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Re: [libvirt] [PATCH] virBitmapFree: Change the function to a macro



On Fri, Sep 06, 2013 at 10:30:56AM +0000, Liuji (Jeremy) wrote:
> The parameter of virBitmapFree function is just a pointer, not a pointer of pointer. 
> The second VIR_FREE on virBitmapFree only assign NULL to the formal parameter.
> After calling the virBitmapFree function, the actual parameter are still not NULL.
> There are many code segment don't assign NULL to the formal parameter after calling 
> the virBitmapFree function. This will bring potential risks.
> 
> A problem scenario:
> 1) The XML of VM contain the below segment:
>     <numatune>
>         <memory mode='preferred' placement='auto' nodeset='0'/>
>     </numatune>
> 2)virsh create the VM
> 3)In the virDomainDefParseXML funtion:
>                     /* Ignore 'nodeset' if 'placement' is 'auto' finally */
>                     if (placement_mode == VIR_NUMA_TUNE_MEM_PLACEMENT_MODE_AUTO) {
>                         virBitmapFree(def->numatune.memory.nodemask);
>                         def->numatune.memory.nodemask = NULL;
>                     }
> 4)Then, virsh destroy the VM. In the virDomainDefFree funtion, it also call the 
> virBitmapFree function to free the nodemask:
>     virBitmapFree(def->numatune.memory.nodemask);
> But after this call, the value of def->numatune.memory.nodemask is still not NULL.
> This will generate an exception.

Have you got an actual crash happening today, or is this just a theoretical
problem you're trying to address ?

Daniel
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