mac80211: split sta_info_add

sta_info_add() has two functions: allocating a station info
structure and inserting it into the hash table/list. Splitting
these two functions allows allocating with GFP_KERNEL in many
places instead of GFP_ATOMIC which is now required by the RCU
protection. Additionally, in many places RCU protection is now
no longer needed at all because between sta_info_alloc() and
sta_info_insert() the caller owns the structure.

This fixes a few race conditions with setting initial flags
and similar, but not all (see comments in ieee80211_sta.c and
cfg.c). More documentation on the existing races will be in
a follow-up patch.

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

1 files changed, 11 insertions, 7 deletions

diff --git a/net/mac80211/ieee80211.c b/net/mac80211/ieee80211.c
index 85b1391375c0..22cba82a0c6f 100644
--- a/net/mac80211/ieee80211.c
+++ b/net/mac80211/ieee80211.c
@@ -899,6 +899,7 @@ int ieee80211_if_update_wds(struct net_device *dev, u8 *remote_addr)
         struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
         struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
         struct sta_info *sta;
+        int err;
         DECLARE_MAC_BUF(mac);
 
         might_sleep();
@@ -906,16 +907,19 @@ int ieee80211_if_update_wds(struct net_device *dev, u8 *remote_addr)
         if (compare_ether_addr(remote_addr, sdata->u.wds.remote_addr) == 0)
                 return 0;
 
-        rcu_read_lock();
-
         /* Create STA entry for the new peer */
-        sta = sta_info_add(sdata, remote_addr);
-        if (IS_ERR(sta)) {
-                rcu_read_unlock();
-                return PTR_ERR(sta);
-        }
+        sta = sta_info_alloc(sdata, remote_addr, GFP_KERNEL);
+        if (!sta)
+                return -ENOMEM;
 
         sta->flags |= WLAN_STA_AUTHORIZED;
+        err = sta_info_insert(sta);
+        if (err) {
+                sta_info_destroy(sta);
+                return err;
+        }
+
+        rcu_read_lock();
 
         /* Remove STA entry for the old peer */
         sta = sta_info_get(local, sdata->u.wds.remote_addr);