[libvirt] RHBZ 1013045: Crash on xen domain startup

[Jim Fehlig]

On 11/01/2013 03:55 AM, Daniel P. Berrange wrote:
> On Thu, Oct 31, 2013 at 06:50:57PM -0600, Jim Fehlig wrote:
>> Jeremy Fitzhardinge wrote:
>>> On 10/30/2013 12:04 PM, Eric Blake wrote:
>>>    
>>>> On 10/30/2013 01:00 PM, Jeremy Fitzhardinge wrote:
>>>>      
>>>>> On 10/30/2013 11:37 AM, Eric Blake wrote:
>>>>>        
>>>>>> On 10/30/2013 11:38 AM, Jeremy Fitzhardinge wrote:
>>>>>>          
>>>>>>>      libxl: fix dubious cpumask handling in libxlDomainSetVcpuAffinities
>>>>>>>
>>>>>>>      Rather than casting the virBitmap pointer to uint8_t* and then
>>>>>>>            
>>> using
>>>    
>>>>>>>      the structure contents as a byte array, use the virBitmap API to
>>>>>>> determine
>>>>>>>      the bitmap size and test each bit.
>>>>>>>            
>>>>>> Hmm, we already have virBitmapToData for converting from a virBitmap to
>>>>>> a uint8_t; using that would be much faster for populating cpumap than
>>>>>> doing a per-bit iteration over cpumask.
>>>>>>          
>>>>> I looked at that, but I couldn't see it being any more efficient given
>>>>> that we're typically talking about a small number of (v)CPUs.
>>>>>        
>>>> Efficiency isn't my concern.  Maintainability is.  It's better to reuse
>>>> existing functions instead of risking open-coding it wrong.  We have a
>>>> testsuite over our existing functions, but not over your open-coding.
>>>>      
>>> Well, that was also a consideration, but using virBitmapToData would be
>>> more complex. The same loop would exist, but I'd also have to manage
>>> freeing the array.  So this seems like the better of the two approaches.
>>>    
>> What is the consensus here? It would be nice to get this pushed for
>> 1.1.4 since it fixes a libvirtd segfault. I prefer Jeremy's approach of
>> less memory management.
>>
> Absolutely want this in 1.1.4. Personally I think Jeremy's patch
> is fine.

Thanks.  I've pushed the revert of 394d6e0a, and Jeremy's patch after removing 
the unreachable error as noted by Eric

https://www.redhat.com/archives/libvir-list/2013-November/msg00006.html

Regards,
Jim