Re: [PATCH 1/4] coresight: tmc-etr: Do not call smp_processor_id() from preemptible

[Suzuki K Poulose]

Hi Robin,

On 10/05/2019 11:38, Robin Murphy wrote:
> Hi Suzuki,
>
> On 10/05/2019 10:31, Suzuki K Poulose wrote:
> > Instead of using smp_processor_id() to figure out the node,
> > use the numa_node_id() for the current CPU node to avoid
> > splats like :


> > diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> > index 793639f..cae9d8a 100644
> > --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> > +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> > @@ -1323,13 +1323,11 @@ static struct etr_perf_buffer *
> >    tmc_etr_setup_perf_buf(struct tmc_drvdata *drvdata, struct perf_event *event,
> >    		       int nr_pages, void **pages, bool snapshot)
> >    {
> > -	int node, cpu = event->cpu;
> > +	int node;
> >    	struct etr_buf *etr_buf;
> >    	struct etr_perf_buffer *etr_perf;
> >    
> > -	if (cpu == -1)
> > -		cpu = smp_processor_id();
> > -	node = cpu_to_node(cpu);
> > +	node = (event->cpu == -1) ? numa_node_id() : cpu_to_node(event->cpu);
>
> If cpu == -1 represents a "don't care" scenario, it might be clearer to
> just use NUMA_NO_NODE instead, and let the allocator handle it.

Thanks for the suggestion, will use that instead

Cheers
Suzuki