phc2sys: Don't exit when reading of PHC fails with EBUSY.

Reading of the PHC can occasionally fail with some drivers, e.g. the ice
driver returns EBUSY when it fails to get a lock. Continue in the loop
instead of exiting on the error.

Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>

phc2sys.c

@@ -622,6 +622,7 @@ static int do_pps_loop(struct phc2sys_private *priv, struct clock *clock,
 	int64_t pps_offset, phc_offset, phc_delay;
 	uint64_t pps_ts, phc_ts;
 	clockid_t src = priv->master->clkid;
+	int err;
 
 	priv->master->source_label = "pps";
 
@@ -640,10 +641,13 @@ static int do_pps_loop(struct phc2sys_private *priv, struct clock *clock,
 		/* If a PHC is available, use it to get the whole number
 		   of seconds in the offset and PPS for the rest. */
 		if (src != CLOCK_INVALID) {
-			if (clockadj_compare(src, clock->clkid,
-					     priv->phc_readings,
-					     &phc_offset, &phc_ts,
-					     &phc_delay))
+			err = clockadj_compare(src, clock->clkid,
+					       priv->phc_readings,
+					       &phc_offset, &phc_ts,
+					       &phc_delay);
+			if (err == -EBUSY)
+				continue;
+			if (err)
 				return -1;
 
 			/* Convert the time stamp to the PHC time. */
@@ -691,6 +695,7 @@ static int do_loop(struct phc2sys_private *priv)
 	struct clock *clock;
 	uint64_t ts;
 	int64_t offset, delay;
+	int err;
 
 	interval.tv_sec = priv->phc_interval;
 	interval.tv_nsec = (priv->phc_interval - interval.tv_sec) * 1e9;
@@ -727,29 +732,32 @@ static int do_loop(struct phc2sys_private *priv)
 			if (clock->clkid == CLOCK_REALTIME &&
 			    priv->master->sysoff_method >= 0) {
 				/* use sysoff */
-				if (sysoff_measure(CLOCKID_TO_FD(priv->master->clkid),
-						   priv->master->sysoff_method,
-						   priv->phc_readings,
-						   &offset, &ts, &delay) < 0)
-					return -1;
+				err = sysoff_measure(CLOCKID_TO_FD(priv->master->clkid),
+						     priv->master->sysoff_method,
+						     priv->phc_readings,
+						     &offset, &ts, &delay);
 			} else if (priv->master->clkid == CLOCK_REALTIME &&
 				   clock->sysoff_method >= 0) {
 				/* use reversed sysoff */
-				if (sysoff_measure(CLOCKID_TO_FD(clock->clkid),
-						   clock->sysoff_method,
-						   priv->phc_readings,
-						   &offset, &ts, &delay) < 0)
-					return -1;
-				offset = -offset;
-				ts += offset;
+				err = sysoff_measure(CLOCKID_TO_FD(clock->clkid),
+						     clock->sysoff_method,
+						     priv->phc_readings,
+						     &offset, &ts, &delay);
+				if (!err) {
+					offset = -offset;
+					ts += offset;
+				}
 			} else {
 				/* use phc */
-				if (clockadj_compare(priv->master->clkid,
-						     clock->clkid,
-						     priv->phc_readings,
-						     &offset, &ts, &delay))
-					return -1;
+				err = clockadj_compare(priv->master->clkid,
+						       clock->clkid,
+						       priv->phc_readings,
+						       &offset, &ts, &delay);
 			}
+			if (err == -EBUSY)
+				continue;
+			if (err)
+				return -1;
 			update_clock(priv, clock, offset, ts, delay);
 		}
 	}