nl80211: rework locking

When I added scanning to cfg80211, we got a lock dependency like this:
	rtnl --> cfg80211_mtx

nl80211, on the other hand, has the reverse lock dependency:
	cfg80211_mtx --> rtnl

which clearly is a bad idea. This patch reworks nl80211 to take these
two locks in the other order to fix the possible, and easily
triggerable, deadlock.

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

1 files changed, 166 insertions, 105 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 58ee1b1aff8..a3ecf8d7389 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -602,9 +602,12 @@ static int nl80211_set_interface(struct sk_buff *skb, struct genl_info *info)
 
         memset(&params, 0, sizeof(params));
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto unlock_rtnl;
+
         ifindex = dev->ifindex;
         type = dev->ieee80211_ptr->iftype;
         dev_put(dev);
@@ -641,17 +644,17 @@ static int nl80211_set_interface(struct sk_buff *skb, struct genl_info *info)
                 if (!err)
                         flags = &_flags;
         }
-        rtnl_lock();
+
         err = drv->ops->change_virtual_intf(&drv->wiphy, ifindex,
                                             type, flags, &params);
 
         dev = __dev_get_by_index(&init_net, ifindex);
         WARN_ON(!dev || (!err && dev->ieee80211_ptr->iftype != type));
 
-        rtnl_unlock();
-
  unlock:
         cfg80211_put_dev(drv);
+ unlock_rtnl:
+        rtnl_unlock();
         return err;
 }
 
@@ -674,9 +677,13 @@ static int nl80211_new_interface(struct sk_buff *skb, struct genl_info *info)
                         return -EINVAL;
         }
 
+        rtnl_lock();
+
         drv = cfg80211_get_dev_from_info(info);
-        if (IS_ERR(drv))
-                return PTR_ERR(drv);
+        if (IS_ERR(drv)) {
+                err = PTR_ERR(drv);
+                goto unlock_rtnl;
+        }
 
         if (!drv->ops->add_virtual_intf ||
             !(drv->wiphy.interface_modes & (1 << type))) {
@@ -690,18 +697,17 @@ static int nl80211_new_interface(struct sk_buff *skb, struct genl_info *info)
                 params.mesh_id_len = nla_len(info->attrs[NL80211_ATTR_MESH_ID]);
         }
 
-        rtnl_lock();
         err = parse_monitor_flags(type == NL80211_IFTYPE_MONITOR ?
                                   info->attrs[NL80211_ATTR_MNTR_FLAGS] : NULL,
                                   &flags);
         err = drv->ops->add_virtual_intf(&drv->wiphy,
                 nla_data(info->attrs[NL80211_ATTR_IFNAME]),
                 type, err ? NULL : &flags, &params);
-        rtnl_unlock();
-
 
  unlock:
         cfg80211_put_dev(drv);
+ unlock_rtnl:
+        rtnl_unlock();
         return err;
 }
 
@@ -711,9 +717,11 @@ static int nl80211_del_interface(struct sk_buff *skb, struct genl_info *info)
         int ifindex, err;
         struct net_device *dev;
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto unlock_rtnl;
         ifindex = dev->ifindex;
         dev_put(dev);
 
@@ -722,12 +730,12 @@ static int nl80211_del_interface(struct sk_buff *skb, struct genl_info *info)
                 goto out;
         }
 
-        rtnl_lock();
         err = drv->ops->del_virtual_intf(&drv->wiphy, ifindex);
-        rtnl_unlock();
 
  out:
         cfg80211_put_dev(drv);
+ unlock_rtnl:
+        rtnl_unlock();
         return err;
 }
 
@@ -779,9 +787,11 @@ static int nl80211_get_key(struct sk_buff *skb, struct genl_info *info)
         if (info->attrs[NL80211_ATTR_MAC])
                 mac_addr = nla_data(info->attrs[NL80211_ATTR_MAC]);
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto unlock_rtnl;
 
         if (!drv->ops->get_key) {
                 err = -EOPNOTSUPP;
@@ -809,10 +819,8 @@ static int nl80211_get_key(struct sk_buff *skb, struct genl_info *info)
         if (mac_addr)
                 NLA_PUT(msg, NL80211_ATTR_MAC, ETH_ALEN, mac_addr);
 
