Hi Greg,
On 07/01/2020 20:55, Greg Kroah-Hartman wrote:
From: Suzuki K Poulose suzuki.poulose@arm.com
[ Upstream commit 024c1fd9dbcc1d8a847f1311f999d35783921b7f ]
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 caller is tmc_alloc_etf_buffer+0x5c/0x60
Fixes: 2e499bbc1a929ac ("coresight: tmc: implementing TMC-ETF AUX space API") Cc: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com Cc: stable stable@vger.kernel.org # 4.7+ Signed-off-by: Mathieu Poirier mathieu.poirier@linaro.org Link: https://lore.kernel.org/r/20190620221237.3536-4-mathieu.poirier@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org
drivers/hwtracing/coresight/coresight-tmc-etf.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c index e31061308e19..4644ac5582cf 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c @@ -304,9 +304,7 @@ static void *tmc_alloc_etf_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 = (event->cpu == -1) ? NUMA_NO_NODE : cpu_to_node(event->cpu);
This will break the build on v4.19 to v4.9 as event was not available to the routine. So please drop this one for now. I will post a backport separately.
Suzuki