[aandrejevic] 61230: [NTVDM] Fix race conditions.

Author: aandrejevic
Date: Fri Dec  6 04:51:47 2013
New Revision: 61230

URL: http://svn.reactos.org/svn/reactos?rev=61230&view=rev
Log:
[NTVDM]
Fix race conditions.


Modified:
    branches/ntvdm/subsystems/ntvdm/ps2.c

Modified: branches/ntvdm/subsystems/ntvdm/ps2.c
URL:
http://svn.reactos.org/svn/reactos/branches/ntvdm/subsystems/ntvdm/ps2.c?re…
==============================================================================
--- branches/ntvdm/subsystems/ntvdm/ps2.c	[iso-8859-1] (original)
+++ branches/ntvdm/subsystems/ntvdm/ps2.c	[iso-8859-1] Fri Dec  6 04:51:47 2013
@@ -32,9 +32,9 @@
 static BOOLEAN KeyboardQueuePush(BYTE ScanCode)
 {
     /* Check if the keyboard queue is full */
+    WaitForSingleObject(QueueMutex, INFINITE);
+
     if (!KeyboardQueueEmpty && (KeyboardQueueStart == KeyboardQueueEnd)) return
FALSE;
-
-    WaitForSingleObject(QueueMutex, INFINITE);
 
     /* Insert the value in the queue */
     KeyboardQueue[KeyboardQueueEnd] = ScanCode;
@@ -50,10 +50,18 @@
 
 static BOOLEAN KeyboardQueuePop(BYTE *ScanCode)
 {
+    BOOLEAN Result = TRUE;
+
     /* Make sure the keyboard queue is not empty */
     if (KeyboardQueueEmpty) return FALSE;
 
     WaitForSingleObject(QueueMutex, INFINITE);
+
+    if (KeyboardQueueEmpty)
+    {
+        Result = FALSE;
+        goto Done;
+    }
 
     /* Get the scan code */
     *ScanCode = KeyboardQueue[KeyboardQueueStart];
@@ -68,8 +76,9 @@
         KeyboardQueueEmpty = TRUE;
     }
 
+Done:
     ReleaseMutex(QueueMutex);
-    return TRUE;
+    return Result;
 }
 
 /* PUBLIC FUNCTIONS ***********************************************************/