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From: Mathieu Poirier <mathieu.poirier@linaro.org>
To: gregkh@linuxfoundation.org
Cc: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 4/5] coresight: etb10: Do not call smp_processor_id from preemptible
Date: Thu, 20 Jun 2019 16:12:36 -0600
Message-ID: <20190620221237.3536-5-mathieu.poirier@linaro.org> (raw)
In-Reply-To: <20190620221237.3536-1-mathieu.poirier@linaro.org>

From: Suzuki K Poulose <suzuki.poulose@arm.com>

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@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: stable <stable@vger.kernel.org> # 4.6+
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
 drivers/hwtracing/coresight/coresight-etb10.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c
index 4ee4c80a4354..543cc3d36e1d 100644
--- a/drivers/hwtracing/coresight/coresight-etb10.c
+++ b/drivers/hwtracing/coresight/coresight-etb10.c
@@ -373,12 +373,10 @@ static void *etb_alloc_buffer(struct coresight_device *csdev,
 			      struct perf_event *event, void **pages,
 			      int nr_pages, bool overwrite)
 {
-	int node, cpu = event->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);
 
 	buf = kzalloc_node(sizeof(struct cs_buffers), GFP_KERNEL, node);
 	if (!buf)
-- 
2.17.1


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  parent reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-20 22:12 [PATCH 0/5] coresight: Fixes for v5.2-rc5 Mathieu Poirier
2019-06-20 22:12 ` [PATCH 1/5] coresight: tmc-etr: Do not call smp_processor_id() from preemptible Mathieu Poirier
2019-07-03 19:14   ` Greg KH
2019-06-20 22:12 ` [PATCH 2/5] coresight: tmc-etr: alloc_perf_buf: Do not call smp_processor_id " Mathieu Poirier
2019-06-20 22:12 ` [PATCH 3/5] coresight: tmc-etf: " Mathieu Poirier
2019-06-20 22:12 ` Mathieu Poirier [this message]
2019-06-20 22:12 ` [PATCH 5/5] coresight: Potential uninitialized variable in probe() Mathieu Poirier
2019-07-02 16:18 ` [PATCH 0/5] coresight: Fixes for v5.2-rc5 Mathieu Poirier
2019-07-03 19:13   ` Greg KH

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