Merge pull request #595 from PawelModrzejewski/open-avb-next

gPTP: add negative time jumps detection

3 files changed, 29 insertions, 7 deletions

diff --git a/daemons/gptp/common/avbts_clock.hpp b/daemons/gptp/common/avbts_clock.hpp
index 9010279e..750433da 100644
--- a/daemons/gptp/common/avbts_clock.hpp
+++ b/daemons/gptp/common/avbts_clock.hpp
@@ -61,6 +61,9 @@
    adjustment is performed */
 #define PHASE_ERROR_MAX_COUNT (6)
 
+/* Value returned by calcMasterLocalClockRateDifference() to indicate
+   detection of negative time jump in follow_up message */
+#define NEGATIVE_TIME_JUMP 0.0
 
 /**
  * @brief Provides the clock quality abstraction.
diff --git a/daemons/gptp/common/ieee1588clock.cpp b/daemons/gptp/common/ieee1588clock.cpp
index c002bd24..dbae6e16 100644
--- a/daemons/gptp/common/ieee1588clock.cpp
+++ b/daemons/gptp/common/ieee1588clock.cpp
@@ -322,8 +322,11 @@ FrequencyRatio IEEE1588Clock::calcMasterLocalClockRateDifference( Timestamp mast
 
 	inter_sync_time =
 		TIMESTAMP_TO_NS(sync_time) - TIMESTAMP_TO_NS(_prev_sync_time);
-	inter_master_time =
-		TIMESTAMP_TO_NS(master_time) -  TIMESTAMP_TO_NS(_prev_master_time);
+
+	uint64_t master_time_ns = TIMESTAMP_TO_NS(master_time);
+	uint64_t prev_master_time_ns = TIMESTAMP_TO_NS(_prev_master_time);
+
+	inter_master_time = master_time_ns - prev_master_time_ns;
 
 	if( inter_sync_time != 0 ) {
 		ppt_offset = ((FrequencyRatio)inter_master_time)/inter_sync_time;
@@ -331,6 +334,14 @@ FrequencyRatio IEEE1588Clock::calcMasterLocalClockRateDifference( Timestamp mast
 		ppt_offset = 1.0;
 	}
 
+	if( master_time_ns < prev_master_time_ns ) {
+		GPTP_LOG_ERROR("Negative time jump detected - inter_master_time: %lld, inter_sync_time: %lld, icorrect ppt_offset: %Lf",
+					   inter_master_time, inter_sync_time, ppt_offset);
+		_master_local_freq_offset_init = false;
+
+		return NEGATIVE_TIME_JUMP;
+	}
+
 	_prev_sync_time = sync_time;
 	_prev_master_time = master_time;
 
diff --git a/daemons/gptp/common/ptp_message.cpp b/daemons/gptp/common/ptp_message.cpp
index b51f0bf7..0e3914fc 100644
--- a/daemons/gptp/common/ptp_message.cpp
+++ b/daemons/gptp/common/ptp_message.cpp
@@ -1013,6 +1013,18 @@ void PTPMessageFollowUp::processMessage( EtherPort *port )
 	if( correction > 0 )
 	  TIMESTAMP_ADD_NS( preciseOriginTimestamp, correction );
 	else TIMESTAMP_SUB_NS( preciseOriginTimestamp, -correction );
+
+	local_clock_adjustment =
+	  port->getClock()->
+	  calcMasterLocalClockRateDifference
+	  ( preciseOriginTimestamp, sync_arrival );
+
+	if( local_clock_adjustment == NEGATIVE_TIME_JUMP )
+	{
+		GPTP_LOG_VERBOSE("Received Follow Up but preciseOrigintimestamp indicates negative time jump");
+		goto done;
+	}
+
 	scalar_offset  = TIMESTAMP_TO_NS( sync_arrival );
 	scalar_offset -= TIMESTAMP_TO_NS( preciseOriginTimestamp );
 
@@ -1022,6 +1034,7 @@ void PTPMessageFollowUp::processMessage( EtherPort *port )
 	GPTP_LOG_VERBOSE
 		("FollowUp Scalar = %lld", scalar_offset);
 
+
 	/* Otherwise synchronize clock with approximate time from Sync message */
 	uint32_t local_clock, nominal_clock_rate;
 	uint32_t device_sync_time_offset;
@@ -1042,11 +1055,6 @@ void PTPMessageFollowUp::processMessage( EtherPort *port )
 	     system_time.seconds_ls, system_time.nanoseconds,
 	     device_time.seconds_ls, device_time.nanoseconds);
 
-	local_clock_adjustment =
-	  port->getClock()->
-	  calcMasterLocalClockRateDifference
-	  ( preciseOriginTimestamp, sync_arrival );
-
 	/*Update information on local status structure.*/
 	scaledLastGmFreqChange = (int32_t)((1.0/local_clock_adjustment -1.0) * (1ULL << 41));
 	scaledLastGmPhaseChange.setLSB( tlv.getRateOffset() );