mac80211: fix RCU warnings in mesh

Sparse RCU checking reports two warnings in the mesh
path table code. These are due to questionable uses of
rcu_dereference.

To fix the first one, get rid of mesh_gate_add() and
just make mesh_path_add_gate() do the correct deref.

To fix the second one, simply remove rcu_dereference()
in mesh_gate_del() -- it already gets a proper pointer
as indicated by the prototype (no __rcu annotation)
and confirmed by the code.

Cc: Javier Cardona <javier@cozybit.com>
Cc: Thomas Pedersen <thomas@cozybit.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 5 insertions, 22 deletions

diff --git a/net/mac80211/mesh_pathtbl.c b/net/mac80211/mesh_pathtbl.c
index 4fc23d1b9c3a..7bd2a76aef0e 100644
--- a/net/mac80211/mesh_pathtbl.c
+++ b/net/mac80211/mesh_pathtbl.c
@@ -69,8 +69,6 @@ static inline struct mesh_table *resize_dereference_mpp_paths(void)
                 lockdep_is_held(&pathtbl_resize_lock));
 }
 
-static int mesh_gate_add(struct mesh_table *tbl, struct mesh_path *mpath);
-
 /*
  * CAREFUL -- "tbl" must not be an expression,
  * in particular not an rcu_dereference(), since
@@ -420,21 +418,18 @@ static void mesh_gate_node_reclaim(struct rcu_head *rp)
 }
 
 /**
- * mesh_gate_add - mark mpath as path to a mesh gate and add to known_gates
- * @mesh_tbl: table which contains known_gates list
- * @mpath: mpath to known mesh gate
- *
- * Returns: 0 on success
- *
+ * mesh_path_add_gate - add the given mpath to a mesh gate to our path table
+ * @mpath: gate path to add to table
  */
-static int mesh_gate_add(struct mesh_table *tbl, struct mesh_path *mpath)
+int mesh_path_add_gate(struct mesh_path *mpath)
 {
+        struct mesh_table *tbl;
         struct mpath_node *gate, *new_gate;
         struct hlist_node *n;
         int err;
 
         rcu_read_lock();
-        tbl = rcu_dereference(tbl);
+        tbl = rcu_dereference(mesh_paths);
 
         hlist_for_each_entry_rcu(gate, n, tbl->known_gates, list)
                 if (gate->mpath == mpath) {
@@ -478,8 +473,6 @@ static int mesh_gate_del(struct mesh_table *tbl, struct mesh_path *mpath)
         struct mpath_node *gate;
         struct hlist_node *p, *q;
 
-        tbl = rcu_dereference(tbl);
-
         hlist_for_each_entry_safe(gate, p, q, tbl->known_gates, list)
                 if (gate->mpath == mpath) {
                         spin_lock_bh(&tbl->gates_lock);
@@ -498,16 +491,6 @@ static int mesh_gate_del(struct mesh_table *tbl, struct mesh_path *mpath)
 }
 
 /**
- *
- * mesh_path_add_gate - add the given mpath to a mesh gate to our path table
- * @mpath: gate path to add to table
- */
-int mesh_path_add_gate(struct mesh_path *mpath)
-{
-        return mesh_gate_add(mesh_paths, mpath);
-}
-
-/**
  * mesh_gate_num - number of gates known to this interface
  * @sdata: subif data
  */