[3.16.y-ckt stable] Patch "mac80211: properly flush delayed scan work on interface removal" 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: properly flush delayed scan work on interface removal

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?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt2.

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 b1101d4898c7f935727afeb053c6d052755a7c6e Mon Sep 17 00:00:00 2001
From: Johannes Berg <johannes at sipsolutions.net>
Date: Tue, 21 Oct 2014 20:56:42 +0200
Subject: mac80211: properly flush delayed scan work on interface removal

commit 46238845bd609a5c0fbe076e1b82b4c5b33360b2 upstream.

When an interface is deleted, an ongoing hardware scan is canceled and
the driver must abort the scan, at the very least reporting completion
while the interface is removed.

However, if it scheduled the work that might only run after everything
is said and done, which leads to cfg80211 warning that the scan isn't
reported as finished yet; this is no fault of the driver, it already
did, but mac80211 hasn't processed it.

To fix this situation, flush the delayed work when the interface being
removed is the one that was executing the scan.

Reported-by: Sujith Manoharan <sujith at msujith.org>
Tested-by: Sujith Manoharan <sujith at msujith.org>
Signed-off-by: Johannes Berg <johannes.berg at intel.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/mac80211/iface.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 388b863e821c..0af1778345b8 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -765,10 +765,12 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
 	int i, flushed;
 	struct ps_data *ps;
 	struct cfg80211_chan_def chandef;
+	bool cancel_scan;

 	clear_bit(SDATA_STATE_RUNNING, &sdata->state);

-	if (rcu_access_pointer(local->scan_sdata) == sdata)
+	cancel_scan = rcu_access_pointer(local->scan_sdata) == sdata;
+	if (cancel_scan)
 		ieee80211_scan_cancel(local);

 	/*
@@ -989,6 +991,9 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,

 	ieee80211_recalc_ps(local, -1);

+	if (cancel_scan)
+		flush_delayed_work(&local->scan_work);
+
 	if (local->open_count == 0) {
 		ieee80211_stop_device(local);

--
2.1.0