Re: [MdeModulePkg/Library v1 1/1] MdeModulePkg/UefiBootManangerLib: Fix exception issue

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

> -----Original Message-----
> From: Leif Lindholm [mailto:leif.lindholm@linaro.org]
> Sent: Monday, March 18, 2019 8:43 PM
> To: Ming Huang
> Cc: linaro-uefi@lists.linaro.org; edk2-devel@lists.01.org; Zeng, Star; Dong,
> Eric; Ni, Ray; dann.frazier@canonical.com; ard.biesheuvel@linaro.org; Kinney,
> Michael D; Gao, Liming; wanghuiqiang@huawei.com;
> huangming23@huawei.com; zhangjinsong2@huawei.com;
> huangdaode@hisilicon.com; waip23@126.com; Wang, Jian J; Wu, Hao A; Ni,
> Ray
> Subject: Re: [MdeModulePkg/Library v1 1/1]
> MdeModulePkg/UefiBootManangerLib: Fix exception issue
> 
> +MdeModulePkg maintainers (you added MdePkg maintainers to cc)
> 
> This looks like an improvement to me.
> 
> Am I correct in guessing this behaviour refers to some specific corner
> case of a USB CDROM emulated from a BMC?
> 
> On Mon, Feb 25, 2019 at 05:10:52PM +0800, Ming Huang wrote:
> > The system environment: virtual-CDROM(USB interface) via BMC, insert a
> > iso file to CDROM, like ubuntu-18.04.1-server-arm64.iso, change CDROM
> > to first boot option.
> > With release version bios, disconnecting CDROM when boot to
> > "1 seconds left, Press Esc or F2 to enter Setup"
> > then system will get a exception.
> >
> > The root cause is the EFI_BLOCK_IO_PROTOCOL for UsbMass will be
> uninstalled
> > in this situation after print some transfer error. The status will be
> > invalid parameter. This line will get a exception for BlockIo not point

Do you mean 'EFI_INVALID_PARAMETER' is returned from:
  Status = gBS->HandleProtocol (Handle, &gEfiBlockIoProtocolGuid, (VOID **) &BlockIo);

If so, my guess is that 'Handle' is NULL at this point. An improvement can
be adding a previous check for 'Status' after the ASSERT at: 

  Status = gBS->LocateDevicePath (&gEfiBlockIoProtocolGuid, &TempDevicePath, &Handle);
  ASSERT_EFI_ERROR (Status);

And leave:

  Status = gBS->HandleProtocol (Handle, &gEfiBlockIoProtocolGuid, (VOID **) &BlockIo);
  ASSERT_EFI_ERROR (Status);

unchanged.

Best Regards,
Hao Wu

> > to right address:
> > AllocatePool (BlockIo->Media->BlockSize)
> > So, here need to judge the status not using ASSERT_EFI_ERROR.
> >
> > Contributed-under: TianoCore Contribution Agreement 1.1
> > Signed-off-by: Ming Huang <ming.huang@linaro.org>
> > ---
> >  MdeModulePkg/Library/UefiBootManagerLib/BmBoot.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/MdeModulePkg/Library/UefiBootManagerLib/BmBoot.c
> b/MdeModulePkg/Library/UefiBootManagerLib/BmBoot.c
> > index d5957db610d9..c2f1c651b02f 100644
> > --- a/MdeModulePkg/Library/UefiBootManagerLib/BmBoot.c
> > +++ b/MdeModulePkg/Library/UefiBootManagerLib/BmBoot.c
> > @@ -1068,7 +1068,9 @@ BmExpandMediaDevicePath (
> >    // Block IO read/write will success.
> >    //
> >    Status = gBS->HandleProtocol (Handle, &gEfiBlockIoProtocolGuid, (VOID
> **) &BlockIo);
> > -  ASSERT_EFI_ERROR (Status);
> > +  if (EFI_ERROR (Status)) {
> 
> It would still be worth including an ASSERT here, to let DEBUG builds
> report on point of failure rather than several steps up the chain.
> 
> /
>     Leif
> 
> > +    return NULL;
> > +  }
> >    Buffer = AllocatePool (BlockIo->Media->BlockSize);
> >    if (Buffer != NULL) {
> >      BlockIo->ReadBlocks (
> > --
> > 2.9.5
> >