[3.16.y-ckt stable] Patch "mac80211: do not actively scan DFS channels" 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: do not actively scan DFS channels

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-ckt22.

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 862d5b6ea0ba1ae37318f4de3a5c73ee1e8446e7 Mon Sep 17 00:00:00 2001
From: Antonio Quartulli <antonio at meshcoding.com>
Date: Sat, 21 Nov 2015 18:13:40 +0800
Subject: mac80211: do not actively scan DFS channels

commit 4e39ccac0d678eacb5dd6ffc5057531af33c12d6 upstream.

DFS channels should not be actively scanned as we can't be sure
if we are allowed or not.

If the current channel is in the DFS band, active scan might be
performed after CSA, but we have no guarantee about other channels,
therefore it is safer to prevent active scanning at all.

Signed-off-by: Antonio Quartulli <antonio at open-mesh.com>
Signed-off-by: Johannes Berg <johannes.berg at intel.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/mac80211/scan.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index f40661eb75b5..96c3e3d5ef70 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -525,8 +525,8 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 		/* We need to ensure power level is at max for scanning. */
 		ieee80211_hw_config(local, 0);

-		if ((req->channels[0]->flags &
-		     IEEE80211_CHAN_NO_IR) ||
+		if ((req->channels[0]->flags & (IEEE80211_CHAN_NO_IR |
+						IEEE80211_CHAN_RADAR)) ||
 		    !local->scan_req->n_ssids) {
 			next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 		} else {
@@ -572,7 +572,7 @@ ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
 	 * TODO: channel switching also consumes quite some time,
 	 * add that delay as well to get a better estimation
 	 */
-	if (chan->flags & IEEE80211_CHAN_NO_IR)
+	if (chan->flags & (IEEE80211_CHAN_NO_IR | IEEE80211_CHAN_RADAR))
 		return IEEE80211_PASSIVE_CHANNEL_TIME;
 	return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
 }
@@ -696,7 +696,7 @@ static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
 	 *
 	 * In any case, it is not necessary for a passive scan.
 	 */
-	if (chan->flags & IEEE80211_CHAN_NO_IR ||
+	if ((chan->flags & (IEEE80211_CHAN_NO_IR | IEEE80211_CHAN_RADAR)) ||
 	    !local->scan_req->n_ssids) {
 		*next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 		local->next_scan_state = SCAN_DECISION;