[PATCH] net: dev: deinit list in unregister_netdevice_many

[PATCH] net: dev: deinit list in unregister_netdevice_many

[Gao feng]

commit ceaaec98ad99859ac90ac6863ad0a6cd075d8e0e
"net: deinit automatic LIST_HEAD"  has already done
part of the deinit list jobs.

This patch push list_del into unregister_netdevice_many
to make sure the unreg_list of netdevice object has valid
pointer always.

Cc: David S. Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
---
 drivers/net/macvlan.c | 1 -
 net/core/dev.c        | 5 ++++-
 net/core/rtnetlink.c  | 1 -
 net/mac80211/iface.c  | 1 -
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index defcd8a..9b728f1 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -945,7 +945,6 @@ static int macvlan_device_event(struct notifier_block *unused,
 		list_for_each_entry_safe(vlan, next, &port->vlans, list)
 			vlan->dev->rtnl_link_ops->dellink(vlan->dev, &list_kill);
 		unregister_netdevice_many(&list_kill);
-		list_del(&list_kill);
 		break;
 	case NETDEV_PRE_TYPE_CHANGE:
 		/* Forbid underlaying device to change its type. */
diff --git a/net/core/dev.c b/net/core/dev.c
index 18d8b5a..c10f322 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5747,6 +5747,9 @@ EXPORT_SYMBOL(unregister_netdevice_queue);
 /**
  *	unregister_netdevice_many - unregister many devices
  *	@head: list of devices
+ *
+ *	Call list_del after unregister devices to make sure
+ *	the unreg_list of netdevice object has valid pointer.
  */
 void unregister_netdevice_many(struct list_head *head)
 {
@@ -5756,6 +5759,7 @@ void unregister_netdevice_many(struct list_head *head)
 		rollback_registered_many(head);
 		list_for_each_entry(dev, head, unreg_list)
 			net_set_todo(dev);
+		list_del(head);
 	}
 }
 EXPORT_SYMBOL(unregister_netdevice_many);
@@ -6172,7 +6176,6 @@ static void __net_exit default_device_exit_batch(struct list_head *net_list)
 		}
 	}
 	unregister_netdevice_many(&dev_kill_list);
-	list_del(&dev_kill_list);
 	rtnl_unlock();
 }
 
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index d8aa20f..8e35210 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1613,7 +1613,6 @@ static int rtnl_dellink(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
 
 	ops->dellink(dev, &list_kill);
 	unregister_netdevice_many(&list_kill);
-	list_del(&list_kill);
 	return 0;
 }
 
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 2c059e5..a799629 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1639,7 +1639,6 @@ void ieee80211_remove_interfaces(struct ieee80211_local *local)
 	}
 	mutex_unlock(&local->iflist_mtx);
 	unregister_netdevice_many(&unreg_list);
-	list_del(&unreg_list);
 
 	list_for_each_entry_safe(sdata, tmp, &wdev_list, list) {
 		list_del(&sdata->list);
-- 
1.7.11.7

Re: [PATCH] net: dev: deinit list in unregister_netdevice_many

[Eric Dumazet]

On Wed, 2013-02-27 at 14:59 +0800, Gao feng wrote:
> commit ceaaec98ad99859ac90ac6863ad0a6cd075d8e0e
> "net: deinit automatic LIST_HEAD"  has already done
> part of the deinit list jobs.
> 
> This patch push list_del into unregister_netdevice_many
> to make sure the unreg_list of netdevice object has valid
> pointer always.
> 
> Cc: David S. Miller <davem@davemloft.net>
> Cc: Eric Dumazet <eric.dumazet@gmail.com>
> Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
> ---

I totally Nack this patch.

1) net-next is not open.

2) We spent enough time chasing bugs, I don't want to reintroduce new
ones.

And this patch introduce nice bugs. No thank you.

Re: [PATCH] net: dev: deinit list in unregister_netdevice_many

[David Miller]

mroute_clean_tables() uses the list after unregister_netdevice_many().

Can you please just stop tinkering in this area?  You are making many
careless errors.

Thanks.

Re: [PATCH] net: dev: deinit list in unregister_netdevice_many

[Eric Dumazet]

On Tue, 2013-02-26 at 23:12 -0800, Eric Dumazet wrote:

> I totally Nack this patch.
> 
> 1) net-next is not open.
> 
> 2) We spent enough time chasing bugs, I don't want to reintroduce new
> ones.
> 
> And this patch introduce nice bugs. No thank you.

Humm... maybe I misread the patch, I'll take another look tomorrow after
some sleep.

Thanks

Re: [PATCH] net: dev: deinit list in unregister_netdevice_many

[Gao feng]

On 2013/02/27 15:21, David Miller wrote:
> 
> mroute_clean_tables() uses the list after unregister_netdevice_many().
>

You mean list_for_each_entry_safe(c, next, &mrt->mfc_cache_array[i], list)
in mroute_clean_tables()?

Isn't this list just a member of struct mfc_cache?
I can't find the other codes in mroute_clean_tables uses this list
after unregister_netdevice_many.

> Can you please just stop tinkering in this area?  You are making many
> careless errors.
> 

Ok,I am fine if you drop this patch,just as commit ceaaec98ad99859ac90ac6863ad0a6cd075d8e0e
said "device is freed without touching its unreg_list". there will be no serious problems
if we don't have this patch.