Make the number of transmit time stamp retries configurable.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>

config.c

@@ -79,6 +79,11 @@ static void scan_line(char *s, struct config *cfg)
 	} else if (1 == sscanf(s, " announceReceiptTimeout %hhu", &u8)) {
 
 		pod->announceReceiptTimeout = u8;
+
+	} else if (1 == sscanf(s, " tx_timestamp_retries %u", &val)) {
+
+		if (val > 0)
+			*cfg->tx_timestamp_retries = val;
 	}
 }
 

config.h

@@ -25,6 +25,7 @@
 struct config {
 	struct defaultDS *dds;
 	struct port_defaults *pod;
+	int *tx_timestamp_retries;
 };
 
 int config_read(char *name, struct config *cfg);

default.cfg

@@ -16,3 +16,7 @@ logAnnounceInterval	1
 logSyncInterval		0
 logMinDelayReqInterval	0
 announceReceiptTimeout	3
+#
+# Run time options
+#
+tx_timestamp_retries	2

ptp4l.c

@@ -29,6 +29,8 @@
 
 #define DEFAULT_PHC "/dev/ptp0"
 
+int sk_tx_retries = 2; /*see sk.c*/
+
 static int running = 1;
 static struct defaultDS ds;
 static struct port_defaults pod;
@@ -178,6 +180,7 @@ int main(int argc, char *argv[])
 
 	cfg_settings.dds = &ds;
 	cfg_settings.pod = &pod;
+	cfg_settings.tx_timestamp_retries = &sk_tx_retries;
 
 	if (config && config_read(config, &cfg_settings)) {
 		fprintf(stderr, "failed to read configuration file\n");

sk.c

@@ -126,7 +126,7 @@ int sk_receive(int fd, void *buf, int buflen,
 	msg.msg_control = control;
 	msg.msg_controllen = sizeof(control);
 
-	try_again = flags == MSG_ERRQUEUE ? 2 : 1;
+	try_again = flags == MSG_ERRQUEUE ? sk_tx_retries : 1;
 
 	for ( ; try_again; try_again--) {
 		cnt = recvmsg(fd, &msg, flags);

sk.h

@@ -60,4 +60,10 @@ int sk_receive(int fd, void *buf, int buflen,
  */
 int sk_timestamping_init(int fd, char *device, enum timestamp_type type);
 
+/**
+ * Limits the number of RECVMSG(2) calls when attempting to obtain a
+ * transmit time stamp on an event message.
+ */
+extern int sk_tx_retries;
+
 #endif