cfg80211: validate scan channels

Currently it is possible to request a scan on only
disabled channels, which could be problematic for
some drivers. Reject such scans, and also ignore
disabled channels that are given. This resuls in
the scan begin/end event only including channels
that are actually used.

This makes the mac80211 check for disabled channels
superfluous. At the same time, remove the no-IBSS
check from mac80211 -- nothing says that we should
not find any networks on channels that cannot be
used for an IBSS, even when operating in IBSS mode.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 2e8c515..e2d344f 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -650,9 +650,15 @@
 	i = 0;
 	for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
 		int j;
+
 		if (!wiphy->bands[band])
 			continue;
+
 		for (j = 0; j < wiphy->bands[band]->n_channels; j++) {
+			/* ignore disabled channels */
+			if (wiphy->bands[band]->channels[j].flags &
+						IEEE80211_CHAN_DISABLED)
+				continue;
 
 			/* If we have a wireless request structure and the
 			 * wireless request specifies frequencies, then search