Re: [edk2-devel] [PATCH 2/2] MdeModulePkg/Bus/Ata/AtaAtapiPassThru: Fix UNUSED_VALUE Coverity issue

["Wu, Hao A" <hao.a.wu@intel.com>]

> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Ard
> Biesheuvel
> Sent: Monday, June 5, 2023 4:32 PM
> To: Ranbir Singh <rsingh@ventanamicro.com>
> Cc: devel@edk2.groups.io; pedro.falcato@gmail.com; Wu, Hao A
> <hao.a.wu@intel.com>; Ni, Ray <ray.ni@intel.com>
> Subject: Re: [edk2-devel] [PATCH 2/2]
> MdeModulePkg/Bus/Ata/AtaAtapiPassThru: Fix UNUSED_VALUE Coverity
> issue
> 
> On Mon, 5 Jun 2023 at 10:10, Ranbir Singh <rsingh@ventanamicro.com>
> wrote:
> >
> > I counted myself as not the right person to decide what all to do if Status is
> not successful. Adding the DEBUG statement from the Coverity aspect
> doesn't count as a fix as RELEASE mode behavior remains the same.
> >
> > In the comments / description, I already mentioned - Assuming, this non-
> usage is deliberate, so as such I did not intend to hide anything - and left it in
> the status quo.
> >
> > The patch proposed may not be appropriate, but should now give a
> thinking point to active module developers / owners / maintainers if they
> indeed feel that there is a bug here and it needs to be fixed.
> >
> 
> Thanks - I agree that it is a good thing that people are aware of this now.


Judging from the context in DetectAndConfigIdeDevice(), I think a fix can be:

  Status = SetDriveParameters (Instance, IdeChannel, IdeDevice, &DriveParameters, NULL);
  if (EFI_ERROR (Status)) {
    DEBUG ((DEBUG_ERROR, "Set drive parameters Fail, Status = %r\n", Status));
    continue;
  }

But I do not have the device and platform environment to verify the change.
Really sorry for this. I am not sure on the potential risk of making this change without at least some kind of 'no-break' tests.

Best Regards,
Hao Wu


> 
> > On Mon, Jun 5, 2023 at 4:33 AM Ard Biesheuvel <ardb@kernel.org> wrote:
> >>
> >> On Sat, 3 Jun 2023 at 18:04, Pedro Falcato <pedro.falcato@gmail.com>
> wrote:
> >> >
> >> > On Fri, Jun 2, 2023 at 8:42 PM Ranbir Singh <rsingh@ventanamicro.com>
> wrote:
> >> > >
> >> > > From: Ranbir Singh <Ranbir.Singh3@Dell.com>
> >> > >
> >> > > The return value stored in Status after call to SetDriveParameters
> >> > > is not made of any use thereafter and hence it remains as UNUSED.
> >> > > Assuming, this non-usage is deliberate, the storage in Status can be
> >> > > done away with.
> >> > >
> >> > > Cc: Hao A Wu <hao.a.wu@intel.com>
> >> > > Cc: Ray Ni <ray.ni@intel.com>
> >> > > REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4204
> >> > > Signed-off-by: Ranbir Singh <Ranbir.Singh3@Dell.com>
> >> > > ---
> >> > >  MdeModulePkg/Bus/Ata/AtaAtapiPassThru/IdeMode.c | 2 +-
> >> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> >> > >
> >> > > diff --git a/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/IdeMode.c
> b/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/IdeMode.c
> >> > > index 75403886e44a..c6d637afa989 100644
> >> > > --- a/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/IdeMode.c
> >> > > +++ b/MdeModulePkg/Bus/Ata/AtaAtapiPassThru/IdeMode.c
> >> > > @@ -2555,7 +2555,7 @@ DetectAndConfigIdeDevice (
> >> > >        DriveParameters.Heads          = (UINT8)(((ATA5_IDENTIFY_DATA
> *)(&Buffer.AtaData))->heads - 1);
> >> > >        DriveParameters.MultipleSector = (UINT8)((ATA5_IDENTIFY_DATA
> *)(&Buffer.AtaData))->multi_sector_cmd_max_sct_cnt;
> >> > >
> >> > > -      Status = SetDriveParameters (Instance, IdeChannel, IdeDevice,
> &DriveParameters, NULL);
> >> > > +      SetDriveParameters (Instance, IdeChannel, IdeDevice,
> &DriveParameters, NULL);
> >> >
> >> > I'm /fairly/ sure this is wrong and that you need to use Status.
> >> >
> >>
> >> Yeah, removing the assignment fixes the coverity warning, but now you
> >> are hiding a bug instead of fixing it.
> >>
> >> SetDriveParameters () can apparently fail, and this is being ignored.
> >> At the very least, we should emit a diagnostic here in DEBUG mode to
> >> log this. E.g.,
> >>
> >> DEBUG ((DEBUG_WARN, "%a: SetDriveParameters () failed - %r\n",
> >> __func__, Status));
> 
> 
> 
>