[ros-diffs] [fireball] 35516: - "When releasing the gmutex my awesome code was removing the woken flag" (c) Alex Ionescu.

[fireball at svn.reactos.org]

Author: fireball
Date: Thu Aug 21 16:07:52 2008
New Revision: 35516

URL: http://svn.reactos.org/svn/reactos?rev=35516&view=rev
Log:
- "When releasing the gmutex my awesome code was removing the woken flag" (c) Alex Ionescu.

Modified:
    trunk/reactos/ntoskrnl/ke/gmutex.c

Modified: trunk/reactos/ntoskrnl/ke/gmutex.c
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/ke/gmutex.c?rev=35516&r1=35515&r2=35516&view=diff
==============================================================================
--- trunk/reactos/ntoskrnl/ke/gmutex.c [iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/ke/gmutex.c [iso-8859-1] Thu Aug 21 16:07:52 2008
@@ -79,6 +79,9 @@
         /* Ok, the wait is done, so set the new bits */
         BitsToRemove = GM_LOCK_BIT | GM_LOCK_WAITER_WOKEN;
         BitsToAdd = GM_LOCK_WAITER_WOKEN;
+        
+        /* We depend on these bits being just right */
+        ASSERT((GM_LOCK_WAITER_WOKEN * 2) == GM_LOCK_WAITER_INC);
     }
 }
 
@@ -103,7 +106,7 @@
 FASTCALL
 KiReleaseGuardedMutex(IN OUT PKGUARDED_MUTEX GuardedMutex)
 {
-    LONG OldValue;
+    LONG OldValue, NewValue;
 
     /* Destroy the Owner */
     GuardedMutex->Owner = NULL;
@@ -117,10 +120,14 @@
     {
         /* Update the Oldvalue to what it should be now */
         OldValue |= GM_LOCK_BIT;
+        
+        /* The mutex will be woken, minus one waiter */
+        NewValue = (OldValue | GM_LOCK_WAITER_WOKEN);
+        NewValue &= ~GM_LOCK_WAITER_INC;
 
         /* Remove the Woken bit */
         if (InterlockedCompareExchange(&GuardedMutex->Count,
-                                       OldValue - GM_LOCK_WAITER_WOKEN,
+                                       NewValue,
                                        OldValue) == OldValue)
         {
             /* Signal the Gate */