[PATCH net-next] vxlan: Use a per-namespace nexthop listener instead of a global one

[PATCH net-next] vxlan: Use a per-namespace nexthop listener instead of a global one

[Ido Schimmel]

From: Ido Schimmel <idosch@nvidia.com>

The nexthop notification chain is a per-namespace chain and not a global
one like the netdev notification chain.

Therefore, a single (global) listener cannot be registered to all these
chains simultaneously as it will result in list corruptions whenever
listeners are registered / unregistered.

Instead, register a different listener in each namespace.

Currently this is not an issue because only the VXLAN driver registers a
listener to this chain, but this is going to change with netdevsim and
mlxsw also registering their own listeners.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
---
 drivers/net/vxlan.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 1a557aeba32b..876679af6f7c 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -66,6 +66,7 @@ struct vxlan_net {
 	struct list_head  vxlan_list;
 	struct hlist_head sock_list[PORT_HASH_SIZE];
 	spinlock_t	  sock_lock;
+	struct notifier_block nexthop_notifier_block;
 };
 
 /* Forwarding table entry */
@@ -4693,10 +4694,6 @@ static int vxlan_nexthop_event(struct notifier_block *nb,
 	return NOTIFY_DONE;
 }
 
-static struct notifier_block vxlan_nexthop_notifier_block __read_mostly = {
-	.notifier_call = vxlan_nexthop_event,
-};
-
 static __net_init int vxlan_init_net(struct net *net)
 {
 	struct vxlan_net *vn = net_generic(net, vxlan_net_id);
@@ -4704,11 +4701,12 @@ static __net_init int vxlan_init_net(struct net *net)
 
 	INIT_LIST_HEAD(&vn->vxlan_list);
 	spin_lock_init(&vn->sock_lock);
+	vn->nexthop_notifier_block.notifier_call = vxlan_nexthop_event;
 
 	for (h = 0; h < PORT_HASH_SIZE; ++h)
 		INIT_HLIST_HEAD(&vn->sock_list[h]);
 
-	return register_nexthop_notifier(net, &vxlan_nexthop_notifier_block);
+	return register_nexthop_notifier(net, &vn->nexthop_notifier_block);
 }
 
 static void vxlan_destroy_tunnels(struct net *net, struct list_head *head)
@@ -4740,8 +4738,11 @@ static void __net_exit vxlan_exit_batch_net(struct list_head *net_list)
 	LIST_HEAD(list);
 
 	rtnl_lock();
-	list_for_each_entry(net, net_list, exit_list)
-		unregister_nexthop_notifier(net, &vxlan_nexthop_notifier_block);
+	list_for_each_entry(net, net_list, exit_list) {
+		struct vxlan_net *vn = net_generic(net, vxlan_net_id);
+
+		unregister_nexthop_notifier(net, &vn->nexthop_notifier_block);
+	}
 	list_for_each_entry(net, net_list, exit_list)
 		vxlan_destroy_tunnels(net, &list);
 
-- 
2.26.2

Re: [PATCH net-next] vxlan: Use a per-namespace nexthop listener instead of a global one

[David Ahern]

On 11/1/20 4:39 AM, Ido Schimmel wrote:
> From: Ido Schimmel <idosch@nvidia.com>
> 
> The nexthop notification chain is a per-namespace chain and not a global
> one like the netdev notification chain.
> 
> Therefore, a single (global) listener cannot be registered to all these
> chains simultaneously as it will result in list corruptions whenever
> listeners are registered / unregistered.
> 
> Instead, register a different listener in each namespace.
> 
> Currently this is not an issue because only the VXLAN driver registers a
> listener to this chain, but this is going to change with netdevsim and
> mlxsw also registering their own listeners.
> 
> Signed-off-by: Ido Schimmel <idosch@nvidia.com>
> ---
>  drivers/net/vxlan.c | 15 ++++++++-------
>  1 file changed, 8 insertions(+), 7 deletions(-)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>

Re: [PATCH net-next] vxlan: Use a per-namespace nexthop listener instead of a global one

[Jakub Kicinski]

On Mon, 2 Nov 2020 18:45:10 -0700 David Ahern wrote:
> On 11/1/20 4:39 AM, Ido Schimmel wrote:
> > From: Ido Schimmel <idosch@nvidia.com>
> > 
> > The nexthop notification chain is a per-namespace chain and not a global
> > one like the netdev notification chain.
> > 
> > Therefore, a single (global) listener cannot be registered to all these
> > chains simultaneously as it will result in list corruptions whenever
> > listeners are registered / unregistered.
> > 
> > Instead, register a different listener in each namespace.
> > 
> > Currently this is not an issue because only the VXLAN driver registers a
> > listener to this chain, but this is going to change with netdevsim and
> > mlxsw also registering their own listeners.
> > 
> > Signed-off-by: Ido Schimmel <idosch@nvidia.com>
> 
> Reviewed-by: David Ahern <dsahern@kernel.org>

Applied, thanks!