Re: [PATCH 1 of 6] x86, UV: smp_processor_id in a preemptable region

["H. Peter Anvin" <hpa@zytor.com>]

On 06/15/2011 09:40 AM, Cliff Wickman wrote:
> 
> So would you say I should really widen the scope of the non-preemptible
> region to include everything done with the results of that call to
> smp_processor_id()?  
> Which in this case is the call to parse_tunables_write().
> Like this:
> 
>         preempt_disable();
>         bcp = &per_cpu(bau_control, smp_processor_id());
> 
>         ret = parse_tunables_write(bcp, instr, count);
>         preempt_enable_no_resched();
> 

Funny enough, this is such a common pattern that we have helpers for it.
We call this get_cpu() ... put_cpu().

	-hpa