From ab3e7b984a14cbc4b491578a36f0e4bdd37b9d45 Mon Sep 17 00:00:00 2001
From: NicJA <NicJA@fb15a70f-31f2-0310-bbcc-cdcc74a49acc>
Date: Sat, 11 Mar 2017 14:42:50 +0000
Subject: [PATCH] protect access to the msgport list in waitport.

git-svn-id: https://svn.aros.org/svn/aros/trunk/AROS@54074 fb15a70f-31f2-0310-bbcc-cdcc74a49acc
---
 rom/exec/waitport.c | 35 +++++++++++++++++++++++++++++++----
 1 file changed, 31 insertions(+), 4 deletions(-)

diff --git a/rom/exec/waitport.c b/rom/exec/waitport.c
index 34ddda6171..3605feaf06 100644
--- a/rom/exec/waitport.c
+++ b/rom/exec/waitport.c
@@ -1,10 +1,14 @@
 /*
-    Copyright © 1995-2001, The AROS Development Team. All rights reserved.
+    Copyright © 1995-2017, The AROS Development Team. All rights reserved.
     $Id$
 
     Desc: Wait for a message on a port.
     Lang: english
 */
+
+#define DEBUG 0
+#include <aros/debug.h>
+
 #include "exec_intern.h"
 #include <exec/ports.h>
 #include <aros/libcall.h>
@@ -50,21 +54,44 @@
 
     ASSERT_VALID_PTR(port);
     /*
-	No Disable() necessary here since emptiness can be checked
-	without and nobody is allowed to change the signal bit as soon
+	On uniprocessors systems, Disable() is not necessary  since emptiness
+            can be checked without it - and nobody is allowed to change the signal bit as soon
 	as the current task entered WaitPort() (and probably did not yet
 	have a chance to Disable()).
     */
+    D(bug("[Exec] WaitPort(0x%p)\n", port);)
 
     /* Is messageport empty? */
-    while (IsListEmpty (&port->mp_MsgList))
+#if defined(__AROSEXEC_SMP__)
+    Disable();
+    EXEC_SPINLOCK_LOCK(&port->mp_SpinLock, NULL, SPINLOCK_MODE_READ);
+#endif
+    while (IsListEmpty(&port->mp_MsgList))
     {
+#if defined(__AROSEXEC_SMP__)
+        EXEC_SPINLOCK_UNLOCK(&port->mp_SpinLock);
+        Enable();
+#endif
+        D(bug("[Exec] WaitPort: Msg list empty, waiting for activity...\n");)
+
 	/*
 	    Yes. Wait for the signal to arrive. Remember that signals may
 	    arrive without a message so check again.
 	*/
 	Wait(1<<port->mp_SigBit);
+
+        D(bug("[Exec] WaitPort: Msgport signal received ...\n");)
+#if defined(__AROSEXEC_SMP__)
+        Disable();
+        EXEC_SPINLOCK_LOCK(&port->mp_SpinLock, NULL, SPINLOCK_MODE_READ);
+#endif
     }
+#if defined(__AROSEXEC_SMP__)
+    EXEC_SPINLOCK_UNLOCK(&port->mp_SpinLock);
+    Enable();
+#endif
+
+    D(bug("[Exec] WaitPort: Returning...\n");)
 
     /* Return the first node in the list. */
     return (struct Message *)port->mp_MsgList.lh_Head;
-- 
2.11.4.GIT