/in.h>
 #include <linux/in6.h>
 
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 1989b61..8d510e2 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -3010,6 +3010,7 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event,
  */
 static struct notifier_block ipv6_dev_notf = {
 	.notifier_call = addrconf_notify,
+	.priority = ADDRCONF_NOTIFY_PRIORITY,
 };
 
 static void addrconf_type_change(struct net_device *dev, unsigned long event)
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 99957f7..3d4d519 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -3216,7 +3216,10 @@ static int ip6_route_dev_notify(struct notifier_block *this,
 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 	struct net *net = dev_net(dev);
 
-	if (event == NETDEV_REGISTER && (dev->flags & IFF_LOOPBACK)) {
+	if (!(dev->flags & IFF_LOOPBACK))
+		return NOTIFY_OK;
+
+	if (event == NETDEV_REGISTER) {
 		net->ipv6.ip6_null_entry->dst.dev = dev;
 		net->ipv6.ip6_null_entry->rt6i_idev = in6_dev_get(dev);
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
@@ -3225,6 +3228,12 @@ static int ip6_route_dev_notify(struct notifier_block *this,
 		net->ipv6.ip6_blk_hole_entry->dst.dev = dev;
 		net->ipv6.ip6_blk_hole_entry->rt6i_idev = in6_dev_get(dev);
 #endif
+	 } else if (event == NETDEV_UNREGISTER) {
+		in6_dev_put(net->ipv6.ip6_null_entry->rt6i_idev);
+#ifdef CONFIG_IPV6_MULTIPLE_TABLES
+		in6_dev_put(net->ipv6.ip6_prohibit_entry->rt6i_idev);
+		in6_dev_put(net->ipv6.ip6_blk_hole_entry->rt6i_idev);
+#endif
 	}
 
 	return NOTIFY_OK;
@@ -3531,7 +3540,7 @@ static struct pernet_operations ip6_route_net_late_ops = {
 
 static struct notifier_block ip6_route_dev_notifier = {
 	.notifier_call = ip6_route_dev_notify,
-	.priority = 0,
+	.priority = ADDRCONF_NOTIFY_PRIORITY - 10,
 };
 
 #if 0