From 4e87bebe004039465548ed432d363f2d7e42fee6 Mon Sep 17 00:00:00 2001
From: Lukas Larsson <lukas.larsson@erlang-solutions.com>
Date: Mon, 13 Jun 2016 10:08:47 +0200
Subject: erts: Allow enif_port_command in non-sched thread

It has to be possible to send trace messages to a port
from non-schedulers threads (specifically from the
sys_msg_dispatcher).
---
 erts/emulator/beam/erl_nif.c            | 25 +++++++++----------------
 erts/emulator/test/trace_port_SUITE.erl | 22 ++++++++++++++++++++++
 2 files changed, 31 insertions(+), 16 deletions(-)

(limited to 'erts/emulator')

diff --git a/erts/emulator/beam/erl_nif.c b/erts/emulator/beam/erl_nif.c
index 039f97ef43..23931f0e54 100644
--- a/erts/emulator/beam/erl_nif.c
+++ b/erts/emulator/beam/erl_nif.c
@@ -769,32 +769,25 @@ enif_port_command(ErlNifEnv *env, const ErlNifPort* to_port,
 
     if (scheduler > 0)
 	prt = erts_port_lookup(to_port->port_id, iflags);
-#ifdef ERTS_DIRTY_SCHEDULERS
-    else if (scheduler < 0) {
+    else {
+#ifdef ERTS_SMP
 	if (ERTS_PROC_IS_EXITING(c_p))
 	    return 0;
 	prt = erts_thr_port_lookup(to_port->port_id, iflags);
-    }
+#else
+        erts_exit(ERTS_ABORT_EXIT,
+		  "enif_port_command: called from non-scheduler "
+                  "thread on non-SMP VM");
 #endif
-    else {
-	erts_exit(ERTS_ABORT_EXIT, "enif_port_command: "
-		  "called from non-scheduler thread");
     }
 
     if (!prt)
 	res = 0;
-    else {
-
-	if (IS_TRACED_FL(prt, F_TRACE_RECEIVE))
-	    trace_port_receive(prt, c_p->common.id, am_command, msg);
-
-	res = erts_port_output_async(prt, c_p->common.id, msg);
-    }
+    else
+        res = erts_port_output_async(prt, c_p->common.id, msg);
 
-#ifdef ERTS_DIRTY_SCHEDULERS
-    if (scheduler < 0)
+    if (scheduler <= 0)
 	erts_port_dec_refc(prt);
-#endif
 
     return res;
 }
diff --git a/erts/emulator/test/trace_port_SUITE.erl b/erts/emulator/test/trace_port_SUITE.erl
index a66563d15b..e4db368ea1 100644
--- a/erts/emulator/test/trace_port_SUITE.erl
+++ b/erts/emulator/test/trace_port_SUITE.erl
@@ -26,6 +26,7 @@
 	 return_trace/1,
 	 send/1,
 	 receive_trace/1,
+	 receive_trace_non_scheduler/1,
 	 process_events/1,
 	 schedule/1,
 	 gc/1,
@@ -40,6 +41,7 @@ suite() ->
 
 all() ->
     [call_trace, return_trace, send, receive_trace,
+     receive_trace_non_scheduler,
      process_events, schedule, gc,
      default_tracer, tracer_port_crash].
 
@@ -184,6 +186,26 @@ receive_trace(Config) when is_list(Config) ->
     expect({trace_ts,Receiver,'receive',Huge,ts}),
     ok.
 
+%% Test sending receive traces to a port.
+receive_trace_non_scheduler(Config) when is_list(Config) ->
+    start_tracer(Config),
+    S = self(),
+    Receiver = spawn(
+                 fun() ->
+                         receive
+                             go ->
+                                 Ref = S ! erlang:trace_delivered(all),
+                                 receive {trace_delivered, Ref, all} -> ok end
+                         end
+                 end),
+    trac(Receiver, true, ['receive']),
+    Receiver ! go,
+    Ref = receive R -> R end,
+    expect({trace,Receiver,'receive',go}),
+    expect({trace,Receiver,'receive',{trace_delivered, all, Ref}}),
+
+    ok.
+
 %% Tests a few process events (like getting linked).
 process_events(Config) when is_list(Config) ->
     start_tracer(Config),
-- 
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