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, 25 insertions, 18 deletions

diff --git a/net/mac80211/mesh_plink.c b/net/mac80211/mesh_plink.c
index c2b80500ae72..85cb75d53c43 100644
--- a/net/mac80211/mesh_plink.c
+++ b/net/mac80211/mesh_plink.c
@@ -89,44 +89,41 @@ static inline void mesh_plink_fsm_restart(struct sta_info *sta)
 }
 
 /**
- * mesh_plink_add - allocate and add a new mesh peer link
+ * mesh_plink_alloc - allocate a new mesh peer link
  *
+ * @sdata: local mesh interface
  * @hw_addr: hardware address (ETH_ALEN length)
  * @rates: rates the mesh peer supports
- * @dev: local mesh interface
  *
  * The initial state of the new plink is set to LISTEN
  *
- * Returns: non-NULL on success, ERR_PTR() on error.
+ * Returns: NULL on error.
  */
-struct sta_info *mesh_plink_add(u8 *hw_addr, u64 rates,
-                                struct ieee80211_sub_if_data *sdata)
+struct sta_info *mesh_plink_alloc(struct ieee80211_sub_if_data *sdata,
+                                  u8 *hw_addr, u64 rates, gfp_t gfp)
 {
         struct ieee80211_local *local = sdata->local;
         struct sta_info *sta;
 
         if (compare_ether_addr(hw_addr, sdata->dev->dev_addr) == 0)
                 /* never add ourselves as neighbours */
-                return ERR_PTR(-EINVAL);
+                return NULL;
 
         if (is_multicast_ether_addr(hw_addr))
-                return ERR_PTR(-EINVAL);
+                return NULL;
 
         if (local->num_sta >= MESH_MAX_PLINKS)
-                return ERR_PTR(-ENOSPC);
+                return NULL;
 
-        sta = sta_info_add(sdata, hw_addr);
-        if (IS_ERR(sta))
-                return sta;
+        sta = sta_info_alloc(sdata, hw_addr, gfp);
+        if (!sta)
+                return NULL;
 
         sta->plink_state = LISTEN;
         spin_lock_init(&sta->plink_lock);
         init_timer(&sta->plink_timer);
         sta->flags |= WLAN_STA_AUTHORIZED;
         sta->supp_rates[local->hw.conf.channel->band] = rates;
-        rate_control_rate_init(sta, local);
-
-        mesh_accept_plinks_update(sdata);
 
         return sta;
 }
@@ -252,8 +249,13 @@ void mesh_neighbour_update(u8 *hw_addr, u64 rates, struct net_device *dev,
 
         sta = sta_info_get(local, hw_addr);
         if (!sta) {
-                sta = mesh_plink_add(hw_addr, rates, sdata);
-                if (IS_ERR(sta)) {
+                sta = mesh_plink_alloc(sdata, hw_addr, rates, GFP_ATOMIC);
+                if (!sta) {
+                        rcu_read_unlock();
+                        return;
+                }
+                if (sta_info_insert(sta)) {
+                        sta_info_destroy(sta);
                         rcu_read_unlock();
                         return;
                 }
@@ -516,12 +518,17 @@ void mesh_rx_plink_frame(struct net_device *dev, struct ieee80211_mgmt *mgmt,
                 }
 
                 rates = ieee80211_sta_get_rates(local, &elems, rx_status->band);
-                sta = mesh_plink_add(mgmt->sa, rates, sdata);
-                if (IS_ERR(sta)) {
+                sta = mesh_plink_alloc(sdata, mgmt->sa, rates, GFP_ATOMIC);
+                if (!sta) {
                         mpl_dbg("Mesh plink error: plink table full\n");
                         rcu_read_unlock();
                         return;
                 }
+                if (sta_info_insert(sta)) {
+                        sta_info_destroy(sta);
+                        rcu_read_unlock();
+                        return;
+                }
                 event = OPN_ACPT;
                 spin_lock_bh(&sta->plink_lock);
         } else {