Merge branch 'maint'

Conflicts:
	erts/emulator/beam/erl_nif.c
	erts/emulator/beam/erl_process.c

2 files changed, 15 insertions, 7 deletions

diff --git a/erts/emulator/beam/erl_nif.c b/erts/emulator/beam/erl_nif.c
index 9ffb53d532..05bcf73451 100644
--- a/erts/emulator/beam/erl_nif.c
+++ b/erts/emulator/beam/erl_nif.c
@@ -587,6 +587,10 @@ int erts_flush_trace_messages(Process *c_p, ErtsProcLocks c_p_locks)
     ErlTraceMessageQueue *msgq, **last_msgq;
     int reds = 0;
 
+    /* Only one thread at a time is allowed to flush trace messages,
+       so we require the main lock to be held when doing the flush */
+    ERTS_CHK_HAVE_ONLY_MAIN_PROC_LOCK(c_p);
+
     erts_proc_lock(c_p, ERTS_PROC_LOCK_TRACE);
 
     msgq = c_p->trace_msg_q;
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index 88b2bda59c..0d4f7305d0 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -11403,9 +11403,11 @@ flush_dirty_trace_messages(void *vpid)
     erts_free(ERTS_ALC_T_DIRTY_SL, vpid);
 #endif
 
-    proc = erts_proc_lookup(pid);
-    if (proc)
-	(void) erts_flush_trace_messages(proc, 0);
+    proc = erts_pid2proc_opt(NULL, 0, pid, ERTS_PROC_LOCK_MAIN, 0);
+    if (proc) {
+	(void) erts_flush_trace_messages(proc, ERTS_PROC_LOCK_MAIN);
+        erts_proc_unlock(proc, ERTS_PROC_LOCK_MAIN);
+    }
 }
 
 #endif /* ERTS_DIRTY_SCHEDULERS */
@@ -13667,16 +13669,18 @@ erts_continue_exit_process(Process *p)
 								 have none here */
     }
 
-    erts_flush_trace_messages(p, 0);
+    erts_proc_lock(p, ERTS_PROC_LOCK_MAIN);
+    ERTS_CHK_HAVE_ONLY_MAIN_PROC_LOCK(p);
+
+#ifdef ERTS_SMP
+    erts_flush_trace_messages(p, ERTS_PROC_LOCK_MAIN);
+#endif
 
     ERTS_TRACER_CLEAR(&ERTS_TRACER(p));
 
     if (!delay_del_proc)
 	delete_process(p);
 
-    erts_proc_lock(p, ERTS_PROC_LOCK_MAIN);
-    ERTS_CHK_HAVE_ONLY_MAIN_PROC_LOCK(p);
-
     return;
 
  yield: