Re: [PATCH v2 net-next 05/16] bonding: use exit_batch_rtnl() method

[Jay Vosburgh <jay.vosburgh@canonical.com>]

Eric Dumazet <edumazet@google.com> wrote:

>exit_batch_rtnl() is called while RTNL is held,
>and devices to be unregistered can be queued in the dev_kill_list.
>
>This saves one rtnl_lock()/rtnl_unlock() pair,
>and one unregister_netdevice_many() call.
>
>v2: Added bond_net_pre_exit() method to make sure bond_destroy_sysfs()
>    is called before we unregister the devices in bond_net_exit_batch_rtnl
>
>Signed-off-by: Eric Dumazet <edumazet@google.com>
>Link: https://lore.kernel.org/netdev/170688415193.5216.10499830272732622816@kwain/
>Cc: Antoine Tenart <atenart@kernel.org>
>Cc: Jay Vosburgh <j.vosburgh@gmail.com>
>Cc: Andy Gospodarek <andy@greyhouse.net>

Acked-by: Jay Vosburgh <jay.vosburgh@canonical.com>


>---
> drivers/net/bonding/bond_main.c | 37 +++++++++++++++++++++++----------
> 1 file changed, 26 insertions(+), 11 deletions(-)
>
>diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>index 4e0600c7b050f21c82a8862e224bb055e95d5039..a5e3d000ebd85c09beba379a2e6a7f69a0fd4c88 100644
>--- a/drivers/net/bonding/bond_main.c
>+++ b/drivers/net/bonding/bond_main.c
>@@ -6415,28 +6415,41 @@ static int __net_init bond_net_init(struct net *net)
> 	return 0;
> }
> 
>-static void __net_exit bond_net_exit_batch(struct list_head *net_list)
>+/* According to commit 69b0216ac255 ("bonding: fix bonding_masters
>+ * race condition in bond unloading") we need to remove sysfs files
>+ * before we remove our devices (done later in bond_net_exit_batch_rtnl())
>+ */
>+static void __net_exit bond_net_pre_exit(struct net *net)
>+{
>+	struct bond_net *bn = net_generic(net, bond_net_id);
>+
>+	bond_destroy_sysfs(bn);
>+}
>+
>+static void __net_exit bond_net_exit_batch_rtnl(struct list_head *net_list,
>+						struct list_head *dev_kill_list)
> {
> 	struct bond_net *bn;
> 	struct net *net;
>-	LIST_HEAD(list);
>-
>-	list_for_each_entry(net, net_list, exit_list) {
>-		bn = net_generic(net, bond_net_id);
>-		bond_destroy_sysfs(bn);
>-	}
> 
> 	/* Kill off any bonds created after unregistering bond rtnl ops */
>-	rtnl_lock();
> 	list_for_each_entry(net, net_list, exit_list) {
> 		struct bonding *bond, *tmp_bond;
> 
> 		bn = net_generic(net, bond_net_id);
> 		list_for_each_entry_safe(bond, tmp_bond, &bn->dev_list, bond_list)
>-			unregister_netdevice_queue(bond->dev, &list);
>+			unregister_netdevice_queue(bond->dev, dev_kill_list);
> 	}
>-	unregister_netdevice_many(&list);
>-	rtnl_unlock();
>+}
>+
>+/* According to commit 23fa5c2caae0 ("bonding: destroy proc directory
>+ * only after all bonds are gone") bond_destroy_proc_dir() is called
>+ * after bond_net_exit_batch_rtnl() has completed.
>+ */
>+static void __net_exit bond_net_exit_batch(struct list_head *net_list)
>+{
>+	struct bond_net *bn;
>+	struct net *net;
> 
> 	list_for_each_entry(net, net_list, exit_list) {
> 		bn = net_generic(net, bond_net_id);
>@@ -6446,6 +6459,8 @@ static void __net_exit bond_net_exit_batch(struct list_head *net_list)
> 
> static struct pernet_operations bond_net_ops = {
> 	.init = bond_net_init,
>+	.pre_exit = bond_net_pre_exit,
>+	.exit_batch_rtnl = bond_net_exit_batch_rtnl,
> 	.exit_batch = bond_net_exit_batch,
> 	.id   = &bond_net_id,
> 	.size = sizeof(struct bond_net),
>-- 
>2.43.0.594.gd9cf4e227d-goog
>
>