cfg80211: accept no-op interface mode changes

When somebody tries to set the interface mode to the existing
mode, don't ask the driver but silently accept the setting.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 21 insertions, 7 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index a7d0b94f6b5e..8808431bd581 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -607,6 +607,7 @@ static int nl80211_set_interface(struct sk_buff *skb, struct genl_info *info)
         enum nl80211_iftype type;
         struct net_device *dev;
         u32 _flags, *flags = NULL;
+        bool change = false;
 
         memset(&params, 0, sizeof(params));
 
@@ -620,11 +621,17 @@ static int nl80211_set_interface(struct sk_buff *skb, struct genl_info *info)
         type = dev->ieee80211_ptr->iftype;
         dev_put(dev);
 
-        err = -EINVAL;
         if (info->attrs[NL80211_ATTR_IFTYPE]) {
-                type = nla_get_u32(info->attrs[NL80211_ATTR_IFTYPE]);
-                if (type > NL80211_IFTYPE_MAX)
+                enum nl80211_iftype ntype;
+
+                ntype = nla_get_u32(info->attrs[NL80211_ATTR_IFTYPE]);
+                if (type != ntype)
+                        change = true;
+                type = ntype;
+                if (type > NL80211_IFTYPE_MAX) {
+                        err = -EINVAL;
                         goto unlock;
+                }
         }
 
         if (!drv->ops->change_virtual_intf ||
@@ -640,6 +647,7 @@ static int nl80211_set_interface(struct sk_buff *skb, struct genl_info *info)
                 }
                 params.mesh_id = nla_data(info->attrs[NL80211_ATTR_MESH_ID]);
                 params.mesh_id_len = nla_len(info->attrs[NL80211_ATTR_MESH_ID]);
+                change = true;
         }
 
         if (info->attrs[NL80211_ATTR_MNTR_FLAGS]) {
@@ -649,12 +657,18 @@ static int nl80211_set_interface(struct sk_buff *skb, struct genl_info *info)
                 }
                 err = parse_monitor_flags(info->attrs[NL80211_ATTR_MNTR_FLAGS],
                                           &_flags);
-                if (!err)
-                        flags = &_flags;
+                if (err)
+                        goto unlock;
+
+                flags = &_flags;
+                change = true;
         }
 
-        err = drv->ops->change_virtual_intf(&drv->wiphy, ifindex,
-                                            type, flags, &params);
+        if (change)
+                err = drv->ops->change_virtual_intf(&drv->wiphy, ifindex,
+                                                    type, flags, &params);
+        else
+                err = 0;
 
         dev = __dev_get_by_index(&init_net, ifindex);
         WARN_ON(!dev || (!err && dev->ieee80211_ptr->iftype != type));