From: Johannes Berg <[email protected]>
Beniamino reported that he was getting an RTM_NEWLINK message for a
given interface, after the RTM_DELLINK for it. It turns out that the
message is a wireless extensions message, which was sent because the
interface had been connected and disconnection while it was deleted
caused a wext message.
It's strange that wext uses RTM_NEWLINK, and the message is somewhat
malformed without any proper attributes, causing "ip monitor link"
to print just rudimentary information:
5: wlan1: <BROADCAST,MULTICAST> mtu 1500 qdisc mq state DOWN group default
link/ether 02:00:00:00:01:00 brd ff:ff:ff:ff:ff:ff
Deleted 5: wlan1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group
default
link/ether 02:00:00:00:01:00 brd ff:ff:ff:ff:ff:ff
5: wlan1: <BROADCAST,MULTICAST,UP>
link/ether
(from my hwsim reproduction)
The reason for this is that wext schedules a worker to send out the
messages, and the scheduling delay can cause the messages to get out
to userspace after the RTM_DELLINK.
To fix this, have wext register a netdevice notifier and flush out
any pending messages when a netdevice is unregistered.
Cc: [email protected]
Reported-by: Beniamino Galvani <[email protected]>
Signed-off-by: Johannes Berg <[email protected]>
---
net/wireless/wext-core.c | 48 ++++++++++++++++++++++++++++++++++++++----------
1 file changed, 38 insertions(+), 10 deletions(-)
diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c
index c8717c1d082e..4e4e1c5236cc 100644
--- a/net/wireless/wext-core.c
+++ b/net/wireless/wext-core.c
@@ -342,6 +342,38 @@ static const int compat_event_type_size[] = {
/* IW event code */
+static void wireless_nlevent_flush(void)
+{
+ struct sk_buff *skb;
+ struct net *net;
+
+ ASSERT_RTNL();
+
+ for_each_net(net) {
+ while ((skb = skb_dequeue(&net->wext_nlevents)))
+ rtnl_notify(skb, net, 0, RTNLGRP_LINK, NULL,
+ GFP_KERNEL);
+ }
+}
+
+static int wext_netdev_notifier_call(struct notifier_block *nb,
+ unsigned long state, void *ptr)
+{
+ /*
+ * When a netdev is unregistered, flush all pending messages
+ * to avoid them going out after the RTM_DELLINK, which can
+ * happen due to the schedule_work().
+ */
+ if (state == NETDEV_UNREGISTER)
+ wireless_nlevent_flush();
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block wext_netdev_notifier = {
+ .notifier_call = wext_netdev_notifier_call,
+};
+
static int __net_init wext_pernet_init(struct net *net)
{
skb_queue_head_init(&net->wext_nlevents);
@@ -360,6 +392,11 @@ static struct pernet_operations wext_pernet_ops = {
static int __init wireless_nlevent_init(void)
{
+ int err = register_netdevice_notifier(&wext_netdev_notifier);
+
+ if (err)
+ return err;
+
return register_pernet_subsys(&wext_pernet_ops);
}
@@ -368,17 +405,8 @@ subsys_initcall(wireless_nlevent_init);
/* Process events generated by the wireless layer or the driver. */
static void wireless_nlevent_process(struct work_struct *work)
{
- struct sk_buff *skb;
- struct net *net;
-
rtnl_lock();
-
- for_each_net(net) {
- while ((skb = skb_dequeue(&net->wext_nlevents)))
- rtnl_notify(skb, net, 0, RTNLGRP_LINK, NULL,
- GFP_KERNEL);
- }
-
+ wireless_nlevent_flush();
rtnl_unlock();
}
--
2.6.2
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