ptp4l is too silent when receiving, for whatever reason, out of order
messages. If the reordering is persistent (which is either a broken
network, or a broken kernel), the behavior looks like a complete
synchronization stall, since the application is designed to never
attempt to recover from such a condition.
At least save some people some debugging hours and print when the
application reaches this code path. Since it's a debugging tool, we
don't want to create false alarms when the occasional packet gets
reordered in a production system, but have this information readily
available when the program's log level is set to debug, instead of
having users fish for it with code instrumentation.
Signed-off-by: Vladimir Oltean <olte...@gmail.com>
---
Changes in v2:
Drop log level to debug.
port.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/port.c b/port.c
index 729cbd784e3b..8c372e2a1256 100644
--- a/port.c
+++ b/port.c
@@ -1215,6 +1215,23 @@ static void port_synchronize(struct port *p,
}
}
+static void port_syfufsm_print_mismatch(struct port *p, enum syfu_event event,
+ struct ptp_message *m)
+{
+ int expected_msgtype;
+
+ if (event == SYNC_MISMATCH)
+ expected_msgtype = FOLLOW_UP;
+ else
+ expected_msgtype = SYNC;
+
+ pr_debug("port %hu: have %s %d, expecting %s but got %s %d, dropping",
+ portnum(p), msg_type_string(msg_type(p->last_syncfup)),
+ p->last_syncfup->header.sequenceId,
+ msg_type_string(expected_msgtype),
+ msg_type_string(msg_type(m)), m->header.sequenceId);
+}
+
/*
* Handle out of order packets. The network stack might
* provide the follow up _before_ the sync message. After all,
@@ -1249,6 +1266,7 @@ static void port_syfufsm(struct port *p, enum syfu_event
event,
case SF_HAVE_SYNC:
switch (event) {
case SYNC_MISMATCH:
+ port_syfufsm_print_mismatch(p, event, m);
msg_put(p->last_syncfup);
msg_get(m);
p->last_syncfup = m;
@@ -1256,6 +1274,7 @@ static void port_syfufsm(struct port *p, enum syfu_event
event,
case SYNC_MATCH:
break;
case FUP_MISMATCH:
+ port_syfufsm_print_mismatch(p, event, m);
msg_put(p->last_syncfup);
msg_get(m);
p->last_syncfup = m;
@@ -1277,6 +1296,7 @@ static void port_syfufsm(struct port *p, enum syfu_event
event,
case SF_HAVE_FUP:
switch (event) {
case SYNC_MISMATCH:
+ port_syfufsm_print_mismatch(p, event, m);
msg_put(p->last_syncfup);
msg_get(m);
p->last_syncfup = m;
@@ -1293,6 +1313,7 @@ static void port_syfufsm(struct port *p, enum syfu_event
event,
p->syfu = SF_EMPTY;
break;
case FUP_MISMATCH:
+ port_syfufsm_print_mismatch(p, event, m);
msg_put(p->last_syncfup);
msg_get(m);
p->last_syncfup = m;
--
2.25.1
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