mac80211: annotate station rcu dereferences

The new RCU lockdep support warns about these
in some contexts -- make it aware of the locks
used to protect all this. Different locks are
used in different contexts which unfortunately
means we can't get perfect checking.

Also remove rcu_dereference() from two places
that don't actually dereference the pointers.

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

1 files changed, 16 insertions, 4 deletions

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 56422d894351..fb12cec4d333 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -93,12 +93,18 @@ struct sta_info *sta_info_get(struct ieee80211_sub_if_data *sdata,
         struct ieee80211_local *local = sdata->local;
         struct sta_info *sta;
 
-        sta = rcu_dereference(local->sta_hash[STA_HASH(addr)]);
+        sta = rcu_dereference_check(local->sta_hash[STA_HASH(addr)],
+                                    rcu_read_lock_held() ||
+                                    lockdep_is_held(&local->sta_lock) ||
+                                    lockdep_is_held(&local->sta_mtx));
         while (sta) {
                 if (sta->sdata == sdata &&
                     memcmp(sta->sta.addr, addr, ETH_ALEN) == 0)
                         break;
-                sta = rcu_dereference(sta->hnext);
+                sta = rcu_dereference_check(sta->hnext,
+                                            rcu_read_lock_held() ||
+                                            lockdep_is_held(&local->sta_lock) ||
+                                            lockdep_is_held(&local->sta_mtx));
         }
         return sta;
 }
@@ -113,13 +119,19 @@ struct sta_info *sta_info_get_bss(struct ieee80211_sub_if_data *sdata,
         struct ieee80211_local *local = sdata->local;
         struct sta_info *sta;
 
-        sta = rcu_dereference(local->sta_hash[STA_HASH(addr)]);
+        sta = rcu_dereference_check(local->sta_hash[STA_HASH(addr)],
+                                    rcu_read_lock_held() ||
+                                    lockdep_is_held(&local->sta_lock) ||
+                                    lockdep_is_held(&local->sta_mtx));
         while (sta) {
                 if ((sta->sdata == sdata ||
                      sta->sdata->bss == sdata->bss) &&
                     memcmp(sta->sta.addr, addr, ETH_ALEN) == 0)
                         break;
-                sta = rcu_dereference(sta->hnext);
+                sta = rcu_dereference_check(sta->hnext,
+                                            rcu_read_lock_held() ||
+                                            lockdep_is_held(&local->sta_lock) ||
+                                            lockdep_is_held(&local->sta_mtx));
         }
         return sta;
 }