[weiden] 13641: fixed RtlEnterCriticalSection not to fail on wrong assumptions and added comment on why the debug message "Critical section not initialized (guess)" is wrong

fixed RtlEnterCriticalSection not to fail on wrong assumptions and added
comment on why the debug message "Critical section not initialized
(guess)" is wrong
Modified: trunk/reactos/lib/ntdll/rtl/critical.c
  _____

Modified: trunk/reactos/lib/ntdll/rtl/critical.c
--- trunk/reactos/lib/ntdll/rtl/critical.c	2005-02-19 11:13:41 UTC
(rev 13640)
+++ trunk/reactos/lib/ntdll/rtl/critical.c	2005-02-19 13:13:17 UTC
(rev 13641)
@@ -144,23 +144,27 @@

*/
         if (Thread == CriticalSection->OwningThread) {

-            /* You own it, so you'll get it when you're done with it!
*/
+            /* You own it, so you'll get it when you're done with it!
No need to
+               use the interlocked functions as only the thread who
already owns
+               the lock can modify this data. */
             CriticalSection->RecursionCount++;
             return STATUS_SUCCESS;
         }
-        else if (CriticalSection->OwningThread == (HANDLE)0)
-        {
-            /* No one else owns it either! */
-            DPRINT1("Critical section not initialized (guess)!\n");
-            /* FIXME: raise exception */
-            return STATUS_INVALID_PARAMETER;            
-        }
+
+        /* NOTE - CriticalSection->OwningThread can be NULL here
because changing
+                  this information is not serialized. This happens when
thread a
+                  acquires the lock (LockCount == 0) and thread b tries
to
+                  acquire it as well (LockCount == 1) but thread a
hasn't had a
+                  chance to set the OwningThread! So it's not an error
when
+                  OwningThread is NULL here! */

/* We don't own it, so we must wait for it */
         RtlpWaitForCriticalSection(CriticalSection);
     }

-    /* Lock successful */
+    /* Lock successful. Changing this information has not to be
serialized because
+       only one thread at a time can actually change it (the one who
acquired
+       the lock)! */
     CriticalSection->OwningThread = Thread;
     CriticalSection->RecursionCount = 1;
     return STATUS_SUCCESS;