Congrats on once again breaking another key part of Windows compatibility.
This function is DOCUMENTED to tear. It was DESIGNED that way on purpose.
Utter failure, once more.
Best regards,
Alex Ionescu
On Sat, May 14, 2011 at 12:29 PM,
<tkreuzer@svn.reactos.org> wrote:
Author: tkreuzer
Date: Sat May 14 19:29:42 2011
New Revision: 51748
URL: http://svn.reactos.org/svn/reactos?rev=51748&view=rev
Log:
[NTOSKRNL]
Patch by Paolo Bonzini <bonzini [at] gnu [dot] org>
Fix implementation of ExInterlockedAddLargeStatistic
The old version wasn't really atomic.
See issue #6223 for more details.
Modified:
trunk/reactos/ntoskrnl/ex/i386/fastinterlck_asm.S
Modified: trunk/reactos/ntoskrnl/ex/i386/fastinterlck_asm.S
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/ex/i386/fastinterlck_asm.S?rev=51748&r1=51747&r2=51748&view=diff
==============================================================================
--- trunk/reactos/ntoskrnl/ex/i386/fastinterlck_asm.S [iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/ex/i386/fastinterlck_asm.S [iso-8859-1] Sat May 14 19:29:42 2011
@@ -4,8 +4,9 @@
* FILE: ntoskrnl/ex/i386/fastinterlck_asm.S
* PURPOSE: FASTCALL Interlocked Functions
* PROGRAMMERS: Alex Ionescu (alex@relsoft.net)
- */
-
+ * Paolo Bonzini <bonzini [at] gnu [dot] org>
+ */
+
/* INCLUDES ******************************************************************/
#include <asm.inc>
@@ -31,25 +32,55 @@
*/
PUBLIC @ExInterlockedAddLargeStatistic@8
@ExInterlockedAddLargeStatistic@8:
-
-#ifdef CONFIG_SMP
- /* Do the addition */
- lock add [ecx], edx
-
- /* Check for carry bit and return */
- jb .l1
- ret
-
-.l1:
- /* Add carry */
- lock adc dword ptr [ecx+4], 0
-#else
- /* Do the addition and add the carry */
- add dword ptr [ecx], edx
- adc dword ptr [ecx+4], 0
-#endif
- /* Return */
- ret
+ push ebp
+ push ebx
+ mov ebp, ecx
+
+Again:
+ /* Load comparand in eax for cmpxchg */
+ mov eax, [ebp]
+
+ /* Compute low word of the result in ebx */
+ mov ebx, edx
+ add ebx, eax
+
+ /* Carry needs cmpxchg8b */
+ jc Slow
+
+ /* Fast path still needs to be atomic, so use cmpxchg and retry if it fails
+ * Hopefully it will still get through this path :) */
+ LOCK cmpxchg [ecx], ebx
+ jnz Again
+
+ /* Thats it */
+ pop ebx
+ pop ebp
+ ret
+
+Slow:
+ /* Save increment across cmpxchg8b */
+ push edx
+
+ /* Finish loading comparand in edx:eax */
+ mov edx, [ebp+4]
+
+ /* Result in ecx:ebx (we know there's carry) */
+ lea ecx, [edx+1]
+
+ /* Do a full exchange */
+ LOCK cmpxchg8b [ebp]
+
+ /* restore increment */
+ pop edx
+
+ /* Need to retry */
+ jnz Again
+
+ /* Thats it */
+ pop ebx
+ pop ebp
+ ret
+
/*ULONG
*FASTCALL