mac80211: Improve mpath state locking

No need to take the mpath state lock when an mpath is removed.
Also, no need checking the lock when reading mpath flags.

Signed-off-by: Javier Cardona <javier@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

2 files changed, 7 insertions, 11 deletions

diff --git a/net/mac80211/mesh.h b/net/mac80211/mesh.h
index 57a2ad021bee..7118e8e8855c 100644
--- a/net/mac80211/mesh.h
+++ b/net/mac80211/mesh.h
@@ -80,7 +80,9 @@ enum mesh_deferred_task_flags {
  *      retry
  * @discovery_retries: number of discovery retries
  * @flags: mesh path flags, as specified on &enum mesh_path_flags
- * @state_lock: mesh path state lock
+ * @state_lock: mesh path state lock used to protect changes to the
+ * mpath itself.  No need to take this lock when adding or removing
+ * an mpath to a hash bucket on a path table.
  * @is_gate: the destination station of this path is a mesh gate
  *
  *
diff --git a/net/mac80211/mesh_pathtbl.c b/net/mac80211/mesh_pathtbl.c
index d07279911a0c..618f84148a75 100644
--- a/net/mac80211/mesh_pathtbl.c
+++ b/net/mac80211/mesh_pathtbl.c
@@ -776,18 +776,17 @@ void mesh_plink_broken(struct sta_info *sta)
         tbl = rcu_dereference(mesh_paths);
         for_each_mesh_entry(tbl, p, node, i) {
                 mpath = node->mpath;
-                spin_lock_bh(&mpath->state_lock);
                 if (rcu_dereference(mpath->next_hop) == sta &&
                     mpath->flags & MESH_PATH_ACTIVE &&
                     !(mpath->flags & MESH_PATH_FIXED)) {
+                        spin_lock_bh(&mpath->state_lock);
                         mpath->flags &= ~MESH_PATH_ACTIVE;
                         ++mpath->sn;
                         spin_unlock_bh(&mpath->state_lock);
                         mesh_path_error_tx(sdata->u.mesh.mshcfg.element_ttl,
                                         mpath->dst, cpu_to_le32(mpath->sn),
                                         reason, bcast, sdata);
-                } else
-                spin_unlock_bh(&mpath->state_lock);
+                }
         }
         rcu_read_unlock();
 }
@@ -866,7 +865,7 @@ static void mpp_path_flush(struct ieee80211_sub_if_data *sdata)
                 if (mpath->sdata != sdata)
                         continue;
                 spin_lock_bh(&tbl->hashwlock[i]);
-                spin_lock_bh(&mpath->state_lock);
+                hlist_del_rcu(&node->list);
                 call_rcu(&node->rcu, mesh_path_node_reclaim);
                 atomic_dec(&tbl->entries);
                 spin_unlock_bh(&tbl->hashwlock[i]);
@@ -1160,15 +1159,10 @@ void mesh_path_expire(struct ieee80211_sub_if_data *sdata)
                 if (node->mpath->sdata != sdata)
                         continue;
                 mpath = node->mpath;
-                spin_lock_bh(&mpath->state_lock);
                 if ((!(mpath->flags & MESH_PATH_RESOLVING)) &&
                     (!(mpath->flags & MESH_PATH_FIXED)) &&
-                     time_after(jiffies, mpath->exp_time + MESH_PATH_EXPIRE)) {
-                        spin_unlock_bh(&mpath->state_lock);
+                     time_after(jiffies, mpath->exp_time + MESH_PATH_EXPIRE))
                         mesh_path_del(mpath->dst, mpath->sdata);
-                } else
-                        spin_unlock_bh(&mpath->state_lock);
-        }
         rcu_read_unlock();
 }