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>

1 files changed, 20 insertions, 6 deletions

diff --git a/net/mac80211/mesh_sync.c b/net/mac80211/mesh_sync.c
index f78b0139856f..22a5f1e66996 100644
--- 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