1 files changed, 48 insertions, 19 deletions

diff --git a/net/mac80211/chan.c b/net/mac80211/chan.c
index f0f87e5a1d35..0bfc914ddd15 100644
--- a/net/mac80211/chan.c
+++ b/net/mac80211/chan.c
@@ -68,16 +68,14 @@ ieee80211_get_channel_mode(struct ieee80211_local *local,
         return mode;
 }
 
-bool ieee80211_set_channel_type(struct ieee80211_local *local,
-                                struct ieee80211_sub_if_data *sdata,
-                                enum nl80211_channel_type chantype)
+static enum nl80211_channel_type
+ieee80211_get_superchan(struct ieee80211_local *local,
+                        struct ieee80211_sub_if_data *sdata)
 {
-        struct ieee80211_sub_if_data *tmp;
         enum nl80211_channel_type superchan = NL80211_CHAN_NO_HT;
-        bool result;
+        struct ieee80211_sub_if_data *tmp;
 
         mutex_lock(&local->iflist_mtx);
-
         list_for_each_entry(tmp, &local->interfaces, list) {
                 if (tmp == sdata)
                         continue;
@@ -103,39 +101,70 @@ bool ieee80211_set_channel_type(struct ieee80211_local *local,
                         break;
                 }
         }
+        mutex_unlock(&local->iflist_mtx);
 
-        switch (superchan) {
+        return superchan;
+}
+
+static bool
+ieee80211_channel_types_are_compatible(enum nl80211_channel_type chantype1,
+                                       enum nl80211_channel_type chantype2,
+                                       enum nl80211_channel_type *compat)
+{
+        /*
+         * start out with chantype1 being the result,
+         * overwriting later if needed
+         */
+        if (compat)
+                *compat = chantype1;
+
+        switch (chantype1) {
         case NL80211_CHAN_NO_HT:
+                if (compat)
+                        *compat = chantype2;
+                break;
         case NL80211_CHAN_HT20:
                 /*
                  * allow any change that doesn't go to no-HT
                  * (if it already is no-HT no change is needed)
                  */
-                if (chantype == NL80211_CHAN_NO_HT)
+                if (chantype2 == NL80211_CHAN_NO_HT)
                         break;
-                superchan = chantype;
+                if (compat)
+                        *compat = chantype2;
                 break;
         case NL80211_CHAN_HT40PLUS:
         case NL80211_CHAN_HT40MINUS:
                 /* allow smaller bandwidth and same */
-                if (chantype == NL80211_CHAN_NO_HT)
+                if (chantype2 == NL80211_CHAN_NO_HT)
                         break;
-                if (chantype == NL80211_CHAN_HT20)
+                if (chantype2 == NL80211_CHAN_HT20)
                         break;
-                if (superchan == chantype)
+                if (chantype2 == chantype1)
                         break;
-                result = false;
-                goto out;
+                return false;
         }
 
-        local->_oper_channel_type = superchan;
+        return true;
+}
+
+bool ieee80211_set_channel_type(struct ieee80211_local *local,
+                                struct ieee80211_sub_if_data *sdata,
+                                enum nl80211_channel_type chantype)
+{
+        enum nl80211_channel_type superchan;
+        enum nl80211_channel_type compatchan;
+
+        superchan = ieee80211_get_superchan(local, sdata);
+        if (!ieee80211_channel_types_are_compatible(superchan, chantype,
+                                                    &compatchan))
+                return false;
+
+        local->_oper_channel_type = compatchan;
 
         if (sdata)
                 sdata->vif.bss_conf.channel_type = chantype;
 
-        result = true;
- out:
-        mutex_unlock(&local->iflist_mtx);
+        return true;
 
-        return result;
 }