erts: Fix seq_trace to not clear token for system messages

A lot of erts internal messages used behind APIs to create
non-blocking calls, e.g. port_command, would cause the seq_trace
token to be cleared from the caller when it should not.
This commit fixes that and adds asserts that makes sure
that all messages sent have to correct token set.

Fixes: ERL-602

1 files changed, 15 insertions, 3 deletions

diff --git a/erts/emulator/beam/erl_message.c b/erts/emulator/beam/erl_message.c
index 507cc989d2..a3274d7443 100644
--- a/erts/emulator/beam/erl_message.c
+++ b/erts/emulator/beam/erl_message.c
@@ -409,6 +409,11 @@ ErtsMessage* prepend_pending_sig_maybe(Process* sender, Process* receiver,
  *
  * @brief Send one message from *NOT* a local process.
  *
+ * seq_trace does not work with this type of messages
+ * to it is set to am_undefined which means that the
+ * receiving process will not remove the seq_trace token
+ * when it gets this message.
+ *
  */
 void
 erts_queue_message(Process* receiver, ErtsProcLocks receiver_locks,
@@ -417,11 +422,19 @@ erts_queue_message(Process* receiver, ErtsProcLocks receiver_locks,
     ASSERT(is_not_internal_pid(from));
     ERL_MESSAGE_TERM(mp) = msg;
     ERL_MESSAGE_FROM(mp) = from;
+    ERL_MESSAGE_TOKEN(mp) = am_undefined;
     queue_messages(receiver, receiver_locks, mp, &mp->next, 1);
 }
 
 /**
  * @brief Send one message from a local process.
+ *
+ * It is up to the caller of this function to set the
+ * correct seq_trace. The general rule of thumb is that
+ * it should be set to am_undefined if the message
+ * cannot be traced using seq_trace, if it can be
+ * traced it should be set to the trace token. It should
+ * very rarely be explicitly set to NIL!
  */
 void
 erts_queue_proc_message(Process* sender,
@@ -584,8 +597,7 @@ void
 erts_send_message(Process* sender,
 		  Process* receiver,
 		  ErtsProcLocks *receiver_locks,
-		  Eterm message,
-		  unsigned flags)
+		  Eterm message)
 {
     Uint msize;
     ErtsMessage* mp;
@@ -619,7 +631,7 @@ erts_send_message(Process* sender,
 
     receiver_state = erts_atomic32_read_nob(&receiver->state);
 
-    if (SEQ_TRACE_TOKEN(sender) != NIL && !(flags & ERTS_SND_FLG_NO_SEQ_TRACE)) {
+    if (SEQ_TRACE_TOKEN(sender) != NIL) {
         Eterm* hp;
 	Eterm stoken = SEQ_TRACE_TOKEN(sender);
 	Uint seq_trace_size = 0;