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, 52 insertions, 0 deletions

diff --git a/erts/emulator/beam/erl_nif.c b/erts/emulator/beam/erl_nif.c
index 0fbf0eb03a..26498eda7b 100644
--- a/erts/emulator/beam/erl_nif.c
+++ b/erts/emulator/beam/erl_nif.c
@@ -744,8 +744,58 @@ int enif_send(ErlNifEnv* env, const ErlNifPid* to_pid,
 	rp_locks = ERTS_PROC_LOCK_MAIN;
 
     if (menv) {
+        Eterm token = c_p ? SEQ_TRACE_TOKEN(c_p) : am_undefined;
+        if (token != NIL && token != am_undefined) {
+            /* This code is copied from erts_send_message */
+            Eterm stoken = SEQ_TRACE_TOKEN(c_p);
+#ifdef USE_VM_PROBES
+            DTRACE_CHARBUF(sender_name, 64);
+            DTRACE_CHARBUF(receiver_name, 64);
+            Sint tok_label = 0;
+            Sint tok_lastcnt = 0;
+            Sint tok_serial = 0;
+            Eterm utag = NIL;
+            *sender_name = *receiver_name = '\0';
+            if (DTRACE_ENABLED(message_send)) {
+                erts_snprintf(sender_name, sizeof(DTRACE_CHARBUF_NAME(sender_name)),
+                              "%T", c_p->common.id);
+                erts_snprintf(receiver_name, sizeof(DTRACE_CHARBUF_NAME(receiver_name)),
+                              "%T", rp->common.id);
+            }
+#endif
+            if (have_seqtrace(stoken)) {
+                seq_trace_update_send(c_p);
+                seq_trace_output(stoken, msg, SEQ_TRACE_SEND,
+                                 rp->common.id, c_p);
+            }
+#ifdef USE_VM_PROBES
+            if (!(DT_UTAG_FLAGS(c_p) & DT_UTAG_SPREADING)) {
+                stoken = NIL;
+            }
+#endif
+            token = enif_make_copy(msg_env, stoken);
+
+#ifdef USE_VM_PROBES
+            if (DT_UTAG_FLAGS(c_p) & DT_UTAG_SPREADING) {
+                if (is_immed(DT_UTAG(c_p)))
+                    utag = DT_UTAG(c_p);
+                else
+                    utag = enif_make_copy(msg_env, DT_UTAG(c_p));
+            }
+            if (DTRACE_ENABLED(message_send)) {
+                if (have_seqtrace(stoken)) {
+                    tok_label = SEQ_TRACE_T_DTRACE_LABEL(stoken);
+                    tok_lastcnt = signed_val(SEQ_TRACE_T_LASTCNT(stoken));
+                    tok_serial = signed_val(SEQ_TRACE_T_SERIAL(stoken));
+                }
+                DTRACE6(message_send, sender_name, receiver_name,
+                        size_object(msg), tok_label, tok_lastcnt, tok_serial);
+            }
+#endif
+        }
         flush_env(msg_env);
         mp = erts_alloc_message(0, NULL);
+        ERL_MESSAGE_TOKEN(mp) = token;
         mp->data.heap_frag = menv->env.heap_frag;
         ASSERT(mp->data.heap_frag == MBUF(&menv->phony_proc));
         if (mp->data.heap_frag != NULL) {
@@ -783,6 +833,7 @@ int enif_send(ErlNifEnv* env, const ErlNifPid* to_pid,
 		ohp = &bp->off_heap;
 	    }
 	}
+        ERL_MESSAGE_TOKEN(mp) = am_undefined;
         msg = copy_struct_litopt(msg, sz, &hp, ohp, &litarea);
     }
 
@@ -826,6 +877,7 @@ int enif_send(ErlNifEnv* env, const ErlNifPid* to_pid,
 
             ERL_MESSAGE_TERM(mp) = msg;
             ERL_MESSAGE_FROM(mp) = from;
+            ERL_MESSAGE_TOKEN(mp) = am_undefined;
 
             if (!msgq) {
                 msgq = erts_alloc(ERTS_ALC_T_TRACE_MSG_QUEUE,