Re: [PATCH 2/2] crypto: qat - Enforce valid numa configuration.

[Tadeusz Struk <tadeusz.struk@intel.com>]

On 10/10/2014 04:23 AM, Prarit Bhargava wrote:
>> Sure, but I still think that we are safe here.
>> > 
> No, you're not.  Dropping a single CPU changes num_online_cpus(), which results in
> 
> static uint8_t adf_get_dev_node_id(struct pci_dev *pdev)
> {
>         unsigned int bus_per_cpu = 0;
>         struct cpuinfo_x86 *c = &cpu_data(num_online_cpus() - 1);  <<< this
> being different.
> 
>         if (!c->phys_proc_id)
>                 return 0;
> 
>         bus_per_cpu = 256 / (c->phys_proc_id + 1);  <<< this being different
> 
>         if (bus_per_cpu != 0)
>                 return pdev->bus->number / bus_per_cpu; <<< and this being different
>         return 0;
> }

You forgot to explain how this is not safe.
T.