-        rtnl_lock();
         err = drv->ops->get_key(&drv->wiphy, dev, key_idx, mac_addr,
                                 &cookie, get_key_callback);
-        rtnl_unlock();
 
         if (err)
                 goto out;
@@ -830,6 +838,9 @@ static int nl80211_get_key(struct sk_buff *skb, struct genl_info *info)
  out:
         cfg80211_put_dev(drv);
         dev_put(dev);
+ unlock_rtnl:
+        rtnl_unlock();
+
         return err;
 }
 
@@ -858,9 +869,11 @@ static int nl80211_set_key(struct sk_buff *skb, struct genl_info *info)
             !info->attrs[NL80211_ATTR_KEY_DEFAULT_MGMT])
                 return -EINVAL;
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto unlock_rtnl;
 
         if (info->attrs[NL80211_ATTR_KEY_DEFAULT])
                 func = drv->ops->set_default_key;
@@ -872,13 +885,15 @@ static int nl80211_set_key(struct sk_buff *skb, struct genl_info *info)
                 goto out;
         }
 
-        rtnl_lock();
         err = func(&drv->wiphy, dev, key_idx);
-        rtnl_unlock();
 
  out:
         cfg80211_put_dev(drv);
         dev_put(dev);
+
+ unlock_rtnl:
+        rtnl_unlock();
+
         return err;
 }
 
@@ -948,22 +963,25 @@ static int nl80211_new_key(struct sk_buff *skb, struct genl_info *info)
                 return -EINVAL;
         }
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto unlock_rtnl;
 
         if (!drv->ops->add_key) {
                 err = -EOPNOTSUPP;
                 goto out;
         }
 
-        rtnl_lock();
         err = drv->ops->add_key(&drv->wiphy, dev, key_idx, mac_addr, &params);
-        rtnl_unlock();
 
  out:
         cfg80211_put_dev(drv);
         dev_put(dev);
+ unlock_rtnl:
+        rtnl_unlock();
+
         return err;
 }
 
@@ -984,22 +1002,26 @@ static int nl80211_del_key(struct sk_buff *skb, struct genl_info *info)
         if (info->attrs[NL80211_ATTR_MAC])
                 mac_addr = nla_data(info->attrs[NL80211_ATTR_MAC]);
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto unlock_rtnl;
 
         if (!drv->ops->del_key) {
                 err = -EOPNOTSUPP;
                 goto out;
         }
 
-        rtnl_lock();
         err = drv->ops->del_key(&drv->wiphy, dev, key_idx, mac_addr);
-        rtnl_unlock();
 
  out:
         cfg80211_put_dev(drv);
         dev_put(dev);
+
+ unlock_rtnl:
+        rtnl_unlock();
+
         return err;
 }
 
@@ -1013,9 +1035,11 @@ static int nl80211_addset_beacon(struct sk_buff *skb, struct genl_info *info)
         struct beacon_parameters params;
         int haveinfo = 0;
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto unlock_rtnl;
 
         switch (info->genlhdr->cmd) {
         case NL80211_CMD_NEW_BEACON:
@@ -1076,13 +1100,14 @@ static int nl80211_addset_beacon(struct sk_buff *skb, struct genl_info *info)
                 goto out;
         }
 
-        rtnl_lock();
         err = call(&drv->wiphy, dev, &params);
-        rtnl_unlock();
 
  out:
         cfg80211_put_dev(drv);
         dev_put(dev);
+ unlock_rtnl:
+        rtnl_unlock();
+
         return err;
 }
 
@@ -1092,22 +1117,25 @@ static int nl80211_del_beacon(struct sk_buff *skb, struct genl_info *info)
         int err;
         struct net_device *dev;
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto unlock_rtnl;
 
         if (!drv->ops->del_beacon) {
                 err = -EOPNOTSUPP;
                 goto out;
         }
 
