1 files changed, 51 insertions, 0 deletions

diff --git a/net/wireless/chan.c b/net/wireless/chan.c
index d0c92dddb26b..d8f443b70b08 100644
--- a/net/wireless/chan.c
+++ b/net/wireless/chan.c
@@ -44,6 +44,36 @@ rdev_freq_to_chan(struct cfg80211_registered_device *rdev,
         return chan;
 }
 
+static bool can_beacon_sec_chan(struct wiphy *wiphy,
+                                struct ieee80211_channel *chan,
+                                enum nl80211_channel_type channel_type)
+{
+        struct ieee80211_channel *sec_chan;
+        int diff;
+
+        switch (channel_type) {
+        case NL80211_CHAN_HT40PLUS:
+                diff = 20;
+        case NL80211_CHAN_HT40MINUS:
+                diff = -20;
+        default:
+                return false;
+        }
+
+        sec_chan = ieee80211_get_channel(wiphy, chan->center_freq + diff);
+        if (!sec_chan)
+                return false;
+
+        /* we'll need a DFS capability later */
+        if (sec_chan->flags & (IEEE80211_CHAN_DISABLED |
+                               IEEE80211_CHAN_PASSIVE_SCAN |
+                               IEEE80211_CHAN_NO_IBSS |
+                               IEEE80211_CHAN_RADAR))
+                return false;
+
+        return true;
+}
+
 int cfg80211_set_freq(struct cfg80211_registered_device *rdev,
                       struct wireless_dev *wdev, int freq,
                       enum nl80211_channel_type channel_type)
@@ -68,6 +98,27 @@ int cfg80211_set_freq(struct cfg80211_registered_device *rdev,
         if (!chan)
                 return -EINVAL;
 
+        /* Both channels should be able to initiate communication */
+        if (wdev && (wdev->iftype == NL80211_IFTYPE_ADHOC ||
+                     wdev->iftype == NL80211_IFTYPE_AP ||
+                     wdev->iftype == NL80211_IFTYPE_AP_VLAN ||
+                     wdev->iftype == NL80211_IFTYPE_MESH_POINT)) {
+                switch (channel_type) {
+                case NL80211_CHAN_HT40PLUS:
+                case NL80211_CHAN_HT40MINUS:
+                        if (!can_beacon_sec_chan(&rdev->wiphy, chan,
+                                                 channel_type)) {
+                                printk(KERN_DEBUG
+                                       "cfg80211: Secondary channel not "
+                                       "allowed to initiate communication\n");
+                                return -EINVAL;
+                        }
+                        break;
+                default:
+                        break;
+                }
+        }
+
         result = rdev->ops->set_channel(&rdev->wiphy,
                                         wdev ? wdev->netdev : NULL,
                                         chan, channel_type);