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Commit 30be52e4 authored by Johannes Berg's avatar Johannes Berg Committed by John W. Linville
Browse files

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: default avatarJohannes Berg <johannes.berg@intel.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 11a2a357

net/mac80211/mesh_pathtbl.c

+5 −22
Original line number Diff line number Diff line
@@ -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);
@@ -497,16 +490,6 @@ static int mesh_gate_del(struct mesh_table *tbl, struct mesh_path *mpath) 
	return 0;

}



/**

 *

 * 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