[libvirt] RHBZ 1013045: Crash on xen domain startup

[Jim Fehlig]

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.

Regards,
Jim