mac80211: Checking IBSS support while changing channel in ad-hoc mode

This patch adds a check to the set_channel flow. When attempting to change
the channel while in IBSS mode, and the new channel does not support IBSS
mode, the flow return with an error value with no consequences on the
mac80211 and driver state.

Signed-off-by: Assaf Krauss <assaf.krauss@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/wext.c b/net/mac80211/wext.c
index 8311bb2..a8bb8e3 100644
--- a/net/mac80211/wext.c
+++ b/net/mac80211/wext.c
@@ -290,14 +290,22 @@
 	return 0;
 }
 
-int ieee80211_set_freq(struct ieee80211_local *local, int freqMHz)
+int ieee80211_set_freq(struct net_device *dev, int freqMHz)
 {
 	int ret = -EINVAL;
 	struct ieee80211_channel *chan;
+	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
+	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 
 	chan = ieee80211_get_channel(local->hw.wiphy, freqMHz);
 
 	if (chan && !(chan->flags & IEEE80211_CHAN_DISABLED)) {
+		if (sdata->vif.type == IEEE80211_IF_TYPE_IBSS &&
+		    chan->flags & IEEE80211_CHAN_NO_IBSS) {
+			printk(KERN_DEBUG "%s: IBSS not allowed on frequency "
+				"%d MHz\n", dev->name, chan->center_freq);
+			return ret;
+		}
 		local->oper_channel = chan;
 
 		if (local->sta_sw_scanning || local->sta_hw_scanning)
@@ -315,7 +323,6 @@
 				   struct iw_request_info *info,
 				   struct iw_freq *freq, char *extra)
 {
-	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
 	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 
 	if (sdata->vif.type == IEEE80211_IF_TYPE_STA)
@@ -329,14 +336,14 @@
 					IEEE80211_STA_AUTO_CHANNEL_SEL;
 			return 0;
 		} else
-			return ieee80211_set_freq(local,
+			return ieee80211_set_freq(dev,
 				ieee80211_channel_to_frequency(freq->m));
 	} else {
 		int i, div = 1000000;
 		for (i = 0; i < freq->e; i++)
 			div /= 10;
 		if (div > 0)
-			return ieee80211_set_freq(local, freq->m / div);
+			return ieee80211_set_freq(dev, freq->m / div);
 		else
 			return -EINVAL;
 	}