[3.16.y-ckt stable] Patch "mac80211: clear subdir_stations when removing debugfs" has been added to staging queue

[Luis Henriques]

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

    mac80211: clear subdir_stations when removing debugfs

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt16.

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

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From be5d25c9e67b8471b25d65b32c54318d7028ad1c Mon Sep 17 00:00:00 2001
From: Tom Hughes <tom at compton.nu>
Date: Mon, 29 Jun 2015 19:41:49 +0100
Subject: mac80211: clear subdir_stations when removing debugfs

commit 4479004e6409087d1b4986881dc98c6c15dffb28 upstream.

If we don't do this, and we then fail to recreate the debugfs
directory during a mode change, then we will fail later trying
to add stations to this now bogus directory:

BUG: unable to handle kernel NULL pointer dereference at 0000006c
IP: [<c0a92202>] mutex_lock+0x12/0x30
Call Trace:
[<c0678ab4>] start_creating+0x44/0xc0
[<c0679203>] debugfs_create_dir+0x13/0xf0
[<f8a938ae>] ieee80211_sta_debugfs_add+0x6e/0x490 [mac80211]

Signed-off-by: Tom Hughes <tom at compton.nu>
Signed-off-by: Johannes Berg <johannes.berg at intel.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/mac80211/debugfs_netdev.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index e205ebabfa50..1ab5e1a51c98 100644
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -725,6 +725,7 @@ void ieee80211_debugfs_remove_netdev(struct ieee80211_sub_if_data *sdata)

 	debugfs_remove_recursive(sdata->vif.debugfs_dir);
 	sdata->vif.debugfs_dir = NULL;
+	sdata->debugfs.subdir_stations = NULL;
 }

 void ieee80211_debugfs_rename_netdev(struct ieee80211_sub_if_data *sdata)