coresight: etb10: Do not call smp_processor_id from preemptible

commit 730766b upstream.

During a perf session we try to allocate buffers on the "node" associated
with the CPU the event is bound to. If it is not bound to a CPU, we
use the current CPU node, using smp_processor_id(). However this is unsafe
in a pre-emptible context and could generate the splats as below :

 BUG: using smp_processor_id() in preemptible [00000000] code: perf/2544

Use NUMA_NO_NODE hint instead of using the current node for events
not bound to CPUs.

Fixes: 2997aa4 ("coresight: etb10: implementing AUX API")
Cc: Mathieu Poirier <[email protected]>
Signed-off-by: Suzuki K Poulose <[email protected]>
Cc: stable <[email protected]> # 4.6+
Signed-off-by: Mathieu Poirier <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Suzuki K Poulose

drivers/hwtracing/coresight/coresight-etb10.c

@@ -275,9 +275,7 @@ static void *etb_alloc_buffer(struct coresight_device *csdev, int cpu,
 	int node;
 	struct cs_buffers *buf;
 
-	if (cpu == -1)
-		cpu = smp_processor_id();
-	node = cpu_to_node(cpu);
+	node = (cpu == -1) ? NUMA_NO_NODE : cpu_to_node(cpu);
 
 	buf = kzalloc_node(sizeof(struct cs_buffers), GFP_KERNEL, node);
 	if (!buf)