Re: [patch] MdeModulePkg/DisplayEngine: Remove useless NULL ptr check for NewPos

[Leif Lindholm <leif.lindholm@linaro.org>]

On Fri, Nov 09, 2018 at 07:56:07AM +0100, Ard Biesheuvel wrote:
> On 9 November 2018 at 01:19, Gao, Liming <liming.gao@intel.com> wrote:
> > Ard:
> >   This is a small fix. And, this patch is sent before the hard
> >   freeze. It is the low risk for this release. So, I push it.
> 
> OK, fair enough.

I don't agree actually.

https://github.com/tianocore/tianocore.github.io/wiki/HardFeatureFreeze
specifies clearly that only bug fixes are permitted in during hard
freeze. Maybe we could document that a bit more explicitly, but this
patch was no bugfix. It should not have gone in.

By my interpretation, it would not even fulfill the requirements for
https://github.com/lersek/edk2/wiki/SoftFeatureFreeze:
"By the date of the soft feature freeze, developers must have sent
their patches to the mailing list and received positive maintainer
reviews."
Soft feature freeze was 1 November. The patch was sent out 7 November.
It received reviews 8 November (after the start of the hard freeze).

The point of these freezes is that sometimes patches are wrong. And
sometimes patches that look correct, are not correct. If we start
making exceptions because "oh, it's trivial", that means we get these
patches into the tree with much reduced time for anyone to catch any
adverse effects before we make the stable tag. And at that point, the
stable tag no longer has value.

(I am much more flexible on the topic of updating documentation, like
Maintainers.txt, but even there we must be very careful.)

Regards,

Leif

> >>-----Original Message-----
> >>From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org]
> >>Sent: Friday, November 09, 2018 2:25 AM
> >>To: Zeng, Star <star.zeng@intel.com>
> >>Cc: Bi, Dandan <dandan.bi@intel.com>; edk2-devel@lists.01.org; Wu, Hao A
> >><hao.a.wu@intel.com>; Dong, Eric <eric.dong@intel.com>; Gao, Liming
> >><liming.gao@intel.com>
> >>Subject: Re: [edk2] [patch] MdeModulePkg/DisplayEngine: Remove useless
> >>NULL ptr check for NewPos
> >>
> >>On 8 November 2018 at 02:09, Zeng, Star <star.zeng@intel.com> wrote:
> >>> Reviewed-by: Star Zeng <star.zeng@intel.com>
> >>>
> >>> -----Original Message-----
> >>> From: Bi, Dandan
> >>> Sent: Wednesday, November 7, 2018 10:53 PM
> >>> To: edk2-devel@lists.01.org
> >>> Cc: Gao, Liming <liming.gao@intel.com>; Dong, Eric <eric.dong@intel.com>;
> >>Zeng, Star <star.zeng@intel.com>; Wu, Hao A <hao.a.wu@intel.com>
> >>> Subject: [patch] MdeModulePkg/DisplayEngine: Remove useless NULL ptr
> >>check for NewPos
> >>>
> >>> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1306
> >>>
> >>> In function UiDisplayMenu, the NewPos ptr which used to point to the
> >>highlight menu entry. It will always point to the menu entry which need to be
> >>highlighted or the gMenuOption menu if the highlight menu is not found.
> >>> So we can remove the NULL ptr check for NewPos in this function.
> >>> And add the ASSERT code to avoid if any false positive reports of NULL
> >>pointer dereference issue raised from static analysis.
> >>>
> >>> Cc: Liming Gao <liming.gao@intel.com>
> >>> Cc: Eric Dong <eric.dong@intel.com>
> >>> Cc: Star Zeng <star.zeng@intel.com>
> >>> Cc: Hao Wu <hao.a.wu@intel.com>
> >>> Contributed-under: TianoCore Contribution Agreement 1.1
> >>> Signed-off-by: Dandan Bi <dandan.bi@intel.com>
> >>
> >>Why was this patch merged today? Surely, this doesn't meet the hard
> >>freeze requirements ?
> >>
> >>> ---
> >>>  MdeModulePkg/Universal/DisplayEngineDxe/FormDisplay.c | 3 ++-
> >>>  1 file changed, 2 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/MdeModulePkg/Universal/DisplayEngineDxe/FormDisplay.c
> >>b/MdeModulePkg/Universal/DisplayEngineDxe/FormDisplay.c
> >>> index 7390f954b6..44f087fe01 100644
> >>> --- a/MdeModulePkg/Universal/DisplayEngineDxe/FormDisplay.c
> >>> +++ b/MdeModulePkg/Universal/DisplayEngineDxe/FormDisplay.c
> >>> @@ -2880,10 +2880,11 @@ UiDisplayMenu (
> >>>        //             MenuOption is set to NULL in Repaint
> >>>        // NewPos:     Current menu option that need to hilight
> >>>        //
> >>>        ControlFlag = CfUpdateHelpString;
> >>>
> >>> +      ASSERT (NewPos != NULL);
> >>>        UpdateHighlightMenuInfo(NewPos, TopOfScreen, SkipValue);
> >>>
> >>>        if (SkipHighLight) {
> >>>          SkipHighLight = FALSE;
> >>>          MenuOption    = SavedMenuOption;
> >>> @@ -2908,11 +2909,11 @@ UiDisplayMenu (
> >>>          Temp2 = SkipValue;
> >>>        } else {
> >>>          Temp2 = 0;
> >>>        }
> >>>
> >>> -      if (NewPos != NULL && (MenuOption == NULL || NewPos !=
> >>&MenuOption->Link)) {
> >>> +      if (MenuOption == NULL || NewPos != &MenuOption->Link) {
> >>>          if (MenuOption != NULL) {
> >>>            //
> >>>            // Remove the old highlight menu.
> >>>            //
> >>>            Status = DisplayOneMenu (MenuOption,
> >>> --
> >>> 2.18.0.windows.1
> >>>
> >>> _______________________________________________
> >>> edk2-devel mailing list
> >>> edk2-devel@lists.01.org
> >>> https://lists.01.org/mailman/listinfo/edk2-devel
> _______________________________________________
> edk2-devel mailing list
> edk2-devel@lists.01.org
> https://lists.01.org/mailman/listinfo/edk2-devel