[PATCH 4.14 38/46] coresight: etb10: Do not call smp_processor_id from preemptible

From: Greg Kroah-Hartman
Date: Tue Jan 28 2020 - 08:59:47 EST


From: Suzuki K Poulose <suzuki.poulose@xxxxxxx>

commit 730766bae3280a25d40ea76a53dc6342e84e6513 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: 2997aa4063d97fdb39 ("coresight: etb10: implementing AUX API")
Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx> # 4.6+
Signed-off-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20190620221237.3536-5-mathieu.poirier@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>


---
drivers/hwtracing/coresight/coresight-etb10.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

--- a/drivers/hwtracing/coresight/coresight-etb10.c
+++ b/drivers/hwtracing/coresight/coresight-etb10.c
@@ -287,9 +287,7 @@ static void *etb_alloc_buffer(struct cor
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)