mac80211: annotate station rcu dereferences
Johannes Berg [Tue, 6 Apr 2010 09:18:42 +0000 (11:18 +0200)]
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>

net/mac80211/main.c
net/mac80211/sta_info.c

index 06c33b6..b887e48 100644 (file)
@@ -225,11 +225,11 @@ void ieee80211_bss_info_change_notify(struct ieee80211_sub_if_data *sdata,
                        switch (sdata->vif.type) {
                        case NL80211_IFTYPE_AP:
                                sdata->vif.bss_conf.enable_beacon =
-                                       !!rcu_dereference(sdata->u.ap.beacon);
+                                       !!sdata->u.ap.beacon;
                                break;
                        case NL80211_IFTYPE_ADHOC:
                                sdata->vif.bss_conf.enable_beacon =
-                                       !!rcu_dereference(sdata->u.ibss.presp);
+                                       !!sdata->u.ibss.presp;
                                break;
                        case NL80211_IFTYPE_MESH_POINT:
                                sdata->vif.bss_conf.enable_beacon = true;
index 56422d8..fb12cec 100644 (file)
@@ -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;
 }