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mac80211: fix RCU warnings in mesh

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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>
This commit is contained in:
Johannes Berg 2011-11-21 11:23:50 +01:00 committed by John W. Linville
parent 11a2a357a9
commit 30be52e44f
1 changed files with 5 additions and 22 deletions
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27
net/mac80211/mesh_pathtbl.c
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@ -69,8 +69,6 @@ static inline struct mesh_table *resize_dereference_mpp_paths(void)
lockdep_is_held(&pathtbl_resize_lock)); 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, * CAREFUL -- "tbl" must not be an expression,
* in particular not an rcu_dereference(), since * 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_path_add_gate - add the given mpath to a mesh gate to our path table
* @mesh_tbl: table which contains known_gates list * @mpath: gate path to add to table
* @mpath: mpath to known mesh gate
*
* Returns: 0 on success
*
*/ */
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 mpath_node *gate, *new_gate;
struct hlist_node *n; struct hlist_node *n;
int err; int err;
rcu_read_lock(); rcu_read_lock();
tbl = rcu_dereference(tbl); tbl = rcu_dereference(mesh_paths);
hlist_for_each_entry_rcu(gate, n, tbl->known_gates, list) hlist_for_each_entry_rcu(gate, n, tbl->known_gates, list)
if (gate->mpath == mpath) { 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 mpath_node *gate;
struct hlist_node *p, *q; struct hlist_node *p, *q;
tbl = rcu_dereference(tbl);
hlist_for_each_entry_safe(gate, p, q, tbl->known_gates, list) hlist_for_each_entry_safe(gate, p, q, tbl->known_gates, list)
if (gate->mpath == mpath) { if (gate->mpath == mpath) {
spin_lock_bh(&tbl->gates_lock); 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; 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 * mesh_gate_num - number of gates known to this interface
* @sdata: subif data * @sdata: subif data