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