mac80211: mesh: only switch path when new metric is at least 10% better

This helps to reduce frequent path switches when multiple path
candidates have the same or very similar path metrics.

Signed-off-by: Julan Hsu <julanhsu@google.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/mesh_hwmp.c b/net/mac80211/mesh_hwmp.c
index f50409635a16c4f1e4cd9e28b61bd3886ba31d9b..e00284afdda598b4dfa2f0f98d1b80f0f48bea1e 100644 (file)
--- a/net/mac80211/mesh_hwmp.c
+++ b/net/mac80211/mesh_hwmp.c
@@ -447,7 +447,10 @@ static u32 hwmp_route_info_get(struct ieee80211_sub_if_data *sdata,
                            (mpath->flags & MESH_PATH_SN_VALID)) {
                                if (SN_GT(mpath->sn, orig_sn) ||
                                    (mpath->sn == orig_sn &&
-                                    new_metric >= mpath->metric)) {
+                                    (rcu_access_pointer(mpath->next_hop) !=
+                                                     sta ?
+                                             mult_frac(new_metric, 10, 9) :
+                                             new_metric) >= mpath->metric)) {
                                        process = false;
                                        fresh_info = false;
                                }
@@ -515,8 +518,10 @@ static u32 hwmp_route_info_get(struct ieee80211_sub_if_data *sdata,
                if (mpath) {
                        spin_lock_bh(&mpath->state_lock);
                        if ((mpath->flags & MESH_PATH_FIXED) ||
-                               ((mpath->flags & MESH_PATH_ACTIVE) &&
-                                       (last_hop_metric > mpath->metric)))
+                           ((mpath->flags & MESH_PATH_ACTIVE) &&
+                            ((rcu_access_pointer(mpath->next_hop) != sta ?
+                                      mult_frac(last_hop_metric, 10, 9) :
+                                      last_hop_metric) > mpath->metric)))
                                fresh_info = false;
                } else {
                        mpath = mesh_path_add(sdata, ta);