linux-kernel - [PATCH 3.16.y-ckt 112/126] mac80211: do not actively scan DFS channels

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Message-Id: <1452076655-12851-113-git-send-email-luis.henriques@canonical.com>
Date:	Wed,  6 Jan 2016 10:37:21 +0000
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Antonio Quartulli <antonio@...n-mesh.com>,
	Johannes Berg <johannes.berg@...el.com>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 112/126] mac80211: do not actively scan DFS channels

3.16.7-ckt22 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Antonio Quartulli <antonio@...hcoding.com>

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@...n-mesh.com>
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@...onical.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;
--
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