mac80211: Choose a new toffset setpoint if a big tsf jump is detected.

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

diff --git a/net/mac80211/mesh_sync.c b/net/mac80211/mesh_sync.c
index f78b013..22a5f1e 100644 (file)
--- a/net/mac80211/mesh_sync.c
+++ b/net/mac80211/mesh_sync.c
@@ -22,7 +22,14 @@
 /* This is not in the standard.  It represents a tolerable tbtt drift below
  * which we do no TSF adjustment.
  */
-#define TBTT_MINIMUM_ADJUSTMENT 10
+#define TOFFSET_MINIMUM_ADJUSTMENT 10
+
+/* This is not in the standard.  It represents the maximum Toffset jump above
+ * which we'll invalidate the Toffset setpoint and choose a new setpoint.  This
+ * could be, for instance, in case a neighbor is restarted and its TSF counter
+ * reset.
+ * */
+#define TOFFSET_MAXIMUM_ADJUSTMENT 30000               /* 30 ms */
 
 struct sync_method {
        u8 method;
@@ -156,15 +163,22 @@ static void mesh_sync_offset_rx_bcn_presp(struct ieee80211_sub_if_data *sdata,
        if (test_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN)) {
                s64 t_clockdrift = sta->t_offset_setpoint
                                   - sta->t_offset;
-
-               msync_dbg("STA %pM : sta->t_offset=%lld,"
-                         " sta->t_offset_setpoint=%lld,"
-                         " t_clockdrift=%lld",
+               msync_dbg("STA %pM : sta->t_offset=%lld, sta->t_offset_setpoint=%lld, t_clockdrift=%lld",
                          sta->sta.addr,
                          (long long) sta->t_offset,
                          (long long)
                          sta->t_offset_setpoint,
                          (long long) t_clockdrift);
+
+               if (t_clockdrift > TOFFSET_MAXIMUM_ADJUSTMENT ||
+                       t_clockdrift < -TOFFSET_MAXIMUM_ADJUSTMENT) {
+                       msync_dbg("STA %pM : t_clockdrift=%lld too large, setpoint reset",
+                                 sta->sta.addr,
+                                 (long long) t_clockdrift);
+                       clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
+                       goto no_sync;
+               }
+
                rcu_read_unlock();
 
                spin_lock_bh(&ifmsh->sync_offset_lock);
@@ -200,7 +214,7 @@ static void mesh_sync_offset_adjust_tbtt(struct ieee80211_sub_if_data *sdata)
        spin_lock_bh(&ifmsh->sync_offset_lock);
 
        if (ifmsh->sync_offset_clockdrift_max >
-               TBTT_MINIMUM_ADJUSTMENT) {
+               TOFFSET_MINIMUM_ADJUSTMENT) {
                /* Since ajusting the tsf here would
                 * require a possibly blocking call
                 * to the driver tsf setter, we punt