Re: [edk2-devel] [PATCH v2 2/5] MdeModulePkg/Bus/Pci/PciBusDxe: Fix MISSING_BREAK Coverity issues

["Ranbir Singh" <rsingh@ventanamicro.com>]

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Hi Mike,

I agree that any manual inspection is sort of a burden, more so when it
becomes repetitive in the long run.

When I was doing these Coverity checks (Nov-Dec' 2022), I was working in
Dell and had access to the real systems to check the execution flow as well
as the Coverity status. I could never post these patches while being there,
but happened to raise Bugzilla's and post them there instead hoping that
they would be taken up by somebody further.

I am no longer with Dell and later on when I found that those BZ / issues
pointed out by Coverity still exist as there are no code changes in related
contexts, I thought of taking them forward in whatever limited capacity I
can. I am a bit hesitant to do any further code changes as now I do not
have any systems to check the execution flow as well as the Coverity
status. So, I do not guarantee, but will try to make the code changes
wherever it is easy to ascertain that the functional flow would not be
impacted and the same issue won't exist anymore.

Ranbir Singh

On Wed, Nov 8, 2023 at 9:35 AM Kinney, Michael D <michael.d.kinney@intel.com>
wrote:

> Hi Ranbir,
>
>
>
> Ignoring false positive in static analysis tools is typically a burden.
>
>
>
> It is better to avoid false positives with code changes as long as the
> code changes do not make the implementation confusing and hard to maintain.
>
>
>
> I think depending on fall through case statements is confusing and
> removing them will make the code easier to understand and maintain.
>
>
>
> Mike
>
>
>
> *From:* Ranbir Singh <rsingh@ventanamicro.com>
> *Sent:* Tuesday, November 7, 2023 7:51 PM
> *To:* Kinney, Michael D <michael.d.kinney@intel.com>
> *Cc:* devel@edk2.groups.io; lersek@redhat.com; Ni, Ray <ray.ni@intel.com>;
> Veeresh Sangolli <veeresh.sangolli@dellteam.com>
> *Subject:* Re: [edk2-devel] [PATCH v2 2/5]
> MdeModulePkg/Bus/Pci/PciBusDxe: Fix MISSING_BREAK Coverity issues
>
>
>
> As mentioned in the commit message, the comment helps in making it
> explicit and evident that the missing break is not a human miss, but
> intentional.
>
> Hence, the comment should be considered as being added for the human code
> readers / developers.
>
>
>
> So even if some static analysis tool flags such an issue, it can be fairly
> easy now to ignore that on manual inspection. If desired this can also be
> stated in the comment itself like -
>
>
>
> +                  //
> +                  // No break here as this is an intentional fall through.
>
> +                  // Ignore any static tool issue if pointed.
> +                  //
>
>
>
> Yes, there can be other solutions (which may or may not be worth the
> effort), but for now I went with the least code change approach.
>
>
>
> On Tue, Nov 7, 2023 at 11:29 PM Kinney, Michael D <
> michael.d.kinney@intel.com> wrote:
>
> This comment style only works with Coverity.
>
> Other static analysis tools may flag the same issue again.
>
> It is better to update the logic so no static analysis tool will
> flag this issue.
>
> Mike
>
> > -----Original Message-----
> > From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Laszlo
> > Ersek
> > Sent: Tuesday, November 7, 2023 8:23 AM
> > To: devel@edk2.groups.io; rsingh@ventanamicro.com
> > Cc: Ni, Ray <ray.ni@intel.com>; Veeresh Sangolli
> > <veeresh.sangolli@dellteam.com>
> > Subject: Re: [edk2-devel] [PATCH v2 2/5]
> > MdeModulePkg/Bus/Pci/PciBusDxe: Fix MISSING_BREAK Coverity issues
> >
> > On 11/7/23 07:19, Ranbir Singh wrote:
> > > From: Ranbir Singh <Ranbir.Singh3@Dell.com>
> > >
> > > The function UpdatePciInfo has switch-case code in which there are
> > fall
> > > through from case 32: to case 64:. While this is seeemingly
> > intentional,
> > > it is not evident to any general code reader why there is no break;
> > in
> > > between. Adding
> > >
> > >     // No break; here as this is an intentional fallthrough.
> > >
> > > as comment in between makes it explicit. Incidentally, the comment
> > > satisfies Coverity as well.
> > >
> > > REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4239
> > >
> > > Cc: Ray Ni <ray.ni@intel.com>
> > > Co-authored-by: Veeresh Sangolli <veeresh.sangolli@dellteam.com>
> > > Signed-off-by: Ranbir Singh <Ranbir.Singh3@Dell.com>
> > > Signed-off-by: Ranbir Singh <rsingh@ventanamicro.com>
> > > ---
> > >  MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c | 6 ++++++
> > >  1 file changed, 6 insertions(+)
> > >
> > > diff --git a/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
> > b/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
> > > index 6594b8eae83f..eda97285ee18 100644
> > > --- a/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
> > > +++ b/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
> > > @@ -1428,6 +1428,9 @@ UpdatePciInfo (
> > >                switch (Ptr->AddrSpaceGranularity) {
> > >                  case 32:
> > >                    PciIoDevice->PciBar[BarIndex].BarType =
> > PciBarTypeMem32;
> > > +                  //
> > > +                  // No break; here as this is an intentional fall
> > through.
> > > +                  //
> > >                  case 64:
> > >                    PciIoDevice->PciBar[BarIndex].BarTypeFixed =
> > TRUE;
> > >                    break;
> > > @@ -1440,6 +1443,9 @@ UpdatePciInfo (
> > >                switch (Ptr->AddrSpaceGranularity) {
> > >                  case 32:
> > >                    PciIoDevice->PciBar[BarIndex].BarType =
> > PciBarTypePMem32;
> > > +                  //
> > > +                  // No break; here as this is an intentional fall
> > through.
> > > +                  //
> > >                  case 64:
> > >                    PciIoDevice->PciBar[BarIndex].BarTypeFixed =
> > TRUE;
> > >                    break;
> >
> > Agree, but the semicolon's placement is awkward. I propose
> >
> >   No break here, as this is an intentional fall through.
> >
> > Reviewed-by: Laszlo Ersek <lersek@redhat.com>
> >
> >
> >
> > 
> >
>
>


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