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Re: [PATCH 3/3] tools/libxl: Rework invariants in libxl__domain_get_device_model_uid()

  • To: Ian Jackson <iwj@xxxxxxxxxxxxxx>
  • From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
  • Date: Wed, 17 Feb 2021 18:13:01 +0000
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On 17/02/2021 17:50, Ian Jackson wrote:
> Andrew Cooper writes ("[PATCH 3/3] tools/libxl: Rework invariants in 
> libxl__domain_get_device_model_uid()"):
>> Various version of gcc, when compiling with -Og, complain:
>>   libxl_dm.c: In function 'libxl__domain_get_device_model_uid':
>>   libxl_dm.c:256:12: error: 'kill_by_uid' may be used uninitialized in this 
>> function [-Werror=maybe-uninitialized]
>>     256 |         if (kill_by_uid)
>>         |            ^
> Thanks for working on this.  I have reviewed your changes and I see
> where you are coming from.  The situation is not very nice, mostly
> because we don't have proper sum types in C.
> I'm sorry to say that with my release manager hat on I think it is too
> late for this kind of reorganisation for 4.15, especially just to work
> around an overzealous compiler warning.
> I think we can fix the compiler warning simply by setting the
> `kill_by_uid` variable on more of the exit paths.  This approach was
> already taken in this code for one of the paths.
> I would prefer that approach at this stage of the release.

Well - I have explained why I'm not happy with that approach, but you
are the maintainer and RM.

I will trade you a minimal patch for formal R-b's so the time invested
so far fixing this mess isn't wasted when 4.16 opens.




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