-        rtnl_lock();
         err = drv->ops->del_beacon(&drv->wiphy, dev);
-        rtnl_unlock();
 
  out:
         cfg80211_put_dev(drv);
         dev_put(dev);
+ unlock_rtnl:
+        rtnl_unlock();
+
         return err;
 }
 
@@ -1273,14 +1301,18 @@ static int nl80211_dump_station(struct sk_buff *skb,
                         return -EINVAL;
         }
 
-        netdev = dev_get_by_index(&init_net, ifidx);
-        if (!netdev)
-                return -ENODEV;
+        rtnl_lock();
+
+        netdev = __dev_get_by_index(&init_net, ifidx);
+        if (!netdev) {
+                err = -ENODEV;
+                goto out_rtnl;
+        }
 
         dev = cfg80211_get_dev_from_ifindex(ifidx);
         if (IS_ERR(dev)) {
                 err = PTR_ERR(dev);
-                goto out_put_netdev;
+                goto out_rtnl;
         }
 
         if (!dev->ops->dump_station) {
@@ -1288,15 +1320,13 @@ static int nl80211_dump_station(struct sk_buff *skb,
                 goto out_err;
         }
 
-        rtnl_lock();
-
         while (1) {
                 err = dev->ops->dump_station(&dev->wiphy, netdev, sta_idx,
                                              mac_addr, &sinfo);
                 if (err == -ENOENT)
                         break;
                 if (err)
-                        goto out_err_rtnl;
+                        goto out_err;
 
                 if (nl80211_send_station(skb,
                                 NETLINK_CB(cb->skb).pid,
@@ -1312,12 +1342,10 @@ static int nl80211_dump_station(struct sk_buff *skb,
  out:
         cb->args[1] = sta_idx;
         err = skb->len;
- out_err_rtnl:
-        rtnl_unlock();
  out_err:
         cfg80211_put_dev(dev);
- out_put_netdev:
-        dev_put(netdev);
+ out_rtnl:
+        rtnl_unlock();
 
         return err;
 }
@@ -1338,19 +1366,18 @@ static int nl80211_get_station(struct sk_buff *skb, struct genl_info *info)
 
         mac_addr = nla_data(info->attrs[NL80211_ATTR_MAC]);
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto out_rtnl;
 
         if (!drv->ops->get_station) {
                 err = -EOPNOTSUPP;
                 goto out;
         }
 
-        rtnl_lock();
         err = drv->ops->get_station(&drv->wiphy, dev, mac_addr, &sinfo);
-        rtnl_unlock();
-
         if (err)
                 goto out;
 
@@ -1367,10 +1394,12 @@ static int nl80211_get_station(struct sk_buff *skb, struct genl_info *info)
 
  out_free:
         nlmsg_free(msg);
-
  out:
         cfg80211_put_dev(drv);
         dev_put(dev);
+ out_rtnl:
+        rtnl_unlock();
+
         return err;
 }
 
@@ -1438,9 +1467,11 @@ static int nl80211_set_station(struct sk_buff *skb, struct genl_info *info)
                 params.plink_action =
                     nla_get_u8(info->attrs[NL80211_ATTR_STA_PLINK_ACTION]);
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto out_rtnl;
 
         err = get_vlan(info->attrs[NL80211_ATTR_STA_VLAN], drv, &params.vlan);
         if (err)
@@ -1451,15 +1482,16 @@ static int nl80211_set_station(struct sk_buff *skb, struct genl_info *info)
                 goto out;
         }
 
-        rtnl_lock();
         err = drv->ops->change_station(&drv->wiphy, dev, mac_addr, &params);
-        rtnl_unlock();
 
  out:
         if (params.vlan)
                 dev_put(params.vlan);
         cfg80211_put_dev(drv);
         dev_put(dev);
+ out_rtnl:
+        rtnl_unlock();
+
         return err;
 }
 
