From 8f484e8312fa8c73e85dfa46ad7850ecc4446075 Mon Sep 17 00:00:00 2001
From: Michael Walle <michael@walle.cc>
Date: Tue, 10 Jul 2018 11:31:45 +0200
Subject: [PATCH] msg: Drop msg->tlv_count.

The field is redundant with the length tlv_list. Replace it with a
function msg_tlv_count() instead. This iterates over the tlv_list. The
computational overhead should be small, because the lists are very short
and the tlv_count is only used in management paths (yet).

Signed-off-by: Michael Walle <michael@walle.cc>
---
 clock.c   |  2 +-
 msg.c     | 15 +++++++++++++--
 msg.h     | 11 +++++++----
 phc2sys.c |  2 +-
 pmc.c     |  2 +-
 5 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/clock.c b/clock.c
index 2400b2f..faf2dea 100644
--- a/clock.c
+++ b/clock.c
@@ -1319,7 +1319,7 @@ int clock_manage(struct clock *c, struct port *p, struct ptp_message *msg)
 	if (!cid_eq(tcid, &wildcard) && !cid_eq(tcid, &c->dds.clockIdentity)) {
 		return changed;
 	}
-	if (msg->tlv_count != 1) {
+	if (msg_tlv_count(msg) != 1) {
 		return changed;
 	}
 	mgt = (struct management_tlv *) msg->management.suffix;
diff --git a/msg.c b/msg.c
index d5b651f..d1a657c 100644
--- a/msg.c
+++ b/msg.c
@@ -318,7 +318,6 @@ struct ptp_message *msg_duplicate(struct ptp_message *msg, int cnt)
 	memcpy(dup, msg, sizeof(*dup));
 	dup->refcnt = 1;
 	TAILQ_INIT(&dup->tlv_list);
-	dup->tlv_count = 0;
 
 	err = msg_post_recv(dup, cnt);
 	if (err) {
@@ -506,7 +505,19 @@ struct tlv_extra *msg_tlv_append(struct ptp_message *msg, int length)
 void msg_tlv_attach(struct ptp_message *msg, struct tlv_extra *extra)
 {
 	TAILQ_INSERT_TAIL(&msg->tlv_list, extra, list);
-	msg->tlv_count++;
+}
+
+int msg_tlv_count(struct ptp_message *msg)
+{
+	int count = 0;
+	struct tlv_extra *extra;
+
+	for (extra = TAILQ_FIRST(&msg->tlv_list);
+			extra != NULL;
+			extra = TAILQ_NEXT(extra, list))
+		count++;
+
+	return count;
 }
 
 const char *msg_type_string(int type)
diff --git a/msg.h b/msg.h
index 58a916c..03fe1fd 100644
--- a/msg.h
+++ b/msg.h
@@ -227,10 +227,6 @@ struct ptp_message {
 	 * pointers to the appended TLVs.
 	 */
 	TAILQ_HEAD(tlv_list, tlv_extra) tlv_list;
-	/**
-	 * Contains the number of TLVs in the suffix.
-	 */
-	int tlv_count;
 };
 
 /**
@@ -279,6 +275,13 @@ struct tlv_extra *msg_tlv_append(struct ptp_message *msg, int length);
  */
 void msg_tlv_attach(struct ptp_message *msg, struct tlv_extra *extra);
 
+/*
+ * Return the number of TLVs attached to a message.
+ * @param msg  A message obtained using @ref msg_allocate().
+ * @return     The number of attached TLVs.
+ */
+int msg_tlv_count(struct ptp_message *msg);
+
 /**
  * Obtain the transportSpecific field from a message.
  * @param m  Message to test.
diff --git a/phc2sys.c b/phc2sys.c
index 66e34d6..21cae75 100644
--- a/phc2sys.c
+++ b/phc2sys.c
@@ -819,7 +819,7 @@ static int is_msg_mgt(struct ptp_message *msg)
 		return 0;
 	if (management_action(msg) != RESPONSE)
 		return 0;
-	if (msg->tlv_count != 1)
+	if (msg_tlv_count(msg) != 1)
 		return 0;
 	tlv = (struct TLV *) msg->management.suffix;
 	if (tlv->type == TLV_MANAGEMENT)
diff --git a/pmc.c b/pmc.c
index 35b1d96..440c905 100644
--- a/pmc.c
+++ b/pmc.c
@@ -80,7 +80,7 @@ static void pmc_show(struct ptp_message *msg, FILE *fp)
 	fprintf(fp, "\t%s seq %hu %s ",
 		pid2str(&msg->header.sourcePortIdentity),
 		msg->header.sequenceId, pmc_action_string(action));
-	if (msg->tlv_count != 1) {
+	if (msg_tlv_count(msg) != 1) {
 		goto out;
 	}
 	extra = TAILQ_FIRST(&msg->tlv_list);