[3.13.y-ckt stable] Patch "cfg80211/wext: fix message ordering" has been added to the 3.13.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    cfg80211/wext: fix message ordering

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt37.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From 00d9e6fdc1e241e5d8221e3566230e82ba1c22ae Mon Sep 17 00:00:00 2001
From: Johannes Berg <johannes.berg at intel.com>
Date: Wed, 27 Jan 2016 13:29:34 +0100
Subject: cfg80211/wext: fix message ordering

commit cb150b9d23be6ee7f3a0fff29784f1c5b5ac514d upstream.

Since cfg80211 frequently takes actions from its netdev notifier
call, wireless extensions messages could still be ordered badly
since the wext netdev notifier, since wext is built into the
kernel, runs before the cfg80211 netdev notifier. For example,
the following can happen:

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
5: wlan1: <BROADCAST,MULTICAST,UP>
    link/ether

when setting the interface down causes the wext message.

To also fix this, export the wireless_nlevent_flush() function
and also call it from the cfg80211 notifier.

Signed-off-by: Johannes Berg <johannes.berg at intel.com>
[ kamal: backport to 3.13-stable: context ]
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 include/net/iw_handler.h | 6 ++++++
 net/wireless/core.c      | 2 ++
 net/wireless/wext-core.c | 3 ++-
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/include/net/iw_handler.h b/include/net/iw_handler.h
index a830b01..e8aa72e 100644
--- a/include/net/iw_handler.h
+++ b/include/net/iw_handler.h
@@ -439,6 +439,12 @@ int dev_get_wireless_info(char *buffer, char **start, off_t offset, int length);
 /* Send a single event to user space */
 void wireless_send_event(struct net_device *dev, unsigned int cmd,
 			 union iwreq_data *wrqu, const char *extra);
+#ifdef CONFIG_WEXT_CORE
+/* flush all previous wext events - if work is done from netdev notifiers */
+void wireless_nlevent_flush(void);
+#else
+static inline void wireless_nlevent_flush(void) {}
+#endif

 /* We may need a function to send a stream of events to user space.
  * More on that later... */
diff --git a/net/wireless/core.c b/net/wireless/core.c
index 52b865f..ae45b83 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -973,6 +973,8 @@ static int cfg80211_netdev_notifier_call(struct notifier_block *nb,
 		break;
 	}

+	wireless_nlevent_flush();
+
 	return NOTIFY_DONE;
 }

diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c
index 87dd619..b50ee5d 100644
--- a/net/wireless/wext-core.c
+++ b/net/wireless/wext-core.c
@@ -342,7 +342,7 @@ static const int compat_event_type_size[] = {

 /* IW event code */

-static void wireless_nlevent_flush(void)
+void wireless_nlevent_flush(void)
 {
 	struct sk_buff *skb;
 	struct net *net;
@@ -355,6 +355,7 @@ static void wireless_nlevent_flush(void)
 				    GFP_KERNEL);
 	}
 }
+EXPORT_SYMBOL_GPL(wireless_nlevent_flush);

 static int wext_netdev_notifier_call(struct notifier_block *nb,
 				     unsigned long state, void *ptr)
--
2.7.0