@@ -1501,9 +1533,11 @@ static int nl80211_new_station(struct sk_buff *skb, struct genl_info *info)
                                 &params.station_flags))
                 return -EINVAL;
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto out_rtnl;
 
         err = get_vlan(info->attrs[NL80211_ATTR_STA_VLAN], drv, &params.vlan);
         if (err)
@@ -1514,15 +1548,16 @@ static int nl80211_new_station(struct sk_buff *skb, struct genl_info *info)
                 goto out;
         }
 
-        rtnl_lock();
         err = drv->ops->add_station(&drv->wiphy, dev, mac_addr, &params);
-        rtnl_unlock();
 
  out:
         if (params.vlan)
                 dev_put(params.vlan);
         cfg80211_put_dev(drv);
         dev_put(dev);
+ out_rtnl:
+        rtnl_unlock();
+
         return err;
 }
 
@@ -1536,22 +1571,25 @@ static int nl80211_del_station(struct sk_buff *skb, struct genl_info *info)
         if (info->attrs[NL80211_ATTR_MAC])
                 mac_addr = nla_data(info->attrs[NL80211_ATTR_MAC]);
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto out_rtnl;
 
         if (!drv->ops->del_station) {
                 err = -EOPNOTSUPP;
                 goto out;
         }
 
-        rtnl_lock();
         err = drv->ops->del_station(&drv->wiphy, dev, mac_addr);
-        rtnl_unlock();
 
  out:
         cfg80211_put_dev(drv);
         dev_put(dev);
+ out_rtnl:
+        rtnl_unlock();
+
         return err;
 }
 
@@ -1632,14 +1670,18 @@ static int nl80211_dump_mpath(struct sk_buff *skb,
                         return -EINVAL;
         }
 
-        netdev = dev_get_by_index(&init_net, ifidx);
-        if (!netdev)
-                return -ENODEV;
+        rtnl_lock();
+
+        netdev = __dev_get_by_index(&init_net, ifidx);
+        if (!netdev) {
+                err = -ENODEV;
+                goto out_rtnl;
+        }
 
         dev = cfg80211_get_dev_from_ifindex(ifidx);
         if (IS_ERR(dev)) {
                 err = PTR_ERR(dev);
-                goto out_put_netdev;
+                goto out_rtnl;
         }
 
         if (!dev->ops->dump_mpath) {
@@ -1647,15 +1689,13 @@ static int nl80211_dump_mpath(struct sk_buff *skb,
                 goto out_err;
         }
 
-        rtnl_lock();
-
         while (1) {
                 err = dev->ops->dump_mpath(&dev->wiphy, netdev, path_idx,
                                            dst, next_hop, &pinfo);
                 if (err == -ENOENT)
                         break;
                 if (err)
-                        goto out_err_rtnl;
+                        goto out_err;
 
                 if (nl80211_send_mpath(skb, NETLINK_CB(cb->skb).pid,
                                        cb->nlh->nlmsg_seq, NLM_F_MULTI,
@@ -1670,12 +1710,10 @@ static int nl80211_dump_mpath(struct sk_buff *skb,
  out:
         cb->args[1] = path_idx;
         err = skb->len;
- out_err_rtnl:
-        rtnl_unlock();
  out_err:
         cfg80211_put_dev(dev);
- out_put_netdev:
-        dev_put(netdev);
+ out_rtnl:
+        rtnl_unlock();
 
         return err;
 }
@@ -1697,19 +1735,18 @@ static int nl80211_get_mpath(struct sk_buff *skb, struct genl_info *info)
 
         dst = nla_data(info->attrs[NL80211_ATTR_MAC]);
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto out_rtnl;
 
         if (!drv->ops->get_mpath) {
                 err = -EOPNOTSUPP;
                 goto out;
         }
 
-        rtnl_lock();
         err = drv->ops->get_mpath(&drv->wiphy, dev, dst, next_hop, &pinfo);
-        rtnl_unlock();
-
         if (err)
                 goto out;
 
