From: Johannes Berg <johannes.berg@intel.com>

The wiphy/interface netlink dumps only need the RTNL for
the list and, possibly, filtering by netdev. This can be
easily replaced now, do that.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 net/wireless/nl80211.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 46b72f3b5ea4..bf64cafa02fc 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -3794,8 +3794,10 @@ static int nl80211_dump_wiphy_parse(struct sk_buff *skb,
 		struct cfg80211_registered_device *rdev;
 		int ifidx = nla_get_u32(tb[NL80211_ATTR_IFINDEX]);
 
-		netdev = __dev_get_by_index(sock_net(skb->sk), ifidx);
+		rcu_read_lock();
+		netdev = dev_get_by_index_rcu(sock_net(skb->sk), ifidx);
 		if (!netdev) {
+			rcu_read_unlock();
 			ret = -ENODEV;
 			goto out;
 		}
@@ -3804,6 +3806,7 @@ static int nl80211_dump_wiphy_parse(struct sk_buff *skb,
 				netdev->ieee80211_ptr->wiphy);
 			state->filter_wiphy = rdev->wiphy_idx;
 		}
+		rcu_read_unlock();
 	}
 
 	ret = 0;
@@ -3818,18 +3821,18 @@ static int nl80211_dump_wiphy(struct sk_buff *skb, struct netlink_callback *cb)
 	struct nl80211_dump_wiphy_state *state = (void *)cb->args[0];
 	struct cfg80211_registered_device *rdev;
 
-	rtnl_lock();
+	mutex_lock(&cfg80211_mutex);
 	if (!state) {
 		state = kzalloc_obj(*state);
 		if (!state) {
-			rtnl_unlock();
+			mutex_unlock(&cfg80211_mutex);
 			return -ENOMEM;
 		}
 		state->filter_wiphy = -1;
 		ret = nl80211_dump_wiphy_parse(skb, cb, state);
 		if (ret) {
 			kfree(state);
-			rtnl_unlock();
+			mutex_unlock(&cfg80211_mutex);
 			return ret;
 		}
 		cb->args[0] = (long)state;
@@ -3871,7 +3874,7 @@ static int nl80211_dump_wiphy(struct sk_buff *skb, struct netlink_callback *cb)
 					cb->min_dump_alloc = 4096;
 					state->split_start = 0;
 					wiphy_unlock(&rdev->wiphy);
-					rtnl_unlock();
+					mutex_unlock(&cfg80211_mutex);
 					return 1;
 				}
 				idx--;
@@ -3881,7 +3884,7 @@ static int nl80211_dump_wiphy(struct sk_buff *skb, struct netlink_callback *cb)
 		wiphy_unlock(&rdev->wiphy);
 		break;
 	}
-	rtnl_unlock();
+	mutex_unlock(&cfg80211_mutex);
 
 	state->start = idx;
 
@@ -4857,7 +4860,7 @@ static int nl80211_dump_interface(struct sk_buff *skb, struct netlink_callback *
 	struct wireless_dev *wdev;
 	int ret;
 
-	rtnl_lock();
+	mutex_lock(&cfg80211_mutex);
 	if (!cb->args[2]) {
 		struct nl80211_dump_wiphy_state state = {
 			.filter_wiphy = -1,
@@ -4920,7 +4923,7 @@ static int nl80211_dump_interface(struct sk_buff *skb, struct netlink_callback *
 
 	ret = skb->len;
  out_unlock:
-	rtnl_unlock();
+	mutex_unlock(&cfg80211_mutex);
 
 	return ret;
 }
-- 
2.56.0