[ros-dev] [ros-diffs] [fireball] 53596: [NTOS/CONFIG] - Remove unnecessary assignments. Spotted by PVS and Dmitry Chapyshev. This may change the behaviour of that codepath, so test results are going to be observed.

[Aleksey Bragin]

Perfect, I have a straight answer from you right away, so my trick worked.

Now, seriously, is that hack still needed? I understand it was needed during early time when you developed this branch, but what about now? With all the changes it had over time when you last worked on it?

From: Alex Ionescu 
Sent: Monday, September 05, 2011 8:25 PM
To: ReactOS Development List 
Subject: Re: [ros-dev] [ros-diffs] [fireball] 53596: [NTOS/CONFIG] - Remove unnecessary assignments. Spotted by PVS and Dmitry Chapyshev. This may change the behaviour of that codepath, so test results are going to be observed.

As a "non-dev" you seem to have understood the issue more than the project developer leader! Good job. 

Indeed, the original code lacks a comment stating that the first assignment is how it's "supposed" to be done, but that the second assignment is currently a hack to make ReactOS work (in the original commit I made, the first line was commented out -- but a comment never added as to why). So that's my fault.

You're also right that this "unneccessary assignment" is actually quite necessary, and that by removing the SECOND ChildList assignment, instead of the first, the entire functionality of the function is modified -- if anything, the first assignment should've been removed (since no comment was there explaining why it was needed).

So yes, good job on understanding both these issues, and for none of the devs seemingly able to see your correct logic...

Best regards,
Alex Ionescu



On Mon, Sep 5, 2011 at 1:03 PM, Vicmarcal <vicmarcal at hotmail.com> wrote:

  Nope,I have asked in #reactos-dev too about that removal just after the commiting was done.
  To begin I dont understand the logic in the original code about reassigning the value to the ChildList two lines later(unless the first assignation is not needed at all)
  And after the commit I dont understand   the commit message "unnecesary assignments".Now,after removing the second assignment,the behavior should be totally different(unless &Kcb->ValueCache; is == &KeyNode->ValueList; , which I doubt). So if the removal is correct,then it wasnt an "unnecesary change" but a "fixing a bug".
  Anyway I am not a dev, so I express my doubts here too if anyone can light me a little :)

  Enviado desde mi iPhone

  El 05/09/2011, a las 13:48, "Alex Ionescu" <ionucu at videotron.ca> escribió:


    Uhhhh... 

    Am I really the *only* one who sees a problem here?

    ChildList = &Kcb->ValueCache;
    -    ChildList = (PCACHED_CHILD_LIST)&KeyNode->ValueList;

    Best regards,
    Alex Ionescu



    On Mon, Sep 5, 2011 at 10:54 AM, <fireball at svn.reactos.org> wrote:

      Author: fireball
      Date: Mon Sep  5 09:54:20 2011
      New Revision: 53596

      URL: http://svn.reactos.org/svn/reactos?rev=53596&view=rev
      Log:
      [NTOS/CONFIG]
      - Remove unnecessary assignments. Spotted by PVS and Dmitry Chapyshev. This may change the behaviour of that codepath, so test results are going to be observed.

      Modified:
         trunk/reactos/ntoskrnl/config/cmvalche.c

      Modified: trunk/reactos/ntoskrnl/config/cmvalche.c
      URL: http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/config/cmvalche.c?rev=53596&r1=53595&r2=53596&view=diff
      ==============================================================================
      --- trunk/reactos/ntoskrnl/config/cmvalche.c [iso-8859-1] (original)
      +++ trunk/reactos/ntoskrnl/config/cmvalche.c [iso-8859-1] Mon Sep  5 09:54:20 2011
      @@ -49,7 +49,6 @@
          PHHIVE Hive;
          PCACHED_CHILD_LIST ChildList;
          HCELL_INDEX CellToRelease;
      -    PCM_KEY_NODE KeyNode;

          /* Set defaults */
          *ValueListToRelease = HCELL_NIL;
      @@ -58,8 +57,6 @@
          /* Get the hive and value cache */
          Hive = Kcb->KeyHive;
          ChildList = &Kcb->ValueCache;
      -    KeyNode = (PCM_KEY_NODE)HvGetCell(Hive, Kcb->KeyCell);
      -    ChildList = (PCACHED_CHILD_LIST)&KeyNode->ValueList;

          /* Check if the value is cached */
          if (CmpIsValueCached(ChildList->ValueList))
      @@ -212,7 +209,6 @@
          BOOLEAN IndexIsCached;
          ULONG i = 0;
          HCELL_INDEX Cell = HCELL_NIL;
      -    PCM_KEY_NODE KeyNode;

          /* Set defaults */
          *CellToRelease = HCELL_NIL;
      @@ -221,8 +217,6 @@
          /* Get the hive and child list */
          Hive = Kcb->KeyHive;
          ChildList = &Kcb->ValueCache;
      -    KeyNode = (PCM_KEY_NODE)HvGetCell(Hive, Kcb->KeyCell);
      -    ChildList = (PCACHED_CHILD_LIST)&KeyNode->ValueList;

          /* Check if the child list has any entries */
          if (ChildList->Count != 0)




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