@@ -1726,10 +1763,12 @@ static int nl80211_get_mpath(struct sk_buff *skb, struct genl_info *info)
 
  out_free:
         nlmsg_free(msg);
-
  out:
         cfg80211_put_dev(drv);
         dev_put(dev);
+ out_rtnl:
+        rtnl_unlock();
+
         return err;
 }
 
@@ -1750,22 +1789,25 @@ static int nl80211_set_mpath(struct sk_buff *skb, struct genl_info *info)
         dst = nla_data(info->attrs[NL80211_ATTR_MAC]);
         next_hop = nla_data(info->attrs[NL80211_ATTR_MPATH_NEXT_HOP]);
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto out_rtnl;
 
         if (!drv->ops->change_mpath) {
                 err = -EOPNOTSUPP;
                 goto out;
         }
 
-        rtnl_lock();
         err = drv->ops->change_mpath(&drv->wiphy, dev, dst, next_hop);
-        rtnl_unlock();
 
  out:
         cfg80211_put_dev(drv);
         dev_put(dev);
+ out_rtnl:
+        rtnl_unlock();
+
         return err;
 }
 static int nl80211_new_mpath(struct sk_buff *skb, struct genl_info *info)
@@ -1785,22 +1827,25 @@ static int nl80211_new_mpath(struct sk_buff *skb, struct genl_info *info)
         dst = nla_data(info->attrs[NL80211_ATTR_MAC]);
         next_hop = nla_data(info->attrs[NL80211_ATTR_MPATH_NEXT_HOP]);
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto out_rtnl;
 
         if (!drv->ops->add_mpath) {
                 err = -EOPNOTSUPP;
                 goto out;
         }
 
-        rtnl_lock();
         err = drv->ops->add_mpath(&drv->wiphy, dev, dst, next_hop);
-        rtnl_unlock();
 
  out:
         cfg80211_put_dev(drv);
         dev_put(dev);
+ out_rtnl:
+        rtnl_unlock();
+
         return err;
 }
 
@@ -1814,22 +1859,25 @@ static int nl80211_del_mpath(struct sk_buff *skb, struct genl_info *info)
         if (info->attrs[NL80211_ATTR_MAC])
                 dst = nla_data(info->attrs[NL80211_ATTR_MAC]);
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto out_rtnl;
 
         if (!drv->ops->del_mpath) {
                 err = -EOPNOTSUPP;
                 goto out;
         }
 
-        rtnl_lock();
         err = drv->ops->del_mpath(&drv->wiphy, dev, dst);
-        rtnl_unlock();
 
  out:
         cfg80211_put_dev(drv);
         dev_put(dev);
+ out_rtnl:
+        rtnl_unlock();
+
         return err;
 }
 
@@ -1862,22 +1910,25 @@ static int nl80211_set_bss(struct sk_buff *skb, struct genl_info *info)
                         nla_len(info->attrs[NL80211_ATTR_BSS_BASIC_RATES]);
         }
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto out_rtnl;
 
         if (!drv->ops->change_bss) {
                 err = -EOPNOTSUPP;
                 goto out;
         }
 
-        rtnl_lock();
         err = drv->ops->change_bss(&drv->wiphy, dev, &params);
-        rtnl_unlock();
 
  out:
         cfg80211_put_dev(drv);
         dev_put(dev);
+ out_rtnl:
+        rtnl_unlock();
+
         return err;
 }
 
@@ -1972,10 +2023,12 @@ static int nl80211_get_mesh_params(struct sk_buff *skb,
         struct nlattr *pinfoattr;
         struct sk_buff *msg;
 
+        rtnl_lock();
+
         /* Look up our device */
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto out_rtnl;
 
         if (!drv->ops->get_mesh_params) {
                 err = -EOPNOTSUPP;
@@ -1983,9 +2036,7 @@ static int nl80211_get_mesh_params(struct sk_buff *skb,
         }
 
         /* Get the mesh params */
-        rtnl_lock();
         err = drv->ops->get_mesh_params(&drv->wiphy, dev, &cur_params);
-        rtnl_unlock();
         if (err)
                 goto out;
 
@@ -2034,13 +2085,16 @@ static int nl80211_get_mesh_params(struct sk_buff *skb,
         err = genlmsg_unicast(msg, info->snd_pid);
         goto out;
 
-nla_put_failure:
+ nla_put_failure:
         genlmsg_cancel(msg, hdr);
         err = -EMSGSIZE;
-out:
+ out:
         /* Cleanup */
         cfg80211_put_dev(drv);
         dev_put(dev);
+ out_rtnl:
+        rtnl_unlock();
+
         return err;
 }
 
@@ -2087,9 +2141,11 @@ static int nl80211_set_mesh_params(struct sk_buff *skb, struct genl_info *info)
                         parent_attr, nl80211_meshconf_params_policy))
                 return -EINVAL;
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto out_rtnl;
 
         if (!drv->ops->set_mesh_params) {
                 err = -EOPNOTSUPP;
@@ -2136,14 +2192,15 @@ static int nl80211_set_mesh_params(struct sk_buff *skb, struct genl_info *info)
                         nla_get_u16);
 
         /* Apply changes */
-        rtnl_lock();
         err = drv->ops->set_mesh_params(&drv->wiphy, dev, &cfg, mask);
-        rtnl_unlock();
 
  out:
         /* cleanup */
         cfg80211_put_dev(drv);
         dev_put(dev);
+ out_rtnl:
+        rtnl_unlock();
+
         return err;
 }
 
@@ -2310,19 +2367,22 @@ static int nl80211_set_mgmt_extra_ie(struct sk_buff *skb,
                 params.ies_len = nla_len(info->attrs[NL80211_ATTR_IE]);
         }
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto out_rtnl;
 
-        if (drv->ops->set_mgmt_extra_ie) {
-                rtnl_lock();
+        if (drv->ops->set_mgmt_extra_ie)
                 err = drv->ops->set_mgmt_extra_ie(&drv->wiphy, dev, &params);
-                rtnl_unlock();
-        } else
+        else
                 err = -EOPNOTSUPP;
 
         cfg80211_put_dev(drv);
         dev_put(dev);
+ out_rtnl:
+        rtnl_unlock();
+
         return err;
 }
 
@@ -2339,9 +2399,11 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
         enum ieee80211_band band;
         size_t ie_len;
 
+        rtnl_lock();
+
         err = get_drv_dev_by_info_ifindex(info->attrs, &drv, &dev);
         if (err)
-                return err;
+                goto out_rtnl;
 
         wiphy = &drv->wiphy;
 
@@ -2350,11 +2412,9 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
                 goto out;
         }
 
-        rtnl_lock();
-
         if (drv->scan_req) {
                 err = -EBUSY;
-                goto out_unlock;
+                goto out;
         }
 
         if (info->attrs[NL80211_ATTR_SCAN_FREQUENCIES]) {
@@ -2362,7 +2422,7 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
                         n_channels++;
                 if (!n_channels) {
                         err = -EINVAL;
-                        goto out_unlock;
+                        goto out;
                 }
         } else {
                 for (band = 0; band < IEEE80211_NUM_BANDS; band++)
@@ -2376,7 +2436,7 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
 
         if (n_ssids > wiphy->max_scan_ssids) {
                 err = -EINVAL;
-                goto out_unlock;
+                goto out;
         }
 
         if (info->attrs[NL80211_ATTR_IE])
@@ -2390,7 +2450,7 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
                         + ie_len, GFP_KERNEL);
         if (!request) {
                 err = -ENOMEM;
-                goto out_unlock;
+                goto out;
         }
 
         request->channels = (void *)((char *)request + sizeof(*request));
@@ -2461,11 +2521,12 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
                 drv->scan_req = NULL;
                 kfree(request);
         }
- out_unlock:
-        rtnl_unlock();
  out:
         cfg80211_put_dev(drv);
         dev_put(dev);
+ out_rtnl:
+        rtnl_unlock();
+
         return err;
 }